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Add support for BIO_DELETE on swap-backed md(4). In the case of BIO_DELETE

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covering the whole page, free the page. Otherwise, clear the region and
mark it clean. Not marking the page dirty could reinstantiate cleared
data, but it is allowed by BIO_DELETE specification and saves unneeded
write to swap.

Reviewed by:	alc
Tested by:	pho
MFC after:	2 weeks
This commit is contained in:
Konstantin Belousov 2011-01-27 16:10:25 +00:00
parent 21835e695a
commit 4a13a769dc
1 changed files with 10 additions and 6 deletions
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16
sys/dev/md/md.c
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@ -649,7 +649,6 @@ mdstart_swap(struct md_s *sc, struct bio *bp)
}
bcopy(p, (void *)(sf_buf_kva(sf) + offs), len);
m->valid = VM_PAGE_BITS_ALL;
#if 0
} else if (bp->bio_cmd == BIO_DELETE) {
if (len != PAGE_SIZE && m->valid != VM_PAGE_BITS_ALL)
rv = vm_pager_get_pages(sc->object, &m, 1, 0);
@ -659,16 +658,21 @@ mdstart_swap(struct md_s *sc, struct bio *bp)
vm_page_wakeup(m);
break;
}
bzero((void *)(sf_buf_kva(sf) + offs), len);
vm_page_dirty(m);
m->valid = VM_PAGE_BITS_ALL;
#endif
if (len != PAGE_SIZE) {
bzero((void *)(sf_buf_kva(sf) + offs), len);
vm_page_clear_dirty(m, offs, len);
m->valid = VM_PAGE_BITS_ALL;
} else
vm_pager_page_unswapped(m);
}
sf_buf_free(sf);
sched_unpin();
vm_page_wakeup(m);
vm_page_lock(m);
vm_page_activate(m);
if (bp->bio_cmd == BIO_DELETE && len == PAGE_SIZE)
vm_page_free(m);
else
vm_page_activate(m);
vm_page_unlock(m);
if (bp->bio_cmd == BIO_WRITE)
vm_page_dirty(m);