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Be a bit smarter about rewriting data so we don't loose too much performance.

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Sponsored by: DARPA & NAI Labs.
This commit is contained in:
phk 2002-05-26 09:38:51 +00:00
parent ec9860cfd0
commit 3a79eba71d
1 changed files with 21 additions and 21 deletions
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42
sys/dev/md/md.c
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@ -296,18 +296,17 @@ s_read(struct indir *ip, off_t offset)
/*
* Write a given sector, prune the tree if the value is 0
* If the new value is different from the old, return the old value.
*/
static int
s_write(struct indir *ip, off_t offset, uintptr_t ptr, uintptr_t *old)
s_write(struct indir *ip, off_t offset, uintptr_t ptr)
{
struct indir *cip, *lip[10];
int idx, li;
uintptr_t up;
if (md_debug > 1)
printf("s_write(%lld, %p, %p)\n", offset, (void *)ptr, old);
printf("s_write(%lld, %p)\n", offset, (void *)ptr);
up = 0;
li = 0;
cip = ip;
@ -333,8 +332,6 @@ s_write(struct indir *ip, off_t offset, uintptr_t ptr, uintptr_t *old)
/* leafnode */
idx = offset & NMASK;
up = cip->array[idx];
if (old != NULL && up != ptr)
*old = up;
if (up != 0)
cip->used--;
cip->array[idx] = ptr;
@ -415,18 +412,19 @@ mdstart_malloc(struct md_s *sc, struct bio *bp)
dst = bp->bio_data;
error = 0;
while (nsec--) {
osp = 0;
osp = s_read(sc->indir, secno);
if (bp->bio_cmd == BIO_DELETE) {
error = s_write(sc->indir, secno, 0, &osp);
if (osp != 0)
error = s_write(sc->indir, secno, 0);
} else if (bp->bio_cmd == BIO_READ) {
sp = s_read(sc->indir, secno);
if (sp == 0)
if (osp == 0)
bzero(dst, sc->secsize);
else if (sp <= 255)
else if (osp <= 255)
for (i = 0; i < sc->secsize; i++)
dst[i] = sp;
dst[i] = osp;
else
bcopy((void *)sp, dst, sc->secsize);
bcopy((void *)osp, dst, sc->secsize);
osp = 0;
} else if (bp->bio_cmd == BIO_WRITE) {
if (sc->flags & MD_COMPRESS) {
uc = dst[0];
@ -438,18 +436,20 @@ mdstart_malloc(struct md_s *sc, struct bio *bp)
uc = 0;
}
if (i == sc->secsize) {
error = s_write(sc->indir, secno, uc, &osp);
if (osp != uc)
error = s_write(sc->indir, secno, uc);
} else {
sp = s_read(sc->indir, secno);
if (sp <= 255)
if (osp <= 255) {
sp = (uintptr_t) uma_zalloc(
sc->uma, M_NOWAIT);
if (sp == 0) {
error = ENOMEM;
if (sp == 0) {
error = ENOSPC;
break;
}
error = s_write(sc->indir, secno, sp);
} else {
bcopy(dst, (void *)sp, sc->secsize);
error = s_write(sc->indir, secno,
sp, &osp);
bcopy(dst, (void *)osp, sc->secsize);
osp = 0;
}
}
} else {
@ -726,7 +726,7 @@ mdcreate_malloc(struct md_ioctl *mdio)
for (u = 0; u < sc->nsect; u++) {
sp = (uintptr_t) uma_zalloc(sc->uma, M_NOWAIT | M_ZERO);
if (sp != 0)
error = s_write(sc->indir, u, sp, NULL);
error = s_write(sc->indir, u, sp);
else
error = ENOMEM;
if (error)