linux-stable.git/fs/ext4/file.c, branch linux-3.16.y Linux kernel stable tree ext4: fix races between page faults and hole punching 2020-04-28T18:02:19+00:00 Jan Kara jack@suse.com 2015-12-07T19:28:03+00:00 81a2281115c28be55d3489c3a79c84db294b722a commit ea3d7209ca01da209cda6f0dea8be9cc4b7a933b upstream. Currently, page faults and hole punching are completely unsynchronized. This can result in page fault faulting in a page into a range that we are punching after truncate_pagecache_range() has been called and thus we can end up with a page mapped to disk blocks that will be shortly freed. Filesystem corruption will shortly follow. Note that the same race is avoided for truncate by checking page fault offset against i_size but there isn't similar mechanism available for punching holes. Fix the problem by creating new rw semaphore i_mmap_sem in inode and grab it for writing over truncate, hole punching, and other functions removing blocks from extent tree and for read over page faults. We cannot easily use i_data_sem for this since that ranks below transaction start and we need something ranking above it so that it can be held over the whole truncate / hole punching operation. Also remove various workarounds we had in the code to reduce race window when page fault could have created pages with stale mapping information. Signed-off-by: Jan Kara <jack@suse.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> [bwh: Backported to 3.16: - Drop changes in ext4_insert_range(), ext4_dax_* - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit ea3d7209ca01da209cda6f0dea8be9cc4b7a933b upstream.

Currently, page faults and hole punching are completely unsynchronized.
This can result in page fault faulting in a page into a range that we
are punching after truncate_pagecache_range() has been called and thus
we can end up with a page mapped to disk blocks that will be shortly
freed. Filesystem corruption will shortly follow. Note that the same
race is avoided for truncate by checking page fault offset against
i_size but there isn't similar mechanism available for punching holes.

Fix the problem by creating new rw semaphore i_mmap_sem in inode and
grab it for writing over truncate, hole punching, and other functions
removing blocks from extent tree and for read over page faults. We
cannot easily use i_data_sem for this since that ranks below transaction
start and we need something ranking above it so that it can be held over
the whole truncate / hole punching operation. Also remove various
workarounds we had in the code to reduce race window when page fault
could have created pages with stale mapping information.

Signed-off-by: Jan Kara <jack@suse.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
[bwh: Backported to 3.16:
 - Drop changes in ext4_insert_range(), ext4_dax_*
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ext4: fix data corruption caused by overlapping unaligned and aligned IO 2019-09-23T20:12:04+00:00 Lukas Czerner lczerner@redhat.com 2019-05-11T01:45:33+00:00 36f680c1be1b46d2470fbf577ba229f4d81a154e commit 57a0da28ced8707cb9f79f071a016b9d005caf5a upstream. Unaligned AIO must be serialized because the zeroing of partial blocks of unaligned AIO can result in data corruption in case it's overlapping another in flight IO. Currently we wait for all unwritten extents before we submit unaligned AIO which protects data in case of unaligned AIO is following overlapping IO. However if a unaligned AIO is followed by overlapping aligned AIO we can still end up corrupting data. To fix this, we must make sure that the unaligned AIO is the only IO in flight by waiting for unwritten extents conversion not just before the IO submission, but right after it as well. This problem can be reproduced by xfstest generic/538 Signed-off-by: Lukas Czerner <lczerner@redhat.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> [bwh: Backported to 3.16: - Test aio_mutex instead of unaligned_aio - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 57a0da28ced8707cb9f79f071a016b9d005caf5a upstream.

Unaligned AIO must be serialized because the zeroing of partial blocks
of unaligned AIO can result in data corruption in case it's overlapping
another in flight IO.

Currently we wait for all unwritten extents before we submit unaligned
AIO which protects data in case of unaligned AIO is following overlapping
IO. However if a unaligned AIO is followed by overlapping aligned AIO we
can still end up corrupting data.

To fix this, we must make sure that the unaligned AIO is the only IO in
flight by waiting for unwritten extents conversion not just before the
IO submission, but right after it as well.

This problem can be reproduced by xfstest generic/538

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
[bwh: Backported to 3.16:
 - Test aio_mutex instead of unaligned_aio
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ext4: fix data corruption caused by unaligned direct AIO 2019-08-13T11:38:41+00:00 Lukas Czerner lczerner@redhat.com 2019-03-15T03:20:25+00:00 3668fd2619fed84326bc449a79ee4ad9e270f229 commit 372a03e01853f860560eade508794dd274e9b390 upstream. Ext4 needs to serialize unaligned direct AIO because the zeroing of partial blocks of two competing unaligned AIOs can result in data corruption. However it decides not to serialize if the potentially unaligned aio is past i_size with the rationale that no pending writes are possible past i_size. Unfortunately if the i_size is not block aligned and the second unaligned write lands past i_size, but still into the same block, it has the potential of corrupting the previous unaligned write to the same block. This is (very simplified) reproducer from Frank // 41472 = (10 * 4096) + 512 // 37376 = 41472 - 4096 ftruncate(fd, 41472); io_prep_pwrite(iocbs[0], fd, buf[0], 4096, 37376); io_prep_pwrite(iocbs[1], fd, buf[1], 4096, 41472); io_submit(io_ctx, 1, &iocbs[1]); io_submit(io_ctx, 1, &iocbs[2]); io_getevents(io_ctx, 2, 2, events, NULL); Without this patch the 512B range from 40960 up to the start of the second unaligned write (41472) is going to be zeroed overwriting the data written by the first write. This is a data corruption. 00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 * 00009200 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 * 0000a000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 * 0000a200 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 With this patch the data corruption is avoided because we will recognize the unaligned_aio and wait for the unwritten extent conversion. 00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 * 00009200 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 * 0000a200 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 * 0000b200 Reported-by: Frank Sorenson <fsorenso@redhat.com> Signed-off-by: Lukas Czerner <lczerner@redhat.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Fixes: e9e3bcecf44c ("ext4: serialize unaligned asynchronous DIO") Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 372a03e01853f860560eade508794dd274e9b390 upstream.

Ext4 needs to serialize unaligned direct AIO because the zeroing of
partial blocks of two competing unaligned AIOs can result in data
corruption.

However it decides not to serialize if the potentially unaligned aio is
past i_size with the rationale that no pending writes are possible past
i_size. Unfortunately if the i_size is not block aligned and the second
unaligned write lands past i_size, but still into the same block, it has
the potential of corrupting the previous unaligned write to the same
block.

This is (very simplified) reproducer from Frank

    // 41472 = (10 * 4096) + 512
    // 37376 = 41472 - 4096

    ftruncate(fd, 41472);
    io_prep_pwrite(iocbs[0], fd, buf[0], 4096, 37376);
    io_prep_pwrite(iocbs[1], fd, buf[1], 4096, 41472);

    io_submit(io_ctx, 1, &iocbs[1]);
    io_submit(io_ctx, 1, &iocbs[2]);

    io_getevents(io_ctx, 2, 2, events, NULL);

Without this patch the 512B range from 40960 up to the start of the
second unaligned write (41472) is going to be zeroed overwriting the data
written by the first write. This is a data corruption.

00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
*
00009200  30 30 30 30 30 30 30 30  30 30 30 30 30 30 30 30
*
0000a000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
*
0000a200  31 31 31 31 31 31 31 31  31 31 31 31 31 31 31 31

With this patch the data corruption is avoided because we will recognize
the unaligned_aio and wait for the unwritten extent conversion.

00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
*
00009200  30 30 30 30 30 30 30 30  30 30 30 30 30 30 30 30
*
0000a200  31 31 31 31 31 31 31 31  31 31 31 31 31 31 31 31
*
0000b200

Reported-by: Frank Sorenson <fsorenso@redhat.com>
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Fixes: e9e3bcecf44c ("ext4: serialize unaligned asynchronous DIO")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ext4: do not update s_last_mounted of a frozen fs 2018-11-20T18:04:53+00:00 Amir Goldstein amir73il@gmail.com 2018-05-14T02:54:44+00:00 c7aeaa4227002d6b24feb4746d6a342ae0c88a17 commit db6516a5e7ddb6dc72d167b920f2f272596ea22d upstream. If fs is frozen after mount and before the first file open, the update of s_last_mounted bypasses freeze protection and prints out a WARNING splat: $ mount /vdf $ fsfreeze -f /vdf $ cat /vdf/foo [ 31.578555] WARNING: CPU: 1 PID: 1415 at fs/ext4/ext4_jbd2.c:53 ext4_journal_check_start+0x48/0x82 [ 31.614016] Call Trace: [ 31.614997] __ext4_journal_start_sb+0xe4/0x1a4 [ 31.616771] ? ext4_file_open+0xb6/0x189 [ 31.618094] ext4_file_open+0xb6/0x189 If fs is frozen, skip s_last_mounted update. [backport hint: to apply to stable tree, need to apply also patches vfs: add the sb_start_intwrite_trylock() helper ext4: factor out helper ext4_sample_last_mounted()] Fixes: bc0b0d6d69ee ("ext4: update the s_last_mounted field in the superblock") Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit db6516a5e7ddb6dc72d167b920f2f272596ea22d upstream.

If fs is frozen after mount and before the first file open, the
update of s_last_mounted bypasses freeze protection and prints out
a WARNING splat:

$ mount /vdf
$ fsfreeze -f /vdf
$ cat /vdf/foo

[   31.578555] WARNING: CPU: 1 PID: 1415 at
fs/ext4/ext4_jbd2.c:53 ext4_journal_check_start+0x48/0x82

[   31.614016] Call Trace:
[   31.614997]  __ext4_journal_start_sb+0xe4/0x1a4
[   31.616771]  ? ext4_file_open+0xb6/0x189
[   31.618094]  ext4_file_open+0xb6/0x189

If fs is frozen, skip s_last_mounted update.

[backport hint: to apply to stable tree, need to apply also patches
 vfs: add the sb_start_intwrite_trylock() helper
 ext4: factor out helper ext4_sample_last_mounted()]

Fixes: bc0b0d6d69ee ("ext4: update the s_last_mounted field in the superblock")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ext4: factor out helper ext4_sample_last_mounted() 2018-11-20T18:04:53+00:00 Amir Goldstein amir73il@gmail.com 2018-05-14T02:44:23+00:00 8efefbfda5240e03418c9bdd3b35956eac9619f9 commit 833a950882d33a7dfc319d5e152fdf35028936eb upstream. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz> [bwh: Backported to 3.16: - Move up declaration of ret in ext4_file_open() - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 833a950882d33a7dfc319d5e152fdf35028936eb upstream.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
[bwh: Backported to 3.16:
 - Move up declaration of ret in ext4_file_open()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
mm: drop vm_ops->remap_pages and generic_file_remap_pages() stub 2018-10-03T03:09:51+00:00 Kirill A. Shutemov kirill.shutemov@linux.intel.com 2015-02-10T22:09:54+00:00 ae347f225e91a960c61f7470a3b21bcb4ea5fcfa commit d83a08db5ba6072caa658745881f4baa9bad6a08 upstream. Nobody uses it anymore. [akpm@linux-foundation.org: fix filemap_xip.c] Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bwh: Backported to 3.16: - Deleted code is slightly different - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit d83a08db5ba6072caa658745881f4baa9bad6a08 upstream.

Nobody uses it anymore.

[akpm@linux-foundation.org: fix filemap_xip.c]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16:
 - Deleted code is slightly different
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ext4: fix SEEK_HOLE/SEEK_DATA for blocksize < pagesize 2017-11-11T13:33:16+00:00 Jan Kara jack@suse.cz 2017-08-05T21:43:24+00:00 9ce36a5423e65a70ea2b8a895de8f6ddda1e6557 commit fcf5ea10992fbac3c7473a1db33d56a139333cd1 upstream. ext4_find_unwritten_pgoff() does not properly handle a situation when starting index is in the middle of a page and blocksize < pagesize. The following command shows the bug on filesystem with 1k blocksize: xfs_io -f -c "falloc 0 4k" \ -c "pwrite 1k 1k" \ -c "pwrite 3k 1k" \ -c "seek -a -r 0" foo In this example, neither lseek(fd, 1024, SEEK_HOLE) nor lseek(fd, 2048, SEEK_DATA) will return the correct result. Fix the problem by neglecting buffers in a page before starting offset. Reported-by: Andreas Gruenbacher <agruenba@redhat.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit fcf5ea10992fbac3c7473a1db33d56a139333cd1 upstream.

ext4_find_unwritten_pgoff() does not properly handle a situation when
starting index is in the middle of a page and blocksize < pagesize. The
following command shows the bug on filesystem with 1k blocksize:

  xfs_io -f -c "falloc 0 4k" \
            -c "pwrite 1k 1k" \
            -c "pwrite 3k 1k" \
            -c "seek -a -r 0" foo

In this example, neither lseek(fd, 1024, SEEK_HOLE) nor lseek(fd, 2048,
SEEK_DATA) will return the correct result.

Fix the problem by neglecting buffers in a page before starting offset.

Reported-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ext4: fix SEEK_HOLE 2017-09-15T17:29:47+00:00 Jan Kara jack@suse.cz 2017-05-22T02:33:23+00:00 0914537d5fa5616d41975b647e6f5a1bdd79c32d commit 7d95eddf313c88b24f99d4ca9c2411a4b82fef33 upstream. Currently, SEEK_HOLE implementation in ext4 may both return that there's a hole at some offset although that offset already has data and skip some holes during a search for the next hole. The first problem is demostrated by: xfs_io -c "falloc 0 256k" -c "pwrite 0 56k" -c "seek -h 0" file wrote 57344/57344 bytes at offset 0 56 KiB, 14 ops; 0.0000 sec (2.054 GiB/sec and 538461.5385 ops/sec) Whence Result HOLE 0 Where we can see that SEEK_HOLE wrongly returned offset 0 as containing a hole although we have written data there. The second problem can be demonstrated by: xfs_io -c "falloc 0 256k" -c "pwrite 0 56k" -c "pwrite 128k 8k" -c "seek -h 0" file wrote 57344/57344 bytes at offset 0 56 KiB, 14 ops; 0.0000 sec (1.978 GiB/sec and 518518.5185 ops/sec) wrote 8192/8192 bytes at offset 131072 8 KiB, 2 ops; 0.0000 sec (2 GiB/sec and 500000.0000 ops/sec) Whence Result HOLE 139264 Where we can see that hole at offsets 56k..128k has been ignored by the SEEK_HOLE call. The underlying problem is in the ext4_find_unwritten_pgoff() which is just buggy. In some cases it fails to update returned offset when it finds a hole (when no pages are found or when the first found page has higher index than expected), in some cases conditions for detecting hole are just missing (we fail to detect a situation where indices of returned pages are not contiguous). Fix ext4_find_unwritten_pgoff() to properly detect non-contiguous page indices and also handle all cases where we got less pages then expected in one place and handle it properly there. Fixes: c8c0df241cc2719b1262e627f999638411934f60 CC: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 7d95eddf313c88b24f99d4ca9c2411a4b82fef33 upstream.

Currently, SEEK_HOLE implementation in ext4 may both return that there's
a hole at some offset although that offset already has data and skip
some holes during a search for the next hole. The first problem is
demostrated by:

xfs_io -c "falloc 0 256k" -c "pwrite 0 56k" -c "seek -h 0" file
wrote 57344/57344 bytes at offset 0
56 KiB, 14 ops; 0.0000 sec (2.054 GiB/sec and 538461.5385 ops/sec)
Whence	Result
HOLE	0

Where we can see that SEEK_HOLE wrongly returned offset 0 as containing
a hole although we have written data there. The second problem can be
demonstrated by:

xfs_io -c "falloc 0 256k" -c "pwrite 0 56k" -c "pwrite 128k 8k"
       -c "seek -h 0" file

wrote 57344/57344 bytes at offset 0
56 KiB, 14 ops; 0.0000 sec (1.978 GiB/sec and 518518.5185 ops/sec)
wrote 8192/8192 bytes at offset 131072
8 KiB, 2 ops; 0.0000 sec (2 GiB/sec and 500000.0000 ops/sec)
Whence	Result
HOLE	139264

Where we can see that hole at offsets 56k..128k has been ignored by the
SEEK_HOLE call.

The underlying problem is in the ext4_find_unwritten_pgoff() which is
just buggy. In some cases it fails to update returned offset when it
finds a hole (when no pages are found or when the first found page has
higher index than expected), in some cases conditions for detecting hole
are just missing (we fail to detect a situation where indices of
returned pages are not contiguous).

Fix ext4_find_unwritten_pgoff() to properly detect non-contiguous page
indices and also handle all cases where we got less pages then expected
in one place and handle it properly there.

Fixes: c8c0df241cc2719b1262e627f999638411934f60
CC: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ext4: prevent bugon on race between write/fcntl 2014-11-13T11:48:59+00:00 Dmitry Monakhov dmonakhov@openvz.org 2014-10-30T14:53:16+00:00 01eca100c06d5b043e828fc2838189ae0c785285 commit a41537e69b4aa43f0fea02498c2595a81267383b upstream. O_DIRECT flags can be toggeled via fcntl(F_SETFL). But this value checked twice inside ext4_file_write_iter() and __generic_file_write() which result in BUG_ON inside ext4_direct_IO. Let's initialize iocb->private unconditionally. TESTCASE: xfstest:generic/036 https://patchwork.ozlabs.org/patch/402445/ #TYPICAL STACK TRACE: kernel BUG at fs/ext4/inode.c:2960! invalid opcode: 0000 [#1] SMP Modules linked in: brd iTCO_wdt lpc_ich mfd_core igb ptp dm_mirror dm_region_hash dm_log dm_mod CPU: 6 PID: 5505 Comm: aio-dio-fcntl-r Not tainted 3.17.0-rc2-00176-gff5c017 #161 Hardware name: Intel Corporation W2600CR/W2600CR, BIOS SE5C600.86B.99.99.x028.061320111235 06/13/2011 task: ffff88080e95a7c0 ti: ffff88080f908000 task.ti: ffff88080f908000 RIP: 0010:[<ffffffff811fabf2>] [<ffffffff811fabf2>] ext4_direct_IO+0x162/0x3d0 RSP: 0018:ffff88080f90bb58 EFLAGS: 00010246 RAX: 0000000000000400 RBX: ffff88080fdb2a28 RCX: 00000000a802c818 RDX: 0000040000080000 RSI: ffff88080d8aeb80 RDI: 0000000000000001 RBP: ffff88080f90bbc8 R08: 0000000000000000 R09: 0000000000001581 R10: 0000000000000000 R11: 0000000000000000 R12: ffff88080d8aeb80 R13: ffff88080f90bbf8 R14: ffff88080fdb28c8 R15: ffff88080fdb2a28 FS: 00007f23b2055700(0000) GS:ffff880818400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f23b2045000 CR3: 000000080cedf000 CR4: 00000000000407e0 Stack: ffff88080f90bb98 0000000000000000 7ffffffffffffffe ffff88080fdb2c30 0000000000000200 0000000000000200 0000000000000001 0000000000000200 ffff88080f90bbc8 ffff88080fdb2c30 ffff88080f90be08 0000000000000200 Call Trace: [<ffffffff8112ca9d>] generic_file_direct_write+0xed/0x180 [<ffffffff8112f2b2>] __generic_file_write_iter+0x222/0x370 [<ffffffff811f495b>] ext4_file_write_iter+0x34b/0x400 [<ffffffff811bd709>] ? aio_run_iocb+0x239/0x410 [<ffffffff811bd709>] ? aio_run_iocb+0x239/0x410 [<ffffffff810990e5>] ? local_clock+0x25/0x30 [<ffffffff810abd94>] ? __lock_acquire+0x274/0x700 [<ffffffff811f4610>] ? ext4_unwritten_wait+0xb0/0xb0 [<ffffffff811bd756>] aio_run_iocb+0x286/0x410 [<ffffffff810990e5>] ? local_clock+0x25/0x30 [<ffffffff810ac359>] ? lock_release_holdtime+0x29/0x190 [<ffffffff811bc05b>] ? lookup_ioctx+0x4b/0xf0 [<ffffffff811bde3b>] do_io_submit+0x55b/0x740 [<ffffffff811bdcaa>] ? do_io_submit+0x3ca/0x740 [<ffffffff811be030>] SyS_io_submit+0x10/0x20 [<ffffffff815ce192>] system_call_fastpath+0x16/0x1b Code: 01 48 8b 80 f0 01 00 00 48 8b 18 49 8b 45 10 0f 85 f1 01 00 00 48 03 45 c8 48 3b 43 48 0f 8f e3 01 00 00 49 83 7c 24 18 00 75 04 <0f> 0b eb fe f0 ff 83 ec 01 00 00 49 8b 44 24 18 8b 00 85 c0 89 RIP [<ffffffff811fabf2>] ext4_direct_IO+0x162/0x3d0 RSP <ffff88080f90bb58> Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> 
commit a41537e69b4aa43f0fea02498c2595a81267383b upstream.

O_DIRECT flags can be toggeled via fcntl(F_SETFL). But this value checked
twice inside ext4_file_write_iter() and __generic_file_write() which
result in BUG_ON inside ext4_direct_IO.

Let's initialize iocb->private unconditionally.

TESTCASE: xfstest:generic/036  https://patchwork.ozlabs.org/patch/402445/

#TYPICAL STACK TRACE:
kernel BUG at fs/ext4/inode.c:2960!
invalid opcode: 0000 [#1] SMP
Modules linked in: brd iTCO_wdt lpc_ich mfd_core igb ptp dm_mirror dm_region_hash dm_log dm_mod
CPU: 6 PID: 5505 Comm: aio-dio-fcntl-r Not tainted 3.17.0-rc2-00176-gff5c017 #161
Hardware name: Intel Corporation W2600CR/W2600CR, BIOS SE5C600.86B.99.99.x028.061320111235 06/13/2011
task: ffff88080e95a7c0 ti: ffff88080f908000 task.ti: ffff88080f908000
RIP: 0010:[<ffffffff811fabf2>]  [<ffffffff811fabf2>] ext4_direct_IO+0x162/0x3d0
RSP: 0018:ffff88080f90bb58  EFLAGS: 00010246
RAX: 0000000000000400 RBX: ffff88080fdb2a28 RCX: 00000000a802c818
RDX: 0000040000080000 RSI: ffff88080d8aeb80 RDI: 0000000000000001
RBP: ffff88080f90bbc8 R08: 0000000000000000 R09: 0000000000001581
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88080d8aeb80
R13: ffff88080f90bbf8 R14: ffff88080fdb28c8 R15: ffff88080fdb2a28
FS:  00007f23b2055700(0000) GS:ffff880818400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f23b2045000 CR3: 000000080cedf000 CR4: 00000000000407e0
Stack:
 ffff88080f90bb98 0000000000000000 7ffffffffffffffe ffff88080fdb2c30
 0000000000000200 0000000000000200 0000000000000001 0000000000000200
 ffff88080f90bbc8 ffff88080fdb2c30 ffff88080f90be08 0000000000000200
Call Trace:
 [<ffffffff8112ca9d>] generic_file_direct_write+0xed/0x180
 [<ffffffff8112f2b2>] __generic_file_write_iter+0x222/0x370
 [<ffffffff811f495b>] ext4_file_write_iter+0x34b/0x400
 [<ffffffff811bd709>] ? aio_run_iocb+0x239/0x410
 [<ffffffff811bd709>] ? aio_run_iocb+0x239/0x410
 [<ffffffff810990e5>] ? local_clock+0x25/0x30
 [<ffffffff810abd94>] ? __lock_acquire+0x274/0x700
 [<ffffffff811f4610>] ? ext4_unwritten_wait+0xb0/0xb0
 [<ffffffff811bd756>] aio_run_iocb+0x286/0x410
 [<ffffffff810990e5>] ? local_clock+0x25/0x30
 [<ffffffff810ac359>] ? lock_release_holdtime+0x29/0x190
 [<ffffffff811bc05b>] ? lookup_ioctx+0x4b/0xf0
 [<ffffffff811bde3b>] do_io_submit+0x55b/0x740
 [<ffffffff811bdcaa>] ? do_io_submit+0x3ca/0x740
 [<ffffffff811be030>] SyS_io_submit+0x10/0x20
 [<ffffffff815ce192>] system_call_fastpath+0x16/0x1b
Code: 01 48 8b 80 f0 01 00 00 48 8b 18 49 8b 45 10 0f 85 f1 01 00 00 48 03 45 c8 48 3b 43 48 0f 8f e3 01 00 00 49 83 7c
24 18 00 75 04 <0f> 0b eb fe f0 ff 83 ec 01 00 00 49 8b 44 24 18 8b 00 85 c0 89
RIP  [<ffffffff811fabf2>] ext4_direct_IO+0x162/0x3d0
 RSP <ffff88080f90bb58>

Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12T17:30:18+00:00 Linus Torvalds torvalds@linux-foundation.org 2014-06-12T17:30:18+00:00 16b9057804c02e2d351e9c8f606e909b43cbd9e7 Pull vfs updates from Al Viro: "This the bunch that sat in -next + lock_parent() fix. This is the minimal set; there's more pending stuff. In particular, I really hope to get acct.c fixes merged this cycle - we need that to deal sanely with delayed-mntput stuff. In the next pile, hopefully - that series is fairly short and localized (kernel/acct.c, fs/super.c and fs/namespace.c). In this pile: more iov_iter work. Most of prereqs for ->splice_write with sane locking order are there and Kent's dio rewrite would also fit nicely on top of this pile" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (70 commits) lock_parent: don't step on stale ->d_parent of all-but-freed one kill generic_file_splice_write() ceph: switch to iter_file_splice_write() shmem: switch to iter_file_splice_write() nfs: switch to iter_splice_write_file() fs/splice.c: remove unneeded exports ocfs2: switch to iter_file_splice_write() ->splice_write() via ->write_iter() bio_vec-backed iov_iter optimize copy_page_{to,from}_iter() bury generic_file_aio_{read,write} lustre: get rid of messing with iovecs ceph: switch to ->write_iter() ceph_sync_direct_write: stop poking into iov_iter guts ceph_sync_read: stop poking into iov_iter guts new helper: copy_page_from_iter() fuse: switch to ->write_iter() btrfs: switch to ->write_iter() ocfs2: switch to ->write_iter() xfs: switch to ->write_iter() ... 
Pull vfs updates from Al Viro:
 "This the bunch that sat in -next + lock_parent() fix.  This is the
  minimal set; there's more pending stuff.

  In particular, I really hope to get acct.c fixes merged this cycle -
  we need that to deal sanely with delayed-mntput stuff.  In the next
  pile, hopefully - that series is fairly short and localized
  (kernel/acct.c, fs/super.c and fs/namespace.c).  In this pile: more
  iov_iter work.  Most of prereqs for ->splice_write with sane locking
  order are there and Kent's dio rewrite would also fit nicely on top of
  this pile"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (70 commits)
  lock_parent: don't step on stale ->d_parent of all-but-freed one
  kill generic_file_splice_write()
  ceph: switch to iter_file_splice_write()
  shmem: switch to iter_file_splice_write()
  nfs: switch to iter_splice_write_file()
  fs/splice.c: remove unneeded exports
  ocfs2: switch to iter_file_splice_write()
  ->splice_write() via ->write_iter()
  bio_vec-backed iov_iter
  optimize copy_page_{to,from}_iter()
  bury generic_file_aio_{read,write}
  lustre: get rid of messing with iovecs
  ceph: switch to ->write_iter()
  ceph_sync_direct_write: stop poking into iov_iter guts
  ceph_sync_read: stop poking into iov_iter guts
  new helper: copy_page_from_iter()
  fuse: switch to ->write_iter()
  btrfs: switch to ->write_iter()
  ocfs2: switch to ->write_iter()
  xfs: switch to ->write_iter()
  ...