Merge with /pub/scm/linux/kernel/git/sfrench/cifs-2.6.git/
[linux-2.6] / fs / bfs / file.c
1 /*
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
20 struct 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
28 static 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
43 static int bfs_move_blocks(struct super_block *sb, unsigned long start,
44                            unsigned long end, 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
57 static int bfs_get_block(struct inode * inode, sector_t block, 
58         struct buffer_head * bh_result, int create)
59 {
60         unsigned 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 > 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=%09lx (granted)\n",
74                                 create, (unsigned long)block, phys);
75                         map_bh(bh_result, sb, phys);
76                 }
77                 return 0;
78         }
79
80         /* if the file is not empty and the requested block is within the range
81            of blocks allocated for this file, we can grant it */
82         if (inode->i_size && phys <= bi->i_eblock) {
83                 dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n", 
84                                 create, (unsigned long)block, phys);
85                 map_bh(bh_result, sb, phys);
86                 return 0;
87         }
88
89         /* the rest has to be protected against itself */
90         lock_kernel();
91
92         /* if the last data block for this file is the last allocated
93            block, we can extend the file trivially, without moving it
94            anywhere */
95         if (bi->i_eblock == info->si_lf_eblk) {
96                 dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n", 
97                                 create, (unsigned long)block, phys);
98                 map_bh(bh_result, sb, phys);
99                 info->si_freeb -= phys - bi->i_eblock;
100                 info->si_lf_eblk = bi->i_eblock = phys;
101                 mark_inode_dirty(inode);
102                 mark_buffer_dirty(sbh);
103                 err = 0;
104                 goto out;
105         }
106
107         /* Ok, we have to move this entire file to the next free block */
108         phys = info->si_lf_eblk + 1;
109         if (bi->i_sblock) { /* if data starts on block 0 then there is no data */
110                 err = bfs_move_blocks(inode->i_sb, bi->i_sblock, 
111                                 bi->i_eblock, phys);
112                 if (err) {
113                         dprintf("failed to move ino=%08lx -> fs corruption\n", inode->i_ino);
114                         goto out;
115                 }
116         } else
117                 err = 0;
118
119         dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n",
120                 create, (unsigned long)block, phys);
121         bi->i_sblock = phys;
122         phys += block;
123         info->si_lf_eblk = bi->i_eblock = phys;
124
125         /* this assumes nothing can write the inode back while we are here
126          * and thus update inode->i_blocks! (XXX)*/
127         info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks;
128         mark_inode_dirty(inode);
129         mark_buffer_dirty(sbh);
130         map_bh(bh_result, sb, phys);
131 out:
132         unlock_kernel();
133         return err;
134 }
135
136 static int bfs_writepage(struct page *page, struct writeback_control *wbc)
137 {
138         return block_write_full_page(page, bfs_get_block, wbc);
139 }
140
141 static int bfs_readpage(struct file *file, struct page *page)
142 {
143         return block_read_full_page(page, bfs_get_block);
144 }
145
146 static int bfs_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
147 {
148         return block_prepare_write(page, from, to, bfs_get_block);
149 }
150
151 static sector_t bfs_bmap(struct address_space *mapping, sector_t block)
152 {
153         return generic_block_bmap(mapping, block, bfs_get_block);
154 }
155
156 struct address_space_operations bfs_aops = {
157         .readpage       = bfs_readpage,
158         .writepage      = bfs_writepage,
159         .sync_page      = block_sync_page,
160         .prepare_write  = bfs_prepare_write,
161         .commit_write   = generic_commit_write,
162         .bmap           = bfs_bmap,
163 };
164
165 struct inode_operations bfs_file_inops;