1 // SPDX-License-Identifier: GPL-2.0
5 * Copyright (C) 1999-2018 Tigran Aivazian <aivazian.tigran@gmail.com>
7 * Make the file block allocation algorithm understand the size
8 * of the underlying block device.
9 * Copyright (C) 2007 Dmitri Vorobiev <dmitri.vorobiev@gmail.com>
14 #include <linux/buffer_head.h>
20 #define dprintf(x...) printf(x)
25 const struct file_operations bfs_file_operations = {
26 .llseek = generic_file_llseek,
27 .read_iter = generic_file_read_iter,
28 .write_iter = generic_file_write_iter,
29 .mmap = generic_file_mmap,
30 .splice_read = generic_file_splice_read,
33 static int bfs_move_block(unsigned long from, unsigned long to,
34 struct super_block *sb)
36 struct buffer_head *bh, *new;
38 bh = sb_bread(sb, from);
41 new = sb_getblk(sb, to);
42 memcpy(new->b_data, bh->b_data, bh->b_size);
43 mark_buffer_dirty(new);
49 static int bfs_move_blocks(struct super_block *sb, unsigned long start,
50 unsigned long end, unsigned long where)
54 dprintf("%08lx-%08lx->%08lx\n", start, end, where);
55 for (i = start; i <= end; i++)
56 if(bfs_move_block(i, where + i, sb)) {
57 dprintf("failed to move block %08lx -> %08lx\n", i,
64 static int bfs_get_block(struct inode *inode, sector_t block,
65 struct buffer_head *bh_result, int create)
69 struct super_block *sb = inode->i_sb;
70 struct bfs_sb_info *info = BFS_SB(sb);
71 struct bfs_inode_info *bi = BFS_I(inode);
73 phys = bi->i_sblock + block;
75 if (phys <= bi->i_eblock) {
76 dprintf("c=%d, b=%08lx, phys=%09lx (granted)\n",
77 create, (unsigned long)block, phys);
78 map_bh(bh_result, sb, phys);
84 * If the file is not empty and the requested block is within the
85 * range of blocks allocated for this file, we can grant it.
87 if (bi->i_sblock && (phys <= bi->i_eblock)) {
88 dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n",
89 create, (unsigned long)block, phys);
90 map_bh(bh_result, sb, phys);
94 /* The file will be extended, so let's see if there is enough space. */
95 if (phys >= info->si_blocks)
98 /* The rest has to be protected against itself. */
99 mutex_lock(&info->bfs_lock);
102 * If the last data block for this file is the last allocated
103 * block, we can extend the file trivially, without moving it
106 if (bi->i_eblock == info->si_lf_eblk) {
107 dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n",
108 create, (unsigned long)block, phys);
109 map_bh(bh_result, sb, phys);
110 info->si_freeb -= phys - bi->i_eblock;
111 info->si_lf_eblk = bi->i_eblock = phys;
112 mark_inode_dirty(inode);
117 /* Ok, we have to move this entire file to the next free block. */
118 phys = info->si_lf_eblk + 1;
119 if (phys + block >= info->si_blocks) {
125 err = bfs_move_blocks(inode->i_sb, bi->i_sblock,
128 dprintf("failed to move ino=%08lx -> fs corruption\n",
135 dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n",
136 create, (unsigned long)block, phys);
139 info->si_lf_eblk = bi->i_eblock = phys;
142 * This assumes nothing can write the inode back while we are here
143 * and thus update inode->i_blocks! (XXX)
145 info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks;
146 mark_inode_dirty(inode);
147 map_bh(bh_result, sb, phys);
149 mutex_unlock(&info->bfs_lock);
153 static int bfs_writepage(struct page *page, struct writeback_control *wbc)
155 return block_write_full_page(page, bfs_get_block, wbc);
158 static int bfs_readpage(struct file *file, struct page *page)
160 return block_read_full_page(page, bfs_get_block);
163 static void bfs_write_failed(struct address_space *mapping, loff_t to)
165 struct inode *inode = mapping->host;
167 if (to > inode->i_size)
168 truncate_pagecache(inode, inode->i_size);
171 static int bfs_write_begin(struct file *file, struct address_space *mapping,
172 loff_t pos, unsigned len, unsigned flags,
173 struct page **pagep, void **fsdata)
177 ret = block_write_begin(mapping, pos, len, flags, pagep,
180 bfs_write_failed(mapping, pos + len);
185 static sector_t bfs_bmap(struct address_space *mapping, sector_t block)
187 return generic_block_bmap(mapping, block, bfs_get_block);
190 const struct address_space_operations bfs_aops = {
191 .readpage = bfs_readpage,
192 .writepage = bfs_writepage,
193 .write_begin = bfs_write_begin,
194 .write_end = generic_write_end,
198 const struct inode_operations bfs_file_inops;