2 * Copyright (c) 1982, 1986, 1989, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * @(#)ffs_subr.c 8.5 (Berkeley) 3/21/95
30 * $FreeBSD: src/sys/ufs/ffs/ffs_subr.c,v 1.25 1999/12/29 04:55:04 peter Exp $
33 #include <sys/param.h>
38 extern void panic(const char *, ...) __printflike(1, 2) __dead2;
40 #include <sys/systm.h>
42 #include <sys/vnode.h>
44 #include <sys/ucred.h>
45 #include <sys/mount.h>
52 #include "ffs_extern.h"
55 * Return buffer with the contents of block "offset" from the beginning of
56 * vnode "vp". If "res" is non-zero, fill it in with a pointer to the
57 * remaining space in the vnode.
60 ffs_blkatoff(struct vnode *vp, off_t uoffset, char **res, struct buf **bpp)
70 lbn = lblkno(fs, uoffset);
71 bsize = blksize(fs, ip, lbn);
74 error = bread(vp, lblktodoff(fs, lbn), bsize, &bp);
80 *res = (char *)bp->b_data + blkoff(fs, uoffset);
86 * Return buffer with the contents of block "offset" from the beginning of
87 * vnode "vp". If "res" is non-zero, fill it in with a pointer to the
88 * remaining space in the vnode.
90 * This version includes a read-ahead optimization.
93 ffs_blkatoff_ra(struct vnode *vp, off_t uoffset, char **res, struct buf **bpp,
108 lbn = lblkno(fs, uoffset);
109 base_loffset = lblktodoff(fs, lbn);
110 bsize = blksize(fs, ip, lbn);
113 next_loffset = lblktodoff(fs, nextlbn);
118 if (next_loffset >= ip->i_size) {
120 * Do not do readahead if this is the last block,
121 * bsize might represent a fragment.
123 error = bread(vp, base_loffset, bsize, &bp);
124 } else if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
126 * Try to cluster if we allowed to.
128 error = cluster_read(vp, (off_t)ip->i_size,
130 bsize, seqcount * BKVASIZE, &bp);
131 } else if (seqcount > 1) {
135 nextbsize = blksize(fs, ip, nextlbn);
136 error = breadn(vp, base_loffset, bsize,
137 &next_loffset, &nextbsize, 1, &bp);
140 * Failing all of the above, just read what the
141 * user asked for. Interestingly, the same as
142 * the first option above.
144 error = bread(vp, base_loffset, bsize, &bp);
151 *res = (char *)bp->b_data + (int)(uoffset - base_loffset);
159 * Update the frsum fields to reflect addition or deletion
163 ffs_fragacct(struct fs *fs, int fragmap, int32_t fraglist[], int cnt)
170 * inblk represents a bitmap of fragment sizes which may be
171 * contained in the data 'fragmap'. e.g. if a fragment of size
172 * 1 is available, bit 0 would be set. inblk is shifted left
173 * by one so we do not have to calculate (1 << (siz - 1)).
175 * fragment represents the data pattern we are trying to decipher,
176 * we shift it left by one to align it with the 'around' and 'inside'
179 * around represents the bits around the subfield and is a mask.
180 * inside represents what we must match within the mask, it is
181 * basically the mask with the first and last bit set to 0, allowing
182 * us to represent a whole fragment.
184 * When we find a match we bump our position by the size of the
185 * matching fragment, then bump the position again:
187 * 010101010 fragmap (shifted left by 1)
190 * 111 (shifted by siz)
192 * 111 (shifted again)
195 inblk = (int)(fragtbl[fs->fs_frag][fragmap]) << 1;
197 for (siz = 1; siz < fs->fs_frag; siz++) {
198 if ((inblk & (1 << (siz + (fs->fs_frag % NBBY)))) == 0)
201 subfield = inside[siz];
202 for (pos = siz; pos <= fs->fs_frag; pos++) {
203 if ((fragmap & field) == subfield) {
204 fraglist[siz] += cnt;
218 * check if a block is available
221 ffs_isblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
225 switch ((int)fs->fs_frag) {
227 return (cp[h] == 0xff);
229 mask = 0x0f << ((h & 0x1) << 2);
230 return ((cp[h >> 1] & mask) == mask);
232 mask = 0x03 << ((h & 0x3) << 1);
233 return ((cp[h >> 2] & mask) == mask);
235 mask = 0x01 << (h & 0x7);
236 return ((cp[h >> 3] & mask) == mask);
238 panic("ffs_isblock");
243 * check if a block is free
246 ffs_isfreeblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
248 switch ((int)fs->fs_frag) {
252 return ((cp[h >> 1] & (0x0f << ((h & 0x1) << 2))) == 0);
254 return ((cp[h >> 2] & (0x03 << ((h & 0x3) << 1))) == 0);
256 return ((cp[h >> 3] & (0x01 << (h & 0x7))) == 0);
258 panic("ffs_isfreeblock");
263 * take a block out of the map
266 ffs_clrblock(struct fs *fs, u_char *cp, ufs_daddr_t h)
268 switch ((int)fs->fs_frag) {
273 cp[h >> 1] &= ~(0x0f << ((h & 0x1) << 2));
276 cp[h >> 2] &= ~(0x03 << ((h & 0x3) << 1));
279 cp[h >> 3] &= ~(0x01 << (h & 0x7));
282 panic("ffs_clrblock");
287 * put a block into the map
290 ffs_setblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
292 switch ((int)fs->fs_frag) {
297 cp[h >> 1] |= (0x0f << ((h & 0x1) << 2));
300 cp[h >> 2] |= (0x03 << ((h & 0x3) << 1));
303 cp[h >> 3] |= (0x01 << (h & 0x7));
306 panic("ffs_setblock");