tree 5148a0440674ef618a5af4e1b549794db9f783c1
parent 538f8ea6c85232d00bfa5edd9ba85f16c01057c9
author Nick Piggin <npiggin@suse.de> 1219266560 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1219272032 -0700

mm: xip/ext2 fix block allocation race

XIP can call into get_xip_mem concurrently with the same file,offset with
create=1.  This usually maps down to get_block, which expects the page
lock to prevent such a situation.  This causes ext2 to explode for one
reason or another.

Serialise those calls for the moment.  For common usages today, I suspect
get_xip_mem rarely is called to create new blocks.  In future as XIP
technologies evolve we might need to look at which operations require
scalability, and rework the locking to suit.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Jared Hulbert <jaredeh@gmail.com>
Acked-by: Carsten Otte <cotte@freenet.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>