Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH 2.6.19 5/5] fs: freeze_bdev with semaphore not mutex | Date | Wed, 8 Nov 2006 00:05:49 +0100 |
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On Tuesday, 7 November 2006 23:45, Eric Sandeen wrote: > Andrew Morton wrote: > > >> --- linux-2.6.19-rc4.orig/fs/buffer.c 2006-11-07 17:06:20.000000000 +0000 > >> +++ linux-2.6.19-rc4/fs/buffer.c 2006-11-07 17:26:04.000000000 +0000 > >> @@ -188,7 +188,9 @@ struct super_block *freeze_bdev(struct b > >> { > >> struct super_block *sb; > >> > >> - mutex_lock(&bdev->bd_mount_mutex); > >> + if (down_trylock(&bdev->bd_mount_sem)) > >> + return -EBUSY; > >> + > > > > This is a functional change which isn't described in the changelog. What's > > happening here? > > Only allow one bdev-freezer in at a time, rather than queueing them up?
But freeze_bdev() is supposed to return the result of get_super(bdev) _unconditionally_. Moreover, in its current form freeze_bdev() _cannot_ _fail_, so I don't see how this change doesn't break any existing code.
For example freeze_filesystems() (recently added to -mm) will be broken if the down_trylock() is unsuccessful.
Greetings, Rafael
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