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1// SPDX-License-Identifier: GPL-2.02/*3 * fs/bfs/file.c4 * BFS file operations.5 * Copyright (C) 1999-2018 Tigran Aivazian <aivazian.tigran@gmail.com>6 *7 * Make the file block allocation algorithm understand the size8 * of the underlying block device.9 * Copyright (C) 2007 Dmitri Vorobiev <dmitri.vorobiev@gmail.com>10 *11 */12 13#include <linux/fs.h>14#include <linux/mpage.h>15#include <linux/buffer_head.h>16#include "bfs.h"17 18#undef DEBUG19 20#ifdef DEBUG21#define dprintf(x...) printf(x)22#else23#define dprintf(x...)24#endif25 26const struct file_operations bfs_file_operations = {27 .llseek = generic_file_llseek,28 .read_iter = generic_file_read_iter,29 .write_iter = generic_file_write_iter,30 .mmap = generic_file_mmap,31 .splice_read = filemap_splice_read,32};33 34static int bfs_move_block(unsigned long from, unsigned long to,35 struct super_block *sb)36{37 struct buffer_head *bh, *new;38 39 bh = sb_bread(sb, from);40 if (!bh)41 return -EIO;42 new = sb_getblk(sb, to);43 memcpy(new->b_data, bh->b_data, bh->b_size);44 mark_buffer_dirty(new);45 bforget(bh);46 brelse(new);47 return 0;48}49 50static int bfs_move_blocks(struct super_block *sb, unsigned long start,51 unsigned long end, unsigned long where)52{53 unsigned long i;54 55 dprintf("%08lx-%08lx->%08lx\n", start, end, where);56 for (i = start; i <= end; i++)57 if(bfs_move_block(i, where + i, sb)) {58 dprintf("failed to move block %08lx -> %08lx\n", i,59 where + i);60 return -EIO;61 }62 return 0;63}64 65static int bfs_get_block(struct inode *inode, sector_t block,66 struct buffer_head *bh_result, int create)67{68 unsigned long phys;69 int err;70 struct super_block *sb = inode->i_sb;71 struct bfs_sb_info *info = BFS_SB(sb);72 struct bfs_inode_info *bi = BFS_I(inode);73 74 phys = bi->i_sblock + block;75 if (!create) {76 if (phys <= bi->i_eblock) {77 dprintf("c=%d, b=%08lx, phys=%09lx (granted)\n",78 create, (unsigned long)block, phys);79 map_bh(bh_result, sb, phys);80 }81 return 0;82 }83 84 /*85 * If the file is not empty and the requested block is within the86 * range of blocks allocated for this file, we can grant it.87 */88 if (bi->i_sblock && (phys <= bi->i_eblock)) {89 dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n", 90 create, (unsigned long)block, phys);91 map_bh(bh_result, sb, phys);92 return 0;93 }94 95 /* The file will be extended, so let's see if there is enough space. */96 if (phys >= info->si_blocks)97 return -ENOSPC;98 99 /* The rest has to be protected against itself. */100 mutex_lock(&info->bfs_lock);101 102 /*103 * If the last data block for this file is the last allocated104 * block, we can extend the file trivially, without moving it105 * anywhere.106 */107 if (bi->i_eblock == info->si_lf_eblk) {108 dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n", 109 create, (unsigned long)block, phys);110 map_bh(bh_result, sb, phys);111 info->si_freeb -= phys - bi->i_eblock;112 info->si_lf_eblk = bi->i_eblock = phys;113 mark_inode_dirty(inode);114 err = 0;115 goto out;116 }117 118 /* Ok, we have to move this entire file to the next free block. */119 phys = info->si_lf_eblk + 1;120 if (phys + block >= info->si_blocks) {121 err = -ENOSPC;122 goto out;123 }124 125 if (bi->i_sblock) {126 err = bfs_move_blocks(inode->i_sb, bi->i_sblock, 127 bi->i_eblock, phys);128 if (err) {129 dprintf("failed to move ino=%08lx -> fs corruption\n",130 inode->i_ino);131 goto out;132 }133 } else134 err = 0;135 136 dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n",137 create, (unsigned long)block, phys);138 bi->i_sblock = phys;139 phys += block;140 info->si_lf_eblk = bi->i_eblock = phys;141 142 /*143 * This assumes nothing can write the inode back while we are here144 * and thus update inode->i_blocks! (XXX)145 */146 info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks;147 mark_inode_dirty(inode);148 map_bh(bh_result, sb, phys);149out:150 mutex_unlock(&info->bfs_lock);151 return err;152}153 154static int bfs_writepages(struct address_space *mapping,155 struct writeback_control *wbc)156{157 return mpage_writepages(mapping, wbc, bfs_get_block);158}159 160static int bfs_read_folio(struct file *file, struct folio *folio)161{162 return block_read_full_folio(folio, bfs_get_block);163}164 165static void bfs_write_failed(struct address_space *mapping, loff_t to)166{167 struct inode *inode = mapping->host;168 169 if (to > inode->i_size)170 truncate_pagecache(inode, inode->i_size);171}172 173static int bfs_write_begin(struct file *file, struct address_space *mapping,174 loff_t pos, unsigned len,175 struct folio **foliop, void **fsdata)176{177 int ret;178 179 ret = block_write_begin(mapping, pos, len, foliop, bfs_get_block);180 if (unlikely(ret))181 bfs_write_failed(mapping, pos + len);182 183 return ret;184}185 186static sector_t bfs_bmap(struct address_space *mapping, sector_t block)187{188 return generic_block_bmap(mapping, block, bfs_get_block);189}190 191const struct address_space_operations bfs_aops = {192 .dirty_folio = block_dirty_folio,193 .invalidate_folio = block_invalidate_folio,194 .read_folio = bfs_read_folio,195 .writepages = bfs_writepages,196 .write_begin = bfs_write_begin,197 .write_end = generic_write_end,198 .migrate_folio = buffer_migrate_folio,199 .bmap = bfs_bmap,200};201 202const struct inode_operations bfs_file_inops;203