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, unsigned long end, 44 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 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 < 0 || 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=%08lx (granted)\n", create, block, phys); 74 map_bh(bh_result, sb, phys); 75 } 76 return 0; 77 } 78 79 /* if the file is not empty and the requested block is within the range 80 of blocks allocated for this file, we can grant it */ 81 if (inode->i_size && phys <= bi->i_eblock) { 82 dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n", 83 create, block, phys); 84 map_bh(bh_result, sb, phys); 85 return 0; 86 } 87 88 /* the rest has to be protected against itself */ 89 lock_kernel(); 90 91 /* if the last data block for this file is the last allocated block, we can 92 extend the file trivially, without moving it anywhere */ 93 if (bi->i_eblock == info->si_lf_eblk) { 94 dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n", 95 create, block, phys); 96 map_bh(bh_result, sb, phys); 97 info->si_freeb -= phys - bi->i_eblock; 98 info->si_lf_eblk = bi->i_eblock = phys; 99 mark_inode_dirty(inode); 100 mark_buffer_dirty(sbh); 101 err = 0; 102 goto out; 103 } 104 105 /* Ok, we have to move this entire file to the next free block */ 106 phys = info->si_lf_eblk + 1; 107 if (bi->i_sblock) { /* if data starts on block 0 then there is no data */ 108 err = bfs_move_blocks(inode->i_sb, bi->i_sblock, 109 bi->i_eblock, phys); 110 if (err) { 111 dprintf("failed to move ino=%08lx -> fs corruption\n", inode->i_ino); 112 goto out; 113 } 114 } else 115 err = 0; 116 117 dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n", create, block, phys); 118 bi->i_sblock = phys; 119 phys += block; 120 info->si_lf_eblk = bi->i_eblock = phys; 121 122 /* this assumes nothing can write the inode back while we are here 123 * and thus update inode->i_blocks! (XXX)*/ 124 info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks; 125 mark_inode_dirty(inode); 126 mark_buffer_dirty(sbh); 127 map_bh(bh_result, sb, phys); 128 out: 129 unlock_kernel(); 130 return err; 131 } 132 133 static int bfs_writepage(struct page *page, struct writeback_control *wbc) 134 { 135 return block_write_full_page(page, bfs_get_block, wbc); 136 } 137 138 static int bfs_readpage(struct file *file, struct page *page) 139 { 140 return block_read_full_page(page, bfs_get_block); 141 } 142 143 static int bfs_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to) 144 { 145 return block_prepare_write(page, from, to, bfs_get_block); 146 } 147 148 static sector_t bfs_bmap(struct address_space *mapping, sector_t block) 149 { 150 return generic_block_bmap(mapping, block, bfs_get_block); 151 } 152 153 struct address_space_operations bfs_aops = { 154 .readpage = bfs_readpage, 155 .writepage = bfs_writepage, 156 .sync_page = block_sync_page, 157 .prepare_write = bfs_prepare_write, 158 .commit_write = generic_commit_write, 159 .bmap = bfs_bmap, 160 }; 161 162 struct inode_operations bfs_file_inops; 163