xfs: fix getbmap vs mmap deadlock

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xfs_getbmap (or rather the formatters called by it) copy out the getbmap
structures under the ilock, which can deadlock against mmap.  This has
been reported via bugzilla a while ago (#717) and has recently also
shown up via lockdep.

So allocate a temporary buffer to format the kernel getbmap structures
into and then copy them out after dropping the locks.

A little problem with this is that we limit the number of extents we
can copy out by the maximum allocation size, but I see no real way
around that.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Eric Sandeen <sandeen@sandeen.net>
Reviewed-by: Felix Blyakher <felixb@sgi.com>
Signed-off-by: Felix Blyakher <felixb@sgi.com>

...

This commit is contained in:

Christoph Hellwig 2009-02-24 08:39:02 -05:00 • committed by Felix Blyakher

parent 4be4a00fb5

commit 6321e3ed2a

1 changed files with 35 additions and 17 deletions

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fs/xfs/xfs_bmap.c

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