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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 $
35 * $DragonFly: src/sys/vfs/ufs/ffs_subr.c,v 1.13 2006/05/26 19:57:33 dillon Exp $
38 #include <sys/param.h>
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
126 error = bread(vp, base_loffset, bsize, &bp);
127 } else if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
129 * Try to cluster if we allowed to.
131 error = cluster_read(vp, (off_t)ip->i_size,
133 MAXBSIZE, seqcount, &bp);
134 } else if (seqcount > 1) {
138 nextbsize = blksize(fs, ip, nextlbn);
139 error = breadn(vp, base_loffset, bsize,
140 &next_loffset, &nextbsize, 1, &bp);
143 * Failing all of the above, just read what the
144 * user asked for. Interestingly, the same as
145 * the first option above.
147 error = bread(vp, base_loffset, bsize, &bp);
154 *res = (char *)bp->b_data + (int)(uoffset - base_loffset);
162 * Update the frsum fields to reflect addition or deletion
166 ffs_fragacct(struct fs *fs, int fragmap, int32_t fraglist[], int cnt)
173 * inblk represents a bitmap of fragment sizes which may be
174 * contained in the data 'fragmap'. e.g. if a fragment of size
175 * 1 is available, bit 0 would be set. inblk is shifted left
176 * by one so we do not have to calculate (1 << (siz - 1)).
178 * fragment represents the data pattern we are trying to decipher,
179 * we shift it left by one to align it with the 'around' and 'inside'
182 * around represents the bits around the subfield and is a mask.
183 * inside represents what we must match within the mask, it is
184 * basically the mask with the first and last bit set to 0, allowing
185 * us to represent a whole fragment.
187 * When we find a match we bump our position by the size of the
188 * matching fragment, then bump the position again:
190 * 010101010 fragmap (shifted left by 1)
193 * 111 (shifted by siz)
195 * 111 (shifted again)
198 inblk = (int)(fragtbl[fs->fs_frag][fragmap]) << 1;
200 for (siz = 1; siz < fs->fs_frag; siz++) {
201 if ((inblk & (1 << (siz + (fs->fs_frag % NBBY)))) == 0)
204 subfield = inside[siz];
205 for (pos = siz; pos <= fs->fs_frag; pos++) {
206 if ((fragmap & field) == subfield) {
207 fraglist[siz] += cnt;
221 * check if a block is available
224 ffs_isblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
228 switch ((int)fs->fs_frag) {
230 return (cp[h] == 0xff);
232 mask = 0x0f << ((h & 0x1) << 2);
233 return ((cp[h >> 1] & mask) == mask);
235 mask = 0x03 << ((h & 0x3) << 1);
236 return ((cp[h >> 2] & mask) == mask);
238 mask = 0x01 << (h & 0x7);
239 return ((cp[h >> 3] & mask) == mask);
241 panic("ffs_isblock");
246 * check if a block is free
249 ffs_isfreeblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
251 switch ((int)fs->fs_frag) {
255 return ((cp[h >> 1] & (0x0f << ((h & 0x1) << 2))) == 0);
257 return ((cp[h >> 2] & (0x03 << ((h & 0x3) << 1))) == 0);
259 return ((cp[h >> 3] & (0x01 << (h & 0x7))) == 0);
261 panic("ffs_isfreeblock");
266 * take a block out of the map
269 ffs_clrblock(struct fs *fs, u_char *cp, ufs_daddr_t h)
271 switch ((int)fs->fs_frag) {
276 cp[h >> 1] &= ~(0x0f << ((h & 0x1) << 2));
279 cp[h >> 2] &= ~(0x03 << ((h & 0x3) << 1));
282 cp[h >> 3] &= ~(0x01 << (h & 0x7));
285 panic("ffs_clrblock");
290 * put a block into the map
293 ffs_setblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
295 switch ((int)fs->fs_frag) {
300 cp[h >> 1] |= (0x0f << ((h & 0x1) << 2));
303 cp[h >> 2] |= (0x03 << ((h & 0x3) << 1));
306 cp[h >> 3] |= (0x01 << (h & 0x7));
309 panic("ffs_setblock");