aio/migratepages: make aio migrate pages sane
authorBenjamin LaHaise <bcrl@kvack.org>
Sat, 21 Dec 2013 22:56:08 +0000 (17:56 -0500)
committerBenjamin LaHaise <bcrl@kvack.org>
Sat, 21 Dec 2013 22:56:08 +0000 (17:56 -0500)
commit8e321fefb0e60bae4e2a28d20fc4fa30758d27c6
treec00de123ad058cc2d69a2e3d59dd7a2bb7500542
parent1881686f842065d2f92ec9c6424830ffc17d23b0
aio/migratepages: make aio migrate pages sane

The arbitrary restriction on page counts offered by the core
migrate_page_move_mapping() code results in rather suspicious looking
fiddling with page reference counts in the aio_migratepage() operation.
To fix this, make migrate_page_move_mapping() take an extra_count parameter
that allows aio to tell the code about its own reference count on the page
being migrated.

While cleaning up aio_migratepage(), make it validate that the old page
being passed in is actually what aio_migratepage() expects to prevent
misbehaviour in the case of races.

Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
fs/aio.c
include/linux/migrate.h
mm/migrate.c