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Fix a deadlock where fscow_disestablish() blocks because outstanding

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copy-on-write operations wait for si_snaplock.
This commit is contained in:
hannken 2009-10-13 12:38:14 +00:00
parent 64747bca1d
commit 8deb3262b5
1 changed files with 6 additions and 9 deletions
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15
sys/ufs/ffs/ffs_snapshot.c
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@ -1,4 +1,4 @@
/* $NetBSD: ffs_snapshot.c,v 1.95 2009/04/18 14:58:07 tsutsui Exp $ */
/* $NetBSD: ffs_snapshot.c,v 1.96 2009/10/13 12:38:14 hannken Exp $ */
/*
* Copyright 2000 Marshall Kirk McKusick. All Rights Reserved.
@ -38,7 +38,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ffs_snapshot.c,v 1.95 2009/04/18 14:58:07 tsutsui Exp $");
__KERNEL_RCSID(0, "$NetBSD: ffs_snapshot.c,v 1.96 2009/10/13 12:38:14 hannken Exp $");
#if defined(_KERNEL_OPT)
#include "opt_ffs.h"
@ -1311,7 +1311,6 @@ ffs_snapremove(struct vnode *vp)
int error, loc, last;
si = VFSTOUFS(mp)->um_snapinfo;
mutex_enter(&si->si_snaplock);
/*
* If active, delete from incore list (this snapshot may
* already have been in the process of being deleted, so
@ -1327,21 +1326,19 @@ ffs_snapremove(struct vnode *vp)
/* Roll back the list of preallocated blocks. */
xp = TAILQ_LAST(&si->si_snapshots, inodelst);
si->si_snapblklist = xp->i_snapblklist;
si->si_gen++;
mutex_exit(&si->si_lock);
} else {
si->si_snapblklist = 0;
si->si_gen++;
mutex_exit(&si->si_lock);
fscow_disestablish(mp, ffs_copyonwrite, devvp);
mutex_enter(&si->si_lock);
}
si->si_gen++;
mutex_exit(&si->si_lock);
if (ip->i_snapblklist != NULL) {
free(ip->i_snapblklist, M_UFSMNT);
ip->i_snapblklist = NULL;
}
}
mutex_exit(&si->si_snaplock);
/*
* Clear all BLK_NOCOPY fields. Pass any block claims to other
* snapshots that want them (see ffs_snapblkfree below).
@ -1734,10 +1731,10 @@ ffs_snapshot_unmount(struct mount *mp)
mutex_enter(&si->si_lock);
}
}
if (vp)
fscow_disestablish(mp, ffs_copyonwrite, devvp);
si->si_gen++;
mutex_exit(&si->si_lock);
if (vp)
fscow_disestablish(mp, ffs_copyonwrite, devvp);
}
/*