xfs: fix getbmap vs mmap deadlock

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 <[email protected]>
Reviewed-by: Eric Sandeen <[email protected]>
Reviewed-by: Felix Blyakher <[email protected]>
Signed-off-by: Felix Blyakher <[email protected]>

0 files changed, 0 insertions, 0 deletions