Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux...
[pandora-kernel.git] / fs / ext4 / inode.c
1 /*
2  *  linux/fs/ext4/inode.c
3  *
4  * Copyright (C) 1992, 1993, 1994, 1995
5  * Remy Card (card@masi.ibp.fr)
6  * Laboratoire MASI - Institut Blaise Pascal
7  * Universite Pierre et Marie Curie (Paris VI)
8  *
9  *  from
10  *
11  *  linux/fs/minix/inode.c
12  *
13  *  Copyright (C) 1991, 1992  Linus Torvalds
14  *
15  *  Goal-directed block allocation by Stephen Tweedie
16  *      (sct@redhat.com), 1993, 1998
17  *  Big-endian to little-endian byte-swapping/bitmaps by
18  *        David S. Miller (davem@caip.rutgers.edu), 1995
19  *  64-bit file support on 64-bit platforms by Jakub Jelinek
20  *      (jj@sunsite.ms.mff.cuni.cz)
21  *
22  *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
23  */
24
25 #include <linux/module.h>
26 #include <linux/fs.h>
27 #include <linux/time.h>
28 #include <linux/jbd2.h>
29 #include <linux/highuid.h>
30 #include <linux/pagemap.h>
31 #include <linux/quotaops.h>
32 #include <linux/string.h>
33 #include <linux/buffer_head.h>
34 #include <linux/writeback.h>
35 #include <linux/pagevec.h>
36 #include <linux/mpage.h>
37 #include <linux/namei.h>
38 #include <linux/uio.h>
39 #include <linux/bio.h>
40 #include <linux/workqueue.h>
41 #include <linux/kernel.h>
42 #include <linux/slab.h>
43
44 #include "ext4_jbd2.h"
45 #include "xattr.h"
46 #include "acl.h"
47 #include "ext4_extents.h"
48
49 #include <trace/events/ext4.h>
50
51 #define MPAGE_DA_EXTENT_TAIL 0x01
52
53 static inline int ext4_begin_ordered_truncate(struct inode *inode,
54                                               loff_t new_size)
55 {
56         trace_ext4_begin_ordered_truncate(inode, new_size);
57         return jbd2_journal_begin_ordered_truncate(
58                                         EXT4_SB(inode->i_sb)->s_journal,
59                                         &EXT4_I(inode)->jinode,
60                                         new_size);
61 }
62
63 static void ext4_invalidatepage(struct page *page, unsigned long offset);
64 static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
65                                    struct buffer_head *bh_result, int create);
66 static int ext4_set_bh_endio(struct buffer_head *bh, struct inode *inode);
67 static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate);
68 static int __ext4_journalled_writepage(struct page *page, unsigned int len);
69 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
70
71 /*
72  * Test whether an inode is a fast symlink.
73  */
74 static int ext4_inode_is_fast_symlink(struct inode *inode)
75 {
76         int ea_blocks = EXT4_I(inode)->i_file_acl ?
77                 (inode->i_sb->s_blocksize >> 9) : 0;
78
79         return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
80 }
81
82 /*
83  * Work out how many blocks we need to proceed with the next chunk of a
84  * truncate transaction.
85  */
86 static unsigned long blocks_for_truncate(struct inode *inode)
87 {
88         ext4_lblk_t needed;
89
90         needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
91
92         /* Give ourselves just enough room to cope with inodes in which
93          * i_blocks is corrupt: we've seen disk corruptions in the past
94          * which resulted in random data in an inode which looked enough
95          * like a regular file for ext4 to try to delete it.  Things
96          * will go a bit crazy if that happens, but at least we should
97          * try not to panic the whole kernel. */
98         if (needed < 2)
99                 needed = 2;
100
101         /* But we need to bound the transaction so we don't overflow the
102          * journal. */
103         if (needed > EXT4_MAX_TRANS_DATA)
104                 needed = EXT4_MAX_TRANS_DATA;
105
106         return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
107 }
108
109 /*
110  * Truncate transactions can be complex and absolutely huge.  So we need to
111  * be able to restart the transaction at a conventient checkpoint to make
112  * sure we don't overflow the journal.
113  *
114  * start_transaction gets us a new handle for a truncate transaction,
115  * and extend_transaction tries to extend the existing one a bit.  If
116  * extend fails, we need to propagate the failure up and restart the
117  * transaction in the top-level truncate loop. --sct
118  */
119 static handle_t *start_transaction(struct inode *inode)
120 {
121         handle_t *result;
122
123         result = ext4_journal_start(inode, blocks_for_truncate(inode));
124         if (!IS_ERR(result))
125                 return result;
126
127         ext4_std_error(inode->i_sb, PTR_ERR(result));
128         return result;
129 }
130
131 /*
132  * Try to extend this transaction for the purposes of truncation.
133  *
134  * Returns 0 if we managed to create more room.  If we can't create more
135  * room, and the transaction must be restarted we return 1.
136  */
137 static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
138 {
139         if (!ext4_handle_valid(handle))
140                 return 0;
141         if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
142                 return 0;
143         if (!ext4_journal_extend(handle, blocks_for_truncate(inode)))
144                 return 0;
145         return 1;
146 }
147
148 /*
149  * Restart the transaction associated with *handle.  This does a commit,
150  * so before we call here everything must be consistently dirtied against
151  * this transaction.
152  */
153 int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode,
154                                  int nblocks)
155 {
156         int ret;
157
158         /*
159          * Drop i_data_sem to avoid deadlock with ext4_map_blocks.  At this
160          * moment, get_block can be called only for blocks inside i_size since
161          * page cache has been already dropped and writes are blocked by
162          * i_mutex. So we can safely drop the i_data_sem here.
163          */
164         BUG_ON(EXT4_JOURNAL(inode) == NULL);
165         jbd_debug(2, "restarting handle %p\n", handle);
166         up_write(&EXT4_I(inode)->i_data_sem);
167         ret = ext4_journal_restart(handle, blocks_for_truncate(inode));
168         down_write(&EXT4_I(inode)->i_data_sem);
169         ext4_discard_preallocations(inode);
170
171         return ret;
172 }
173
174 /*
175  * Called at the last iput() if i_nlink is zero.
176  */
177 void ext4_evict_inode(struct inode *inode)
178 {
179         handle_t *handle;
180         int err;
181
182         trace_ext4_evict_inode(inode);
183         if (inode->i_nlink) {
184                 truncate_inode_pages(&inode->i_data, 0);
185                 goto no_delete;
186         }
187
188         if (!is_bad_inode(inode))
189                 dquot_initialize(inode);
190
191         if (ext4_should_order_data(inode))
192                 ext4_begin_ordered_truncate(inode, 0);
193         truncate_inode_pages(&inode->i_data, 0);
194
195         if (is_bad_inode(inode))
196                 goto no_delete;
197
198         handle = ext4_journal_start(inode, blocks_for_truncate(inode)+3);
199         if (IS_ERR(handle)) {
200                 ext4_std_error(inode->i_sb, PTR_ERR(handle));
201                 /*
202                  * If we're going to skip the normal cleanup, we still need to
203                  * make sure that the in-core orphan linked list is properly
204                  * cleaned up.
205                  */
206                 ext4_orphan_del(NULL, inode);
207                 goto no_delete;
208         }
209
210         if (IS_SYNC(inode))
211                 ext4_handle_sync(handle);
212         inode->i_size = 0;
213         err = ext4_mark_inode_dirty(handle, inode);
214         if (err) {
215                 ext4_warning(inode->i_sb,
216                              "couldn't mark inode dirty (err %d)", err);
217                 goto stop_handle;
218         }
219         if (inode->i_blocks)
220                 ext4_truncate(inode);
221
222         /*
223          * ext4_ext_truncate() doesn't reserve any slop when it
224          * restarts journal transactions; therefore there may not be
225          * enough credits left in the handle to remove the inode from
226          * the orphan list and set the dtime field.
227          */
228         if (!ext4_handle_has_enough_credits(handle, 3)) {
229                 err = ext4_journal_extend(handle, 3);
230                 if (err > 0)
231                         err = ext4_journal_restart(handle, 3);
232                 if (err != 0) {
233                         ext4_warning(inode->i_sb,
234                                      "couldn't extend journal (err %d)", err);
235                 stop_handle:
236                         ext4_journal_stop(handle);
237                         ext4_orphan_del(NULL, inode);
238                         goto no_delete;
239                 }
240         }
241
242         /*
243          * Kill off the orphan record which ext4_truncate created.
244          * AKPM: I think this can be inside the above `if'.
245          * Note that ext4_orphan_del() has to be able to cope with the
246          * deletion of a non-existent orphan - this is because we don't
247          * know if ext4_truncate() actually created an orphan record.
248          * (Well, we could do this if we need to, but heck - it works)
249          */
250         ext4_orphan_del(handle, inode);
251         EXT4_I(inode)->i_dtime  = get_seconds();
252
253         /*
254          * One subtle ordering requirement: if anything has gone wrong
255          * (transaction abort, IO errors, whatever), then we can still
256          * do these next steps (the fs will already have been marked as
257          * having errors), but we can't free the inode if the mark_dirty
258          * fails.
259          */
260         if (ext4_mark_inode_dirty(handle, inode))
261                 /* If that failed, just do the required in-core inode clear. */
262                 ext4_clear_inode(inode);
263         else
264                 ext4_free_inode(handle, inode);
265         ext4_journal_stop(handle);
266         return;
267 no_delete:
268         ext4_clear_inode(inode);        /* We must guarantee clearing of inode... */
269 }
270
271 typedef struct {
272         __le32  *p;
273         __le32  key;
274         struct buffer_head *bh;
275 } Indirect;
276
277 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
278 {
279         p->key = *(p->p = v);
280         p->bh = bh;
281 }
282
283 /**
284  *      ext4_block_to_path - parse the block number into array of offsets
285  *      @inode: inode in question (we are only interested in its superblock)
286  *      @i_block: block number to be parsed
287  *      @offsets: array to store the offsets in
288  *      @boundary: set this non-zero if the referred-to block is likely to be
289  *             followed (on disk) by an indirect block.
290  *
291  *      To store the locations of file's data ext4 uses a data structure common
292  *      for UNIX filesystems - tree of pointers anchored in the inode, with
293  *      data blocks at leaves and indirect blocks in intermediate nodes.
294  *      This function translates the block number into path in that tree -
295  *      return value is the path length and @offsets[n] is the offset of
296  *      pointer to (n+1)th node in the nth one. If @block is out of range
297  *      (negative or too large) warning is printed and zero returned.
298  *
299  *      Note: function doesn't find node addresses, so no IO is needed. All
300  *      we need to know is the capacity of indirect blocks (taken from the
301  *      inode->i_sb).
302  */
303
304 /*
305  * Portability note: the last comparison (check that we fit into triple
306  * indirect block) is spelled differently, because otherwise on an
307  * architecture with 32-bit longs and 8Kb pages we might get into trouble
308  * if our filesystem had 8Kb blocks. We might use long long, but that would
309  * kill us on x86. Oh, well, at least the sign propagation does not matter -
310  * i_block would have to be negative in the very beginning, so we would not
311  * get there at all.
312  */
313
314 static int ext4_block_to_path(struct inode *inode,
315                               ext4_lblk_t i_block,
316                               ext4_lblk_t offsets[4], int *boundary)
317 {
318         int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb);
319         int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb);
320         const long direct_blocks = EXT4_NDIR_BLOCKS,
321                 indirect_blocks = ptrs,
322                 double_blocks = (1 << (ptrs_bits * 2));
323         int n = 0;
324         int final = 0;
325
326         if (i_block < direct_blocks) {
327                 offsets[n++] = i_block;
328                 final = direct_blocks;
329         } else if ((i_block -= direct_blocks) < indirect_blocks) {
330                 offsets[n++] = EXT4_IND_BLOCK;
331                 offsets[n++] = i_block;
332                 final = ptrs;
333         } else if ((i_block -= indirect_blocks) < double_blocks) {
334                 offsets[n++] = EXT4_DIND_BLOCK;
335                 offsets[n++] = i_block >> ptrs_bits;
336                 offsets[n++] = i_block & (ptrs - 1);
337                 final = ptrs;
338         } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
339                 offsets[n++] = EXT4_TIND_BLOCK;
340                 offsets[n++] = i_block >> (ptrs_bits * 2);
341                 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
342                 offsets[n++] = i_block & (ptrs - 1);
343                 final = ptrs;
344         } else {
345                 ext4_warning(inode->i_sb, "block %lu > max in inode %lu",
346                              i_block + direct_blocks +
347                              indirect_blocks + double_blocks, inode->i_ino);
348         }
349         if (boundary)
350                 *boundary = final - 1 - (i_block & (ptrs - 1));
351         return n;
352 }
353
354 static int __ext4_check_blockref(const char *function, unsigned int line,
355                                  struct inode *inode,
356                                  __le32 *p, unsigned int max)
357 {
358         struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es;
359         __le32 *bref = p;
360         unsigned int blk;
361
362         while (bref < p+max) {
363                 blk = le32_to_cpu(*bref++);
364                 if (blk &&
365                     unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb),
366                                                     blk, 1))) {
367                         es->s_last_error_block = cpu_to_le64(blk);
368                         ext4_error_inode(inode, function, line, blk,
369                                          "invalid block");
370                         return -EIO;
371                 }
372         }
373         return 0;
374 }
375
376
377 #define ext4_check_indirect_blockref(inode, bh)                         \
378         __ext4_check_blockref(__func__, __LINE__, inode,                \
379                               (__le32 *)(bh)->b_data,                   \
380                               EXT4_ADDR_PER_BLOCK((inode)->i_sb))
381
382 #define ext4_check_inode_blockref(inode)                                \
383         __ext4_check_blockref(__func__, __LINE__, inode,                \
384                               EXT4_I(inode)->i_data,                    \
385                               EXT4_NDIR_BLOCKS)
386
387 /**
388  *      ext4_get_branch - read the chain of indirect blocks leading to data
389  *      @inode: inode in question
390  *      @depth: depth of the chain (1 - direct pointer, etc.)
391  *      @offsets: offsets of pointers in inode/indirect blocks
392  *      @chain: place to store the result
393  *      @err: here we store the error value
394  *
395  *      Function fills the array of triples <key, p, bh> and returns %NULL
396  *      if everything went OK or the pointer to the last filled triple
397  *      (incomplete one) otherwise. Upon the return chain[i].key contains
398  *      the number of (i+1)-th block in the chain (as it is stored in memory,
399  *      i.e. little-endian 32-bit), chain[i].p contains the address of that
400  *      number (it points into struct inode for i==0 and into the bh->b_data
401  *      for i>0) and chain[i].bh points to the buffer_head of i-th indirect
402  *      block for i>0 and NULL for i==0. In other words, it holds the block
403  *      numbers of the chain, addresses they were taken from (and where we can
404  *      verify that chain did not change) and buffer_heads hosting these
405  *      numbers.
406  *
407  *      Function stops when it stumbles upon zero pointer (absent block)
408  *              (pointer to last triple returned, *@err == 0)
409  *      or when it gets an IO error reading an indirect block
410  *              (ditto, *@err == -EIO)
411  *      or when it reads all @depth-1 indirect blocks successfully and finds
412  *      the whole chain, all way to the data (returns %NULL, *err == 0).
413  *
414  *      Need to be called with
415  *      down_read(&EXT4_I(inode)->i_data_sem)
416  */
417 static Indirect *ext4_get_branch(struct inode *inode, int depth,
418                                  ext4_lblk_t  *offsets,
419                                  Indirect chain[4], int *err)
420 {
421         struct super_block *sb = inode->i_sb;
422         Indirect *p = chain;
423         struct buffer_head *bh;
424
425         *err = 0;
426         /* i_data is not going away, no lock needed */
427         add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets);
428         if (!p->key)
429                 goto no_block;
430         while (--depth) {
431                 bh = sb_getblk(sb, le32_to_cpu(p->key));
432                 if (unlikely(!bh))
433                         goto failure;
434
435                 if (!bh_uptodate_or_lock(bh)) {
436                         if (bh_submit_read(bh) < 0) {
437                                 put_bh(bh);
438                                 goto failure;
439                         }
440                         /* validate block references */
441                         if (ext4_check_indirect_blockref(inode, bh)) {
442                                 put_bh(bh);
443                                 goto failure;
444                         }
445                 }
446
447                 add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets);
448                 /* Reader: end */
449                 if (!p->key)
450                         goto no_block;
451         }
452         return NULL;
453
454 failure:
455         *err = -EIO;
456 no_block:
457         return p;
458 }
459
460 /**
461  *      ext4_find_near - find a place for allocation with sufficient locality
462  *      @inode: owner
463  *      @ind: descriptor of indirect block.
464  *
465  *      This function returns the preferred place for block allocation.
466  *      It is used when heuristic for sequential allocation fails.
467  *      Rules are:
468  *        + if there is a block to the left of our position - allocate near it.
469  *        + if pointer will live in indirect block - allocate near that block.
470  *        + if pointer will live in inode - allocate in the same
471  *          cylinder group.
472  *
473  * In the latter case we colour the starting block by the callers PID to
474  * prevent it from clashing with concurrent allocations for a different inode
475  * in the same block group.   The PID is used here so that functionally related
476  * files will be close-by on-disk.
477  *
478  *      Caller must make sure that @ind is valid and will stay that way.
479  */
480 static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
481 {
482         struct ext4_inode_info *ei = EXT4_I(inode);
483         __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
484         __le32 *p;
485         ext4_fsblk_t bg_start;
486         ext4_fsblk_t last_block;
487         ext4_grpblk_t colour;
488         ext4_group_t block_group;
489         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
490
491         /* Try to find previous block */
492         for (p = ind->p - 1; p >= start; p--) {
493                 if (*p)
494                         return le32_to_cpu(*p);
495         }
496
497         /* No such thing, so let's try location of indirect block */
498         if (ind->bh)
499                 return ind->bh->b_blocknr;
500
501         /*
502          * It is going to be referred to from the inode itself? OK, just put it
503          * into the same cylinder group then.
504          */
505         block_group = ei->i_block_group;
506         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
507                 block_group &= ~(flex_size-1);
508                 if (S_ISREG(inode->i_mode))
509                         block_group++;
510         }
511         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
512         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
513
514         /*
515          * If we are doing delayed allocation, we don't need take
516          * colour into account.
517          */
518         if (test_opt(inode->i_sb, DELALLOC))
519                 return bg_start;
520
521         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
522                 colour = (current->pid % 16) *
523                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
524         else
525                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
526         return bg_start + colour;
527 }
528
529 /**
530  *      ext4_find_goal - find a preferred place for allocation.
531  *      @inode: owner
532  *      @block:  block we want
533  *      @partial: pointer to the last triple within a chain
534  *
535  *      Normally this function find the preferred place for block allocation,
536  *      returns it.
537  *      Because this is only used for non-extent files, we limit the block nr
538  *      to 32 bits.
539  */
540 static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
541                                    Indirect *partial)
542 {
543         ext4_fsblk_t goal;
544
545         /*
546          * XXX need to get goal block from mballoc's data structures
547          */
548
549         goal = ext4_find_near(inode, partial);
550         goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;
551         return goal;
552 }
553
554 /**
555  *      ext4_blks_to_allocate: Look up the block map and count the number
556  *      of direct blocks need to be allocated for the given branch.
557  *
558  *      @branch: chain of indirect blocks
559  *      @k: number of blocks need for indirect blocks
560  *      @blks: number of data blocks to be mapped.
561  *      @blocks_to_boundary:  the offset in the indirect block
562  *
563  *      return the total number of blocks to be allocate, including the
564  *      direct and indirect blocks.
565  */
566 static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks,
567                                  int blocks_to_boundary)
568 {
569         unsigned int count = 0;
570
571         /*
572          * Simple case, [t,d]Indirect block(s) has not allocated yet
573          * then it's clear blocks on that path have not allocated
574          */
575         if (k > 0) {
576                 /* right now we don't handle cross boundary allocation */
577                 if (blks < blocks_to_boundary + 1)
578                         count += blks;
579                 else
580                         count += blocks_to_boundary + 1;
581                 return count;
582         }
583
584         count++;
585         while (count < blks && count <= blocks_to_boundary &&
586                 le32_to_cpu(*(branch[0].p + count)) == 0) {
587                 count++;
588         }
589         return count;
590 }
591
592 /**
593  *      ext4_alloc_blocks: multiple allocate blocks needed for a branch
594  *      @indirect_blks: the number of blocks need to allocate for indirect
595  *                      blocks
596  *
597  *      @new_blocks: on return it will store the new block numbers for
598  *      the indirect blocks(if needed) and the first direct block,
599  *      @blks:  on return it will store the total number of allocated
600  *              direct blocks
601  */
602 static int ext4_alloc_blocks(handle_t *handle, struct inode *inode,
603                              ext4_lblk_t iblock, ext4_fsblk_t goal,
604                              int indirect_blks, int blks,
605                              ext4_fsblk_t new_blocks[4], int *err)
606 {
607         struct ext4_allocation_request ar;
608         int target, i;
609         unsigned long count = 0, blk_allocated = 0;
610         int index = 0;
611         ext4_fsblk_t current_block = 0;
612         int ret = 0;
613
614         /*
615          * Here we try to allocate the requested multiple blocks at once,
616          * on a best-effort basis.
617          * To build a branch, we should allocate blocks for
618          * the indirect blocks(if not allocated yet), and at least
619          * the first direct block of this branch.  That's the
620          * minimum number of blocks need to allocate(required)
621          */
622         /* first we try to allocate the indirect blocks */
623         target = indirect_blks;
624         while (target > 0) {
625                 count = target;
626                 /* allocating blocks for indirect blocks and direct blocks */
627                 current_block = ext4_new_meta_blocks(handle, inode,
628                                                         goal, &count, err);
629                 if (*err)
630                         goto failed_out;
631
632                 if (unlikely(current_block + count > EXT4_MAX_BLOCK_FILE_PHYS)) {
633                         EXT4_ERROR_INODE(inode,
634                                          "current_block %llu + count %lu > %d!",
635                                          current_block, count,
636                                          EXT4_MAX_BLOCK_FILE_PHYS);
637                         *err = -EIO;
638                         goto failed_out;
639                 }
640
641                 target -= count;
642                 /* allocate blocks for indirect blocks */
643                 while (index < indirect_blks && count) {
644                         new_blocks[index++] = current_block++;
645                         count--;
646                 }
647                 if (count > 0) {
648                         /*
649                          * save the new block number
650                          * for the first direct block
651                          */
652                         new_blocks[index] = current_block;
653                         printk(KERN_INFO "%s returned more blocks than "
654                                                 "requested\n", __func__);
655                         WARN_ON(1);
656                         break;
657                 }
658         }
659
660         target = blks - count ;
661         blk_allocated = count;
662         if (!target)
663                 goto allocated;
664         /* Now allocate data blocks */
665         memset(&ar, 0, sizeof(ar));
666         ar.inode = inode;
667         ar.goal = goal;
668         ar.len = target;
669         ar.logical = iblock;
670         if (S_ISREG(inode->i_mode))
671                 /* enable in-core preallocation only for regular files */
672                 ar.flags = EXT4_MB_HINT_DATA;
673
674         current_block = ext4_mb_new_blocks(handle, &ar, err);
675         if (unlikely(current_block + ar.len > EXT4_MAX_BLOCK_FILE_PHYS)) {
676                 EXT4_ERROR_INODE(inode,
677                                  "current_block %llu + ar.len %d > %d!",
678                                  current_block, ar.len,
679                                  EXT4_MAX_BLOCK_FILE_PHYS);
680                 *err = -EIO;
681                 goto failed_out;
682         }
683
684         if (*err && (target == blks)) {
685                 /*
686                  * if the allocation failed and we didn't allocate
687                  * any blocks before
688                  */
689                 goto failed_out;
690         }
691         if (!*err) {
692                 if (target == blks) {
693                         /*
694                          * save the new block number
695                          * for the first direct block
696                          */
697                         new_blocks[index] = current_block;
698                 }
699                 blk_allocated += ar.len;
700         }
701 allocated:
702         /* total number of blocks allocated for direct blocks */
703         ret = blk_allocated;
704         *err = 0;
705         return ret;
706 failed_out:
707         for (i = 0; i < index; i++)
708                 ext4_free_blocks(handle, inode, 0, new_blocks[i], 1, 0);
709         return ret;
710 }
711
712 /**
713  *      ext4_alloc_branch - allocate and set up a chain of blocks.
714  *      @inode: owner
715  *      @indirect_blks: number of allocated indirect blocks
716  *      @blks: number of allocated direct blocks
717  *      @offsets: offsets (in the blocks) to store the pointers to next.
718  *      @branch: place to store the chain in.
719  *
720  *      This function allocates blocks, zeroes out all but the last one,
721  *      links them into chain and (if we are synchronous) writes them to disk.
722  *      In other words, it prepares a branch that can be spliced onto the
723  *      inode. It stores the information about that chain in the branch[], in
724  *      the same format as ext4_get_branch() would do. We are calling it after
725  *      we had read the existing part of chain and partial points to the last
726  *      triple of that (one with zero ->key). Upon the exit we have the same
727  *      picture as after the successful ext4_get_block(), except that in one
728  *      place chain is disconnected - *branch->p is still zero (we did not
729  *      set the last link), but branch->key contains the number that should
730  *      be placed into *branch->p to fill that gap.
731  *
732  *      If allocation fails we free all blocks we've allocated (and forget
733  *      their buffer_heads) and return the error value the from failed
734  *      ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
735  *      as described above and return 0.
736  */
737 static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
738                              ext4_lblk_t iblock, int indirect_blks,
739                              int *blks, ext4_fsblk_t goal,
740                              ext4_lblk_t *offsets, Indirect *branch)
741 {
742         int blocksize = inode->i_sb->s_blocksize;
743         int i, n = 0;
744         int err = 0;
745         struct buffer_head *bh;
746         int num;
747         ext4_fsblk_t new_blocks[4];
748         ext4_fsblk_t current_block;
749
750         num = ext4_alloc_blocks(handle, inode, iblock, goal, indirect_blks,
751                                 *blks, new_blocks, &err);
752         if (err)
753                 return err;
754
755         branch[0].key = cpu_to_le32(new_blocks[0]);
756         /*
757          * metadata blocks and data blocks are allocated.
758          */
759         for (n = 1; n <= indirect_blks;  n++) {
760                 /*
761                  * Get buffer_head for parent block, zero it out
762                  * and set the pointer to new one, then send
763                  * parent to disk.
764                  */
765                 bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
766                 if (unlikely(!bh)) {
767                         err = -EIO;
768                         goto failed;
769                 }
770
771                 branch[n].bh = bh;
772                 lock_buffer(bh);
773                 BUFFER_TRACE(bh, "call get_create_access");
774                 err = ext4_journal_get_create_access(handle, bh);
775                 if (err) {
776                         /* Don't brelse(bh) here; it's done in
777                          * ext4_journal_forget() below */
778                         unlock_buffer(bh);
779                         goto failed;
780                 }
781
782                 memset(bh->b_data, 0, blocksize);
783                 branch[n].p = (__le32 *) bh->b_data + offsets[n];
784                 branch[n].key = cpu_to_le32(new_blocks[n]);
785                 *branch[n].p = branch[n].key;
786                 if (n == indirect_blks) {
787                         current_block = new_blocks[n];
788                         /*
789                          * End of chain, update the last new metablock of
790                          * the chain to point to the new allocated
791                          * data blocks numbers
792                          */
793                         for (i = 1; i < num; i++)
794                                 *(branch[n].p + i) = cpu_to_le32(++current_block);
795                 }
796                 BUFFER_TRACE(bh, "marking uptodate");
797                 set_buffer_uptodate(bh);
798                 unlock_buffer(bh);
799
800                 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
801                 err = ext4_handle_dirty_metadata(handle, inode, bh);
802                 if (err)
803                         goto failed;
804         }
805         *blks = num;
806         return err;
807 failed:
808         /* Allocation failed, free what we already allocated */
809         ext4_free_blocks(handle, inode, 0, new_blocks[0], 1, 0);
810         for (i = 1; i <= n ; i++) {
811                 /*
812                  * branch[i].bh is newly allocated, so there is no
813                  * need to revoke the block, which is why we don't
814                  * need to set EXT4_FREE_BLOCKS_METADATA.
815                  */
816                 ext4_free_blocks(handle, inode, 0, new_blocks[i], 1,
817                                  EXT4_FREE_BLOCKS_FORGET);
818         }
819         for (i = n+1; i < indirect_blks; i++)
820                 ext4_free_blocks(handle, inode, 0, new_blocks[i], 1, 0);
821
822         ext4_free_blocks(handle, inode, 0, new_blocks[i], num, 0);
823
824         return err;
825 }
826
827 /**
828  * ext4_splice_branch - splice the allocated branch onto inode.
829  * @inode: owner
830  * @block: (logical) number of block we are adding
831  * @chain: chain of indirect blocks (with a missing link - see
832  *      ext4_alloc_branch)
833  * @where: location of missing link
834  * @num:   number of indirect blocks we are adding
835  * @blks:  number of direct blocks we are adding
836  *
837  * This function fills the missing link and does all housekeeping needed in
838  * inode (->i_blocks, etc.). In case of success we end up with the full
839  * chain to new block and return 0.
840  */
841 static int ext4_splice_branch(handle_t *handle, struct inode *inode,
842                               ext4_lblk_t block, Indirect *where, int num,
843                               int blks)
844 {
845         int i;
846         int err = 0;
847         ext4_fsblk_t current_block;
848
849         /*
850          * If we're splicing into a [td]indirect block (as opposed to the
851          * inode) then we need to get write access to the [td]indirect block
852          * before the splice.
853          */
854         if (where->bh) {
855                 BUFFER_TRACE(where->bh, "get_write_access");
856                 err = ext4_journal_get_write_access(handle, where->bh);
857                 if (err)
858                         goto err_out;
859         }
860         /* That's it */
861
862         *where->p = where->key;
863
864         /*
865          * Update the host buffer_head or inode to point to more just allocated
866          * direct blocks blocks
867          */
868         if (num == 0 && blks > 1) {
869                 current_block = le32_to_cpu(where->key) + 1;
870                 for (i = 1; i < blks; i++)
871                         *(where->p + i) = cpu_to_le32(current_block++);
872         }
873
874         /* We are done with atomic stuff, now do the rest of housekeeping */
875         /* had we spliced it onto indirect block? */
876         if (where->bh) {
877                 /*
878                  * If we spliced it onto an indirect block, we haven't
879                  * altered the inode.  Note however that if it is being spliced
880                  * onto an indirect block at the very end of the file (the
881                  * file is growing) then we *will* alter the inode to reflect
882                  * the new i_size.  But that is not done here - it is done in
883                  * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
884                  */
885                 jbd_debug(5, "splicing indirect only\n");
886                 BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
887                 err = ext4_handle_dirty_metadata(handle, inode, where->bh);
888                 if (err)
889                         goto err_out;
890         } else {
891                 /*
892                  * OK, we spliced it into the inode itself on a direct block.
893                  */
894                 ext4_mark_inode_dirty(handle, inode);
895                 jbd_debug(5, "splicing direct\n");
896         }
897         return err;
898
899 err_out:
900         for (i = 1; i <= num; i++) {
901                 /*
902                  * branch[i].bh is newly allocated, so there is no
903                  * need to revoke the block, which is why we don't
904                  * need to set EXT4_FREE_BLOCKS_METADATA.
905                  */
906                 ext4_free_blocks(handle, inode, where[i].bh, 0, 1,
907                                  EXT4_FREE_BLOCKS_FORGET);
908         }
909         ext4_free_blocks(handle, inode, 0, le32_to_cpu(where[num].key),
910                          blks, 0);
911
912         return err;
913 }
914
915 /*
916  * The ext4_ind_map_blocks() function handles non-extents inodes
917  * (i.e., using the traditional indirect/double-indirect i_blocks
918  * scheme) for ext4_map_blocks().
919  *
920  * Allocation strategy is simple: if we have to allocate something, we will
921  * have to go the whole way to leaf. So let's do it before attaching anything
922  * to tree, set linkage between the newborn blocks, write them if sync is
923  * required, recheck the path, free and repeat if check fails, otherwise
924  * set the last missing link (that will protect us from any truncate-generated
925  * removals - all blocks on the path are immune now) and possibly force the
926  * write on the parent block.
927  * That has a nice additional property: no special recovery from the failed
928  * allocations is needed - we simply release blocks and do not touch anything
929  * reachable from inode.
930  *
931  * `handle' can be NULL if create == 0.
932  *
933  * return > 0, # of blocks mapped or allocated.
934  * return = 0, if plain lookup failed.
935  * return < 0, error case.
936  *
937  * The ext4_ind_get_blocks() function should be called with
938  * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
939  * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
940  * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
941  * blocks.
942  */
943 static int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
944                                struct ext4_map_blocks *map,
945                                int flags)
946 {
947         int err = -EIO;
948         ext4_lblk_t offsets[4];
949         Indirect chain[4];
950         Indirect *partial;
951         ext4_fsblk_t goal;
952         int indirect_blks;
953         int blocks_to_boundary = 0;
954         int depth;
955         int count = 0;
956         ext4_fsblk_t first_block = 0;
957
958         J_ASSERT(!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)));
959         J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
960         depth = ext4_block_to_path(inode, map->m_lblk, offsets,
961                                    &blocks_to_boundary);
962
963         if (depth == 0)
964                 goto out;
965
966         partial = ext4_get_branch(inode, depth, offsets, chain, &err);
967
968         /* Simplest case - block found, no allocation needed */
969         if (!partial) {
970                 first_block = le32_to_cpu(chain[depth - 1].key);
971                 count++;
972                 /*map more blocks*/
973                 while (count < map->m_len && count <= blocks_to_boundary) {
974                         ext4_fsblk_t blk;
975
976                         blk = le32_to_cpu(*(chain[depth-1].p + count));
977
978                         if (blk == first_block + count)
979                                 count++;
980                         else
981                                 break;
982                 }
983                 goto got_it;
984         }
985
986         /* Next simple case - plain lookup or failed read of indirect block */
987         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0 || err == -EIO)
988                 goto cleanup;
989
990         /*
991          * Okay, we need to do block allocation.
992         */
993         goal = ext4_find_goal(inode, map->m_lblk, partial);
994
995         /* the number of blocks need to allocate for [d,t]indirect blocks */
996         indirect_blks = (chain + depth) - partial - 1;
997
998         /*
999          * Next look up the indirect map to count the totoal number of
1000          * direct blocks to allocate for this branch.
1001          */
1002         count = ext4_blks_to_allocate(partial, indirect_blks,
1003                                       map->m_len, blocks_to_boundary);
1004         /*
1005          * Block out ext4_truncate while we alter the tree
1006          */
1007         err = ext4_alloc_branch(handle, inode, map->m_lblk, indirect_blks,
1008                                 &count, goal,
1009                                 offsets + (partial - chain), partial);
1010
1011         /*
1012          * The ext4_splice_branch call will free and forget any buffers
1013          * on the new chain if there is a failure, but that risks using
1014          * up transaction credits, especially for bitmaps where the
1015          * credits cannot be returned.  Can we handle this somehow?  We
1016          * may need to return -EAGAIN upwards in the worst case.  --sct
1017          */
1018         if (!err)
1019                 err = ext4_splice_branch(handle, inode, map->m_lblk,
1020                                          partial, indirect_blks, count);
1021         if (err)
1022                 goto cleanup;
1023
1024         map->m_flags |= EXT4_MAP_NEW;
1025
1026         ext4_update_inode_fsync_trans(handle, inode, 1);
1027 got_it:
1028         map->m_flags |= EXT4_MAP_MAPPED;
1029         map->m_pblk = le32_to_cpu(chain[depth-1].key);
1030         map->m_len = count;
1031         if (count > blocks_to_boundary)
1032                 map->m_flags |= EXT4_MAP_BOUNDARY;
1033         err = count;
1034         /* Clean up and exit */
1035         partial = chain + depth - 1;    /* the whole chain */
1036 cleanup:
1037         while (partial > chain) {
1038                 BUFFER_TRACE(partial->bh, "call brelse");
1039                 brelse(partial->bh);
1040                 partial--;
1041         }
1042 out:
1043         return err;
1044 }
1045
1046 #ifdef CONFIG_QUOTA
1047 qsize_t *ext4_get_reserved_space(struct inode *inode)
1048 {
1049         return &EXT4_I(inode)->i_reserved_quota;
1050 }
1051 #endif
1052
1053 /*
1054  * Calculate the number of metadata blocks need to reserve
1055  * to allocate a new block at @lblocks for non extent file based file
1056  */
1057 static int ext4_indirect_calc_metadata_amount(struct inode *inode,
1058                                               sector_t lblock)
1059 {
1060         struct ext4_inode_info *ei = EXT4_I(inode);
1061         sector_t dind_mask = ~((sector_t)EXT4_ADDR_PER_BLOCK(inode->i_sb) - 1);
1062         int blk_bits;
1063
1064         if (lblock < EXT4_NDIR_BLOCKS)
1065                 return 0;
1066
1067         lblock -= EXT4_NDIR_BLOCKS;
1068
1069         if (ei->i_da_metadata_calc_len &&
1070             (lblock & dind_mask) == ei->i_da_metadata_calc_last_lblock) {
1071                 ei->i_da_metadata_calc_len++;
1072                 return 0;
1073         }
1074         ei->i_da_metadata_calc_last_lblock = lblock & dind_mask;
1075         ei->i_da_metadata_calc_len = 1;
1076         blk_bits = order_base_2(lblock);
1077         return (blk_bits / EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb)) + 1;
1078 }
1079
1080 /*
1081  * Calculate the number of metadata blocks need to reserve
1082  * to allocate a block located at @lblock
1083  */
1084 static int ext4_calc_metadata_amount(struct inode *inode, sector_t lblock)
1085 {
1086         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
1087                 return ext4_ext_calc_metadata_amount(inode, lblock);
1088
1089         return ext4_indirect_calc_metadata_amount(inode, lblock);
1090 }
1091
1092 /*
1093  * Called with i_data_sem down, which is important since we can call
1094  * ext4_discard_preallocations() from here.
1095  */
1096 void ext4_da_update_reserve_space(struct inode *inode,
1097                                         int used, int quota_claim)
1098 {
1099         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1100         struct ext4_inode_info *ei = EXT4_I(inode);
1101
1102         spin_lock(&ei->i_block_reservation_lock);
1103         trace_ext4_da_update_reserve_space(inode, used);
1104         if (unlikely(used > ei->i_reserved_data_blocks)) {
1105                 ext4_msg(inode->i_sb, KERN_NOTICE, "%s: ino %lu, used %d "
1106                          "with only %d reserved data blocks\n",
1107                          __func__, inode->i_ino, used,
1108                          ei->i_reserved_data_blocks);
1109                 WARN_ON(1);
1110                 used = ei->i_reserved_data_blocks;
1111         }
1112
1113         /* Update per-inode reservations */
1114         ei->i_reserved_data_blocks -= used;
1115         ei->i_reserved_meta_blocks -= ei->i_allocated_meta_blocks;
1116         percpu_counter_sub(&sbi->s_dirtyblocks_counter,
1117                            used + ei->i_allocated_meta_blocks);
1118         ei->i_allocated_meta_blocks = 0;
1119
1120         if (ei->i_reserved_data_blocks == 0) {
1121                 /*
1122                  * We can release all of the reserved metadata blocks
1123                  * only when we have written all of the delayed
1124                  * allocation blocks.
1125                  */
1126                 percpu_counter_sub(&sbi->s_dirtyblocks_counter,
1127                                    ei->i_reserved_meta_blocks);
1128                 ei->i_reserved_meta_blocks = 0;
1129                 ei->i_da_metadata_calc_len = 0;
1130         }
1131         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1132
1133         /* Update quota subsystem for data blocks */
1134         if (quota_claim)
1135                 dquot_claim_block(inode, used);
1136         else {
1137                 /*
1138                  * We did fallocate with an offset that is already delayed
1139                  * allocated. So on delayed allocated writeback we should
1140                  * not re-claim the quota for fallocated blocks.
1141                  */
1142                 dquot_release_reservation_block(inode, used);
1143         }
1144
1145         /*
1146          * If we have done all the pending block allocations and if
1147          * there aren't any writers on the inode, we can discard the
1148          * inode's preallocations.
1149          */
1150         if ((ei->i_reserved_data_blocks == 0) &&
1151             (atomic_read(&inode->i_writecount) == 0))
1152                 ext4_discard_preallocations(inode);
1153 }
1154
1155 static int __check_block_validity(struct inode *inode, const char *func,
1156                                 unsigned int line,
1157                                 struct ext4_map_blocks *map)
1158 {
1159         if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), map->m_pblk,
1160                                    map->m_len)) {
1161                 ext4_error_inode(inode, func, line, map->m_pblk,
1162                                  "lblock %lu mapped to illegal pblock "
1163                                  "(length %d)", (unsigned long) map->m_lblk,
1164                                  map->m_len);
1165                 return -EIO;
1166         }
1167         return 0;
1168 }
1169
1170 #define check_block_validity(inode, map)        \
1171         __check_block_validity((inode), __func__, __LINE__, (map))
1172
1173 /*
1174  * Return the number of contiguous dirty pages in a given inode
1175  * starting at page frame idx.
1176  */
1177 static pgoff_t ext4_num_dirty_pages(struct inode *inode, pgoff_t idx,
1178                                     unsigned int max_pages)
1179 {
1180         struct address_space *mapping = inode->i_mapping;
1181         pgoff_t index;
1182         struct pagevec pvec;
1183         pgoff_t num = 0;
1184         int i, nr_pages, done = 0;
1185
1186         if (max_pages == 0)
1187                 return 0;
1188         pagevec_init(&pvec, 0);
1189         while (!done) {
1190                 index = idx;
1191                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
1192                                               PAGECACHE_TAG_DIRTY,
1193                                               (pgoff_t)PAGEVEC_SIZE);
1194                 if (nr_pages == 0)
1195                         break;
1196                 for (i = 0; i < nr_pages; i++) {
1197                         struct page *page = pvec.pages[i];
1198                         struct buffer_head *bh, *head;
1199
1200                         lock_page(page);
1201                         if (unlikely(page->mapping != mapping) ||
1202                             !PageDirty(page) ||
1203                             PageWriteback(page) ||
1204                             page->index != idx) {
1205                                 done = 1;
1206                                 unlock_page(page);
1207                                 break;
1208                         }
1209                         if (page_has_buffers(page)) {
1210                                 bh = head = page_buffers(page);
1211                                 do {
1212                                         if (!buffer_delay(bh) &&
1213                                             !buffer_unwritten(bh))
1214                                                 done = 1;
1215                                         bh = bh->b_this_page;
1216                                 } while (!done && (bh != head));
1217                         }
1218                         unlock_page(page);
1219                         if (done)
1220                                 break;
1221                         idx++;
1222                         num++;
1223                         if (num >= max_pages) {
1224                                 done = 1;
1225                                 break;
1226                         }
1227                 }
1228                 pagevec_release(&pvec);
1229         }
1230         return num;
1231 }
1232
1233 /*
1234  * The ext4_map_blocks() function tries to look up the requested blocks,
1235  * and returns if the blocks are already mapped.
1236  *
1237  * Otherwise it takes the write lock of the i_data_sem and allocate blocks
1238  * and store the allocated blocks in the result buffer head and mark it
1239  * mapped.
1240  *
1241  * If file type is extents based, it will call ext4_ext_map_blocks(),
1242  * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
1243  * based files
1244  *
1245  * On success, it returns the number of blocks being mapped or allocate.
1246  * if create==0 and the blocks are pre-allocated and uninitialized block,
1247  * the result buffer head is unmapped. If the create ==1, it will make sure
1248  * the buffer head is mapped.
1249  *
1250  * It returns 0 if plain look up failed (blocks have not been allocated), in
1251  * that casem, buffer head is unmapped
1252  *
1253  * It returns the error in case of allocation failure.
1254  */
1255 int ext4_map_blocks(handle_t *handle, struct inode *inode,
1256                     struct ext4_map_blocks *map, int flags)
1257 {
1258         int retval;
1259
1260         map->m_flags = 0;
1261         ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
1262                   "logical block %lu\n", inode->i_ino, flags, map->m_len,
1263                   (unsigned long) map->m_lblk);
1264         /*
1265          * Try to see if we can get the block without requesting a new
1266          * file system block.
1267          */
1268         down_read((&EXT4_I(inode)->i_data_sem));
1269         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
1270                 retval = ext4_ext_map_blocks(handle, inode, map, 0);
1271         } else {
1272                 retval = ext4_ind_map_blocks(handle, inode, map, 0);
1273         }
1274         up_read((&EXT4_I(inode)->i_data_sem));
1275
1276         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
1277                 int ret = check_block_validity(inode, map);
1278                 if (ret != 0)
1279                         return ret;
1280         }
1281
1282         /* If it is only a block(s) look up */
1283         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
1284                 return retval;
1285
1286         /*
1287          * Returns if the blocks have already allocated
1288          *
1289          * Note that if blocks have been preallocated
1290          * ext4_ext_get_block() returns th create = 0
1291          * with buffer head unmapped.
1292          */
1293         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
1294                 return retval;
1295
1296         /*
1297          * When we call get_blocks without the create flag, the
1298          * BH_Unwritten flag could have gotten set if the blocks
1299          * requested were part of a uninitialized extent.  We need to
1300          * clear this flag now that we are committed to convert all or
1301          * part of the uninitialized extent to be an initialized
1302          * extent.  This is because we need to avoid the combination
1303          * of BH_Unwritten and BH_Mapped flags being simultaneously
1304          * set on the buffer_head.
1305          */
1306         map->m_flags &= ~EXT4_MAP_UNWRITTEN;
1307
1308         /*
1309          * New blocks allocate and/or writing to uninitialized extent
1310          * will possibly result in updating i_data, so we take
1311          * the write lock of i_data_sem, and call get_blocks()
1312          * with create == 1 flag.
1313          */
1314         down_write((&EXT4_I(inode)->i_data_sem));
1315
1316         /*
1317          * if the caller is from delayed allocation writeout path
1318          * we have already reserved fs blocks for allocation
1319          * let the underlying get_block() function know to
1320          * avoid double accounting
1321          */
1322         if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
1323                 EXT4_I(inode)->i_delalloc_reserved_flag = 1;
1324         /*
1325          * We need to check for EXT4 here because migrate
1326          * could have changed the inode type in between
1327          */
1328         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
1329                 retval = ext4_ext_map_blocks(handle, inode, map, flags);
1330         } else {
1331                 retval = ext4_ind_map_blocks(handle, inode, map, flags);
1332
1333                 if (retval > 0 && map->m_flags & EXT4_MAP_NEW) {
1334                         /*
1335                          * We allocated new blocks which will result in
1336                          * i_data's format changing.  Force the migrate
1337                          * to fail by clearing migrate flags
1338                          */
1339                         ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
1340                 }
1341
1342                 /*
1343                  * Update reserved blocks/metadata blocks after successful
1344                  * block allocation which had been deferred till now. We don't
1345                  * support fallocate for non extent files. So we can update
1346                  * reserve space here.
1347                  */
1348                 if ((retval > 0) &&
1349                         (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE))
1350                         ext4_da_update_reserve_space(inode, retval, 1);
1351         }
1352         if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
1353                 EXT4_I(inode)->i_delalloc_reserved_flag = 0;
1354
1355         up_write((&EXT4_I(inode)->i_data_sem));
1356         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
1357                 int ret = check_block_validity(inode, map);
1358                 if (ret != 0)
1359                         return ret;
1360         }
1361         return retval;
1362 }
1363
1364 /* Maximum number of blocks we map for direct IO at once. */
1365 #define DIO_MAX_BLOCKS 4096
1366
1367 static int _ext4_get_block(struct inode *inode, sector_t iblock,
1368                            struct buffer_head *bh, int flags)
1369 {
1370         handle_t *handle = ext4_journal_current_handle();
1371         struct ext4_map_blocks map;
1372         int ret = 0, started = 0;
1373         int dio_credits;
1374
1375         map.m_lblk = iblock;
1376         map.m_len = bh->b_size >> inode->i_blkbits;
1377
1378         if (flags && !handle) {
1379                 /* Direct IO write... */
1380                 if (map.m_len > DIO_MAX_BLOCKS)
1381                         map.m_len = DIO_MAX_BLOCKS;
1382                 dio_credits = ext4_chunk_trans_blocks(inode, map.m_len);
1383                 handle = ext4_journal_start(inode, dio_credits);
1384                 if (IS_ERR(handle)) {
1385                         ret = PTR_ERR(handle);
1386                         return ret;
1387                 }
1388                 started = 1;
1389         }
1390
1391         ret = ext4_map_blocks(handle, inode, &map, flags);
1392         if (ret > 0) {
1393                 map_bh(bh, inode->i_sb, map.m_pblk);
1394                 bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
1395                 bh->b_size = inode->i_sb->s_blocksize * map.m_len;
1396                 ret = 0;
1397         }
1398         if (started)
1399                 ext4_journal_stop(handle);
1400         return ret;
1401 }
1402
1403 int ext4_get_block(struct inode *inode, sector_t iblock,
1404                    struct buffer_head *bh, int create)
1405 {
1406         return _ext4_get_block(inode, iblock, bh,
1407                                create ? EXT4_GET_BLOCKS_CREATE : 0);
1408 }
1409
1410 /*
1411  * `handle' can be NULL if create is zero
1412  */
1413 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
1414                                 ext4_lblk_t block, int create, int *errp)
1415 {
1416         struct ext4_map_blocks map;
1417         struct buffer_head *bh;
1418         int fatal = 0, err;
1419
1420         J_ASSERT(handle != NULL || create == 0);
1421
1422         map.m_lblk = block;
1423         map.m_len = 1;
1424         err = ext4_map_blocks(handle, inode, &map,
1425                               create ? EXT4_GET_BLOCKS_CREATE : 0);
1426
1427         if (err < 0)
1428                 *errp = err;
1429         if (err <= 0)
1430                 return NULL;
1431         *errp = 0;
1432
1433         bh = sb_getblk(inode->i_sb, map.m_pblk);
1434         if (!bh) {
1435                 *errp = -EIO;
1436                 return NULL;
1437         }
1438         if (map.m_flags & EXT4_MAP_NEW) {
1439                 J_ASSERT(create != 0);
1440                 J_ASSERT(handle != NULL);
1441
1442                 /*
1443                  * Now that we do not always journal data, we should
1444                  * keep in mind whether this should always journal the
1445                  * new buffer as metadata.  For now, regular file
1446                  * writes use ext4_get_block instead, so it's not a
1447                  * problem.
1448                  */
1449                 lock_buffer(bh);
1450                 BUFFER_TRACE(bh, "call get_create_access");
1451                 fatal = ext4_journal_get_create_access(handle, bh);
1452                 if (!fatal && !buffer_uptodate(bh)) {
1453                         memset(bh->b_data, 0, inode->i_sb->s_blocksize);
1454                         set_buffer_uptodate(bh);
1455                 }
1456                 unlock_buffer(bh);
1457                 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
1458                 err = ext4_handle_dirty_metadata(handle, inode, bh);
1459                 if (!fatal)
1460                         fatal = err;
1461         } else {
1462                 BUFFER_TRACE(bh, "not a new buffer");
1463         }
1464         if (fatal) {
1465                 *errp = fatal;
1466                 brelse(bh);
1467                 bh = NULL;
1468         }
1469         return bh;
1470 }
1471
1472 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
1473                                ext4_lblk_t block, int create, int *err)
1474 {
1475         struct buffer_head *bh;
1476
1477         bh = ext4_getblk(handle, inode, block, create, err);
1478         if (!bh)
1479                 return bh;
1480         if (buffer_uptodate(bh))
1481                 return bh;
1482         ll_rw_block(READ_META, 1, &bh);
1483         wait_on_buffer(bh);
1484         if (buffer_uptodate(bh))
1485                 return bh;
1486         put_bh(bh);
1487         *err = -EIO;
1488         return NULL;
1489 }
1490
1491 static int walk_page_buffers(handle_t *handle,
1492                              struct buffer_head *head,
1493                              unsigned from,
1494                              unsigned to,
1495                              int *partial,
1496                              int (*fn)(handle_t *handle,
1497                                        struct buffer_head *bh))
1498 {
1499         struct buffer_head *bh;
1500         unsigned block_start, block_end;
1501         unsigned blocksize = head->b_size;
1502         int err, ret = 0;
1503         struct buffer_head *next;
1504
1505         for (bh = head, block_start = 0;
1506              ret == 0 && (bh != head || !block_start);
1507              block_start = block_end, bh = next) {
1508                 next = bh->b_this_page;
1509                 block_end = block_start + blocksize;
1510                 if (block_end <= from || block_start >= to) {
1511                         if (partial && !buffer_uptodate(bh))
1512                                 *partial = 1;
1513                         continue;
1514                 }
1515                 err = (*fn)(handle, bh);
1516                 if (!ret)
1517                         ret = err;
1518         }
1519         return ret;
1520 }
1521
1522 /*
1523  * To preserve ordering, it is essential that the hole instantiation and
1524  * the data write be encapsulated in a single transaction.  We cannot
1525  * close off a transaction and start a new one between the ext4_get_block()
1526  * and the commit_write().  So doing the jbd2_journal_start at the start of
1527  * prepare_write() is the right place.
1528  *
1529  * Also, this function can nest inside ext4_writepage() ->
1530  * block_write_full_page(). In that case, we *know* that ext4_writepage()
1531  * has generated enough buffer credits to do the whole page.  So we won't
1532  * block on the journal in that case, which is good, because the caller may
1533  * be PF_MEMALLOC.
1534  *
1535  * By accident, ext4 can be reentered when a transaction is open via
1536  * quota file writes.  If we were to commit the transaction while thus
1537  * reentered, there can be a deadlock - we would be holding a quota
1538  * lock, and the commit would never complete if another thread had a
1539  * transaction open and was blocking on the quota lock - a ranking
1540  * violation.
1541  *
1542  * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
1543  * will _not_ run commit under these circumstances because handle->h_ref
1544  * is elevated.  We'll still have enough credits for the tiny quotafile
1545  * write.
1546  */
1547 static int do_journal_get_write_access(handle_t *handle,
1548                                        struct buffer_head *bh)
1549 {
1550         int dirty = buffer_dirty(bh);
1551         int ret;
1552
1553         if (!buffer_mapped(bh) || buffer_freed(bh))
1554                 return 0;
1555         /*
1556          * __block_write_begin() could have dirtied some buffers. Clean
1557          * the dirty bit as jbd2_journal_get_write_access() could complain
1558          * otherwise about fs integrity issues. Setting of the dirty bit
1559          * by __block_write_begin() isn't a real problem here as we clear
1560          * the bit before releasing a page lock and thus writeback cannot
1561          * ever write the buffer.
1562          */
1563         if (dirty)
1564                 clear_buffer_dirty(bh);
1565         ret = ext4_journal_get_write_access(handle, bh);
1566         if (!ret && dirty)
1567                 ret = ext4_handle_dirty_metadata(handle, NULL, bh);
1568         return ret;
1569 }
1570
1571 /*
1572  * Truncate blocks that were not used by write. We have to truncate the
1573  * pagecache as well so that corresponding buffers get properly unmapped.
1574  */
1575 static void ext4_truncate_failed_write(struct inode *inode)
1576 {
1577         truncate_inode_pages(inode->i_mapping, inode->i_size);
1578         ext4_truncate(inode);
1579 }
1580
1581 static int ext4_get_block_write(struct inode *inode, sector_t iblock,
1582                    struct buffer_head *bh_result, int create);
1583 static int ext4_write_begin(struct file *file, struct address_space *mapping,
1584                             loff_t pos, unsigned len, unsigned flags,
1585                             struct page **pagep, void **fsdata)
1586 {
1587         struct inode *inode = mapping->host;
1588         int ret, needed_blocks;
1589         handle_t *handle;
1590         int retries = 0;
1591         struct page *page;
1592         pgoff_t index;
1593         unsigned from, to;
1594
1595         trace_ext4_write_begin(inode, pos, len, flags);
1596         /*
1597          * Reserve one block more for addition to orphan list in case
1598          * we allocate blocks but write fails for some reason
1599          */
1600         needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
1601         index = pos >> PAGE_CACHE_SHIFT;
1602         from = pos & (PAGE_CACHE_SIZE - 1);
1603         to = from + len;
1604
1605 retry:
1606         handle = ext4_journal_start(inode, needed_blocks);
1607         if (IS_ERR(handle)) {
1608                 ret = PTR_ERR(handle);
1609                 goto out;
1610         }
1611
1612         /* We cannot recurse into the filesystem as the transaction is already
1613          * started */
1614         flags |= AOP_FLAG_NOFS;
1615
1616         page = grab_cache_page_write_begin(mapping, index, flags);
1617         if (!page) {
1618                 ext4_journal_stop(handle);
1619                 ret = -ENOMEM;
1620                 goto out;
1621         }
1622         *pagep = page;
1623
1624         if (ext4_should_dioread_nolock(inode))
1625                 ret = __block_write_begin(page, pos, len, ext4_get_block_write);
1626         else
1627                 ret = __block_write_begin(page, pos, len, ext4_get_block);
1628
1629         if (!ret && ext4_should_journal_data(inode)) {
1630                 ret = walk_page_buffers(handle, page_buffers(page),
1631                                 from, to, NULL, do_journal_get_write_access);
1632         }
1633
1634         if (ret) {
1635                 unlock_page(page);
1636                 page_cache_release(page);
1637                 /*
1638                  * __block_write_begin may have instantiated a few blocks
1639                  * outside i_size.  Trim these off again. Don't need
1640                  * i_size_read because we hold i_mutex.
1641                  *
1642                  * Add inode to orphan list in case we crash before
1643                  * truncate finishes
1644                  */
1645                 if (pos + len > inode->i_size && ext4_can_truncate(inode))
1646                         ext4_orphan_add(handle, inode);
1647
1648                 ext4_journal_stop(handle);
1649                 if (pos + len > inode->i_size) {
1650                         ext4_truncate_failed_write(inode);
1651                         /*
1652                          * If truncate failed early the inode might
1653                          * still be on the orphan list; we need to
1654                          * make sure the inode is removed from the
1655                          * orphan list in that case.
1656                          */
1657                         if (inode->i_nlink)
1658                                 ext4_orphan_del(NULL, inode);
1659                 }
1660         }
1661
1662         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
1663                 goto retry;
1664 out:
1665         return ret;
1666 }
1667
1668 /* For write_end() in data=journal mode */
1669 static int write_end_fn(handle_t *handle, struct buffer_head *bh)
1670 {
1671         if (!buffer_mapped(bh) || buffer_freed(bh))
1672                 return 0;
1673         set_buffer_uptodate(bh);
1674         return ext4_handle_dirty_metadata(handle, NULL, bh);
1675 }
1676
1677 static int ext4_generic_write_end(struct file *file,
1678                                   struct address_space *mapping,
1679                                   loff_t pos, unsigned len, unsigned copied,
1680                                   struct page *page, void *fsdata)
1681 {
1682         int i_size_changed = 0;
1683         struct inode *inode = mapping->host;
1684         handle_t *handle = ext4_journal_current_handle();
1685
1686         copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
1687
1688         /*
1689          * No need to use i_size_read() here, the i_size
1690          * cannot change under us because we hold i_mutex.
1691          *
1692          * But it's important to update i_size while still holding page lock:
1693          * page writeout could otherwise come in and zero beyond i_size.
1694          */
1695         if (pos + copied > inode->i_size) {
1696                 i_size_write(inode, pos + copied);
1697                 i_size_changed = 1;
1698         }
1699
1700         if (pos + copied >  EXT4_I(inode)->i_disksize) {
1701                 /* We need to mark inode dirty even if
1702                  * new_i_size is less that inode->i_size
1703                  * bu greater than i_disksize.(hint delalloc)
1704                  */
1705                 ext4_update_i_disksize(inode, (pos + copied));
1706                 i_size_changed = 1;
1707         }
1708         unlock_page(page);
1709         page_cache_release(page);
1710
1711         /*
1712          * Don't mark the inode dirty under page lock. First, it unnecessarily
1713          * makes the holding time of page lock longer. Second, it forces lock
1714          * ordering of page lock and transaction start for journaling
1715          * filesystems.
1716          */
1717         if (i_size_changed)
1718                 ext4_mark_inode_dirty(handle, inode);
1719
1720         return copied;
1721 }
1722
1723 /*
1724  * We need to pick up the new inode size which generic_commit_write gave us
1725  * `file' can be NULL - eg, when called from page_symlink().
1726  *
1727  * ext4 never places buffers on inode->i_mapping->private_list.  metadata
1728  * buffers are managed internally.
1729  */
1730 static int ext4_ordered_write_end(struct file *file,
1731                                   struct address_space *mapping,
1732                                   loff_t pos, unsigned len, unsigned copied,
1733                                   struct page *page, void *fsdata)
1734 {
1735         handle_t *handle = ext4_journal_current_handle();
1736         struct inode *inode = mapping->host;
1737         int ret = 0, ret2;
1738
1739         trace_ext4_ordered_write_end(inode, pos, len, copied);
1740         ret = ext4_jbd2_file_inode(handle, inode);
1741
1742         if (ret == 0) {
1743                 ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
1744                                                         page, fsdata);
1745                 copied = ret2;
1746                 if (pos + len > inode->i_size && ext4_can_truncate(inode))
1747                         /* if we have allocated more blocks and copied
1748                          * less. We will have blocks allocated outside
1749                          * inode->i_size. So truncate them
1750                          */
1751                         ext4_orphan_add(handle, inode);
1752                 if (ret2 < 0)
1753                         ret = ret2;
1754         }
1755         ret2 = ext4_journal_stop(handle);
1756         if (!ret)
1757                 ret = ret2;
1758
1759         if (pos + len > inode->i_size) {
1760                 ext4_truncate_failed_write(inode);
1761                 /*
1762                  * If truncate failed early the inode might still be
1763                  * on the orphan list; we need to make sure the inode
1764                  * is removed from the orphan list in that case.
1765                  */
1766                 if (inode->i_nlink)
1767                         ext4_orphan_del(NULL, inode);
1768         }
1769
1770
1771         return ret ? ret : copied;
1772 }
1773
1774 static int ext4_writeback_write_end(struct file *file,
1775                                     struct address_space *mapping,
1776                                     loff_t pos, unsigned len, unsigned copied,
1777                                     struct page *page, void *fsdata)
1778 {
1779         handle_t *handle = ext4_journal_current_handle();
1780         struct inode *inode = mapping->host;
1781         int ret = 0, ret2;
1782
1783         trace_ext4_writeback_write_end(inode, pos, len, copied);
1784         ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
1785                                                         page, fsdata);
1786         copied = ret2;
1787         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1788                 /* if we have allocated more blocks and copied
1789                  * less. We will have blocks allocated outside
1790                  * inode->i_size. So truncate them
1791                  */
1792                 ext4_orphan_add(handle, inode);
1793
1794         if (ret2 < 0)
1795                 ret = ret2;
1796
1797         ret2 = ext4_journal_stop(handle);
1798         if (!ret)
1799                 ret = ret2;
1800
1801         if (pos + len > inode->i_size) {
1802                 ext4_truncate_failed_write(inode);
1803                 /*
1804                  * If truncate failed early the inode might still be
1805                  * on the orphan list; we need to make sure the inode
1806                  * is removed from the orphan list in that case.
1807                  */
1808                 if (inode->i_nlink)
1809                         ext4_orphan_del(NULL, inode);
1810         }
1811
1812         return ret ? ret : copied;
1813 }
1814
1815 static int ext4_journalled_write_end(struct file *file,
1816                                      struct address_space *mapping,
1817                                      loff_t pos, unsigned len, unsigned copied,
1818                                      struct page *page, void *fsdata)
1819 {
1820         handle_t *handle = ext4_journal_current_handle();
1821         struct inode *inode = mapping->host;
1822         int ret = 0, ret2;
1823         int partial = 0;
1824         unsigned from, to;
1825         loff_t new_i_size;
1826
1827         trace_ext4_journalled_write_end(inode, pos, len, copied);
1828         from = pos & (PAGE_CACHE_SIZE - 1);
1829         to = from + len;
1830
1831         if (copied < len) {
1832                 if (!PageUptodate(page))
1833                         copied = 0;
1834                 page_zero_new_buffers(page, from+copied, to);
1835         }
1836
1837         ret = walk_page_buffers(handle, page_buffers(page), from,
1838                                 to, &partial, write_end_fn);
1839         if (!partial)
1840                 SetPageUptodate(page);
1841         new_i_size = pos + copied;
1842         if (new_i_size > inode->i_size)
1843                 i_size_write(inode, pos+copied);
1844         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1845         if (new_i_size > EXT4_I(inode)->i_disksize) {
1846                 ext4_update_i_disksize(inode, new_i_size);
1847                 ret2 = ext4_mark_inode_dirty(handle, inode);
1848                 if (!ret)
1849                         ret = ret2;
1850         }
1851
1852         unlock_page(page);
1853         page_cache_release(page);
1854         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1855                 /* if we have allocated more blocks and copied
1856                  * less. We will have blocks allocated outside
1857                  * inode->i_size. So truncate them
1858                  */
1859                 ext4_orphan_add(handle, inode);
1860
1861         ret2 = ext4_journal_stop(handle);
1862         if (!ret)
1863                 ret = ret2;
1864         if (pos + len > inode->i_size) {
1865                 ext4_truncate_failed_write(inode);
1866                 /*
1867                  * If truncate failed early the inode might still be
1868                  * on the orphan list; we need to make sure the inode
1869                  * is removed from the orphan list in that case.
1870                  */
1871                 if (inode->i_nlink)
1872                         ext4_orphan_del(NULL, inode);
1873         }
1874
1875         return ret ? ret : copied;
1876 }
1877
1878 /*
1879  * Reserve a single block located at lblock
1880  */
1881 static int ext4_da_reserve_space(struct inode *inode, sector_t lblock)
1882 {
1883         int retries = 0;
1884         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1885         struct ext4_inode_info *ei = EXT4_I(inode);
1886         unsigned long md_needed;
1887         int ret;
1888
1889         /*
1890          * recalculate the amount of metadata blocks to reserve
1891          * in order to allocate nrblocks
1892          * worse case is one extent per block
1893          */
1894 repeat:
1895         spin_lock(&ei->i_block_reservation_lock);
1896         md_needed = ext4_calc_metadata_amount(inode, lblock);
1897         trace_ext4_da_reserve_space(inode, md_needed);
1898         spin_unlock(&ei->i_block_reservation_lock);
1899
1900         /*
1901          * We will charge metadata quota at writeout time; this saves
1902          * us from metadata over-estimation, though we may go over by
1903          * a small amount in the end.  Here we just reserve for data.
1904          */
1905         ret = dquot_reserve_block(inode, 1);
1906         if (ret)
1907                 return ret;
1908         /*
1909          * We do still charge estimated metadata to the sb though;
1910          * we cannot afford to run out of free blocks.
1911          */
1912         if (ext4_claim_free_blocks(sbi, md_needed + 1)) {
1913                 dquot_release_reservation_block(inode, 1);
1914                 if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
1915                         yield();
1916                         goto repeat;
1917                 }
1918                 return -ENOSPC;
1919         }
1920         spin_lock(&ei->i_block_reservation_lock);
1921         ei->i_reserved_data_blocks++;
1922         ei->i_reserved_meta_blocks += md_needed;
1923         spin_unlock(&ei->i_block_reservation_lock);
1924
1925         return 0;       /* success */
1926 }
1927
1928 static void ext4_da_release_space(struct inode *inode, int to_free)
1929 {
1930         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1931         struct ext4_inode_info *ei = EXT4_I(inode);
1932
1933         if (!to_free)
1934                 return;         /* Nothing to release, exit */
1935
1936         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1937
1938         trace_ext4_da_release_space(inode, to_free);
1939         if (unlikely(to_free > ei->i_reserved_data_blocks)) {
1940                 /*
1941                  * if there aren't enough reserved blocks, then the
1942                  * counter is messed up somewhere.  Since this
1943                  * function is called from invalidate page, it's
1944                  * harmless to return without any action.
1945                  */
1946                 ext4_msg(inode->i_sb, KERN_NOTICE, "ext4_da_release_space: "
1947                          "ino %lu, to_free %d with only %d reserved "
1948                          "data blocks\n", inode->i_ino, to_free,
1949                          ei->i_reserved_data_blocks);
1950                 WARN_ON(1);
1951                 to_free = ei->i_reserved_data_blocks;
1952         }
1953         ei->i_reserved_data_blocks -= to_free;
1954
1955         if (ei->i_reserved_data_blocks == 0) {
1956                 /*
1957                  * We can release all of the reserved metadata blocks
1958                  * only when we have written all of the delayed
1959                  * allocation blocks.
1960                  */
1961                 percpu_counter_sub(&sbi->s_dirtyblocks_counter,
1962                                    ei->i_reserved_meta_blocks);
1963                 ei->i_reserved_meta_blocks = 0;
1964                 ei->i_da_metadata_calc_len = 0;
1965         }
1966
1967         /* update fs dirty data blocks counter */
1968         percpu_counter_sub(&sbi->s_dirtyblocks_counter, to_free);
1969
1970         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1971
1972         dquot_release_reservation_block(inode, to_free);
1973 }
1974
1975 static void ext4_da_page_release_reservation(struct page *page,
1976                                              unsigned long offset)
1977 {
1978         int to_release = 0;
1979         struct buffer_head *head, *bh;
1980         unsigned int curr_off = 0;
1981
1982         head = page_buffers(page);
1983         bh = head;
1984         do {
1985                 unsigned int next_off = curr_off + bh->b_size;
1986
1987                 if ((offset <= curr_off) && (buffer_delay(bh))) {
1988                         to_release++;
1989                         clear_buffer_delay(bh);
1990                 }
1991                 curr_off = next_off;
1992         } while ((bh = bh->b_this_page) != head);
1993         ext4_da_release_space(page->mapping->host, to_release);
1994 }
1995
1996 /*
1997  * Delayed allocation stuff
1998  */
1999
2000 /*
2001  * mpage_da_submit_io - walks through extent of pages and try to write
2002  * them with writepage() call back
2003  *
2004  * @mpd->inode: inode
2005  * @mpd->first_page: first page of the extent
2006  * @mpd->next_page: page after the last page of the extent
2007  *
2008  * By the time mpage_da_submit_io() is called we expect all blocks
2009  * to be allocated. this may be wrong if allocation failed.
2010  *
2011  * As pages are already locked by write_cache_pages(), we can't use it
2012  */
2013 static int mpage_da_submit_io(struct mpage_da_data *mpd,
2014                               struct ext4_map_blocks *map)
2015 {
2016         struct pagevec pvec;
2017         unsigned long index, end;
2018         int ret = 0, err, nr_pages, i;
2019         struct inode *inode = mpd->inode;
2020         struct address_space *mapping = inode->i_mapping;
2021         loff_t size = i_size_read(inode);
2022         unsigned int len, block_start;
2023         struct buffer_head *bh, *page_bufs = NULL;
2024         int journal_data = ext4_should_journal_data(inode);
2025         sector_t pblock = 0, cur_logical = 0;
2026         struct ext4_io_submit io_submit;
2027
2028         BUG_ON(mpd->next_page <= mpd->first_page);
2029         memset(&io_submit, 0, sizeof(io_submit));
2030         /*
2031          * We need to start from the first_page to the next_page - 1
2032          * to make sure we also write the mapped dirty buffer_heads.
2033          * If we look at mpd->b_blocknr we would only be looking
2034          * at the currently mapped buffer_heads.
2035          */
2036         index = mpd->first_page;
2037         end = mpd->next_page - 1;
2038
2039         pagevec_init(&pvec, 0);
2040         while (index <= end) {
2041                 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
2042                 if (nr_pages == 0)
2043                         break;
2044                 for (i = 0; i < nr_pages; i++) {
2045                         int commit_write = 0, redirty_page = 0;
2046                         struct page *page = pvec.pages[i];
2047
2048                         index = page->index;
2049                         if (index > end)
2050                                 break;
2051
2052                         if (index == size >> PAGE_CACHE_SHIFT)
2053                                 len = size & ~PAGE_CACHE_MASK;
2054                         else
2055                                 len = PAGE_CACHE_SIZE;
2056                         if (map) {
2057                                 cur_logical = index << (PAGE_CACHE_SHIFT -
2058                                                         inode->i_blkbits);
2059                                 pblock = map->m_pblk + (cur_logical -
2060                                                         map->m_lblk);
2061                         }
2062                         index++;
2063
2064                         BUG_ON(!PageLocked(page));
2065                         BUG_ON(PageWriteback(page));
2066
2067                         /*
2068                          * If the page does not have buffers (for
2069                          * whatever reason), try to create them using
2070                          * __block_write_begin.  If this fails,
2071                          * redirty the page and move on.
2072                          */
2073                         if (!page_has_buffers(page)) {
2074                                 if (__block_write_begin(page, 0, len,
2075                                                 noalloc_get_block_write)) {
2076                                 redirty_page:
2077                                         redirty_page_for_writepage(mpd->wbc,
2078                                                                    page);
2079                                         unlock_page(page);
2080                                         continue;
2081                                 }
2082                                 commit_write = 1;
2083                         }
2084
2085                         bh = page_bufs = page_buffers(page);
2086                         block_start = 0;
2087                         do {
2088                                 if (!bh)
2089                                         goto redirty_page;
2090                                 if (map && (cur_logical >= map->m_lblk) &&
2091                                     (cur_logical <= (map->m_lblk +
2092                                                      (map->m_len - 1)))) {
2093                                         if (buffer_delay(bh)) {
2094                                                 clear_buffer_delay(bh);
2095                                                 bh->b_blocknr = pblock;
2096                                         }
2097                                         if (buffer_unwritten(bh) ||
2098                                             buffer_mapped(bh))
2099                                                 BUG_ON(bh->b_blocknr != pblock);
2100                                         if (map->m_flags & EXT4_MAP_UNINIT)
2101                                                 set_buffer_uninit(bh);
2102                                         clear_buffer_unwritten(bh);
2103                                 }
2104
2105                                 /* redirty page if block allocation undone */
2106                                 if (buffer_delay(bh) || buffer_unwritten(bh))
2107                                         redirty_page = 1;
2108                                 bh = bh->b_this_page;
2109                                 block_start += bh->b_size;
2110                                 cur_logical++;
2111                                 pblock++;
2112                         } while (bh != page_bufs);
2113
2114                         if (redirty_page)
2115                                 goto redirty_page;
2116
2117                         if (commit_write)
2118                                 /* mark the buffer_heads as dirty & uptodate */
2119                                 block_commit_write(page, 0, len);
2120
2121                         /*
2122                          * Delalloc doesn't support data journalling,
2123                          * but eventually maybe we'll lift this
2124                          * restriction.
2125                          */
2126                         if (unlikely(journal_data && PageChecked(page)))
2127                                 err = __ext4_journalled_writepage(page, len);
2128                         else if (test_opt(inode->i_sb, MBLK_IO_SUBMIT))
2129                                 err = ext4_bio_write_page(&io_submit, page,
2130                                                           len, mpd->wbc);
2131                         else
2132                                 err = block_write_full_page(page,
2133                                         noalloc_get_block_write, mpd->wbc);
2134
2135                         if (!err)
2136                                 mpd->pages_written++;
2137                         /*
2138                          * In error case, we have to continue because
2139                          * remaining pages are still locked
2140                          */
2141                         if (ret == 0)
2142                                 ret = err;
2143                 }
2144                 pagevec_release(&pvec);
2145         }
2146         ext4_io_submit(&io_submit);
2147         return ret;
2148 }
2149
2150 static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd,
2151                                         sector_t logical, long blk_cnt)
2152 {
2153         int nr_pages, i;
2154         pgoff_t index, end;
2155         struct pagevec pvec;
2156         struct inode *inode = mpd->inode;
2157         struct address_space *mapping = inode->i_mapping;
2158
2159         index = logical >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
2160         end   = (logical + blk_cnt - 1) >>
2161                                 (PAGE_CACHE_SHIFT - inode->i_blkbits);
2162         while (index <= end) {
2163                 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
2164                 if (nr_pages == 0)
2165                         break;
2166                 for (i = 0; i < nr_pages; i++) {
2167                         struct page *page = pvec.pages[i];
2168                         if (page->index > end)
2169                                 break;
2170                         BUG_ON(!PageLocked(page));
2171                         BUG_ON(PageWriteback(page));
2172                         block_invalidatepage(page, 0);
2173                         ClearPageUptodate(page);
2174                         unlock_page(page);
2175                 }
2176                 index = pvec.pages[nr_pages - 1]->index + 1;
2177                 pagevec_release(&pvec);
2178         }
2179         return;
2180 }
2181
2182 static void ext4_print_free_blocks(struct inode *inode)
2183 {
2184         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
2185         printk(KERN_CRIT "Total free blocks count %lld\n",
2186                ext4_count_free_blocks(inode->i_sb));
2187         printk(KERN_CRIT "Free/Dirty block details\n");
2188         printk(KERN_CRIT "free_blocks=%lld\n",
2189                (long long) percpu_counter_sum(&sbi->s_freeblocks_counter));
2190         printk(KERN_CRIT "dirty_blocks=%lld\n",
2191                (long long) percpu_counter_sum(&sbi->s_dirtyblocks_counter));
2192         printk(KERN_CRIT "Block reservation details\n");
2193         printk(KERN_CRIT "i_reserved_data_blocks=%u\n",
2194                EXT4_I(inode)->i_reserved_data_blocks);
2195         printk(KERN_CRIT "i_reserved_meta_blocks=%u\n",
2196                EXT4_I(inode)->i_reserved_meta_blocks);
2197         return;
2198 }
2199
2200 /*
2201  * mpage_da_map_and_submit - go through given space, map them
2202  *       if necessary, and then submit them for I/O
2203  *
2204  * @mpd - bh describing space
2205  *
2206  * The function skips space we know is already mapped to disk blocks.
2207  *
2208  */
2209 static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
2210 {
2211         int err, blks, get_blocks_flags;
2212         struct ext4_map_blocks map, *mapp = NULL;
2213         sector_t next = mpd->b_blocknr;
2214         unsigned max_blocks = mpd->b_size >> mpd->inode->i_blkbits;
2215         loff_t disksize = EXT4_I(mpd->inode)->i_disksize;
2216         handle_t *handle = NULL;
2217
2218         /*
2219          * If the blocks are mapped already, or we couldn't accumulate
2220          * any blocks, then proceed immediately to the submission stage.
2221          */
2222         if ((mpd->b_size == 0) ||
2223             ((mpd->b_state  & (1 << BH_Mapped)) &&
2224              !(mpd->b_state & (1 << BH_Delay)) &&
2225              !(mpd->b_state & (1 << BH_Unwritten))))
2226                 goto submit_io;
2227
2228         handle = ext4_journal_current_handle();
2229         BUG_ON(!handle);
2230
2231         /*
2232          * Call ext4_map_blocks() to allocate any delayed allocation
2233          * blocks, or to convert an uninitialized extent to be
2234          * initialized (in the case where we have written into
2235          * one or more preallocated blocks).
2236          *
2237          * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE to
2238          * indicate that we are on the delayed allocation path.  This
2239          * affects functions in many different parts of the allocation
2240          * call path.  This flag exists primarily because we don't
2241          * want to change *many* call functions, so ext4_map_blocks()
2242          * will set the magic i_delalloc_reserved_flag once the
2243          * inode's allocation semaphore is taken.
2244          *
2245          * If the blocks in questions were delalloc blocks, set
2246          * EXT4_GET_BLOCKS_DELALLOC_RESERVE so the delalloc accounting
2247          * variables are updated after the blocks have been allocated.
2248          */
2249         map.m_lblk = next;
2250         map.m_len = max_blocks;
2251         get_blocks_flags = EXT4_GET_BLOCKS_CREATE;
2252         if (ext4_should_dioread_nolock(mpd->inode))
2253                 get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
2254         if (mpd->b_state & (1 << BH_Delay))
2255                 get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
2256
2257         blks = ext4_map_blocks(handle, mpd->inode, &map, get_blocks_flags);
2258         if (blks < 0) {
2259                 struct super_block *sb = mpd->inode->i_sb;
2260
2261                 err = blks;
2262                 /*
2263                  * If get block returns EAGAIN or ENOSPC and there
2264                  * appears to be free blocks we will call
2265                  * ext4_writepage() for all of the pages which will
2266                  * just redirty the pages.
2267                  */
2268                 if (err == -EAGAIN)
2269                         goto submit_io;
2270
2271                 if (err == -ENOSPC &&
2272                     ext4_count_free_blocks(sb)) {
2273                         mpd->retval = err;
2274                         goto submit_io;
2275                 }
2276
2277                 /*
2278                  * get block failure will cause us to loop in
2279                  * writepages, because a_ops->writepage won't be able
2280                  * to make progress. The page will be redirtied by
2281                  * writepage and writepages will again try to write
2282                  * the same.
2283                  */
2284                 if (!(EXT4_SB(sb)->s_mount_flags & EXT4_MF_FS_ABORTED)) {
2285                         ext4_msg(sb, KERN_CRIT,
2286                                  "delayed block allocation failed for inode %lu "
2287                                  "at logical offset %llu with max blocks %zd "
2288                                  "with error %d", mpd->inode->i_ino,
2289                                  (unsigned long long) next,
2290                                  mpd->b_size >> mpd->inode->i_blkbits, err);
2291                         ext4_msg(sb, KERN_CRIT,
2292                                 "This should not happen!! Data will be lost\n");
2293                         if (err == -ENOSPC)
2294                                 ext4_print_free_blocks(mpd->inode);
2295                 }
2296                 /* invalidate all the pages */
2297                 ext4_da_block_invalidatepages(mpd, next,
2298                                 mpd->b_size >> mpd->inode->i_blkbits);
2299                 return;
2300         }
2301         BUG_ON(blks == 0);
2302
2303         mapp = &map;
2304         if (map.m_flags & EXT4_MAP_NEW) {
2305                 struct block_device *bdev = mpd->inode->i_sb->s_bdev;
2306                 int i;
2307
2308                 for (i = 0; i < map.m_len; i++)
2309                         unmap_underlying_metadata(bdev, map.m_pblk + i);
2310         }
2311
2312         if (ext4_should_order_data(mpd->inode)) {
2313                 err = ext4_jbd2_file_inode(handle, mpd->inode);
2314                 if (err)
2315                         /* This only happens if the journal is aborted */
2316                         return;
2317         }
2318
2319         /*
2320          * Update on-disk size along with block allocation.
2321          */
2322         disksize = ((loff_t) next + blks) << mpd->inode->i_blkbits;
2323         if (disksize > i_size_read(mpd->inode))
2324                 disksize = i_size_read(mpd->inode);
2325         if (disksize > EXT4_I(mpd->inode)->i_disksize) {
2326                 ext4_update_i_disksize(mpd->inode, disksize);
2327                 err = ext4_mark_inode_dirty(handle, mpd->inode);
2328                 if (err)
2329                         ext4_error(mpd->inode->i_sb,
2330                                    "Failed to mark inode %lu dirty",
2331                                    mpd->inode->i_ino);
2332         }
2333
2334 submit_io:
2335         mpage_da_submit_io(mpd, mapp);
2336         mpd->io_done = 1;
2337 }
2338
2339 #define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | \
2340                 (1 << BH_Delay) | (1 << BH_Unwritten))
2341
2342 /*
2343  * mpage_add_bh_to_extent - try to add one more block to extent of blocks
2344  *
2345  * @mpd->lbh - extent of blocks
2346  * @logical - logical number of the block in the file
2347  * @bh - bh of the block (used to access block's state)
2348  *
2349  * the function is used to collect contig. blocks in same state
2350  */
2351 static void mpage_add_bh_to_extent(struct mpage_da_data *mpd,
2352                                    sector_t logical, size_t b_size,
2353                                    unsigned long b_state)
2354 {
2355         sector_t next;
2356         int nrblocks = mpd->b_size >> mpd->inode->i_blkbits;
2357
2358         /*
2359          * XXX Don't go larger than mballoc is willing to allocate
2360          * This is a stopgap solution.  We eventually need to fold
2361          * mpage_da_submit_io() into this function and then call
2362          * ext4_map_blocks() multiple times in a loop
2363          */
2364         if (nrblocks >= 8*1024*1024/mpd->inode->i_sb->s_blocksize)
2365                 goto flush_it;
2366
2367         /* check if thereserved journal credits might overflow */
2368         if (!(ext4_test_inode_flag(mpd->inode, EXT4_INODE_EXTENTS))) {
2369                 if (nrblocks >= EXT4_MAX_TRANS_DATA) {
2370                         /*
2371                          * With non-extent format we are limited by the journal
2372                          * credit available.  Total credit needed to insert
2373                          * nrblocks contiguous blocks is dependent on the
2374                          * nrblocks.  So limit nrblocks.
2375                          */
2376                         goto flush_it;
2377                 } else if ((nrblocks + (b_size >> mpd->inode->i_blkbits)) >
2378                                 EXT4_MAX_TRANS_DATA) {
2379                         /*
2380                          * Adding the new buffer_head would make it cross the
2381                          * allowed limit for which we have journal credit
2382                          * reserved. So limit the new bh->b_size
2383                          */
2384                         b_size = (EXT4_MAX_TRANS_DATA - nrblocks) <<
2385                                                 mpd->inode->i_blkbits;
2386                         /* we will do mpage_da_submit_io in the next loop */
2387                 }
2388         }
2389         /*
2390          * First block in the extent
2391          */
2392         if (mpd->b_size == 0) {
2393                 mpd->b_blocknr = logical;
2394                 mpd->b_size = b_size;
2395                 mpd->b_state = b_state & BH_FLAGS;
2396                 return;
2397         }
2398
2399         next = mpd->b_blocknr + nrblocks;
2400         /*
2401          * Can we merge the block to our big extent?
2402          */
2403         if (logical == next && (b_state & BH_FLAGS) == mpd->b_state) {
2404                 mpd->b_size += b_size;
2405                 return;
2406         }
2407
2408 flush_it:
2409         /*
2410          * We couldn't merge the block to our extent, so we
2411          * need to flush current  extent and start new one
2412          */
2413         mpage_da_map_and_submit(mpd);
2414         return;
2415 }
2416
2417 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
2418 {
2419         return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
2420 }
2421
2422 /*
2423  * __mpage_da_writepage - finds extent of pages and blocks
2424  *
2425  * @page: page to consider
2426  * @wbc: not used, we just follow rules
2427  * @data: context
2428  *
2429  * The function finds extents of pages and scan them for all blocks.
2430  */
2431 static int __mpage_da_writepage(struct page *page,
2432                                 struct writeback_control *wbc,
2433                                 struct mpage_da_data *mpd)
2434 {
2435         struct inode *inode = mpd->inode;
2436         struct buffer_head *bh, *head;
2437         sector_t logical;
2438
2439         /*
2440          * Can we merge this page to current extent?
2441          */
2442         if (mpd->next_page != page->index) {
2443                 /*
2444                  * Nope, we can't. So, we map non-allocated blocks
2445                  * and start IO on them
2446                  */
2447                 if (mpd->next_page != mpd->first_page) {
2448                         mpage_da_map_and_submit(mpd);
2449                         /*
2450                          * skip rest of the page in the page_vec
2451                          */
2452                         redirty_page_for_writepage(wbc, page);
2453                         unlock_page(page);
2454                         return MPAGE_DA_EXTENT_TAIL;
2455                 }
2456
2457                 /*
2458                  * Start next extent of pages ...
2459                  */
2460                 mpd->first_page = page->index;
2461
2462                 /*
2463                  * ... and blocks
2464                  */
2465                 mpd->b_size = 0;
2466                 mpd->b_state = 0;
2467                 mpd->b_blocknr = 0;
2468         }
2469
2470         mpd->next_page = page->index + 1;
2471         logical = (sector_t) page->index <<
2472                   (PAGE_CACHE_SHIFT - inode->i_blkbits);
2473
2474         if (!page_has_buffers(page)) {
2475                 mpage_add_bh_to_extent(mpd, logical, PAGE_CACHE_SIZE,
2476                                        (1 << BH_Dirty) | (1 << BH_Uptodate));
2477                 if (mpd->io_done)
2478                         return MPAGE_DA_EXTENT_TAIL;
2479         } else {
2480                 /*
2481                  * Page with regular buffer heads, just add all dirty ones
2482                  */
2483                 head = page_buffers(page);
2484                 bh = head;
2485                 do {
2486                         BUG_ON(buffer_locked(bh));
2487                         /*
2488                          * We need to try to allocate
2489                          * unmapped blocks in the same page.
2490                          * Otherwise we won't make progress
2491                          * with the page in ext4_writepage
2492                          */
2493                         if (ext4_bh_delay_or_unwritten(NULL, bh)) {
2494                                 mpage_add_bh_to_extent(mpd, logical,
2495                                                        bh->b_size,
2496                                                        bh->b_state);
2497                                 if (mpd->io_done)
2498                                         return MPAGE_DA_EXTENT_TAIL;
2499                         } else if (buffer_dirty(bh) && (buffer_mapped(bh))) {
2500                                 /*
2501                                  * mapped dirty buffer. We need to update
2502                                  * the b_state because we look at
2503                                  * b_state in mpage_da_map_blocks. We don't
2504                                  * update b_size because if we find an
2505                                  * unmapped buffer_head later we need to
2506                                  * use the b_state flag of that buffer_head.
2507                                  */
2508                                 if (mpd->b_size == 0)
2509                                         mpd->b_state = bh->b_state & BH_FLAGS;
2510                         }
2511                         logical++;
2512                 } while ((bh = bh->b_this_page) != head);
2513         }
2514
2515         return 0;
2516 }
2517
2518 /*
2519  * This is a special get_blocks_t callback which is used by
2520  * ext4_da_write_begin().  It will either return mapped block or
2521  * reserve space for a single block.
2522  *
2523  * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
2524  * We also have b_blocknr = -1 and b_bdev initialized properly
2525  *
2526  * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
2527  * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
2528  * initialized properly.
2529  */
2530 static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
2531                                   struct buffer_head *bh, int create)
2532 {
2533         struct ext4_map_blocks map;
2534         int ret = 0;
2535         sector_t invalid_block = ~((sector_t) 0xffff);
2536
2537         if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
2538                 invalid_block = ~0;
2539
2540         BUG_ON(create == 0);
2541         BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
2542
2543         map.m_lblk = iblock;
2544         map.m_len = 1;
2545
2546         /*
2547          * first, we need to know whether the block is allocated already
2548          * preallocated blocks are unmapped but should treated
2549          * the same as allocated blocks.
2550          */
2551         ret = ext4_map_blocks(NULL, inode, &map, 0);
2552         if (ret < 0)
2553                 return ret;
2554         if (ret == 0) {
2555                 if (buffer_delay(bh))
2556                         return 0; /* Not sure this could or should happen */
2557                 /*
2558                  * XXX: __block_write_begin() unmaps passed block, is it OK?
2559                  */
2560                 ret = ext4_da_reserve_space(inode, iblock);
2561                 if (ret)
2562                         /* not enough space to reserve */
2563                         return ret;
2564
2565                 map_bh(bh, inode->i_sb, invalid_block);
2566                 set_buffer_new(bh);
2567                 set_buffer_delay(bh);
2568                 return 0;
2569         }
2570
2571         map_bh(bh, inode->i_sb, map.m_pblk);
2572         bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
2573
2574         if (buffer_unwritten(bh)) {
2575                 /* A delayed write to unwritten bh should be marked
2576                  * new and mapped.  Mapped ensures that we don't do
2577                  * get_block multiple times when we write to the same
2578                  * offset and new ensures that we do proper zero out
2579                  * for partial write.
2580                  */
2581                 set_buffer_new(bh);
2582                 set_buffer_mapped(bh);
2583         }
2584         return 0;
2585 }
2586
2587 /*
2588  * This function is used as a standard get_block_t calback function
2589  * when there is no desire to allocate any blocks.  It is used as a
2590  * callback function for block_write_begin() and block_write_full_page().
2591  * These functions should only try to map a single block at a time.
2592  *
2593  * Since this function doesn't do block allocations even if the caller
2594  * requests it by passing in create=1, it is critically important that
2595  * any caller checks to make sure that any buffer heads are returned
2596  * by this function are either all already mapped or marked for
2597  * delayed allocation before calling  block_write_full_page().  Otherwise,
2598  * b_blocknr could be left unitialized, and the page write functions will
2599  * be taken by surprise.
2600  */
2601 static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
2602                                    struct buffer_head *bh_result, int create)
2603 {
2604         BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
2605         return _ext4_get_block(inode, iblock, bh_result, 0);
2606 }
2607
2608 static int bget_one(handle_t *handle, struct buffer_head *bh)
2609 {
2610         get_bh(bh);
2611         return 0;
2612 }
2613
2614 static int bput_one(handle_t *handle, struct buffer_head *bh)
2615 {
2616         put_bh(bh);
2617         return 0;
2618 }
2619
2620 static int __ext4_journalled_writepage(struct page *page,
2621                                        unsigned int len)
2622 {
2623         struct address_space *mapping = page->mapping;
2624         struct inode *inode = mapping->host;
2625         struct buffer_head *page_bufs;
2626         handle_t *handle = NULL;
2627         int ret = 0;
2628         int err;
2629
2630         ClearPageChecked(page);
2631         page_bufs = page_buffers(page);
2632         BUG_ON(!page_bufs);
2633         walk_page_buffers(handle, page_bufs, 0, len, NULL, bget_one);
2634         /* As soon as we unlock the page, it can go away, but we have
2635          * references to buffers so we are safe */
2636         unlock_page(page);
2637
2638         handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
2639         if (IS_ERR(handle)) {
2640                 ret = PTR_ERR(handle);
2641                 goto out;
2642         }
2643
2644         ret = walk_page_buffers(handle, page_bufs, 0, len, NULL,
2645                                 do_journal_get_write_access);
2646
2647         err = walk_page_buffers(handle, page_bufs, 0, len, NULL,
2648                                 write_end_fn);
2649         if (ret == 0)
2650                 ret = err;
2651         err = ext4_journal_stop(handle);
2652         if (!ret)
2653                 ret = err;
2654
2655         walk_page_buffers(handle, page_bufs, 0, len, NULL, bput_one);
2656         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
2657 out:
2658         return ret;
2659 }
2660
2661 static int ext4_set_bh_endio(struct buffer_head *bh, struct inode *inode);
2662 static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate);
2663
2664 /*
2665  * Note that we don't need to start a transaction unless we're journaling data
2666  * because we should have holes filled from ext4_page_mkwrite(). We even don't
2667  * need to file the inode to the transaction's list in ordered mode because if
2668  * we are writing back data added by write(), the inode is already there and if
2669  * we are writing back data modified via mmap(), noone guarantees in which
2670  * transaction the data will hit the disk. In case we are journaling data, we
2671  * cannot start transaction directly because transaction start ranks above page
2672  * lock so we have to do some magic.
2673  *
2674  * This function can get called via...
2675  *   - ext4_da_writepages after taking page lock (have journal handle)
2676  *   - journal_submit_inode_data_buffers (no journal handle)
2677  *   - shrink_page_list via pdflush (no journal handle)
2678  *   - grab_page_cache when doing write_begin (have journal handle)
2679  *
2680  * We don't do any block allocation in this function. If we have page with
2681  * multiple blocks we need to write those buffer_heads that are mapped. This
2682  * is important for mmaped based write. So if we do with blocksize 1K
2683  * truncate(f, 1024);
2684  * a = mmap(f, 0, 4096);
2685  * a[0] = 'a';
2686  * truncate(f, 4096);
2687  * we have in the page first buffer_head mapped via page_mkwrite call back
2688  * but other bufer_heads would be unmapped but dirty(dirty done via the
2689  * do_wp_page). So writepage should write the first block. If we modify
2690  * the mmap area beyond 1024 we will again get a page_fault and the
2691  * page_mkwrite callback will do the block allocation and mark the
2692  * buffer_heads mapped.
2693  *
2694  * We redirty the page if we have any buffer_heads that is either delay or
2695  * unwritten in the page.
2696  *
2697  * We can get recursively called as show below.
2698  *
2699  *      ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
2700  *              ext4_writepage()
2701  *
2702  * But since we don't do any block allocation we should not deadlock.
2703  * Page also have the dirty flag cleared so we don't get recurive page_lock.
2704  */
2705 static int ext4_writepage(struct page *page,
2706                           struct writeback_control *wbc)
2707 {
2708         int ret = 0, commit_write = 0;
2709         loff_t size;
2710         unsigned int len;
2711         struct buffer_head *page_bufs = NULL;
2712         struct inode *inode = page->mapping->host;
2713
2714         trace_ext4_writepage(inode, page);
2715         size = i_size_read(inode);
2716         if (page->index == size >> PAGE_CACHE_SHIFT)
2717                 len = size & ~PAGE_CACHE_MASK;
2718         else
2719                 len = PAGE_CACHE_SIZE;
2720
2721         /*
2722          * If the page does not have buffers (for whatever reason),
2723          * try to create them using __block_write_begin.  If this
2724          * fails, redirty the page and move on.
2725          */
2726         if (!page_has_buffers(page)) {
2727                 if (__block_write_begin(page, 0, len,
2728                                         noalloc_get_block_write)) {
2729                 redirty_page:
2730                         redirty_page_for_writepage(wbc, page);
2731                         unlock_page(page);
2732                         return 0;
2733                 }
2734                 commit_write = 1;
2735         }
2736         page_bufs = page_buffers(page);
2737         if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
2738                               ext4_bh_delay_or_unwritten)) {
2739                 /*
2740                  * We don't want to do block allocation, so redirty
2741                  * the page and return.  We may reach here when we do
2742                  * a journal commit via journal_submit_inode_data_buffers.
2743                  * We can also reach here via shrink_page_list
2744                  */
2745                 goto redirty_page;
2746         }
2747         if (commit_write)
2748                 /* now mark the buffer_heads as dirty and uptodate */
2749                 block_commit_write(page, 0, len);
2750
2751         if (PageChecked(page) && ext4_should_journal_data(inode))
2752                 /*
2753                  * It's mmapped pagecache.  Add buffers and journal it.  There
2754                  * doesn't seem much point in redirtying the page here.
2755                  */
2756                 return __ext4_journalled_writepage(page, len);
2757
2758         if (buffer_uninit(page_bufs)) {
2759                 ext4_set_bh_endio(page_bufs, inode);
2760                 ret = block_write_full_page_endio(page, noalloc_get_block_write,
2761                                             wbc, ext4_end_io_buffer_write);
2762         } else
2763                 ret = block_write_full_page(page, noalloc_get_block_write,
2764                                             wbc);
2765
2766         return ret;
2767 }
2768
2769 /*
2770  * This is called via ext4_da_writepages() to
2771  * calulate the total number of credits to reserve to fit
2772  * a single extent allocation into a single transaction,
2773  * ext4_da_writpeages() will loop calling this before
2774  * the block allocation.
2775  */
2776
2777 static int ext4_da_writepages_trans_blocks(struct inode *inode)
2778 {
2779         int max_blocks = EXT4_I(inode)->i_reserved_data_blocks;
2780
2781         /*
2782          * With non-extent format the journal credit needed to
2783          * insert nrblocks contiguous block is dependent on
2784          * number of contiguous block. So we will limit
2785          * number of contiguous block to a sane value
2786          */
2787         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) &&
2788             (max_blocks > EXT4_MAX_TRANS_DATA))
2789                 max_blocks = EXT4_MAX_TRANS_DATA;
2790
2791         return ext4_chunk_trans_blocks(inode, max_blocks);
2792 }
2793
2794 /*
2795  * write_cache_pages_da - walk the list of dirty pages of the given
2796  * address space and call the callback function (which usually writes
2797  * the pages).
2798  *
2799  * This is a forked version of write_cache_pages().  Differences:
2800  *      Range cyclic is ignored.
2801  *      no_nrwrite_index_update is always presumed true
2802  */
2803 static int write_cache_pages_da(struct address_space *mapping,
2804                                 struct writeback_control *wbc,
2805                                 struct mpage_da_data *mpd,
2806                                 pgoff_t *done_index)
2807 {
2808         int ret = 0;
2809         int done = 0;
2810         struct pagevec pvec;
2811         unsigned nr_pages;
2812         pgoff_t index;
2813         pgoff_t end;            /* Inclusive */
2814         long nr_to_write = wbc->nr_to_write;
2815         int tag;
2816
2817         pagevec_init(&pvec, 0);
2818         index = wbc->range_start >> PAGE_CACHE_SHIFT;
2819         end = wbc->range_end >> PAGE_CACHE_SHIFT;
2820
2821         if (wbc->sync_mode == WB_SYNC_ALL)
2822                 tag = PAGECACHE_TAG_TOWRITE;
2823         else
2824                 tag = PAGECACHE_TAG_DIRTY;
2825
2826         *done_index = index;
2827         while (!done && (index <= end)) {
2828                 int i;
2829
2830                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
2831                               min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
2832                 if (nr_pages == 0)
2833                         break;
2834
2835                 for (i = 0; i < nr_pages; i++) {
2836                         struct page *page = pvec.pages[i];
2837
2838                         /*
2839                          * At this point, the page may be truncated or
2840                          * invalidated (changing page->mapping to NULL), or
2841                          * even swizzled back from swapper_space to tmpfs file
2842                          * mapping. However, page->index will not change
2843                          * because we have a reference on the page.
2844                          */
2845                         if (page->index > end) {
2846                                 done = 1;
2847                                 break;
2848                         }
2849
2850                         *done_index = page->index + 1;
2851
2852                         lock_page(page);
2853
2854                         /*
2855                          * Page truncated or invalidated. We can freely skip it
2856                          * then, even for data integrity operations: the page
2857                          * has disappeared concurrently, so there could be no
2858                          * real expectation of this data interity operation
2859                          * even if there is now a new, dirty page at the same
2860                          * pagecache address.
2861                          */
2862                         if (unlikely(page->mapping != mapping)) {
2863 continue_unlock:
2864                                 unlock_page(page);
2865                                 continue;
2866                         }
2867
2868                         if (!PageDirty(page)) {
2869                                 /* someone wrote it for us */
2870                                 goto continue_unlock;
2871                         }
2872
2873                         if (PageWriteback(page)) {
2874                                 if (wbc->sync_mode != WB_SYNC_NONE)
2875                                         wait_on_page_writeback(page);
2876                                 else
2877                                         goto continue_unlock;
2878                         }
2879
2880                         BUG_ON(PageWriteback(page));
2881                         if (!clear_page_dirty_for_io(page))
2882                                 goto continue_unlock;
2883
2884                         ret = __mpage_da_writepage(page, wbc, mpd);
2885                         if (unlikely(ret)) {
2886                                 if (ret == AOP_WRITEPAGE_ACTIVATE) {
2887                                         unlock_page(page);
2888                                         ret = 0;
2889                                 } else {
2890                                         done = 1;
2891                                         break;
2892                                 }
2893                         }
2894
2895                         if (nr_to_write > 0) {
2896                                 nr_to_write--;
2897                                 if (nr_to_write == 0 &&
2898                                     wbc->sync_mode == WB_SYNC_NONE) {
2899                                         /*
2900                                          * We stop writing back only if we are
2901                                          * not doing integrity sync. In case of
2902                                          * integrity sync we have to keep going
2903                                          * because someone may be concurrently
2904                                          * dirtying pages, and we might have
2905                                          * synced a lot of newly appeared dirty
2906                                          * pages, but have not synced all of the
2907                                          * old dirty pages.
2908                                          */
2909                                         done = 1;
2910                                         break;
2911                                 }
2912                         }
2913                 }
2914                 pagevec_release(&pvec);
2915                 cond_resched();
2916         }
2917         return ret;
2918 }
2919
2920
2921 static int ext4_da_writepages(struct address_space *mapping,
2922                               struct writeback_control *wbc)
2923 {
2924         pgoff_t index;
2925         int range_whole = 0;
2926         handle_t *handle = NULL;
2927         struct mpage_da_data mpd;
2928         struct inode *inode = mapping->host;
2929         int pages_written = 0;
2930         long pages_skipped;
2931         unsigned int max_pages;
2932         int range_cyclic, cycled = 1, io_done = 0;
2933         int needed_blocks, ret = 0;
2934         long desired_nr_to_write, nr_to_writebump = 0;
2935         loff_t range_start = wbc->range_start;
2936         struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2937         pgoff_t done_index = 0;
2938         pgoff_t end;
2939
2940         trace_ext4_da_writepages(inode, wbc);
2941
2942         /*
2943          * No pages to write? This is mainly a kludge to avoid starting
2944          * a transaction for special inodes like journal inode on last iput()
2945          * because that could violate lock ordering on umount
2946          */
2947         if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
2948                 return 0;
2949
2950         /*
2951          * If the filesystem has aborted, it is read-only, so return
2952          * right away instead of dumping stack traces later on that
2953          * will obscure the real source of the problem.  We test
2954          * EXT4_MF_FS_ABORTED instead of sb->s_flag's MS_RDONLY because
2955          * the latter could be true if the filesystem is mounted
2956          * read-only, and in that case, ext4_da_writepages should
2957          * *never* be called, so if that ever happens, we would want
2958          * the stack trace.
2959          */
2960         if (unlikely(sbi->s_mount_flags & EXT4_MF_FS_ABORTED))
2961                 return -EROFS;
2962
2963         if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2964                 range_whole = 1;
2965
2966         range_cyclic = wbc->range_cyclic;
2967         if (wbc->range_cyclic) {
2968                 index = mapping->writeback_index;
2969                 if (index)
2970                         cycled = 0;
2971                 wbc->range_start = index << PAGE_CACHE_SHIFT;
2972                 wbc->range_end  = LLONG_MAX;
2973                 wbc->range_cyclic = 0;
2974                 end = -1;
2975         } else {
2976                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
2977                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
2978         }
2979
2980         /*
2981          * This works around two forms of stupidity.  The first is in
2982          * the writeback code, which caps the maximum number of pages
2983          * written to be 1024 pages.  This is wrong on multiple
2984          * levels; different architectues have a different page size,
2985          * which changes the maximum amount of data which gets
2986          * written.  Secondly, 4 megabytes is way too small.  XFS
2987          * forces this value to be 16 megabytes by multiplying
2988          * nr_to_write parameter by four, and then relies on its
2989          * allocator to allocate larger extents to make them
2990          * contiguous.  Unfortunately this brings us to the second
2991          * stupidity, which is that ext4's mballoc code only allocates
2992          * at most 2048 blocks.  So we force contiguous writes up to
2993          * the number of dirty blocks in the inode, or
2994          * sbi->max_writeback_mb_bump whichever is smaller.
2995          */
2996         max_pages = sbi->s_max_writeback_mb_bump << (20 - PAGE_CACHE_SHIFT);
2997         if (!range_cyclic && range_whole) {
2998                 if (wbc->nr_to_write == LONG_MAX)
2999                         desired_nr_to_write = wbc->nr_to_write;
3000                 else
3001                         desired_nr_to_write = wbc->nr_to_write * 8;
3002         } else
3003                 desired_nr_to_write = ext4_num_dirty_pages(inode, index,
3004                                                            max_pages);
3005         if (desired_nr_to_write > max_pages)
3006                 desired_nr_to_write = max_pages;
3007
3008         if (wbc->nr_to_write < desired_nr_to_write) {
3009                 nr_to_writebump = desired_nr_to_write - wbc->nr_to_write;
3010                 wbc->nr_to_write = desired_nr_to_write;
3011         }
3012
3013         mpd.wbc = wbc;
3014         mpd.inode = mapping->host;
3015
3016         pages_skipped = wbc->pages_skipped;
3017
3018 retry:
3019         if (wbc->sync_mode == WB_SYNC_ALL)
3020                 tag_pages_for_writeback(mapping, index, end);
3021
3022         while (!ret && wbc->nr_to_write > 0) {
3023
3024                 /*
3025                  * we  insert one extent at a time. So we need
3026                  * credit needed for single extent allocation.
3027                  * journalled mode is currently not supported
3028                  * by delalloc
3029                  */
3030                 BUG_ON(ext4_should_journal_data(inode));
3031                 needed_blocks = ext4_da_writepages_trans_blocks(inode);
3032
3033                 /* start a new transaction*/
3034                 handle = ext4_journal_start(inode, needed_blocks);
3035                 if (IS_ERR(handle)) {
3036                         ret = PTR_ERR(handle);
3037                         ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
3038                                "%ld pages, ino %lu; err %d", __func__,
3039                                 wbc->nr_to_write, inode->i_ino, ret);
3040                         goto out_writepages;
3041                 }
3042
3043                 /*
3044                  * Now call __mpage_da_writepage to find the next
3045                  * contiguous region of logical blocks that need
3046                  * blocks to be allocated by ext4.  We don't actually
3047                  * submit the blocks for I/O here, even though
3048                  * write_cache_pages thinks it will, and will set the
3049                  * pages as clean for write before calling
3050                  * __mpage_da_writepage().
3051                  */
3052                 mpd.b_size = 0;
3053                 mpd.b_state = 0;
3054                 mpd.b_blocknr = 0;
3055                 mpd.first_page = 0;
3056                 mpd.next_page = 0;
3057                 mpd.io_done = 0;
3058                 mpd.pages_written = 0;
3059                 mpd.retval = 0;
3060                 ret = write_cache_pages_da(mapping, wbc, &mpd, &done_index);
3061                 /*
3062                  * If we have a contiguous extent of pages and we
3063                  * haven't done the I/O yet, map the blocks and submit
3064                  * them for I/O.
3065                  */
3066                 if (!mpd.io_done && mpd.next_page != mpd.first_page) {
3067                         mpage_da_map_and_submit(&mpd);
3068                         ret = MPAGE_DA_EXTENT_TAIL;
3069                 }
3070                 trace_ext4_da_write_pages(inode, &mpd);
3071                 wbc->nr_to_write -= mpd.pages_written;
3072
3073                 ext4_journal_stop(handle);
3074
3075                 if ((mpd.retval == -ENOSPC) && sbi->s_journal) {
3076                         /* commit the transaction which would
3077                          * free blocks released in the transaction
3078                          * and try again
3079                          */
3080                         jbd2_journal_force_commit_nested(sbi->s_journal);
3081                         wbc->pages_skipped = pages_skipped;
3082                         ret = 0;
3083                 } else if (ret == MPAGE_DA_EXTENT_TAIL) {
3084                         /*
3085                          * got one extent now try with
3086