2 * modified for Lites 1.1
4 * Aug 1995, Godmar Back (gback@cs.utah.edu)
5 * University of Utah, Department of Computer Science
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39 * @(#)ffs_balloc.c 8.4 (Berkeley) 9/23/93
40 * $FreeBSD: src/sys/gnu/ext2fs/ext2_balloc.c,v 1.9.2.1 2000/08/03 00:52:57 peter Exp $
41 * $DragonFly: src/sys/vfs/gnu/ext2fs/ext2_balloc.c,v 1.10 2006/12/23 00:41:29 swildner Exp $
44 #include <sys/param.h>
45 #include <sys/systm.h>
48 #include <sys/ucred.h>
49 #include <sys/vnode.h>
54 #include "ext2_fs_sb.h"
56 #include "ext2_extern.h"
59 * Balloc defines the structure of file system storage
60 * by allocating the physical blocks on a device given
61 * the inode and the logical block number in a file.
64 ext2_balloc(struct inode *ip, daddr_t bn, int size, struct ucred *cred,
65 struct buf **bpp, int flags)
67 struct ext2_sb_info *fs;
70 struct vnode *vp = ITOV(ip);
71 struct indir indirs[NIADDR + 2];
72 daddr_t newb, lbn, *bap, pref;
73 int osize, nsize, num, i, error;
75 ext2_debug("ext2_balloc called (%d, %d, %d)\n",
76 ip->i_number, (int)bn, (int)size);
85 * check if this is a sequential block allocation.
86 * If so, increment next_alloc fields to allow ext2_blkpref
87 * to make a good guess
89 if (lbn == ip->i_next_alloc_block + 1) {
90 ip->i_next_alloc_block++;
91 ip->i_next_alloc_goal++;
95 * The first NDADDR blocks are direct blocks
99 /* no new block is to be allocated, and no need to expand
101 if (nb != 0 && ip->i_size >= (bn + 1) * fs->s_blocksize) {
102 error = bread(vp, lblktodoff(fs, bn),
103 fs->s_blocksize, &bp);
113 * Consider need to reallocate a fragment.
115 osize = fragroundup(fs, blkoff(fs, ip->i_size));
116 nsize = fragroundup(fs, size);
117 if (nsize <= osize) {
118 error = bread(vp, lblktodoff(fs, bn),
125 /* Godmar thinks: this shouldn't happen w/o fragments */
126 kprintf("nsize %d(%d) > osize %d(%d) nb %d\n",
127 (int)nsize, (int)size, (int)osize,
128 (int)ip->i_size, (int)nb);
130 "ext2_balloc: Something is terribly wrong");
132 * please note there haven't been any changes from here on -
137 if (ip->i_size < (bn + 1) * fs->s_blocksize)
138 nsize = fragroundup(fs, size);
140 nsize = fs->s_blocksize;
141 error = ext2_alloc(ip, bn,
142 ext2_blkpref(ip, bn, (int)bn, &ip->i_db[0], 0),
146 bp = getblk(vp, lblktodoff(fs, bn), nsize, 0, 0);
147 bp->b_bio2.bio_offset = fsbtodoff(fs, newb);
148 if (flags & B_CLRBUF)
151 ip->i_db[bn] = dofftofsb(fs, bp->b_bio2.bio_offset);
152 ip->i_flag |= IN_CHANGE | IN_UPDATE;
157 * Determine the number of levels of indirection.
160 if ((error = ext2_getlbns(vp, bn, indirs, &num)) != 0)
164 panic ("ext2_balloc: ext2_bmaparray returned indirect block");
167 * Fetch the first indirect block allocating if necessary.
170 nb = ip->i_ib[indirs[0].in_off];
173 pref = ext2_blkpref(ip, lbn, 0, NULL, 0);
175 /* see the comment by ext2_blkpref. What we do here is
176 to pretend that it'd be good for a block holding indirect
177 pointers to be allocated near its predecessor in terms
178 of indirection, or the last direct block.
179 We shamelessly exploit the fact that i_ib immediately
181 Godmar thinks it make sense to allocate i_ib[0] immediately
182 after i_db[11], but it's not utterly clear whether this also
183 applies to i_ib[1] and i_ib[0]
186 pref = ext2_blkpref(ip, lbn, indirs[0].in_off +
187 EXT2_NDIR_BLOCKS, &ip->i_db[0], 0);
189 if ((error = ext2_alloc(ip, lbn, pref, (int)fs->s_blocksize,
193 bp = getblk(vp, lblktodoff(fs, indirs[1].in_lbn),
194 fs->s_blocksize, 0, 0);
195 bp->b_bio2.bio_offset = fsbtodoff(fs, newb);
198 * Write synchronously so that indirect blocks
199 * never point at garbage.
201 if ((error = bwrite(bp)) != 0) {
202 ext2_blkfree(ip, nb, fs->s_blocksize);
205 ip->i_ib[indirs[0].in_off] = newb;
206 ip->i_flag |= IN_CHANGE | IN_UPDATE;
209 * Fetch through the indirect blocks, allocating as necessary.
213 lblktodoff(fs, indirs[i].in_lbn),
214 (int)fs->s_blocksize, &bp);
219 bap = (daddr_t *)bp->b_data;
220 nb = bap[indirs[i].in_off];
230 /* see the comment above and by ext2_blkpref
231 * I think this implements Linux policy, but
232 * does it really make sense to allocate to
233 * block containing pointers together ?
234 * Also, will it ever succeed ?
236 pref = ext2_blkpref(ip, lbn, indirs[i].in_off, bap,
237 lblkno(fs, bp->b_loffset));
239 pref = ext2_blkpref(ip, lbn, 0, NULL, 0);
242 ext2_alloc(ip, lbn, pref, (int)fs->s_blocksize, cred, &newb)) != 0) {
247 nbp = getblk(vp, lblktodoff(fs, indirs[i].in_lbn),
248 fs->s_blocksize, 0, 0);
249 nbp->b_bio2.bio_offset = fsbtodoff(fs, nb);
252 * Write synchronously so that indirect blocks
253 * never point at garbage.
255 if ((error = bwrite(nbp)) != 0) {
256 ext2_blkfree(ip, nb, fs->s_blocksize);
260 bap[indirs[i - 1].in_off] = nb;
262 * If required, write synchronously, otherwise use
265 if (flags & B_SYNC) {
272 * Get the data block, allocating if necessary.
275 pref = ext2_blkpref(ip, lbn, indirs[i].in_off, &bap[0],
276 lblkno(fs, bp->b_loffset));
277 if ((error = ext2_alloc(ip,
278 lbn, pref, (int)fs->s_blocksize, cred, &newb)) != 0) {
283 nbp = getblk(vp, lblktodoff(fs, lbn), fs->s_blocksize, 0, 0);
284 nbp->b_bio2.bio_offset = fsbtodoff(fs, nb);
285 if (flags & B_CLRBUF)
287 bap[indirs[i].in_off] = nb;
289 * If required, write synchronously, otherwise use
292 if (flags & B_SYNC) {
301 if (flags & B_CLRBUF) {
302 error = bread(vp, lblktodoff(fs, lbn),
303 (int)fs->s_blocksize, &nbp);
309 nbp = getblk(vp, lblktodoff(fs, lbn), fs->s_blocksize, 0, 0);
310 nbp->b_bio2.bio_offset = fsbtodoff(fs, nb);