4 * Copyright (C) 1999,2000 Tigran Aivazian <tigran@veritas.com>
6 * Make the file block allocation algorithm understand the size
7 * of the underlying block device.
8 * Copyright (C) 2007 Dmitri Vorobiev <dmitri.vorobiev@gmail.com>
13 #include <linux/buffer_head.h>
19 #define dprintf(x...) printf(x)
24 const struct file_operations bfs_file_operations = {
25 .llseek = generic_file_llseek,
27 .aio_read = generic_file_aio_read,
28 .write = do_sync_write,
29 .aio_write = generic_file_aio_write,
30 .mmap = generic_file_mmap,
31 .splice_read = generic_file_splice_read,
34 static int bfs_move_block(unsigned long from, unsigned long to,
35 struct super_block *sb)
37 struct buffer_head *bh, *new;
39 bh = sb_bread(sb, from);
42 new = sb_getblk(sb, to);
43 memcpy(new->b_data, bh->b_data, bh->b_size);
44 mark_buffer_dirty(new);
50 static int bfs_move_blocks(struct super_block *sb, unsigned long start,
51 unsigned long end, unsigned long where)
55 dprintf("%08lx-%08lx->%08lx\n", start, end, where);
56 for (i = start; i <= end; i++)
57 if(bfs_move_block(i, where + i, sb)) {
58 dprintf("failed to move block %08lx -> %08lx\n", i,
65 static int bfs_get_block(struct inode *inode, sector_t block,
66 struct buffer_head *bh_result, int create)
70 struct super_block *sb = inode->i_sb;
71 struct bfs_sb_info *info = BFS_SB(sb);
72 struct bfs_inode_info *bi = BFS_I(inode);
74 phys = bi->i_sblock + block;
76 if (phys <= bi->i_eblock) {
77 dprintf("c=%d, b=%08lx, phys=%09lx (granted)\n",
78 create, (unsigned long)block, phys);
79 map_bh(bh_result, sb, phys);
85 * If the file is not empty and the requested block is within the
86 * range of blocks allocated for this file, we can grant it.
88 if (bi->i_sblock && (phys <= bi->i_eblock)) {
89 dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n",
90 create, (unsigned long)block, phys);
91 map_bh(bh_result, sb, phys);
95 /* The file will be extended, so let's see if there is enough space. */
96 if (phys >= info->si_blocks)
99 /* The rest has to be protected against itself. */
100 mutex_lock(&info->bfs_lock);
103 * If the last data block for this file is the last allocated
104 * block, we can extend the file trivially, without moving it
107 if (bi->i_eblock == info->si_lf_eblk) {
108 dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n",
109 create, (unsigned long)block, phys);
110 map_bh(bh_result, sb, phys);
111 info->si_freeb -= phys - bi->i_eblock;
112 info->si_lf_eblk = bi->i_eblock = phys;
113 mark_inode_dirty(inode);
118 /* Ok, we have to move this entire file to the next free block. */
119 phys = info->si_lf_eblk + 1;
120 if (phys + block >= info->si_blocks) {
126 err = bfs_move_blocks(inode->i_sb, bi->i_sblock,
129 dprintf("failed to move ino=%08lx -> fs corruption\n",
136 dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n",
137 create, (unsigned long)block, phys);
140 info->si_lf_eblk = bi->i_eblock = phys;
143 * This assumes nothing can write the inode back while we are here
144 * and thus update inode->i_blocks! (XXX)
146 info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks;
147 mark_inode_dirty(inode);
148 map_bh(bh_result, sb, phys);
150 mutex_unlock(&info->bfs_lock);
154 static int bfs_writepage(struct page *page, struct writeback_control *wbc)
156 return block_write_full_page(page, bfs_get_block, wbc);
159 static int bfs_readpage(struct file *file, struct page *page)
161 return block_read_full_page(page, bfs_get_block);
164 static int bfs_write_begin(struct file *file, struct address_space *mapping,
165 loff_t pos, unsigned len, unsigned flags,
166 struct page **pagep, void **fsdata)
170 ret = block_write_begin(mapping, pos, len, flags, pagep,
173 loff_t isize = mapping->host->i_size;
174 if (pos + len > isize)
175 vmtruncate(mapping->host, isize);
181 static sector_t bfs_bmap(struct address_space *mapping, sector_t block)
183 return generic_block_bmap(mapping, block, bfs_get_block);
186 const struct address_space_operations bfs_aops = {
187 .readpage = bfs_readpage,
188 .writepage = bfs_writepage,
189 .write_begin = bfs_write_begin,
190 .write_end = generic_write_end,
194 const struct inode_operations bfs_file_inops;