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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>
58 #include "ffs_extern.h"
61 * Return buffer with the contents of block "offset" from the beginning of
62 * vnode "vp". If "res" is non-zero, fill it in with a pointer to the
63 * remaining space in the vnode.
66 ffs_blkatoff(struct vnode *vp, off_t uoffset, char **res, struct buf **bpp)
76 lbn = lblkno(fs, uoffset);
77 bsize = blksize(fs, ip, lbn);
80 error = bread(vp, lblktodoff(fs, lbn), bsize, &bp);
86 *res = (char *)bp->b_data + blkoff(fs, uoffset);
92 * Return buffer with the contents of block "offset" from the beginning of
93 * vnode "vp". If "res" is non-zero, fill it in with a pointer to the
94 * remaining space in the vnode.
96 * This version includes a read-ahead optimization.
99 ffs_blkatoff_ra(struct vnode *vp, off_t uoffset, char **res, struct buf **bpp,
114 lbn = lblkno(fs, uoffset);
115 base_loffset = lblktodoff(fs, lbn);
116 bsize = blksize(fs, ip, lbn);
119 next_loffset = lblktodoff(fs, nextlbn);
124 if (next_loffset >= ip->i_size) {
126 * Do not do readahead if this is the last block,
127 * bsize might represent a fragment.
129 error = bread(vp, base_loffset, bsize, &bp);
130 } else if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
132 * Try to cluster if we allowed to.
134 error = cluster_read(vp, (off_t)ip->i_size,
136 bsize, seqcount * BKVASIZE, &bp);
137 } else if (seqcount > 1) {
141 nextbsize = blksize(fs, ip, nextlbn);
142 error = breadn(vp, base_loffset, bsize,
143 &next_loffset, &nextbsize, 1, &bp);
146 * Failing all of the above, just read what the
147 * user asked for. Interestingly, the same as
148 * the first option above.
150 error = bread(vp, base_loffset, bsize, &bp);
157 *res = (char *)bp->b_data + (int)(uoffset - base_loffset);
165 * Update the frsum fields to reflect addition or deletion
169 ffs_fragacct(struct fs *fs, int fragmap, int32_t fraglist[], int cnt)
176 * inblk represents a bitmap of fragment sizes which may be
177 * contained in the data 'fragmap'. e.g. if a fragment of size
178 * 1 is available, bit 0 would be set. inblk is shifted left
179 * by one so we do not have to calculate (1 << (siz - 1)).
181 * fragment represents the data pattern we are trying to decipher,
182 * we shift it left by one to align it with the 'around' and 'inside'
185 * around represents the bits around the subfield and is a mask.
186 * inside represents what we must match within the mask, it is
187 * basically the mask with the first and last bit set to 0, allowing
188 * us to represent a whole fragment.
190 * When we find a match we bump our position by the size of the
191 * matching fragment, then bump the position again:
193 * 010101010 fragmap (shifted left by 1)
196 * 111 (shifted by siz)
198 * 111 (shifted again)
201 inblk = (int)(fragtbl[fs->fs_frag][fragmap]) << 1;
203 for (siz = 1; siz < fs->fs_frag; siz++) {
204 if ((inblk & (1 << (siz + (fs->fs_frag % NBBY)))) == 0)
207 subfield = inside[siz];
208 for (pos = siz; pos <= fs->fs_frag; pos++) {
209 if ((fragmap & field) == subfield) {
210 fraglist[siz] += cnt;
224 * check if a block is available
227 ffs_isblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
231 switch ((int)fs->fs_frag) {
233 return (cp[h] == 0xff);
235 mask = 0x0f << ((h & 0x1) << 2);
236 return ((cp[h >> 1] & mask) == mask);
238 mask = 0x03 << ((h & 0x3) << 1);
239 return ((cp[h >> 2] & mask) == mask);
241 mask = 0x01 << (h & 0x7);
242 return ((cp[h >> 3] & mask) == mask);
244 panic("ffs_isblock");
249 * check if a block is free
252 ffs_isfreeblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
254 switch ((int)fs->fs_frag) {
258 return ((cp[h >> 1] & (0x0f << ((h & 0x1) << 2))) == 0);
260 return ((cp[h >> 2] & (0x03 << ((h & 0x3) << 1))) == 0);
262 return ((cp[h >> 3] & (0x01 << (h & 0x7))) == 0);
264 panic("ffs_isfreeblock");
269 * take a block out of the map
272 ffs_clrblock(struct fs *fs, u_char *cp, ufs_daddr_t h)
274 switch ((int)fs->fs_frag) {
279 cp[h >> 1] &= ~(0x0f << ((h & 0x1) << 2));
282 cp[h >> 2] &= ~(0x03 << ((h & 0x3) << 1));
285 cp[h >> 3] &= ~(0x01 << (h & 0x7));
288 panic("ffs_clrblock");
293 * put a block into the map
296 ffs_setblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
298 switch ((int)fs->fs_frag) {
303 cp[h >> 1] |= (0x0f << ((h & 0x1) << 2));
306 cp[h >> 2] |= (0x03 << ((h & 0x3) << 1));
309 cp[h >> 3] |= (0x01 << (h & 0x7));
312 panic("ffs_setblock");