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33 * @(#)ffs_subr.c 8.5 (Berkeley) 3/21/95
34 * $FreeBSD: src/sys/ufs/ffs/ffs_subr.c,v 1.25 1999/12/29 04:55:04 peter Exp $
37 #include <sys/param.h>
42 extern void panic(const char *, ...);
46 #include <sys/systm.h>
48 #include <sys/vnode.h>
50 #include <sys/ucred.h>
51 #include <sys/mount.h>
56 #include "ffs_extern.h"
59 * Return buffer with the contents of block "offset" from the beginning of
60 * vnode "vp". If "res" is non-zero, fill it in with a pointer to the
61 * remaining space in the vnode.
64 ffs_blkatoff(struct vnode *vp, off_t uoffset, char **res, struct buf **bpp)
74 lbn = lblkno(fs, uoffset);
75 bsize = blksize(fs, ip, lbn);
78 error = bread(vp, lblktodoff(fs, lbn), bsize, &bp);
84 *res = (char *)bp->b_data + blkoff(fs, uoffset);
90 * Return buffer with the contents of block "offset" from the beginning of
91 * vnode "vp". If "res" is non-zero, fill it in with a pointer to the
92 * remaining space in the vnode.
94 * This version includes a read-ahead optimization.
97 ffs_blkatoff_ra(struct vnode *vp, off_t uoffset, char **res, struct buf **bpp,
112 lbn = lblkno(fs, uoffset);
113 base_loffset = lblktodoff(fs, lbn);
114 bsize = blksize(fs, ip, lbn);
117 next_loffset = lblktodoff(fs, nextlbn);
122 if (next_loffset >= ip->i_size) {
124 * Do not do readahead if this is the last block,
125 * bsize might represent a fragment.
127 error = bread(vp, base_loffset, bsize, &bp);
128 } else if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
130 * Try to cluster if we allowed to.
132 error = cluster_read(vp, (off_t)ip->i_size,
134 bsize, seqcount * BKVASIZE, &bp);
135 } else if (seqcount > 1) {
139 nextbsize = blksize(fs, ip, nextlbn);
140 error = breadn(vp, base_loffset, bsize,
141 &next_loffset, &nextbsize, 1, &bp);
144 * Failing all of the above, just read what the
145 * user asked for. Interestingly, the same as
146 * the first option above.
148 error = bread(vp, base_loffset, bsize, &bp);
155 *res = (char *)bp->b_data + (int)(uoffset - base_loffset);
163 * Update the frsum fields to reflect addition or deletion
167 ffs_fragacct(struct fs *fs, int fragmap, int32_t fraglist[], int cnt)
174 * inblk represents a bitmap of fragment sizes which may be
175 * contained in the data 'fragmap'. e.g. if a fragment of size
176 * 1 is available, bit 0 would be set. inblk is shifted left
177 * by one so we do not have to calculate (1 << (siz - 1)).
179 * fragment represents the data pattern we are trying to decipher,
180 * we shift it left by one to align it with the 'around' and 'inside'
183 * around represents the bits around the subfield and is a mask.
184 * inside represents what we must match within the mask, it is
185 * basically the mask with the first and last bit set to 0, allowing
186 * us to represent a whole fragment.
188 * When we find a match we bump our position by the size of the
189 * matching fragment, then bump the position again:
191 * 010101010 fragmap (shifted left by 1)
194 * 111 (shifted by siz)
196 * 111 (shifted again)
199 inblk = (int)(fragtbl[fs->fs_frag][fragmap]) << 1;
201 for (siz = 1; siz < fs->fs_frag; siz++) {
202 if ((inblk & (1 << (siz + (fs->fs_frag % NBBY)))) == 0)
205 subfield = inside[siz];
206 for (pos = siz; pos <= fs->fs_frag; pos++) {
207 if ((fragmap & field) == subfield) {
208 fraglist[siz] += cnt;
222 * check if a block is available
225 ffs_isblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
229 switch ((int)fs->fs_frag) {
231 return (cp[h] == 0xff);
233 mask = 0x0f << ((h & 0x1) << 2);
234 return ((cp[h >> 1] & mask) == mask);
236 mask = 0x03 << ((h & 0x3) << 1);
237 return ((cp[h >> 2] & mask) == mask);
239 mask = 0x01 << (h & 0x7);
240 return ((cp[h >> 3] & mask) == mask);
242 panic("ffs_isblock");
247 * check if a block is free
250 ffs_isfreeblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
252 switch ((int)fs->fs_frag) {
256 return ((cp[h >> 1] & (0x0f << ((h & 0x1) << 2))) == 0);
258 return ((cp[h >> 2] & (0x03 << ((h & 0x3) << 1))) == 0);
260 return ((cp[h >> 3] & (0x01 << (h & 0x7))) == 0);
262 panic("ffs_isfreeblock");
267 * take a block out of the map
270 ffs_clrblock(struct fs *fs, u_char *cp, ufs_daddr_t h)
272 switch ((int)fs->fs_frag) {
277 cp[h >> 1] &= ~(0x0f << ((h & 0x1) << 2));
280 cp[h >> 2] &= ~(0x03 << ((h & 0x3) << 1));
283 cp[h >> 3] &= ~(0x01 << (h & 0x7));
286 panic("ffs_clrblock");
291 * put a block into the map
294 ffs_setblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
296 switch ((int)fs->fs_frag) {
301 cp[h >> 1] |= (0x0f << ((h & 0x1) << 2));
304 cp[h >> 2] |= (0x03 << ((h & 0x3) << 1));
307 cp[h >> 3] |= (0x01 << (h & 0x7));
310 panic("ffs_setblock");