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 <linux/smp_lock.h> 15 #include "bfs.h" 16 17 #undef DEBUG 18 19 #ifdef DEBUG 20 #define dprintf(x...) printf(x) 21 #else 22 #define dprintf(x...) 23 #endif 24 25 const struct file_operations bfs_file_operations = { 26 .llseek = generic_file_llseek, 27 .read = do_sync_read, 28 .aio_read = generic_file_aio_read, 29 .write = do_sync_write, 30 .aio_write = generic_file_aio_write, 31 .mmap = generic_file_mmap, 32 .splice_read = generic_file_splice_read, 33 }; 34 35 static int bfs_move_block(unsigned long from, unsigned long to, 36 struct super_block *sb) 37 { 38 struct buffer_head *bh, *new; 39 40 bh = sb_bread(sb, from); 41 if (!bh) 42 return -EIO; 43 new = sb_getblk(sb, to); 44 memcpy(new->b_data, bh->b_data, bh->b_size); 45 mark_buffer_dirty(new); 46 bforget(bh); 47 brelse(new); 48 return 0; 49 } 50 51 static int bfs_move_blocks(struct super_block *sb, unsigned long start, 52 unsigned long end, unsigned long where) 53 { 54 unsigned long i; 55 56 dprintf("%08lx-%08lx->%08lx\n", start, end, where); 57 for (i = start; i <= end; i++) 58 if(bfs_move_block(i, where + i, sb)) { 59 dprintf("failed to move block %08lx -> %08lx\n", i, 60 where + i); 61 return -EIO; 62 } 63 return 0; 64 } 65 66 static int bfs_get_block(struct inode *inode, sector_t block, 67 struct buffer_head *bh_result, int create) 68 { 69 unsigned long phys; 70 int err; 71 struct super_block *sb = inode->i_sb; 72 struct bfs_sb_info *info = BFS_SB(sb); 73 struct bfs_inode_info *bi = BFS_I(inode); 74 struct buffer_head *sbh = info->si_sbh; 75 76 phys = bi->i_sblock + block; 77 if (!create) { 78 if (phys <= bi->i_eblock) { 79 dprintf("c=%d, b=%08lx, phys=%09lx (granted)\n", 80 create, (unsigned long)block, phys); 81 map_bh(bh_result, sb, phys); 82 } 83 return 0; 84 } 85 86 /* 87 * If the file is not empty and the requested block is within the 88 * range of blocks allocated for this file, we can grant it. 89 */ 90 if (bi->i_sblock && (phys <= bi->i_eblock)) { 91 dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n", 92 create, (unsigned long)block, phys); 93 map_bh(bh_result, sb, phys); 94 return 0; 95 } 96 97 /* The file will be extended, so let's see if there is enough space. */ 98 if (phys >= info->si_blocks) 99 return -ENOSPC; 100 101 /* The rest has to be protected against itself. */ 102 mutex_lock(&info->bfs_lock); 103 104 /* 105 * If the last data block for this file is the last allocated 106 * block, we can extend the file trivially, without moving it 107 * anywhere. 108 */ 109 if (bi->i_eblock == info->si_lf_eblk) { 110 dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n", 111 create, (unsigned long)block, phys); 112 map_bh(bh_result, sb, phys); 113 info->si_freeb -= phys - bi->i_eblock; 114 info->si_lf_eblk = bi->i_eblock = phys; 115 mark_inode_dirty(inode); 116 mark_buffer_dirty(sbh); 117 err = 0; 118 goto out; 119 } 120 121 /* Ok, we have to move this entire file to the next free block. */ 122 phys = info->si_lf_eblk + 1; 123 if (phys + block >= info->si_blocks) { 124 err = -ENOSPC; 125 goto out; 126 } 127 128 if (bi->i_sblock) { 129 err = bfs_move_blocks(inode->i_sb, bi->i_sblock, 130 bi->i_eblock, phys); 131 if (err) { 132 dprintf("failed to move ino=%08lx -> fs corruption\n", 133 inode->i_ino); 134 goto out; 135 } 136 } else 137 err = 0; 138 139 dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n", 140 create, (unsigned long)block, phys); 141 bi->i_sblock = phys; 142 phys += block; 143 info->si_lf_eblk = bi->i_eblock = phys; 144 145 /* 146 * This assumes nothing can write the inode back while we are here 147 * and thus update inode->i_blocks! (XXX) 148 */ 149 info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks; 150 mark_inode_dirty(inode); 151 mark_buffer_dirty(sbh); 152 map_bh(bh_result, sb, phys); 153 out: 154 mutex_unlock(&info->bfs_lock); 155 return err; 156 } 157 158 static int bfs_writepage(struct page *page, struct writeback_control *wbc) 159 { 160 return block_write_full_page(page, bfs_get_block, wbc); 161 } 162 163 static int bfs_readpage(struct file *file, struct page *page) 164 { 165 return block_read_full_page(page, bfs_get_block); 166 } 167 168 static int bfs_write_begin(struct file *file, struct address_space *mapping, 169 loff_t pos, unsigned len, unsigned flags, 170 struct page **pagep, void **fsdata) 171 { 172 *pagep = NULL; 173 return block_write_begin(file, mapping, pos, len, flags, 174 pagep, fsdata, bfs_get_block); 175 } 176 177 static sector_t bfs_bmap(struct address_space *mapping, sector_t block) 178 { 179 return generic_block_bmap(mapping, block, bfs_get_block); 180 } 181 182 const struct address_space_operations bfs_aops = { 183 .readpage = bfs_readpage, 184 .writepage = bfs_writepage, 185 .sync_page = block_sync_page, 186 .write_begin = bfs_write_begin, 187 .write_end = generic_write_end, 188 .bmap = bfs_bmap, 189 }; 190 191 const struct inode_operations bfs_file_inops; 192