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| author | kib <kib@FreeBSD.org> | 2013-07-09 20:49:32 +0000 |
|---|---|---|
| committer | kib <kib@FreeBSD.org> | 2013-07-09 20:49:32 +0000 |
| commit | a7b76b76e17881d47ffd2715135b3512e07d0fbf (patch) | |
| tree | 163763327fb3a8dbae9807ce2cbea1c3bb9f69f6 /sys/ufs/ffs | |
| parent | 247743cbbaf231a82a50f74ca849e50b747d1401 (diff) | |
| download | FreeBSD-src-a7b76b76e17881d47ffd2715135b3512e07d0fbf.zip FreeBSD-src-a7b76b76e17881d47ffd2715135b3512e07d0fbf.tar.gz | |
There are several code sequences like
vfs_busy(mp);
vfs_write_suspend(mp);
which are problematic if other thread starts unmount between two
calls. The unmount starts a write, while vfs_write_suspend() drain
writers. On the other hand, unmount drains busy references, causing
the deadlock.
Add a flag argument to vfs_write_suspend and require the callers of it
to specify VS_SKIP_UNMOUNT flag, when the call is performed not in the
mount path, i.e. the covered vnode is not locked. The suspension is
not attempted if VS_SKIP_UNMOUNT is specified and unmount is in
progress.
Reported and tested by: Andreas Longwitz <longwitz@incore.de>
Sponsored by: The FreeBSD Foundation
MFC after: 3 weeks
Diffstat (limited to 'sys/ufs/ffs')
| -rw-r--r-- | sys/ufs/ffs/ffs_snapshot.c | 2 | ||||
| -rw-r--r-- | sys/ufs/ffs/ffs_suspend.c | 2 | ||||
| -rw-r--r-- | sys/ufs/ffs/ffs_vfsops.c | 4 |
3 files changed, 4 insertions, 4 deletions
diff --git a/sys/ufs/ffs/ffs_snapshot.c b/sys/ufs/ffs/ffs_snapshot.c index 9a9c88a..ad157aa 100644 --- a/sys/ufs/ffs/ffs_snapshot.c +++ b/sys/ufs/ffs/ffs_snapshot.c @@ -423,7 +423,7 @@ restart: */ for (;;) { vn_finished_write(wrtmp); - if ((error = vfs_write_suspend(vp->v_mount)) != 0) { + if ((error = vfs_write_suspend(vp->v_mount, 0)) != 0) { vn_start_write(NULL, &wrtmp, V_WAIT); vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); goto out; diff --git a/sys/ufs/ffs/ffs_suspend.c b/sys/ufs/ffs/ffs_suspend.c index 3198c1a..a8c4578 100644 --- a/sys/ufs/ffs/ffs_suspend.c +++ b/sys/ufs/ffs/ffs_suspend.c @@ -206,7 +206,7 @@ ffs_susp_suspend(struct mount *mp) return (EPERM); #endif - if ((error = vfs_write_suspend(mp)) != 0) + if ((error = vfs_write_suspend(mp, VS_SKIP_UNMOUNT)) != 0) return (error); ump->um_writesuspended = 1; diff --git a/sys/ufs/ffs/ffs_vfsops.c b/sys/ufs/ffs/ffs_vfsops.c index 57f092c..a87fdfa 100644 --- a/sys/ufs/ffs/ffs_vfsops.c +++ b/sys/ufs/ffs/ffs_vfsops.c @@ -257,7 +257,7 @@ ffs_mount(struct mount *mp) return (error); for (;;) { vn_finished_write(mp); - if ((error = vfs_write_suspend(mp)) != 0) + if ((error = vfs_write_suspend(mp, 0)) != 0) return (error); MNT_ILOCK(mp); if (mp->mnt_kern_flag & MNTK_SUSPENDED) { @@ -1255,7 +1255,7 @@ ffs_unmount(mp, mntflags) */ for (;;) { vn_finished_write(mp); - if ((error = vfs_write_suspend(mp)) != 0) + if ((error = vfs_write_suspend(mp, 0)) != 0) return (error); MNT_ILOCK(mp); if (mp->mnt_kern_flag & MNTK_SUSPENDED) { |
