Re: linux-next: build failure after merge of the vfs tree

From: Dave Chinner
Date: Tue Jan 03 2012 - 21:50:27 EST


On Wed, Jan 04, 2012 at 02:17:54AM +0000, Al Viro wrote:
> I'm still not
> sure about ->statfs(), BTW - any input on that would be welcome. Can
> it end up blocked on a frozen fs until said fs is thawed?

I don't see why this should ever happen - ->statfs has to work on
read-only filesystems so shoul dnot be modifying state, and hence
should never need to care about the frozen state of the superblock.
So from a ->statfs POV, a frozen filesystem should look just like a
read-only filesystem. If frozen filesystems are holding locks that
->statfs can block on until the filesystem us thawed, then I'd
consider that a bug in the filesystem freeze implementation....

> to convert ustat(2) to "wait for thaw" semantics (should be interruptible,
> BTW) or document that ->statfs() is not allowed to wait for thawing.
> It's far too subtle to leave undocumented...

The latter, IMO.

Cheers,

Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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