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