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Clean up reassignbuf() and buf_vlist_remove() a bit.

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- Convert panic() calls to INVARIANTS-only assertions.  The PCTRIE code
  provides some of the same protection since it will panic upon an
  attempt to remove a non-resident buffer.
- Update the comment above reassignbuf() to reflect reality.

Reviewed by:	cem, kib, mjg
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D25965
This commit is contained in:
Mark Johnston 2020-08-06 15:43:15 +00:00
parent 7013797e34
commit 0ffec1b03d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=363960
1 changed files with 15 additions and 24 deletions
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39
sys/kern/vfs_subr.c
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@ -2256,13 +2256,17 @@ static void
buf_vlist_remove(struct buf *bp)
{
struct bufv *bv;
b_xflags_t flags;
flags = bp->b_xflags;
KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
ASSERT_BO_WLOCKED(bp->b_bufobj);
KASSERT((bp->b_xflags & (BX_VNDIRTY|BX_VNCLEAN)) !=
(BX_VNDIRTY|BX_VNCLEAN),
("buf_vlist_remove: Buf %p is on two lists", bp));
if (bp->b_xflags & BX_VNDIRTY)
KASSERT((flags & (BX_VNDIRTY | BX_VNCLEAN)) != 0 &&
(flags & (BX_VNDIRTY | BX_VNCLEAN)) != (BX_VNDIRTY | BX_VNCLEAN),
("%s: buffer %p has invalid queue state", __func__, bp));
if ((flags & BX_VNDIRTY) != 0)
bv = &bp->b_bufobj->bo_dirty;
else
bv = &bp->b_bufobj->bo_clean;
@ -2391,10 +2395,7 @@ brelvp(struct buf *bp)
vp = bp->b_vp; /* XXX */
bo = bp->b_bufobj;
BO_LOCK(bo);
if (bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN))
buf_vlist_remove(bp);
else
panic("brelvp: Buffer %p not on queue.", bp);
buf_vlist_remove(bp);
if ((bo->bo_flag & BO_ONWORKLST) && bo->bo_dirty.bv_cnt == 0) {
bo->bo_flag &= ~BO_ONWORKLST;
mtx_lock(&sync_mtx);
@ -2707,9 +2708,7 @@ syncer_resume(void)
}
/*
* Reassign a buffer from one vnode to another.
* Used to assign file specific control information
* (indirect blocks) to the vnode to which they belong.
* Move the buffer between the clean and dirty lists of its vnode.
*/
void
reassignbuf(struct buf *bp)
@ -2724,23 +2723,15 @@ reassignbuf(struct buf *bp)
vp = bp->b_vp;
bo = bp->b_bufobj;
KASSERT((bp->b_flags & B_PAGING) == 0,
("%s: cannot reassign paging buffer %p", __func__, bp));
CTR3(KTR_BUF, "reassignbuf(%p) vp %p flags %X",
bp, bp->b_vp, bp->b_flags);
/*
* B_PAGING flagged buffers cannot be reassigned because their vp
* is not fully linked in.
*/
if (bp->b_flags & B_PAGING)
panic("cannot reassign paging buffer");
/*
* Delete from old vnode list, if on one.
*/
BO_LOCK(bo);
if (bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN))
buf_vlist_remove(bp);
else
panic("reassignbuf: Buffer %p not on queue.", bp);
buf_vlist_remove(bp);
/*
* If dirty, put on list of dirty buffers; otherwise insert onto list
* of clean buffers.