Date: Sun, 29 Sep 2013 18:10:00 GMT From: dfilter@FreeBSD.ORG (dfilter service) To: freebsd-bugs@FreeBSD.org Subject: Re: kern/178997: commit references a PR Message-ID: <201309291810.r8TIA0Ql000850@freefall.freebsd.org>
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The following reply was made to PR kern/178997; it has been noted by GNATS. From: dfilter@FreeBSD.ORG (dfilter service) To: bug-followup@FreeBSD.org Cc: Subject: Re: kern/178997: commit references a PR Date: Sun, 29 Sep 2013 18:05:10 +0000 (UTC) Author: kib Date: Sun Sep 29 18:04:57 2013 New Revision: 255941 URL: http://svnweb.freebsd.org/changeset/base/255941 Log: Reimplement r255797 using LK_TRYUPGRADE. The r255797 was: Increase the chance of the buffer write from the bufdaemon helper context to succeed. If the locked vnode which owns the buffer to be written is shared locked, try the non-blocking upgrade of the lock to exclusive. PR: kern/178997 Reported and tested by: Klaus Weber <fbsd-bugs-2013-1@unix-admin.de> Sponsored by: The FreeBSD Foundation MFC after: 1 week Approved by: re (glebius) Modified: head/sys/kern/vfs_bio.c Modified: head/sys/kern/vfs_bio.c ============================================================================== --- head/sys/kern/vfs_bio.c Sun Sep 29 18:02:23 2013 (r255940) +++ head/sys/kern/vfs_bio.c Sun Sep 29 18:04:57 2013 (r255941) @@ -2624,6 +2624,8 @@ flushbufqueues(struct vnode *lvp, int ta int hasdeps; int flushed; int queue; + int error; + bool unlock; flushed = 0; queue = QUEUE_DIRTY; @@ -2699,7 +2701,16 @@ flushbufqueues(struct vnode *lvp, int ta BUF_UNLOCK(bp); continue; } - if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) { + if (lvp == NULL) { + unlock = true; + error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); + } else { + ASSERT_VOP_LOCKED(vp, "getbuf"); + unlock = false; + error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : + vn_lock(vp, LK_TRYUPGRADE); + } + if (error == 0) { mtx_unlock(&bqdirty); CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); @@ -2711,7 +2722,8 @@ flushbufqueues(struct vnode *lvp, int ta notbufdflushes++; } vn_finished_write(mp); - VOP_UNLOCK(vp, 0); + if (unlock) + VOP_UNLOCK(vp, 0); flushwithdeps += hasdeps; flushed++; _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscribe@freebsd.org"
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