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 const struct file_operations bfs_file_operations = { 21 .llseek = generic_file_llseek, 22 .read = do_sync_read, 23 .aio_read = generic_file_aio_read, 24 .write = do_sync_write, 25 .aio_write = generic_file_aio_write, 26 .mmap = generic_file_mmap, 27 .sendfile = generic_file_sendfile, 28 }; 29 30 static int bfs_move_block(unsigned long from, unsigned long to, struct super_block *sb) 31 { 32 struct buffer_head *bh, *new; 33 34 bh = sb_bread(sb, from); 35 if (!bh) 36 return -EIO; 37 new = sb_getblk(sb, to); 38 memcpy(new->b_data, bh->b_data, bh->b_size); 39 mark_buffer_dirty(new); 40 bforget(bh); 41 brelse(new); 42 return 0; 43 } 44 45 static int bfs_move_blocks(struct super_block *sb, unsigned long start, 46 unsigned long end, unsigned long where) 47 { 48 unsigned long i; 49 50 dprintf("%08lx-%08lx->%08lx\n", start, end, where); 51 for (i = start; i <= end; i++) 52 if(bfs_move_block(i, where + i, sb)) { 53 dprintf("failed to move block %08lx -> %08lx\n", i, where + i); 54 return -EIO; 55 } 56 return 0; 57 } 58 59 static int bfs_get_block(struct inode * inode, sector_t block, 60 struct buffer_head * bh_result, int create) 61 { 62 unsigned long phys; 63 int err; 64 struct super_block *sb = inode->i_sb; 65 struct bfs_sb_info *info = BFS_SB(sb); 66 struct bfs_inode_info *bi = BFS_I(inode); 67 struct buffer_head *sbh = info->si_sbh; 68 69 if (block > info->si_blocks) 70 return -EIO; 71 72 phys = bi->i_sblock + block; 73 if (!create) { 74 if (phys <= bi->i_eblock) { 75 dprintf("c=%d, b=%08lx, phys=%09lx (granted)\n", 76 create, (unsigned long)block, phys); 77 map_bh(bh_result, sb, phys); 78 } 79 return 0; 80 } 81 82 /* if the file is not empty and the requested block is within the range 83 of blocks allocated for this file, we can grant it */ 84 if (inode->i_size && phys <= bi->i_eblock) { 85 dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n", 86 create, (unsigned long)block, phys); 87 map_bh(bh_result, sb, phys); 88 return 0; 89 } 90 91 /* the rest has to be protected against itself */ 92 lock_kernel(); 93 94 /* if the last data block for this file is the last allocated 95 block, we can extend the file trivially, without moving it 96 anywhere */ 97 if (bi->i_eblock == info->si_lf_eblk) { 98 dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n", 99 create, (unsigned long)block, phys); 100 map_bh(bh_result, sb, phys); 101 info->si_freeb -= phys - bi->i_eblock; 102 info->si_lf_eblk = bi->i_eblock = phys; 103 mark_inode_dirty(inode); 104 mark_buffer_dirty(sbh); 105 err = 0; 106 goto out; 107 } 108 109 /* Ok, we have to move this entire file to the next free block */ 110 phys = info->si_lf_eblk + 1; 111 if (bi->i_sblock) { /* if data starts on block 0 then there is no data */ 112 err = bfs_move_blocks(inode->i_sb, bi->i_sblock, 113 bi->i_eblock, phys); 114 if (err) { 115 dprintf("failed to move ino=%08lx -> fs corruption\n", inode->i_ino); 116 goto out; 117 } 118 } else 119 err = 0; 120 121 dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n", 122 create, (unsigned long)block, phys); 123 bi->i_sblock = phys; 124 phys += block; 125 info->si_lf_eblk = bi->i_eblock = phys; 126 127 /* this assumes nothing can write the inode back while we are here 128 * and thus update inode->i_blocks! (XXX)*/ 129 info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks; 130 mark_inode_dirty(inode); 131 mark_buffer_dirty(sbh); 132 map_bh(bh_result, sb, phys); 133 out: 134 unlock_kernel(); 135 return err; 136 } 137 138 static int bfs_writepage(struct page *page, struct writeback_control *wbc) 139 { 140 return block_write_full_page(page, bfs_get_block, wbc); 141 } 142 143 static int bfs_readpage(struct file *file, struct page *page) 144 { 145 return block_read_full_page(page, bfs_get_block); 146 } 147 148 static int bfs_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to) 149 { 150 return block_prepare_write(page, from, to, bfs_get_block); 151 } 152 153 static sector_t bfs_bmap(struct address_space *mapping, sector_t block) 154 { 155 return generic_block_bmap(mapping, block, bfs_get_block); 156 } 157 158 const struct address_space_operations bfs_aops = { 159 .readpage = bfs_readpage, 160 .writepage = bfs_writepage, 161 .sync_page = block_sync_page, 162 .prepare_write = bfs_prepare_write, 163 .commit_write = generic_commit_write, 164 .bmap = bfs_bmap, 165 }; 166 167 const struct inode_operations bfs_file_inops; 168