Messages in this thread | | | Date | Wed, 8 Nov 2006 19:27:22 +1100 | From | David Chinner <> | Subject | Re: [PATCH 2.6.19 5/5] fs: freeze_bdev with semaphore not mutex |
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On Wed, Nov 08, 2006 at 12:01:09AM +0000, Alasdair G Kergon wrote: > On Wed, Nov 08, 2006 at 12:42:02AM +0100, Rafael J. Wysocki wrote: > > On Wednesday, 8 November 2006 00:18, Eric Sandeen wrote: > > > But, how is a stampede of fs-freezers -supposed- to work? I could > > > imagine something like a freezer count, and the filesystem is only > > > unfrozen after everyone has thawed? Or should only one freezer be > > > active at a time... which is what we have now I guess. > > I think it shouldn't be possible to freeze an fs more than once. > > In device-mapper today, the only way to get more than one freeze on the > same device is to use xfs and issue xfs_freeze before creating an lvm snapshot > (or issuing the dmsetup equivalent), and at the moment we tell people not to do > that any more.
But it's trivial to detect this condition - if (sb->s_frozen != SB_UNFROZEN) then the filesystem is already frozen and you shouldn't try to freeze it again. It's simple to do, and the whole problem then just goes away....
Cheers,
Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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