Author: markj
Date: Thu Aug 6 15:43:15 2020
New Revision: 363960
URL: https://svnweb.freebsd.org/changeset/base/363960
Log:
Clean up reassignbuf() and buf_vlist_remove() a bit.
- 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
Modified:
head/sys/kern/vfs_subr.c
Modified: head/sys/kern/vfs_subr.c
==============================================================================
--- head/sys/kern/vfs_subr.c Thu Aug 6 15:42:59 2020 (r363959)
+++ head/sys/kern/vfs_subr.c Thu Aug 6 15:43:15 2020 (r363960)
@@ -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.
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