xfs: I/O completion handlers must use NOFS allocations
When completing I/O requests we must not allow the memory allocator to
recurse into the filesystem, as we might deadlock on waiting for the
I/O completion otherwise. The only thing currently allocating normal
GFP_KERNEL memory is the allocation of the transaction structure for
the unwritten extent conversion. Add a memflags argument to
_xfs_trans_alloc to allow controlling the allocator behaviour.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reported-by: Thomas Neumann <tneumann@users.sourceforge.net> Tested-by: Thomas Neumann <tneumann@users.sourceforge.net> Reviewed-by: Alex Elder <aelder@sgi.com> Signed-off-by: Alex Elder <aelder@sgi.com>