1 /* 2 * fs/bfs/file.c 3 * BFS file operations. 4 * Copyright (C) 1999,2000 Tigran Aivazian <tigran@veritas.com> 5 * 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> 9 * 10 */ 11 12 #include <linux/fs.h> 13 #include <linux/buffer_head.h> 14 #include "bfs.h" 15 16 #undef DEBUG 17 18 #ifdef DEBUG 19 #define dprintf(x...) printf(x) 20 #else 21 #define dprintf(x...) 22 #endif 23 24 const struct file_operations bfs_file_operations = { 25 .llseek = generic_file_llseek, 26 .read = do_sync_read, 27 .aio_read = generic_file_aio_read, 28 .write = do_sync_write, 29 .aio_write = generic_file_aio_write, 30 .mmap = generic_file_mmap, 31 .splice_read = generic_file_splice_read, 32 }; 33 34 static 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 50 static 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 65 static 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 struct buffer_head *sbh = info->si_sbh; 74 75 phys = bi->i_sblock + block; 76 if (!create) { 77 if (phys <= bi->i_eblock) { 78 dprintf("c=%d, b=%08lx, phys=%09lx (granted)\n", 79 create, (unsigned long)block, phys); 80 map_bh(bh_result, sb, phys); 81 } 82 return 0; 83 } 84 85 /* 86 * If the file is not empty and the requested block is within the 87 * range of blocks allocated for this file, we can grant it. 88 */ 89 if (bi->i_sblock && (phys <= bi->i_eblock)) { 90 dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n", 91 create, (unsigned long)block, phys); 92 map_bh(bh_result, sb, phys); 93 return 0; 94 } 95 96 /* The file will be extended, so let's see if there is enough space. */ 97 if (phys >= info->si_blocks) 98 return -ENOSPC; 99 100 /* The rest has to be protected against itself. */ 101 mutex_lock(&info->bfs_lock); 102 103 /* 104 * If the last data block for this file is the last allocated 105 * block, we can extend the file trivially, without moving it 106 * anywhere. 107 */ 108 if (bi->i_eblock == info->si_lf_eblk) { 109 dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n", 110 create, (unsigned long)block, phys); 111 map_bh(bh_result, sb, phys); 112 info->si_freeb -= phys - bi->i_eblock; 113 info->si_lf_eblk = bi->i_eblock = phys; 114 mark_inode_dirty(inode); 115 mark_buffer_dirty(sbh); 116 err = 0; 117 goto out; 118 } 119 120 /* Ok, we have to move this entire file to the next free block. */ 121 phys = info->si_lf_eblk + 1; 122 if (phys + block >= info->si_blocks) { 123 err = -ENOSPC; 124 goto out; 125 } 126 127 if (bi->i_sblock) { 128 err = bfs_move_blocks(inode->i_sb, bi->i_sblock, 129 bi->i_eblock, phys); 130 if (err) { 131 dprintf("failed to move ino=%08lx -> fs corruption\n", 132 inode->i_ino); 133 goto out; 134 } 135 } else 136 err = 0; 137 138 dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n", 139 create, (unsigned long)block, phys); 140 bi->i_sblock = phys; 141 phys += block; 142 info->si_lf_eblk = bi->i_eblock = phys; 143 144 /* 145 * This assumes nothing can write the inode back while we are here 146 * and thus update inode->i_blocks! (XXX) 147 */ 148 info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks; 149 mark_inode_dirty(inode); 150 mark_buffer_dirty(sbh); 151 map_bh(bh_result, sb, phys); 152 out: 153 mutex_unlock(&info->bfs_lock); 154 return err; 155 } 156 157 static int bfs_writepage(struct page *page, struct writeback_control *wbc) 158 { 159 return block_write_full_page(page, bfs_get_block, wbc); 160 } 161 162 static int bfs_readpage(struct file *file, struct page *page) 163 { 164 return block_read_full_page(page, bfs_get_block); 165 } 166 167 static int bfs_write_begin(struct file *file, struct address_space *mapping, 168 loff_t pos, unsigned len, unsigned flags, 169 struct page **pagep, void **fsdata) 170 { 171 *pagep = NULL; 172 return block_write_begin(file, mapping, pos, len, flags, 173 pagep, fsdata, bfs_get_block); 174 } 175 176 static sector_t bfs_bmap(struct address_space *mapping, sector_t block) 177 { 178 return generic_block_bmap(mapping, block, bfs_get_block); 179 } 180 181 const struct address_space_operations bfs_aops = { 182 .readpage = bfs_readpage, 183 .writepage = bfs_writepage, 184 .sync_page = block_sync_page, 185 .write_begin = bfs_write_begin, 186 .write_end = generic_write_end, 187 .bmap = bfs_bmap, 188 }; 189 190 const struct inode_operations bfs_file_inops; 191