fs/omfs/file.c

   1 /*
   2  * OMFS (as used by RIO Karma) file operations.
   3  * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
   4  * Released under GPL v2.
   5  */
   6
   7 #include <linux/version.h>
   8 #include <linux/module.h>
   9 #include <linux/fs.h>
  10 #include <linux/buffer_head.h>
  11 #include <linux/mpage.h>
  12 #include "omfs.h"
  13
  14 static int omfs_sync_file(struct file *file, struct dentry *dentry,
  15                 int datasync)
  16 {
  17         struct inode *inode = dentry->d_inode;
  18         int err;
  19
  20         err = sync_mapping_buffers(inode->i_mapping);
  21         if (!(inode->i_state & I_DIRTY))
  22                 return err;
  23         if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
  24                 return err;
  25         err |= omfs_sync_inode(inode);
  26         return err ? -EIO : 0;
  27 }
  28
  29 void omfs_make_empty_table(struct buffer_head *bh, int offset)
  30 {
  31         struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];
  32
  33         oe->e_next = ~cpu_to_be64(0ULL);
  34         oe->e_extent_count = cpu_to_be32(1),
  35         oe->e_fill = cpu_to_be32(0x22),
  36         oe->e_entry.e_cluster = ~cpu_to_be64(0ULL);
  37         oe->e_entry.e_blocks = ~cpu_to_be64(0ULL);
  38 }
  39
  40 int omfs_shrink_inode(struct inode *inode)
  41 {
  42         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
  43         struct omfs_extent *oe;
  44         struct omfs_extent_entry *entry;
  45         struct buffer_head *bh;
  46         u64 next, last;
  47         u32 extent_count;
  48         int ret;
  49
  50         /* traverse extent table, freeing each entry that is greater
  51          * than inode->i_size;
  52          */
  53         next = inode->i_ino;
  54
  55         /* only support truncate -> 0 for now */
  56         ret = -EIO;
  57         if (inode->i_size != 0)
  58                 goto out;
  59
  60         bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
  61         if (!bh)
  62                 goto out;
  63
  64         oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
  65
  66         for (;;) {
  67
  68                 if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next)) {
  69                         brelse(bh);
  70                         goto out;
  71                 }
  72
  73                 extent_count = be32_to_cpu(oe->e_extent_count);
  74                 last = next;
  75                 next = be64_to_cpu(oe->e_next);
  76                 entry = &oe->e_entry;
  77
  78                 /* ignore last entry as it is the terminator */
  79                 for (; extent_count > 1; extent_count--) {
  80                         u64 start, count;
  81                         start = be64_to_cpu(entry->e_cluster);
  82                         count = be64_to_cpu(entry->e_blocks);
  83
  84                         omfs_clear_range(inode->i_sb, start, (int) count);
  85                         entry++;
  86                 }
  87                 omfs_make_empty_table(bh, (char *) oe - bh->b_data);
  88                 mark_buffer_dirty(bh);
  89                 brelse(bh);
  90
  91                 if (last != inode->i_ino)
  92                         omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);
  93
  94                 if (next == ~0)
  95                         break;
  96
  97                 bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
  98                 if (!bh)
  99                         goto out;
 100                 oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
 101         }
 102         ret = 0;
 103 out:
 104         return ret;
 105 }
 106
 107 static void omfs_truncate(struct inode *inode)
 108 {
 109         omfs_shrink_inode(inode);
 110         mark_inode_dirty(inode);
 111 }
 112
 113 /*
 114  * Add new blocks to the current extent, or create new entries/continuations
 115  * as necessary.
 116  */
 117 static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,
 118                         u64 *ret_block)
 119 {
 120         struct omfs_extent_entry *terminator;
 121         struct omfs_extent_entry *entry = &oe->e_entry;
 122         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
 123         u32 extent_count = be32_to_cpu(oe->e_extent_count);
 124         u64 new_block = 0;
 125         u32 max_count;
 126         int new_count;
 127         int ret = 0;
 128
 129         /* reached the end of the extent table with no blocks mapped.
 130          * there are three possibilities for adding: grow last extent,
 131          * add a new extent to the current extent table, and add a
 132          * continuation inode.  in last two cases need an allocator for
 133          * sbi->s_cluster_size
 134          */
 135
 136         /* TODO: handle holes */
 137
 138         /* should always have a terminator */
 139         if (extent_count < 1)
 140                 return -EIO;
 141
 142         /* trivially grow current extent, if next block is not taken */
 143         terminator = entry + extent_count - 1;
 144         if (extent_count > 1) {
 145                 entry = terminator-1;
 146                 new_block = be64_to_cpu(entry->e_cluster) +
 147                         be64_to_cpu(entry->e_blocks);
 148
 149                 if (omfs_allocate_block(inode->i_sb, new_block)) {
 150                         entry->e_blocks =
 151                                 cpu_to_be64(be64_to_cpu(entry->e_blocks) + 1);
 152                         terminator->e_blocks = ~(cpu_to_be64(
 153                                 be64_to_cpu(~terminator->e_blocks) + 1));
 154                         goto out;
 155                 }
 156         }
 157         max_count = (sbi->s_sys_blocksize - OMFS_EXTENT_START -
 158                 sizeof(struct omfs_extent)) /
 159                 sizeof(struct omfs_extent_entry) + 1;
 160
 161         /* TODO: add a continuation block here */
 162         if (be32_to_cpu(oe->e_extent_count) > max_count-1)
 163                 return -EIO;
 164
 165         /* try to allocate a new cluster */
 166         ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
 167                 &new_block, &new_count);
 168         if (ret)
 169                 goto out_fail;
 170
 171         /* copy terminator down an entry */
 172         entry = terminator;
 173         terminator++;
 174         memcpy(terminator, entry, sizeof(struct omfs_extent_entry));
 175
 176         entry->e_cluster = cpu_to_be64(new_block);
 177         entry->e_blocks = cpu_to_be64((u64) new_count);
 178
 179         terminator->e_blocks = ~(cpu_to_be64(
 180                 be64_to_cpu(~terminator->e_blocks) + (u64) new_count));
 181
 182         /* write in new entry */
 183         oe->e_extent_count = cpu_to_be32(1 + be32_to_cpu(oe->e_extent_count));
 184
 185 out:
 186         *ret_block = new_block;
 187 out_fail:
 188         return ret;
 189 }
 190
 191 /*
 192  * Scans across the directory table for a given file block number.
 193  * If block not found, return 0.
 194  */
 195 static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
 196                         sector_t block, int count, int *left)
 197 {
 198         /* count > 1 because of terminator */
 199         sector_t searched = 0;
 200         for (; count > 1; count--) {
 201                 int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
 202                         be64_to_cpu(ent->e_blocks));
 203
 204                 if (block >= searched  &&
 205                     block < searched + numblocks) {
 206                         /*
 207                          * found it at cluster + (block - searched)
 208                          * numblocks - (block - searched) is remainder
 209                          */
 210                         *left = numblocks - (block - searched);
 211                         return clus_to_blk(OMFS_SB(inode->i_sb),
 212                                 be64_to_cpu(ent->e_cluster)) +
 213                                 block - searched;
 214                 }
 215                 searched += numblocks;
 216                 ent++;
 217         }
 218         return 0;
 219 }
 220
 221 static int omfs_get_block(struct inode *inode, sector_t block,
 222                           struct buffer_head *bh_result, int create)
 223 {
 224         struct buffer_head *bh;
 225         sector_t next, offset;
 226         int ret;
 227         u64 new_block;
 228         int extent_count;
 229         struct omfs_extent *oe;
 230         struct omfs_extent_entry *entry;
 231         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
 232         int max_blocks = bh_result->b_size >> inode->i_blkbits;
 233         int remain;
 234
 235         ret = -EIO;
 236         bh = sb_bread(inode->i_sb, clus_to_blk(sbi, inode->i_ino));
 237         if (!bh)
 238                 goto out;
 239
 240         oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
 241         next = inode->i_ino;
 242
 243         for (;;) {
 244
 245                 if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
 246                         goto out_brelse;
 247
 248                 extent_count = be32_to_cpu(oe->e_extent_count);
 249                 next = be64_to_cpu(oe->e_next);
 250                 entry = &oe->e_entry;
 251
 252                 offset = find_block(inode, entry, block, extent_count, &remain);
 253                 if (offset > 0) {
 254                         ret = 0;
 255                         map_bh(bh_result, inode->i_sb, offset);
 256                         if (remain > max_blocks)
 257                                 remain = max_blocks;
 258                         bh_result->b_size = (remain << inode->i_blkbits);
 259                         goto out_brelse;
 260                 }
 261                 if (next == ~0)
 262                         break;
 263
 264                 brelse(bh);
 265                 bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
 266                 if (!bh)
 267                         goto out;
 268                 oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
 269         }
 270         if (create) {
 271                 ret = omfs_grow_extent(inode, oe, &new_block);
 272                 if (ret == 0) {
 273                         mark_buffer_dirty(bh);
 274                         mark_inode_dirty(inode);
 275                         map_bh(bh_result, inode->i_sb,
 276                                         clus_to_blk(sbi, new_block));
 277                 }
 278         }
 279 out_brelse:
 280         brelse(bh);
 281 out:
 282         return ret;
 283 }
 284
 285 static int omfs_readpage(struct file *file, struct page *page)
 286 {
 287         return block_read_full_page(page, omfs_get_block);
 288 }
 289
 290 static int omfs_readpages(struct file *file, struct address_space *mapping,
 291                 struct list_head *pages, unsigned nr_pages)
 292 {
 293         return mpage_readpages(mapping, pages, nr_pages, omfs_get_block);
 294 }
 295
 296 static int omfs_writepage(struct page *page, struct writeback_control *wbc)
 297 {
 298         return block_write_full_page(page, omfs_get_block, wbc);
 299 }
 300
 301 static int
 302 omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 303 {
 304         return mpage_writepages(mapping, wbc, omfs_get_block);
 305 }
 306
 307 static int omfs_write_begin(struct file *file, struct address_space *mapping,
 308                         loff_t pos, unsigned len, unsigned flags,
 309                         struct page **pagep, void **fsdata)
 310 {
 311         *pagep = NULL;
 312         return block_write_begin(file, mapping, pos, len, flags,
 313                                 pagep, fsdata, omfs_get_block);
 314 }
 315
 316 static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
 317 {
 318         return generic_block_bmap(mapping, block, omfs_get_block);
 319 }
 320
 321 struct file_operations omfs_file_operations = {
 322         .llseek = generic_file_llseek,
 323         .read = do_sync_read,
 324         .write = do_sync_write,
 325         .aio_read = generic_file_aio_read,
 326         .aio_write = generic_file_aio_write,
 327         .mmap = generic_file_mmap,
 328         .fsync = omfs_sync_file,
 329         .splice_read = generic_file_splice_read,
 330 };
 331
 332 struct inode_operations omfs_file_inops = {
 333         .truncate = omfs_truncate
 334 };
 335
 336 struct address_space_operations omfs_aops = {
 337         .readpage = omfs_readpage,
 338         .readpages = omfs_readpages,
 339         .writepage = omfs_writepage,
 340         .writepages = omfs_writepages,
 341         .sync_page = block_sync_page,
 342         .write_begin = omfs_write_begin,
 343         .write_end = generic_write_end,
 344         .bmap = omfs_bmap,
 345 };
 346