Linux 4.6-rc6
[cris-mirror.git] / fs / bfs / file.c
blob97f1b51601550e38c8c4e45bf49c4336da04bed9
1 /*
2 * fs/bfs/file.c
3 * BFS file operations.
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>
12 #include <linux/fs.h>
13 #include <linux/buffer_head.h>
14 #include "bfs.h"
16 #undef DEBUG
18 #ifdef DEBUG
19 #define dprintf(x...) printf(x)
20 #else
21 #define dprintf(x...)
22 #endif
24 const struct file_operations bfs_file_operations = {
25 .llseek = generic_file_llseek,
26 .read_iter = generic_file_read_iter,
27 .write_iter = generic_file_write_iter,
28 .mmap = generic_file_mmap,
29 .splice_read = generic_file_splice_read,
32 static int bfs_move_block(unsigned long from, unsigned long to,
33 struct super_block *sb)
35 struct buffer_head *bh, *new;
37 bh = sb_bread(sb, from);
38 if (!bh)
39 return -EIO;
40 new = sb_getblk(sb, to);
41 memcpy(new->b_data, bh->b_data, bh->b_size);
42 mark_buffer_dirty(new);
43 bforget(bh);
44 brelse(new);
45 return 0;
48 static int bfs_move_blocks(struct super_block *sb, unsigned long start,
49 unsigned long end, unsigned long where)
51 unsigned long i;
53 dprintf("%08lx-%08lx->%08lx\n", start, end, where);
54 for (i = start; i <= end; i++)
55 if(bfs_move_block(i, where + i, sb)) {
56 dprintf("failed to move block %08lx -> %08lx\n", i,
57 where + i);
58 return -EIO;
60 return 0;
63 static int bfs_get_block(struct inode *inode, sector_t block,
64 struct buffer_head *bh_result, int create)
66 unsigned long phys;
67 int err;
68 struct super_block *sb = inode->i_sb;
69 struct bfs_sb_info *info = BFS_SB(sb);
70 struct bfs_inode_info *bi = BFS_I(inode);
72 phys = bi->i_sblock + block;
73 if (!create) {
74 if (phys <= bi->i_eblock) {
75 dprintf("c=%d, b=%08lx, phys=%09lx (granted)\n",
76 create, (unsigned long)block, phys);
77 map_bh(bh_result, sb, phys);
79 return 0;
83 * If the file is not empty and the requested block is within the
84 * range of blocks allocated for this file, we can grant it.
86 if (bi->i_sblock && (phys <= bi->i_eblock)) {
87 dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n",
88 create, (unsigned long)block, phys);
89 map_bh(bh_result, sb, phys);
90 return 0;
93 /* The file will be extended, so let's see if there is enough space. */
94 if (phys >= info->si_blocks)
95 return -ENOSPC;
97 /* The rest has to be protected against itself. */
98 mutex_lock(&info->bfs_lock);
101 * If the last data block for this file is the last allocated
102 * block, we can extend the file trivially, without moving it
103 * anywhere.
105 if (bi->i_eblock == info->si_lf_eblk) {
106 dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n",
107 create, (unsigned long)block, phys);
108 map_bh(bh_result, sb, phys);
109 info->si_freeb -= phys - bi->i_eblock;
110 info->si_lf_eblk = bi->i_eblock = phys;
111 mark_inode_dirty(inode);
112 err = 0;
113 goto out;
116 /* Ok, we have to move this entire file to the next free block. */
117 phys = info->si_lf_eblk + 1;
118 if (phys + block >= info->si_blocks) {
119 err = -ENOSPC;
120 goto out;
123 if (bi->i_sblock) {
124 err = bfs_move_blocks(inode->i_sb, bi->i_sblock,
125 bi->i_eblock, phys);
126 if (err) {
127 dprintf("failed to move ino=%08lx -> fs corruption\n",
128 inode->i_ino);
129 goto out;
131 } else
132 err = 0;
134 dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n",
135 create, (unsigned long)block, phys);
136 bi->i_sblock = phys;
137 phys += block;
138 info->si_lf_eblk = bi->i_eblock = phys;
141 * This assumes nothing can write the inode back while we are here
142 * and thus update inode->i_blocks! (XXX)
144 info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks;
145 mark_inode_dirty(inode);
146 map_bh(bh_result, sb, phys);
147 out:
148 mutex_unlock(&info->bfs_lock);
149 return err;
152 static int bfs_writepage(struct page *page, struct writeback_control *wbc)
154 return block_write_full_page(page, bfs_get_block, wbc);
157 static int bfs_readpage(struct file *file, struct page *page)
159 return block_read_full_page(page, bfs_get_block);
162 static void bfs_write_failed(struct address_space *mapping, loff_t to)
164 struct inode *inode = mapping->host;
166 if (to > inode->i_size)
167 truncate_pagecache(inode, inode->i_size);
170 static int bfs_write_begin(struct file *file, struct address_space *mapping,
171 loff_t pos, unsigned len, unsigned flags,
172 struct page **pagep, void **fsdata)
174 int ret;
176 ret = block_write_begin(mapping, pos, len, flags, pagep,
177 bfs_get_block);
178 if (unlikely(ret))
179 bfs_write_failed(mapping, pos + len);
181 return ret;
184 static sector_t bfs_bmap(struct address_space *mapping, sector_t block)
186 return generic_block_bmap(mapping, block, bfs_get_block);
189 const struct address_space_operations bfs_aops = {
190 .readpage = bfs_readpage,
191 .writepage = bfs_writepage,
192 .write_begin = bfs_write_begin,
193 .write_end = generic_write_end,
194 .bmap = bfs_bmap,
197 const struct inode_operations bfs_file_inops;