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authorJun'ichi Nomura <j-nomura@ce.jp.nec.com>2010-01-28 19:56:22 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2010-02-07 03:06:21 -0500
commit4b06e5b9ad8abb20105b2b25e42c509ebe9b2d76 (patch)
treea151e21fef671e9d046a6c456d2f048eea56fb99 /fs
parent8dd5ca532c2d2c2b85f16bc038ebfff05b8853e1 (diff)
freeze_bdev: don't deactivate successfully frozen MS_RDONLY sb
Thanks Thomas and Christoph for testing and review. I removed 'smp_wmb()' before up_write from the previous patch, since up_write() should have necessary ordering constraints. (I.e. the change of s_frozen is visible to others after up_write) I'm quite sure the change is harmless but if you are uncomfortable with Tested-by/Reviewed-by on the modified patch, please remove them. If MS_RDONLY, freeze_bdev should just up_write(s_umount) instead of deactivate_locked_super(). Also, keep sb->s_frozen consistent so that remount can check the frozen state. Otherwise a crash reported here can happen: http://lkml.org/lkml/2010/1/16/37 http://lkml.org/lkml/2010/1/28/53 This patch should be applied for 2.6.32 stable series, too. Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Thomas Backlund <tmb@mandriva.org> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Cc: stable@kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
-rw-r--r--fs/block_dev.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 73d6a735b8f3..d11d0289f3d2 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -246,7 +246,8 @@ struct super_block *freeze_bdev(struct block_device *bdev)
246 if (!sb) 246 if (!sb)
247 goto out; 247 goto out;
248 if (sb->s_flags & MS_RDONLY) { 248 if (sb->s_flags & MS_RDONLY) {
249 deactivate_locked_super(sb); 249 sb->s_frozen = SB_FREEZE_TRANS;
250 up_write(&sb->s_umount);
250 mutex_unlock(&bdev->bd_fsfreeze_mutex); 251 mutex_unlock(&bdev->bd_fsfreeze_mutex);
251 return sb; 252 return sb;
252 } 253 }
@@ -307,7 +308,7 @@ int thaw_bdev(struct block_device *bdev, struct super_block *sb)
307 BUG_ON(sb->s_bdev != bdev); 308 BUG_ON(sb->s_bdev != bdev);
308 down_write(&sb->s_umount); 309 down_write(&sb->s_umount);
309 if (sb->s_flags & MS_RDONLY) 310 if (sb->s_flags & MS_RDONLY)
310 goto out_deactivate; 311 goto out_unfrozen;
311 312
312 if (sb->s_op->unfreeze_fs) { 313 if (sb->s_op->unfreeze_fs) {
313 error = sb->s_op->unfreeze_fs(sb); 314 error = sb->s_op->unfreeze_fs(sb);
@@ -321,11 +322,11 @@ int thaw_bdev(struct block_device *bdev, struct super_block *sb)
321 } 322 }
322 } 323 }
323 324
325out_unfrozen:
324 sb->s_frozen = SB_UNFROZEN; 326 sb->s_frozen = SB_UNFROZEN;
325 smp_wmb(); 327 smp_wmb();
326 wake_up(&sb->s_wait_unfrozen); 328 wake_up(&sb->s_wait_unfrozen);
327 329
328out_deactivate:
329 if (sb) 330 if (sb)
330 deactivate_locked_super(sb); 331 deactivate_locked_super(sb);
331out_unlock: 332out_unlock: