xref: /openbmc/linux/fs/bfs/file.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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;
166