linux-toradex.git/fs/aio.c, branch v3.12.12

aio/migratepages: make aio migrate pages sane

2014-01-09T20:25:16+00:00

commit 8e321fefb0e60bae4e2a28d20fc4fa30758d27c6 upstream.

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 
Signed-off-by: Greg Kroah-Hartman

aio: clean up and fix aio_setup_ring page mapping

2014-01-09T20:25:15+00:00

commit 3dc9acb67600393249a795934ccdfc291a200e6b upstream.

Since commit 36bc08cc01709 ("fs/aio: Add support to aio ring pages
migration") the aio ring setup code has used a special per-ring backing
inode for the page allocations, rather than just using random anonymous
pages.

However, rather than remembering the pages as it allocated them, it
would allocate the pages, insert them into the file mapping (dirty, so
that they couldn't be free'd), and then forget about them.  And then to
look them up again, it would mmap the mapping, and then use
"get_user_pages()" to get back an array of the pages we just created.

Now, not only is that incredibly inefficient, it also leaked all the
pages if the mmap failed (which could happen due to excessive number of
mappings, for example).

So clean it all up, making it much more straightforward.  Also remove
some left-overs of the previous (broken) mm_populate() usage that was
removed in commit d6c355c7dabc ("aio: fix race in ring buffer page
lookup introduced by page migration support") but left the pointless and
now misleading MAP_POPULATE flag around.

Tested-and-acked-by: Benjamin LaHaise 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

aio: fix kioctx leak introduced by "aio: Fix a trinity splat"

2014-01-09T20:25:08+00:00

commit 1881686f842065d2f92ec9c6424830ffc17d23b0 upstream.

e34ecee2ae791df674dfb466ce40692ca6218e43 reworked the percpu reference
counting to correct a bug trinity found.  Unfortunately, the change lead
to kioctxes being leaked because there was no final reference count to
put.  Add that reference count back in to fix things.

Signed-off-by: Benjamin LaHaise 
Signed-off-by: Greg Kroah-Hartman

aio: clean up aio ring in the fail path

2013-12-08T15:29:17+00:00

commit d1b9432712a25eeb06114fb4b587133525a47de5 upstream.

Clean up the aio ring file in the fail path of aio_setup_ring
and ioctx_alloc. And maybe it can fix the GPF issue reported by
Dave Jones:
https://lkml.org/lkml/2013/11/25/898

Signed-off-by: Gu Zheng 
Signed-off-by: Benjamin LaHaise 
Signed-off-by: Greg Kroah-Hartman

aio: nullify aio->ring_pages after freeing it

2013-12-08T15:29:17+00:00

commit ddb8c45ba15149ebd41d7586261c05f7ca37f9a1 upstream.

After freeing ring_pages we leave it as is causing a dangling pointer. This
has already caused an issue so to help catching any issues in the future
NULL it out.

Signed-off-by: Sasha Levin 
Signed-off-by: Benjamin LaHaise 
Signed-off-by: Greg Kroah-Hartman

aio: prevent double free in ioctx_alloc

2013-12-08T15:29:16+00:00

commit d558023207e008a4476a3b7bb8706b2a2bf5d84f upstream.

ioctx_alloc() calls aio_setup_ring() to allocate a ring. If aio_setup_ring()
fails to do so it would call aio_free_ring() before returning, but
ioctx_alloc() would call aio_free_ring() again causing a double free of
the ring.

This is easily reproducible from userspace.

Signed-off-by: Sasha Levin 
Signed-off-by: Benjamin LaHaise 
Signed-off-by: Greg Kroah-Hartman

aio: checking for NULL instead of IS_ERR

2013-12-08T15:29:16+00:00

commit 7f62656be8a8ef14c168db2d98021fb9c8cc1076 upstream.

alloc_anon_inode() returns an ERR_PTR(), it doesn't return NULL.

Fixes: 71ad7490c1f3 ('rework aio migrate pages to use aio fs')
Signed-off-by: Dan Carpenter 
Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

rework aio migrate pages to use aio fs

2013-12-08T15:29:16+00:00

commit 71ad7490c1f32bd7829df76360f9fa17829868f3 upstream.

Don't abuse anon_inodes.c to host private files needed by aio;
we can bloody well declare a mini-fs of our own instead of
patching up what anon_inodes can create for us.

Tested-by: Benjamin LaHaise 
Acked-by: Benjamin LaHaise 
Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

aio: Fix a trinity splat

2013-12-08T15:29:16+00:00

commit e34ecee2ae791df674dfb466ce40692ca6218e43 upstream.

aio kiocb refcounting was broken - it was relying on keeping track of
the number of available ring buffer entries, which it needs to do
anyways; then at shutdown time it'd wait for completions to be delivered
until the # of available ring buffer entries equalled what it was
initialized to.

Problem with  that is that the ring buffer is mapped writable into
userspace, so userspace could futz with the head and tail pointers to
cause the kernel to see extra completions, and cause free_ioctx() to
return while there were still outstanding kiocbs. Which would be bad.

Fix is just to directly refcount the kiocbs - which is more
straightforward, and with the new percpu refcounting code doesn't cost
us any cacheline bouncing which was the whole point of the original
scheme.

Also clean up ioctx_alloc()'s error path and fix a bug where it wasn't
subtracting from aio_nr if ioctx_add_table() failed.

Signed-off-by: Kent Overstreet 
Cc: Benjamin LaHaise 
Signed-off-by: Greg Kroah-Hartman

aio: fix use-after-free in aio_migratepage

2013-09-27T00:34:51+00:00

Dmitry Vyukov managed to trigger a case where aio_migratepage can cause a
use-after-free during teardown of the aio ring buffer's mapping.  This turns
out to be caused by access to the ioctx's ring_pages via the migratepage
operation which was not being protected by any locks during ioctx freeing.
Use the address_space's private_lock to protect use and updates of the mapping's
private_data, and make ioctx teardown unlink the ioctx from the address space.

Reported-by: Dmitry Vyukov 
Tested-by: Dmitry Vyukov 
Signed-off-by: Benjamin LaHaise