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- If caller specifies readbehind and readahead that together with count

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doesn't fit into a buf, then trim readbehind and readahead evenly.  If
  rbehind was limited by the previous BMAP, then roundup its trim to
  block size.
- Add KASSERT to check that b_blkno has proper offset from original
  blkno returned by BMAP. [1]
- Add KASSERT to check that pages in buf are consecutive.

Reviewed by:	kib
Submitted by:	kib [1]
This commit is contained in:
Gleb Smirnoff 2016-11-17 20:32:32 +00:00
parent b22fe30db1
commit e48b82bd83
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=308778
1 changed files with 38 additions and 1 deletions
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39
sys/vm/vnode_pager.c
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@ -743,6 +743,9 @@ vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int count,
struct bufobj *bo;
struct buf *bp;
off_t foff;
#ifdef INVARIANTS
off_t blkno0;
#endif
int bsize, pagesperblock, *freecnt;
int error, before, after, rbehind, rahead, poff, i;
int bytecount, secmask;
@ -843,6 +846,9 @@ vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int count,
return (VM_PAGER_OK);
}
#ifdef INVARIANTS
blkno0 = bp->b_blkno;
#endif
bp->b_blkno += (foff % bsize) / DEV_BSIZE;
/* Recalculate blocks available after/before to pages. */
@ -864,7 +870,25 @@ vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int count,
rbehind = min(rbehind, m[0]->pindex);
rahead = min(rahead, after);
rahead = min(rahead, object->size - m[count - 1]->pindex);
KASSERT(rbehind + rahead + count <= sizeof(bp->b_pages),
/*
* Check that total amount of pages fit into buf. Trim rbehind and
* rahead evenly if not.
*/
if (rbehind + rahead + count > nitems(bp->b_pages)) {
int trim, sum;
trim = rbehind + rahead + count - nitems(bp->b_pages) + 1;
sum = rbehind + rahead;
if (rbehind == before) {
/* Roundup rbehind trim to block size. */
rbehind -= roundup(trim * rbehind / sum, pagesperblock);
if (rbehind < 0)
rbehind = 0;
} else
rbehind -= trim * rbehind / sum;
rahead -= trim * rahead / sum;
}
KASSERT(rbehind + rahead + count <= nitems(bp->b_pages),
("%s: behind %d ahead %d count %d", __func__,
rbehind, rahead, count));
@ -947,8 +971,14 @@ vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int count,
if (a_rahead)
*a_rahead = bp->b_pgafter;
#ifdef INVARIANTS
KASSERT(bp->b_npages <= nitems(bp->b_pages),
("%s: buf %p overflowed", __func__, bp));
for (int j = 1; j < bp->b_npages; j++)
KASSERT(bp->b_pages[j]->pindex - 1 ==
bp->b_pages[j - 1]->pindex,
("%s: pages array not consecutive, bp %p", __func__, bp));
#endif
/*
* Recalculate first offset and bytecount with regards to read behind.
@ -987,6 +1017,13 @@ vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int count,
bp->b_vp = vp;
bp->b_bcount = bp->b_bufsize = bp->b_runningbufspace = bytecount;
bp->b_iooffset = dbtob(bp->b_blkno);
KASSERT(IDX_TO_OFF(m[0]->pindex - bp->b_pages[0]->pindex) ==
(blkno0 - bp->b_blkno) * DEV_BSIZE +
IDX_TO_OFF(m[0]->pindex) % bsize,
("wrong offsets bsize %d m[0] %ju b_pages[0] %ju "
"blkno0 %ju b_blkno %ju", bsize,
(uintmax_t)m[0]->pindex, (uintmax_t)bp->b_pages[0]->pindex,
(uintmax_t)blkno0, (uintmax_t)bp->b_blkno));
atomic_add_long(&runningbufspace, bp->b_runningbufspace);
PCPU_INC(cnt.v_vnodein);