Date: Fri, 27 Mar 2015 09:43:15 -0600 From: Ian Lepore <ian@freebsd.org> To: Konstantin Belousov <kib@FreeBSD.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r280760 - head/sys/ufs/ffs Message-ID: <1427470995.91374.7.camel@freebsd.org> In-Reply-To: <201503271355.t2RDtuLt071068@svn.freebsd.org> References: <201503271355.t2RDtuLt071068@svn.freebsd.org>
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On Fri, 2015-03-27 at 13:55 +0000, Konstantin Belousov wrote: > Author: kib > Date: Fri Mar 27 13:55:56 2015 > New Revision: 280760 > URL: https://svnweb.freebsd.org/changeset/base/280760 > > Log: > Fix the hand after the immediate reboot when the following command > sequence is performed on UFS SU+J rootfs: > cp -Rp /sbin/init /sbin/init.old > mv -f /sbin/init.old /sbin/init > > Hang occurs on the rootfs unmount. There are two issues: > > 1. Removed init binary, which is still mapped, creates a reference to > the removed vnode. The inodeblock for such vnode must have active > inodedep, which is (eventually) linked through the unlinked list. This > means that ffs_sync(MNT_SUSPEND) cannot succeed, because number of > softdep workitems for the mp is always > 0. FFS is suspended during > unmount, so unmount just hangs. > > 2. As noted above, the inodedep is linked eventually. It is not > linked until the superblock is written. But at the vfs_unmountall() > time, when the rootfs is unmounted, the call is made to > ffs_unmount()->ffs_sync() before vflush(), and ffs_sync() only calls > ffs_sbupdate() after all workitems are flushed. It is masked for > normal system operations, because syncer works in parallel and > eventually flushes superblock. Syncer is stopped when rootfs > unmounted, so ffs_sync() must do sb update on its own. > > Correct the issues listed above. For MNT_SUSPEND, count the number of > linked unlinked inodedeps (this is not a typo) and substract the count > of such workitems from the total. For the second issue, the > ffs_sbupdate() is called right after device sync in ffs_sync() loop. > > There is third problem, occuring with both SU and SU+J. The > softdep_waitidle() loop, which waits for softdep_flush() thread to > clear the worklist, only waits 20ms max. It seems that the 1 tick, > specified for msleep(9), was a typo. > > Add fsync(devvp, MNT_WAIT) call to softdep_waitidle(), which seems to > significantly help the softdep thread, and change the MNT_LAZY update > at the reboot time to MNT_WAIT for similar reasons. Note that > userspace cannot create more work while devvp is flushed, since the > mount point is always suspended before the call to softdep_waitidle() > in unmount or remount path. > > PR: 195458 > In collaboration with: gjb, pho > Reviewed by: mckusick > Sponsored by: The FreeBSD Foundation > MFC after: 2 weeks > > Modified: > head/sys/ufs/ffs/ffs_softdep.c > head/sys/ufs/ffs/ffs_vfsops.c This is causing warning: function declaration isn't a prototype on platforms that still compile with old gcc. Simple fix, but I thought you might want to do the commit so you can get an mfc reminder along with the main commit. -- Ian Index: sys/ufs/ffs/ffs_softdep.c =================================================================== --- sys/ufs/ffs/ffs_softdep.c (revision 280761) +++ sys/ufs/ffs/ffs_softdep.c (working copy) @@ -804,6 +804,7 @@ static struct indirdep *indirdep_lookup(struct mou struct buf *); static void cancel_indirdep(struct indirdep *, struct buf *, struct freeblks *); +static int check_inodedep_free(struct inodedep *); static void free_indirdep(struct indirdep *); static void free_diradd(struct diradd *, struct workhead *); static void merge_diradd(struct inodedep *, struct diradd *);
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