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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 1.10 2006/03/24 18:35:34 dillon Exp $
38 #include <sys/param.h>
46 #include <sys/systm.h>
48 #include <sys/vnode.h>
50 #include <sys/ucred.h>
54 #include "ffs_extern.h"
57 void ffs_checkoverlap (struct buf *, struct inode *);
61 * Return buffer with the contents of block "offset" from the beginning of
62 * directory "ip". If "res" is non-zero, fill it in with a pointer to the
63 * remaining space in the directory.
66 ffs_blkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp)
76 lbn = lblkno(fs, offset);
77 bsize = blksize(fs, ip, lbn);
80 error = bread(vp, lblktodoff(fs, lbn), bsize, &bp);
86 *res = (char *)bp->b_data + blkoff(fs, offset);
93 * Update the frsum fields to reflect addition or deletion
97 ffs_fragacct(struct fs *fs, int fragmap, int32_t fraglist[], int cnt)
104 * inblk represents a bitmap of fragment sizes which may be
105 * contained in the data 'fragmap'. e.g. if a fragment of size
106 * 1 is available, bit 0 would be set. inblk is shifted left
107 * by one so we do not have to calculate (1 << (siz - 1)).
109 * fragment represents the data pattern we are trying to decipher,
110 * we shift it left by one to align it with the 'around' and 'inside'
113 * around represents the bits around the subfield and is a mask.
114 * inside represents what we must match within the mask, it is
115 * basically the mask with the first and last bit set to 0, allowing
116 * us to represent a whole fragment.
118 * When we find a match we bump our position by the size of the
119 * matching fragment, then bump the position again:
121 * 010101010 fragmap (shifted left by 1)
124 * 111 (shifted by siz)
126 * 111 (shifted again)
129 inblk = (int)(fragtbl[fs->fs_frag][fragmap]) << 1;
131 for (siz = 1; siz < fs->fs_frag; siz++) {
132 if ((inblk & (1 << (siz + (fs->fs_frag % NBBY)))) == 0)
135 subfield = inside[siz];
136 for (pos = siz; pos <= fs->fs_frag; pos++) {
137 if ((fragmap & field) == subfield) {
138 fraglist[siz] += cnt;
151 ffs_checkoverlap(struct buf *bp, struct inode *ip)
153 struct buf *ebp, *ep;
158 start = bp->b_bio2.bio_offset;
159 last = start + bp->b_bcount - 1;
160 for (ep = buf; ep < ebp; ep++) {
161 if (ep == bp || (ep->b_flags & B_INVAL) ||
164 if (VOP_BMAP(ep->b_vp, (off_t)0, &vp, NULL, NULL, NULL))
166 if (vp != ip->i_devvp)
168 /* look for overlap */
169 if (ep->b_bcount == 0 || ep->b_bio2.bio_offset == NOOFFSET ||
170 ep->b_bio2.bio_offset > last ||
171 ep->b_bio2.bio_offset + ep->b_bcount <= start)
173 vprint("Disk overlap", vp);
174 printf("\tstart %lld, end %lld overlap start %lld, end %lld\n",
176 ep->b_bio2.bio_offset,
177 ep->b_bio2.bio_offset + ep->b_bcount - 1);
178 panic("ffs_checkoverlap: Disk buffer overlap");
186 * check if a block is available
189 ffs_isblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
193 switch ((int)fs->fs_frag) {
195 return (cp[h] == 0xff);
197 mask = 0x0f << ((h & 0x1) << 2);
198 return ((cp[h >> 1] & mask) == mask);
200 mask = 0x03 << ((h & 0x3) << 1);
201 return ((cp[h >> 2] & mask) == mask);
203 mask = 0x01 << (h & 0x7);
204 return ((cp[h >> 3] & mask) == mask);
206 panic("ffs_isblock");
211 * check if a block is free
214 ffs_isfreeblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
216 switch ((int)fs->fs_frag) {
220 return ((cp[h >> 1] & (0x0f << ((h & 0x1) << 2))) == 0);
222 return ((cp[h >> 2] & (0x03 << ((h & 0x3) << 1))) == 0);
224 return ((cp[h >> 3] & (0x01 << (h & 0x7))) == 0);
226 panic("ffs_isfreeblock");
231 * take a block out of the map
234 ffs_clrblock(struct fs *fs, u_char *cp, ufs_daddr_t h)
236 switch ((int)fs->fs_frag) {
241 cp[h >> 1] &= ~(0x0f << ((h & 0x1) << 2));
244 cp[h >> 2] &= ~(0x03 << ((h & 0x3) << 1));
247 cp[h >> 3] &= ~(0x01 << (h & 0x7));
250 panic("ffs_clrblock");
255 * put a block into the map
258 ffs_setblock(struct fs *fs, unsigned char *cp, ufs_daddr_t h)
260 switch ((int)fs->fs_frag) {
265 cp[h >> 1] |= (0x0f << ((h & 0x1) << 2));
268 cp[h >> 2] |= (0x03 << ((h & 0x3) << 1));
271 cp[h >> 3] |= (0x01 << (h & 0x7));
274 panic("ffs_setblock");