blob: 747fd1ea55e0c20e8ae2c7f7044b88af8710af87 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * fs/bfs/file.c
3 * BFS file operations.
4 * Copyright (C) 1999,2000 Tigran Aivazian <tigran@veritas.com>
5 */
6
7#include <linux/fs.h>
8#include <linux/buffer_head.h>
9#include <linux/smp_lock.h>
10#include "bfs.h"
11
12#undef DEBUG
13
14#ifdef DEBUG
15#define dprintf(x...) printf(x)
16#else
17#define dprintf(x...)
18#endif
19
20struct file_operations bfs_file_operations = {
21 .llseek = generic_file_llseek,
22 .read = generic_file_read,
23 .write = generic_file_write,
24 .mmap = generic_file_mmap,
25 .sendfile = generic_file_sendfile,
26};
27
28static int bfs_move_block(unsigned long from, unsigned long to, struct super_block *sb)
29{
30 struct buffer_head *bh, *new;
31
32 bh = sb_bread(sb, from);
33 if (!bh)
34 return -EIO;
35 new = sb_getblk(sb, to);
36 memcpy(new->b_data, bh->b_data, bh->b_size);
37 mark_buffer_dirty(new);
38 bforget(bh);
39 brelse(new);
40 return 0;
41}
42
43static int bfs_move_blocks(struct super_block *sb, unsigned long start, unsigned long end,
44 unsigned long where)
45{
46 unsigned long i;
47
48 dprintf("%08lx-%08lx->%08lx\n", start, end, where);
49 for (i = start; i <= end; i++)
50 if(bfs_move_block(i, where + i, sb)) {
51 dprintf("failed to move block %08lx -> %08lx\n", i, where + i);
52 return -EIO;
53 }
54 return 0;
55}
56
57static int bfs_get_block(struct inode * inode, sector_t block,
58 struct buffer_head * bh_result, int create)
59{
60 long phys;
61 int err;
62 struct super_block *sb = inode->i_sb;
63 struct bfs_sb_info *info = BFS_SB(sb);
64 struct bfs_inode_info *bi = BFS_I(inode);
65 struct buffer_head *sbh = info->si_sbh;
66
67 if (block < 0 || block > info->si_blocks)
68 return -EIO;
69
70 phys = bi->i_sblock + block;
71 if (!create) {
72 if (phys <= bi->i_eblock) {
73 dprintf("c=%d, b=%08lx, phys=%08lx (granted)\n", create, block, phys);
74 map_bh(bh_result, sb, phys);
75 }
76 return 0;
77 }
78
79 /* if the file is not empty and the requested block is within the range
80 of blocks allocated for this file, we can grant it */
81 if (inode->i_size && phys <= bi->i_eblock) {
82 dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n",
83 create, block, phys);
84 map_bh(bh_result, sb, phys);
85 return 0;
86 }
87
88 /* the rest has to be protected against itself */
89 lock_kernel();
90
91 /* if the last data block for this file is the last allocated block, we can
92 extend the file trivially, without moving it anywhere */
93 if (bi->i_eblock == info->si_lf_eblk) {
94 dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n",
95 create, block, phys);
96 map_bh(bh_result, sb, phys);
97 info->si_freeb -= phys - bi->i_eblock;
98 info->si_lf_eblk = bi->i_eblock = phys;
99 mark_inode_dirty(inode);
100 mark_buffer_dirty(sbh);
101 err = 0;
102 goto out;
103 }
104
105 /* Ok, we have to move this entire file to the next free block */
106 phys = info->si_lf_eblk + 1;
107 if (bi->i_sblock) { /* if data starts on block 0 then there is no data */
108 err = bfs_move_blocks(inode->i_sb, bi->i_sblock,
109 bi->i_eblock, phys);
110 if (err) {
111 dprintf("failed to move ino=%08lx -> fs corruption\n", inode->i_ino);
112 goto out;
113 }
114 } else
115 err = 0;
116
117 dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n", create, block, phys);
118 bi->i_sblock = phys;
119 phys += block;
120 info->si_lf_eblk = bi->i_eblock = phys;
121
122 /* this assumes nothing can write the inode back while we are here
123 * and thus update inode->i_blocks! (XXX)*/
124 info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks;
125 mark_inode_dirty(inode);
126 mark_buffer_dirty(sbh);
127 map_bh(bh_result, sb, phys);
128out:
129 unlock_kernel();
130 return err;
131}
132
133static int bfs_writepage(struct page *page, struct writeback_control *wbc)
134{
135 return block_write_full_page(page, bfs_get_block, wbc);
136}
137
138static int bfs_readpage(struct file *file, struct page *page)
139{
140 return block_read_full_page(page, bfs_get_block);
141}
142
143static int bfs_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
144{
145 return block_prepare_write(page, from, to, bfs_get_block);
146}
147
148static sector_t bfs_bmap(struct address_space *mapping, sector_t block)
149{
150 return generic_block_bmap(mapping, block, bfs_get_block);
151}
152
153struct address_space_operations bfs_aops = {
154 .readpage = bfs_readpage,
155 .writepage = bfs_writepage,
156 .sync_page = block_sync_page,
157 .prepare_write = bfs_prepare_write,
158 .commit_write = generic_commit_write,
159 .bmap = bfs_bmap,
160};
161
162struct inode_operations bfs_file_inops;