forked from luck/tmp_suning_uos_patched
2e60d7683c
The current gfs2 freezing code is considerably more complicated than it should be because it doesn't use the vfs freezing code on any node except the one that begins the freeze. This is because it needs to acquire a cluster glock before calling the vfs code to prevent a deadlock, and without the new freeze_super and thaw_super hooks, that was impossible. To deal with the issue, gfs2 had to do some hacky locking tricks to make sure that a frozen node couldn't be holding on a lock it needed to do the unfreeze ioctl. This patch makes use of the new hooks to simply the gfs2 locking code. Now, all the nodes in the cluster freeze and thaw in exactly the same way. Every node in the cluster caches the freeze glock in the shared state. The new freeze_super hook allows the freezing node to grab this freeze glock in the exclusive state without first calling the vfs freeze_super function. All the nodes in the cluster see this lock change, and call the vfs freeze_super function. The vfs locking code guarantees that the nodes can't get stuck holding the glocks necessary to unfreeze the system. To unfreeze, the freezing node uses the new thaw_super hook to drop the freeze glock. Again, all the nodes notice this, reacquire the glock in shared mode and call the vfs thaw_super function. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
31 lines
1.1 KiB
C
31 lines
1.1 KiB
C
/*
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* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
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* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU General Public License version 2.
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*/
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#ifndef __GLOPS_DOT_H__
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#define __GLOPS_DOT_H__
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#include "incore.h"
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extern struct workqueue_struct *gfs2_freeze_wq;
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extern const struct gfs2_glock_operations gfs2_meta_glops;
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extern const struct gfs2_glock_operations gfs2_inode_glops;
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extern const struct gfs2_glock_operations gfs2_rgrp_glops;
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extern const struct gfs2_glock_operations gfs2_freeze_glops;
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extern const struct gfs2_glock_operations gfs2_iopen_glops;
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extern const struct gfs2_glock_operations gfs2_flock_glops;
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extern const struct gfs2_glock_operations gfs2_nondisk_glops;
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extern const struct gfs2_glock_operations gfs2_quota_glops;
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extern const struct gfs2_glock_operations gfs2_journal_glops;
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extern const struct gfs2_glock_operations *gfs2_glops_list[];
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extern void gfs2_ail_flush(struct gfs2_glock *gl, bool fsync);
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#endif /* __GLOPS_DOT_H__ */
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