32-bit bug in iovec iterator changes

From: Theodore Ts'o
Date: Fri Jun 20 2014 - 23:52:09 EST

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On Fri, Jun 20, 2014 at 08:38:20AM +1000, Dave Chinner wrote:
>
> Short reads are more likely a bug in all the iovec iterator stuff
> that got merged in from the vfs tree. ISTR a 32 bit-only bug in that
> stuff go past in to do with not being able to partition a 32GB block
> dev on a 32 bit system due to a 32 bit size_t overflow somewhere....

Dave Chinner called it.

Al, I'm seeing a regression which shows up using a 32-bit x86 kernel.
The symptoms of the bug is when run under KVM, with a 5 GB /dev/vdc
virtual block device, a read at offset 2 ** 30 fails with a short
read:

# dd if=/dev/vdc of=/dev/null bs=4k skip=262144 count=1
0+0 records in
0+0 records out
0 bytes (0 B) copied, 0.0164144 s, 0.0 kB/s

On a 3.15 kernel, this command works:

# dd if=/dev/vdc of=/dev/null bs=4k skip=262144 count=1
1+0 records in
1+0 records out
4096 bytes (4.1 kB) copied, 0.0457984 s, 89.4 kB/s

I tried bisecting it, but unfortunately the iovec iterator changes are
not cleanly bisectable, since copy_page_from_iter() gets introduced
some two dozen patches before it gets defined. :-(

However, the bisect leads quite squarely to to the iovec iterator
patches.

Al, I'd appreciate it if you could take a look?

Thanks!!

- Ted

% git bisect start
# good: [1860e379875dfe7271c649058aeddffe5afd9d0d] Linux 3.15
git bisect good 1860e379875dfe7271c649058aeddffe5afd9d0d
# bad: [7171511eaec5bf23fb06078f59784a3a0626b38f] Linux 3.16-rc1
git bisect bad 7171511eaec5bf23fb06078f59784a3a0626b38f
# good: [aaeb2554337217dfa4eac2fcc90da7be540b9a73] Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media into next
git bisect good aaeb2554337217dfa4eac2fcc90da7be540b9a73
# bad: [16b9057804c02e2d351e9c8f606e909b43cbd9e7] Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
git bisect bad 16b9057804c02e2d351e9c8f606e909b43cbd9e7
# good: [82abb273d838318424644d8f02825db0fbbd400a] Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus
git bisect good 82abb273d838318424644d8f02825db0fbbd400a
# good: [d1e1cda862c16252087374ac75949b0e89a5717e] Merge tag 'nfs-for-3.16-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs
git bisect good d1e1cda862c16252087374ac75949b0e89a5717e
# good: [23d4ed53b7342bf5999b3ea227d9f69e75e5a625] Merge branch 'for-linus' of git://git.kernel.dk/linux-block
git bisect good 23d4ed53b7342bf5999b3ea227d9f69e75e5a625
# good: [2840c566e95599cd60c7143762ca8b49d9395050] Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
git bisect good 2840c566e95599cd60c7143762ca8b49d9395050
# good: [4251c2a67011801caecd63671f26dd8c9aedb24c] Merge tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
git bisect good 4251c2a67011801caecd63671f26dd8c9aedb24c
# skip: [3dae8750c368f8ac11c3c8c2a28f56dcee865c01] cifs: switch to ->write_iter()
git bisect skip 3dae8750c368f8ac11c3c8c2a28f56dcee865c01
# good: [5c02c392cd2320e8d612376d6b72b6548a680923] Merge tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
git bisect good 5c02c392cd2320e8d612376d6b72b6548a680923
# bad: [5f073850602084fbcbb987948ff3e70ae273f7d2] kill generic_file_splice_write()
git bisect bad 5f073850602084fbcbb987948ff3e70ae273f7d2
# good: [38583f095c5a8138ae2a1c9173d0fd8a9f10e8aa] Merge branch 'akpm' (incoming from Andrew)
git bisect good 38583f095c5a8138ae2a1c9173d0fd8a9f10e8aa
# good: [f5ccfe1ddbaf9d923a3ebdadcb1e5e32d83e9c28] ext4: fix locking for O_APPEND writes
git bisect good f5ccfe1ddbaf9d923a3ebdadcb1e5e32d83e9c28
# bad: [f0d1bec9d58d4c038d0ac958c9af82be6eb18045] new helper: copy_page_from_iter()
git bisect bad f0d1bec9d58d4c038d0ac958c9af82be6eb18045

% (unset DISPLAY; git bisect visualize)
commit f0d1bec9d58d4c038d0ac958c9af82be6eb18045
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 3 15:05:18 2014 -0400

new helper: copy_page_from_iter()

parallel to copy_page_to_iter(). pipe_write() switched to it (and became
->write_iter()).

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 84c3d55cc474f9c234c023c92e2769f940d5548c
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 3 14:33:23 2014 -0400

fuse: switch to ->write_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit b30ac0fc4109701fc122d41ee085c65b52dc44a3
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 3 14:29:04 2014 -0400

btrfs: switch to ->write_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 3ef045c3d8ae8550abbfd44074efce6ff642cc86
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 3 14:25:22 2014 -0400

ocfs2: switch to ->write_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit bf97f3bc0c32140c43fe5ca53d23514ea46a54ca
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 3 14:20:23 2014 -0400

xfs: switch to ->write_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 50b5551d1719c8bce60c6d4027b814cfc72c2307
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 3 14:13:46 2014 -0400

afs: switch to ->write_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit da56e45b6ee83b67a586c61819cd2b5cfd806eb8
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 3 14:11:01 2014 -0400

gfs2: switch to ->write_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit edaf43694898c5d7deb9a394335c60e888039100
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 3 14:07:25 2014 -0400

nfs: switch to ->write_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit f5674c31ee1f968606702e82c160d6ae11032ded
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 3 14:00:23 2014 -0400

ubifs: switch to ->write_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit a8f3550cd228b6edc5d17fce1a9af8cc7004f185
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 3 03:32:25 2014 -0400

bury __generic_file_aio_write()

all users converted to __generic_file_write_iter() now

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 3dae8750c368f8ac11c3c8c2a28f56dcee865c01
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 3 12:05:17 2014 -0400

cifs: switch to ->write_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit d4637bc18f3bf89bd63fe7b967043523aa3a6170
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 3 03:31:17 2014 -0400

udf: switch to ->write_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 9b884164d59707216840159d45f6be68073fac6e
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 17 16:09:22 2014 -0400

convert ext4 to ->write_iter()

unfortunately, Ted's changes to ext4_file_write() are *still* an
incomplete fix - playing with rlimits can let you smuggle an
unaligned request past the checks. So there almost certainly
will be more merge PITA around that place...

[fix from Peter Ujfalusi <peter.ujfalusi@xxxxxx> folded]

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit a8324754889c0a491b216bc0502ef9ba557eeac7
Merge: 1456c0a f5ccfe1
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Tue May 6 17:38:41 2014 -0400

Merge ext4 changes in ext4_file_write() into for-next

From ext4.git#dev, needed for switch of ext4 to ->write_iter() ;-/

commit 1456c0a87c4241d3a801651019e66983c69ad17d
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 3 03:21:50 2014 -0400

blkdev_aio_write() - turn into blkdev_write_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 8174202b34c30e0c07231bf63f18ab29af634f0b
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 3 03:17:43 2014 -0400

write_iter variants of {__,}generic_file_aio_write()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 3644424dc6309439c4c8d97590cdac4100376255
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Apr 2 20:28:01 2014 -0400

ceph: switch to ->read_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 3aa2d199f8eb8149a88005e88736d583cbc39d31
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Apr 2 20:14:12 2014 -0400

nfs: switch to ->read_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit a886038baa48a17f2cf77fb5dcc204fd28659d8f
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Apr 2 20:02:21 2014 -0400

fs/block_dev.c: switch to ->read_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 2ba5bbed0cd7429dbd567fa885ae3bc7a76de3d4
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Apr 2 20:00:02 2014 -0400

shmem: switch to ->read_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit fb9096a344e2964c6a71520931c08abb1301248e
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Apr 2 19:56:54 2014 -0400

pipe: switch to ->read_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit e6a7bcb4c489e3e078ba3cc92ae6621b2b8bb9a7
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Apr 2 19:53:36 2014 -0400

cifs: switch to ->read_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 37c20f16e7a73e5fe34815e785ca6c5a46e4d260
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Apr 2 14:47:09 2014 -0400

fuse_file_aio_read(): convert to ->read_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 3cd9ad5a303a0d503492002c4af95becfa99af03
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Apr 2 14:44:18 2014 -0400

ocfs2: switch to ->read_iter()

tracepoints are evil, exhibit #6969...

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 027978295d455b2fdff0cb36570f83ada7385ea6
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Apr 2 14:40:38 2014 -0400

ecryptfs: switch to ->read_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit b4f5d2c6d1f88c79e48f1296076b3a6a22f58c0f
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Apr 2 14:37:59 2014 -0400

xfs: switch to ->read_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit aad4f8bb42af06371aa0e85bf0cd9d52c0494985
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Apr 2 14:33:16 2014 -0400

switch simple generic_file_aio_read() users to ->read_iter()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 293bc9822fa9b3c9d4b7893bcb241e085580771a
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Tue Feb 11 18:37:41 2014 -0500

new methods: ->read_iter() and ->write_iter()

Beginning to introduce those. Just the callers for now, and it's
clumsier than it'll eventually become; once we finish converting
aio_read and aio_write instances, the things will get nicer.

For now, these guys are in parallel to ->aio_read() and ->aio_write();
they take iocb and iov_iter, with everything in iov_iter already
validated. File offset is passed in iocb->ki_pos, iov/nr_segs -
in iov_iter.

Main concerns in that series are stack footprint and ability to
split the damn thing cleanly.

[fix from Peter Ujfalusi <peter.ujfalusi@xxxxxx> folded]

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 7f7f25e82d54870df24d415a7007fbd327da027b
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Tue Feb 11 17:49:24 2014 -0500

replace checking for ->read/->aio_read presence with check in ->f_mode

Since we are about to introduce new methods (read_iter/write_iter), the
tests in a bunch of places would have to grow inconveniently. Check
once (at open() time) and store results in ->f_mode as FMODE_CAN_READ
and FMODE_CAN_WRITE resp. It might end up being a temporary measure -
once everything switches from ->aio_{read,write} to ->{read,write}_iter
it might make sense to return to open-coded checks. We'll see...

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit b318891929c2750055a4002bee3e7636ca3684de
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Apr 2 07:06:30 2014 -0400

xfs: trim the argument lists of xfs_file_{dio,buffered}_aio_write()

pos is redundant (it's iocb->ki_pos), and iov/nr_segs/count are taken
care of by lifting iov_iter into the caller.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 37938463540b075e9166cf774c59274379f7a8ca
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Sat Mar 22 06:57:37 2014 -0400

blkdev_aio_read(): switch to generic_file_read_iter(), get rid of iov_shorten()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 0c949334a9e2581646c6ff0d1470a805b1e5be99
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Sat Mar 22 06:51:37 2014 -0400

iov_iter_truncate()

Now It Can Be Done(tm) - we don't need to do iov_shorten() in
generic_file_direct_write() anymore, now that all ->direct_IO()
instances are converted to proper iov_iter methods and honour
iter->count and iter->iov_offset properly.

Get rid of count/ocount arguments of generic_file_direct_write(),
while we are at it.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 28060d5d9b261da110afe48aae7a2aa6555f798f
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Sat Mar 22 05:15:17 2014 -0400

btrfs: switch check_direct_IO() to iov_iter

... and don't open-code iov_iter_alignment() there

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 91f79c43d1b54d7154b118860d81b39bad07dfff
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Fri Mar 21 04:58:33 2014 -0400

new helper: iov_iter_get_pages_alloc()

same as iov_iter_get_pages(), except that pages array is allocated
(kmalloc if possible, vmalloc if that fails) and left for caller to
free. Lustre and NFS ->direct_IO() switched to it.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit f67da30c1d5fc9e341bc8121708874bfd7b31e45
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Mar 19 01:16:16 2014 -0400

new helper: iov_iter_npages()

counts the pages covered by iov_iter, up to given limit.
do_block_direct_io() and fuse_iter_npages() switched to
it.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 5b46f25ddc6edf4adff1a137d453da542c27a640
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Sun Mar 16 18:07:34 2014 -0400

f2fs: switch to iov_iter_alignment()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit c9c37e2e63786c595d704244cbb7d19dc5630493
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Sun Mar 16 16:08:30 2014 -0400

fuse: switch to iov_iter_get_pages()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit d22a943f44c79c98ac7a93653fdd330378581741
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Sun Mar 16 15:50:47 2014 -0400

fuse: pull iov_iter initializations up

... to fuse_direct_{read,write}(). ->direct_IO() path uses the
iov_iter passed by the caller instead.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 7b2c99d15559e285384c742db52316802e24b0bd
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Sat Mar 15 04:05:57 2014 -0400

new helper: iov_iter_get_pages()

iov_iter_get_pages(iter, pages, maxsize, &start) grabs references pinning
the pages of up to maxsize of (contiguous) data from iter. Returns the
amount of memory grabbed or -error. In case of success, the requested
area begins at offset start in pages[0] and runs through pages[1], etc.
Less than requested amount might be returned - either because the contiguous
area in the beginning of iterator is smaller than requested, or because
the kernel failed to pin that many pages.

direct-io.c switched to using iov_iter_get_pages()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 3320c60b3a26d05666285c55ab08ee043c017ba3
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Mon Mar 10 02:30:55 2014 -0400

dio: take updating ->result into do_direct_IO()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 71d8e532b1549a478e6a6a8a44f309d050294d00
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Mar 5 19:28:09 2014 -0500

start adding the tag to iov_iter

For now, just use the same thing we pass to ->direct_IO() - it's all
iovec-based at the moment. Pass it explicitly to iov_iter_init() and
account for kvec vs. iovec in there, by the same kludge NFS ->direct_IO()
uses.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit ed978a811ec528dbe40243605c3afab55892f722
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Mar 5 22:53:04 2014 -0500

new helper: generic_file_read_iter()

iov_iter-using variant of generic_file_aio_read(). Some callers
converted. Note that it's still not quite there for use as ->read_iter() -
we depend on having zero iter->iov_offset in O_DIRECT case. Fortunately,
that's true for all converted callers (and for generic_file_aio_read() itself).

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 23faa7b8db9be0be4f158cfc558460bb95d9b245
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Mar 5 22:52:34 2014 -0500

fuse_file_aio_write(): merge initializations of iov_iter

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 05bb2e0bc77cb005248be318d2b0ba369b8bbab3
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Mar 5 19:22:23 2014 -0500

ceph_aio_read(): keep iov_iter across retries

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 886a39115005ced8b15ab067c9c2a8d546b40a5e
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Mar 5 13:50:45 2014 -0500

new primitive: iov_iter_alignment()

returns the value aligned as badly as the worst remaining segment
in iov_iter is. Use instead of open-coded equivalents.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 26978b8b4d83c46f4310b253db70fa9e65149e7c
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Mon Mar 10 14:08:45 2014 -0400

give ->direct_IO() a copy of iov_iter

the thing is, we want to advance what's given to ->direct_IO() as we
are forming the request; however, the callers care about the amount
of data actually transferred, not the amount we tried to transfer.
It's more convenient to allow ->direct_IO() instances do use
iov_iter_advance() on the copy of iov_iter, leaving the actual
advancing of the original to caller.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 31b140398ce56ab41646eda7f02bcb78d6a4c916
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Mar 5 01:33:16 2014 -0500

switch {__,}blockdev_direct_IO() to iov_iter

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit a6cbcd4a4a85e2fdb0b3344b88df2e8b3d526b9e
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Tue Mar 4 22:38:00 2014 -0500

get rid of pointless iov_length() in ->direct_IO()

all callers have iov_length(iter->iov, iter->nr_segs) == iov_iter_count(iter)

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 16b1f05d7f5ab4ce570963aca5f3b2b5d21822fa
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Tue Mar 4 22:14:00 2014 -0500

ext4: switch the guts of ->direct_IO() to iov_iter

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 619d30b4b8c488042b4a720ca79dccc346d1a516
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Tue Mar 4 21:53:33 2014 -0500

convert the guts of nfs_direct_IO() to iov_iter

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit d8d3d94b80aa1a1c0ca75c58b8abdc7356f38418
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Tue Mar 4 21:27:34 2014 -0500

pass iov_iter to ->direct_IO()

unmodified, for now

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit cb66a7a1f149ff705fa37cad6d1252b046e0ad4f
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Tue Mar 4 15:24:06 2014 -0500

kill generic_segment_checks()

all callers of ->aio_read() and ->aio_write() have iov/nr_segs already
checked - generic_segment_checks() done after that is just an odd way
to spell iov_length().

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 0ae5e4d370599592eab845527b31708a4f3411be
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Mon Mar 3 22:09:39 2014 -0500

__btrfs_direct_write(): switch to iov_iter

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit f8579f8673b7ecdb7a81d5d5bb1d981093d9aa94
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Mon Mar 3 22:03:20 2014 -0500

generic_file_direct_write(): switch to iov_iter

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit e7c24607b5d68a4cdc56e09d70a3c8bae5f0519f
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu Apr 10 20:54:51 2014 -0400

kill iov_iter_copy_from_user()

all callers can use copy_page_from_iter() and it actually simplifies
them.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit f6c0a1920e0180175bd5e8e4aff8ea5556f1895d
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Wed Apr 23 10:18:46 2014 -0400

fs/file.c: don't open-code kvfree()

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
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