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34 * @(#)ufs_bmap.c 8.7 (Berkeley) 3/21/95
38 #include <sys/param.h>
39 #include <sys/systm.h>
43 #include <sys/vnode.h>
44 #include <sys/mount.h>
45 #include <sys/resourcevar.h>
48 #include <gnu/fs/ext2fs/inode.h>
49 #include <gnu/fs/ext2fs/ext2_fs.h>
50 #include <gnu/fs/ext2fs/ext2_fs_sb.h>
51 #include <gnu/fs/ext2fs/ext2_mount.h>
52 #include <gnu/fs/ext2fs/ext2_extern.h>
55 * Bmap converts a the logical block number of a file to its physical block
56 * number on the disk. The conversion is done by using the logical block
57 * number to index into the array of block pointers described by the dinode.
61 struct vop_bmap_args /* {
64 struct bufobj **a_bop;
74 * Check for underlying vnode requests and ensure that logical
75 * to physical mapping is requested.
77 if (ap->a_bop != NULL)
78 *ap->a_bop = &VTOI(ap->a_vp)->i_devvp->v_bufobj;
79 if (ap->a_bnp == NULL)
82 error = ext2_bmaparray(ap->a_vp, ap->a_bn, &blkno,
83 ap->a_runp, ap->a_runb);
89 * Indirect blocks are now on the vnode for the file. They are given negative
90 * logical block numbers. Indirect blocks are addressed by the negative
91 * address of the first data block to which they point. Double indirect blocks
92 * are addressed by one less than the address of the first indirect block to
93 * which they point. Triple indirect blocks are addressed by one less than
94 * the address of the first double indirect block to which they point.
96 * ufs_bmaparray does the bmap conversion, and if requested returns the
97 * array of logical blocks which must be traversed to get to a block.
98 * Each entry contains the offset into that block that gets you to the
99 * next block and the disk address of the block (if it is assigned).
103 ext2_bmaparray(vp, bn, bnp, runp, runb)
112 struct ext2mount *ump;
115 struct indir a[NIADDR+1], *ap;
118 int error, num, maxrun = 0, bsize;
125 devvp = ump->um_devvp;
127 bsize = EXT2_BLOCK_SIZE(ump->um_e2fs);
130 maxrun = mp->mnt_iosize_max / bsize - 1;
141 error = ext2_getlbns(vp, bn, ap, nump);
147 *bnp = blkptrtodb(ump, ip->i_db[bn]);
152 for (++bn; bn < NDADDR && *runp < maxrun &&
153 is_sequential(ump, ip->i_db[bn - 1], ip->i_db[bn]);
156 if (runb && (bn > 0)) {
157 for (--bn; (bn >= 0) && (*runb < maxrun) &&
158 is_sequential(ump, ip->i_db[bn],
167 /* Get disk address out of indirect block array */
168 daddr = ip->i_ib[ap->in_off];
170 for (bp = NULL, ++ap; --num; ++ap) {
172 * Exit the loop if there is no disk address assigned yet and
173 * the indirect block isn't in the cache, or if we were
174 * looking for an indirect block and we've found it.
177 metalbn = ap->in_lbn;
178 if ((daddr == 0 && !incore(&vp->v_bufobj, metalbn)) || metalbn == bn)
181 * If we get here, we've either got the block in the cache
182 * or we have a disk address for it, go fetch it.
188 bp = getblk(vp, metalbn, bsize, 0, 0, 0);
189 if ((bp->b_flags & B_CACHE) == 0) {
192 panic("ufs_bmaparray: indirect block not in cache");
194 bp->b_blkno = blkptrtodb(ump, daddr);
195 bp->b_iocmd = BIO_READ;
196 bp->b_flags &= ~B_INVAL;
197 bp->b_ioflags &= ~BIO_ERROR;
198 vfs_busy_pages(bp, 0);
199 bp->b_iooffset = dbtob(bp->b_blkno);
201 curthread->td_ru.ru_inblock++;
209 daddr = ((int32_t *)bp->b_data)[ap->in_off];
210 if (num == 1 && daddr && runp) {
211 for (bn = ap->in_off + 1;
212 bn < MNINDIR(ump) && *runp < maxrun &&
214 ((int32_t *)bp->b_data)[bn - 1],
215 ((int32_t *)bp->b_data)[bn]);
219 for(--bn; bn >= 0 && *runb < maxrun &&
220 is_sequential(ump, ((int32_t *)bp->b_data)[bn],
221 ((int32_t *)bp->b_data)[bn+1]);
230 * Since this is FFS independent code, we are out of scope for the
231 * definitions of BLK_NOCOPY and BLK_SNAP, but we do know that they
232 * will fall in the range 1..um_seqinc, so we use that test and
233 * return a request for a zeroed out buffer if attempts are made
234 * to read a BLK_NOCOPY or BLK_SNAP block.
236 if ((ip->i_flags & SF_SNAPSHOT) && daddr > 0 && daddr < ump->um_seqinc){
240 *bnp = blkptrtodb(ump, daddr);
248 * Create an array of logical block number/offset pairs which represent the
249 * path of indirect blocks required to access a data block. The first "pair"
250 * contains the logical block number of the appropriate single, double or
251 * triple indirect block and the offset into the inode indirect block array.
252 * Note, the logical block number of the inode single/double/triple indirect
253 * block appears twice in the array, once with the offset into the i_ib and
254 * once with the offset into the page itself.
257 ext2_getlbns(vp, bn, ap, nump)
263 long blockcnt, metalbn, realbn;
264 struct ext2mount *ump;
265 int i, numlevels, off;
268 ump = VFSTOEXT2(vp->v_mount);
276 /* The first NDADDR blocks are direct blocks. */
281 * Determine the number of levels of indirection. After this loop
282 * is done, blockcnt indicates the number of data blocks possible
283 * at the previous level of indirection, and NIADDR - i is the number
284 * of levels of indirection needed to locate the requested block.
286 for (blockcnt = 1, i = NIADDR, bn -= NDADDR;; i--, bn -= blockcnt) {
290 * Use int64_t's here to avoid overflow for triple indirect
291 * blocks when longs have 32 bits and the block size is more
294 qblockcnt = (int64_t)blockcnt * MNINDIR(ump);
297 blockcnt = qblockcnt;
300 /* Calculate the address of the first meta-block. */
302 metalbn = -(realbn - bn + NIADDR - i);
304 metalbn = -(-realbn - bn + NIADDR - i);
307 * At each iteration, off is the offset into the bap array which is
308 * an array of disk addresses at the current level of indirection.
309 * The logical block number and the offset in that block are stored
310 * into the argument array.
312 ap->in_lbn = metalbn;
313 ap->in_off = off = NIADDR - i;
316 for (++numlevels; i <= NIADDR; i++) {
317 /* If searching for a meta-data block, quit when found. */
318 if (metalbn == realbn)
321 off = (bn / blockcnt) % MNINDIR(ump);
324 ap->in_lbn = metalbn;
329 metalbn -= -1 + off * blockcnt;
330 blockcnt /= MNINDIR(ump);