1 /* vi: set sw=4 ts=4: */
3 * bmap.c --- logical to physical block mapping
5 * Copyright (C) 1997 Theodore Ts'o.
8 * This file may be redistributed under the terms of the GNU Public
22 extern errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino,
23 struct ext2_inode *inode,
24 char *block_buf, int bmap_flags,
25 blk_t block, blk_t *phys_blk);
27 #define inode_bmap(inode, nr) ((inode)->i_block[(nr)])
29 static errcode_t block_ind_bmap(ext2_filsys fs, int flags,
30 blk_t ind, char *block_buf,
32 blk_t nr, blk_t *ret_blk)
39 return EXT2_ET_SET_BMAP_NO_IND;
43 retval = io_channel_read_blk(fs->io, ind, 1, block_buf);
47 if (flags & BMAP_SET) {
50 if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
51 (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
54 ((blk_t *) block_buf)[nr] = b;
55 return io_channel_write_blk(fs->io, ind, 1, block_buf);
58 b = ((blk_t *) block_buf)[nr];
61 if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
62 (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
66 if (!b && (flags & BMAP_ALLOC)) {
67 b = nr ? ((blk_t *) block_buf)[nr-1] : 0;
68 retval = ext2fs_alloc_block(fs, b,
69 block_buf + fs->blocksize, &b);
74 if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
75 (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
76 ((blk_t *) block_buf)[nr] = ext2fs_swab32(b);
79 ((blk_t *) block_buf)[nr] = b;
81 retval = io_channel_write_blk(fs->io, ind, 1, block_buf);
92 static errcode_t block_dind_bmap(ext2_filsys fs, int flags,
93 blk_t dind, char *block_buf,
95 blk_t nr, blk_t *ret_blk)
101 addr_per_block = (blk_t) fs->blocksize >> 2;
103 retval = block_ind_bmap(fs, flags & ~BMAP_SET, dind, block_buf,
104 blocks_alloc, nr / addr_per_block, &b);
107 retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
108 nr % addr_per_block, ret_blk);
112 static errcode_t block_tind_bmap(ext2_filsys fs, int flags,
113 blk_t tind, char *block_buf,
115 blk_t nr, blk_t *ret_blk)
119 blk_t addr_per_block;
121 addr_per_block = (blk_t) fs->blocksize >> 2;
123 retval = block_dind_bmap(fs, flags & ~BMAP_SET, tind, block_buf,
124 blocks_alloc, nr / addr_per_block, &b);
127 retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
128 nr % addr_per_block, ret_blk);
132 errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
133 char *block_buf, int bmap_flags, blk_t block,
136 struct ext2_inode inode_buf;
137 blk_t addr_per_block;
140 errcode_t retval = 0;
141 int blocks_alloc = 0, inode_dirty = 0;
143 if (!(bmap_flags & BMAP_SET))
146 /* Read inode structure if necessary */
148 retval = ext2fs_read_inode(fs, ino, &inode_buf);
153 addr_per_block = (blk_t) fs->blocksize >> 2;
156 retval = ext2fs_get_mem(fs->blocksize * 2, &buf);
162 if (block < EXT2_NDIR_BLOCKS) {
163 if (bmap_flags & BMAP_SET) {
166 if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
167 (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
168 b = ext2fs_swab32(b);
170 inode_bmap(inode, block) = b;
175 *phys_blk = inode_bmap(inode, block);
176 b = block ? inode_bmap(inode, block-1) : 0;
178 if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
179 retval = ext2fs_alloc_block(fs, b, block_buf, &b);
182 inode_bmap(inode, block) = b;
190 block -= EXT2_NDIR_BLOCKS;
191 if (block < addr_per_block) {
192 b = inode_bmap(inode, EXT2_IND_BLOCK);
194 if (!(bmap_flags & BMAP_ALLOC)) {
195 if (bmap_flags & BMAP_SET)
196 retval = EXT2_ET_SET_BMAP_NO_IND;
200 b = inode_bmap(inode, EXT2_IND_BLOCK-1);
201 retval = ext2fs_alloc_block(fs, b, block_buf, &b);
204 inode_bmap(inode, EXT2_IND_BLOCK) = b;
207 retval = block_ind_bmap(fs, bmap_flags, b, block_buf,
208 &blocks_alloc, block, phys_blk);
212 /* Doubly indirect block */
213 block -= addr_per_block;
214 if (block < addr_per_block * addr_per_block) {
215 b = inode_bmap(inode, EXT2_DIND_BLOCK);
217 if (!(bmap_flags & BMAP_ALLOC)) {
218 if (bmap_flags & BMAP_SET)
219 retval = EXT2_ET_SET_BMAP_NO_IND;
223 b = inode_bmap(inode, EXT2_IND_BLOCK);
224 retval = ext2fs_alloc_block(fs, b, block_buf, &b);
227 inode_bmap(inode, EXT2_DIND_BLOCK) = b;
230 retval = block_dind_bmap(fs, bmap_flags, b, block_buf,
231 &blocks_alloc, block, phys_blk);
235 /* Triply indirect block */
236 block -= addr_per_block * addr_per_block;
237 b = inode_bmap(inode, EXT2_TIND_BLOCK);
239 if (!(bmap_flags & BMAP_ALLOC)) {
240 if (bmap_flags & BMAP_SET)
241 retval = EXT2_ET_SET_BMAP_NO_IND;
245 b = inode_bmap(inode, EXT2_DIND_BLOCK);
246 retval = ext2fs_alloc_block(fs, b, block_buf, &b);
249 inode_bmap(inode, EXT2_TIND_BLOCK) = b;
252 retval = block_tind_bmap(fs, bmap_flags, b, block_buf,
253 &blocks_alloc, block, phys_blk);
255 ext2fs_free_mem(&buf);
256 if ((retval == 0) && (blocks_alloc || inode_dirty)) {
257 inode->i_blocks += (blocks_alloc * fs->blocksize) / 512;
258 retval = ext2fs_write_inode(fs, ino, inode);