Files
android_kernel_xiaomi_sm8450/include/linux
Mikulas Patocka b87570f5d3 Fix a crash when block device is read and block size is changed at the same time
The kernel may crash when block size is changed and I/O is issued
simultaneously.

Because some subsystems (udev or lvm) may read any block device anytime,
the bug actually puts any code that changes a block device size in
jeopardy.

The crash can be reproduced if you place "msleep(1000)" to
blkdev_get_blocks just before "bh->b_size = max_blocks <<
inode->i_blkbits;".
Then, run "dd if=/dev/ram0 of=/dev/null bs=4k count=1 iflag=direct"
While it is waiting in msleep, run "blockdev --setbsz 2048 /dev/ram0"
You get a BUG.

The direct and non-direct I/O is written with the assumption that block
size does not change. It doesn't seem practical to fix these crashes
one-by-one there may be many crash possibilities when block size changes
at a certain place and it is impossible to find them all and verify the
code.

This patch introduces a new rw-lock bd_block_size_semaphore. The lock is
taken for read during I/O. It is taken for write when changing block
size. Consequently, block size can't be changed while I/O is being
submitted.

For asynchronous I/O, the patch only prevents block size change while
the I/O is being submitted. The block size can change when the I/O is in
progress or when the I/O is being finished. This is acceptable because
there are no accesses to block size when asynchronous I/O is being
finished.

The patch prevents block size changing while the device is mapped with
mmap.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-09-26 07:46:40 +02:00
..
2012-08-02 13:51:46 -04:00
2012-07-30 18:16:01 -07:00
2012-07-30 18:15:23 -07:00
2011-03-31 11:26:23 -03:00
2012-04-23 14:23:32 +03:00
2011-03-31 11:26:23 -03:00
2012-05-15 17:30:30 -04:00
2012-06-06 15:20:22 -04:00
2011-07-22 08:25:37 -07:00
2012-07-30 17:25:21 -07:00
2011-07-20 20:47:43 -04:00
2012-06-29 11:38:17 -04:00
2011-10-26 15:43:25 -04:00
2011-03-22 17:43:59 -07:00
2011-03-11 14:25:50 +00:00
2012-03-20 21:29:46 -04:00
2012-09-20 14:31:45 +02:00
2011-08-03 11:30:42 -04:00
2011-07-26 16:49:47 -07:00
2012-08-07 10:10:57 +02:00
2011-03-31 11:26:23 -03:00
2011-03-31 11:26:23 -03:00
2012-07-31 18:42:43 -07:00
2012-06-06 19:12:30 -07:00
2012-07-30 17:25:11 -07:00
2011-03-31 11:26:23 -03:00
2012-02-28 16:02:54 +01:00
2012-01-03 22:54:57 -05:00
2011-10-29 21:20:22 +02:00
2011-03-31 11:26:23 -03:00
2012-03-23 16:58:38 -07:00
2011-07-25 20:57:16 -07:00
2011-12-13 09:26:45 +00:00
2012-04-14 15:24:26 -04:00
2012-02-20 19:46:36 +11:00
2011-05-23 10:47:06 -05:00
2012-05-02 14:15:27 -05:00
2011-05-29 13:03:09 +01:00
2012-05-25 12:46:23 +05:30
2012-05-10 12:00:56 +02:00
2011-11-26 14:59:39 -05:00
2011-12-11 18:25:16 -05:00
2012-06-27 15:42:24 -07:00
2011-09-14 15:24:51 -04:00
2012-05-29 23:28:33 -04:00
2011-03-14 19:12:20 -04:00
2012-07-22 23:57:58 +04:00
2012-04-27 10:46:45 +08:00
2012-07-05 15:04:10 +02:00
2011-07-01 15:34:45 -07:00
2011-03-31 11:26:23 -03:00
2012-03-26 21:47:19 +02:00
2012-03-26 21:47:19 +02:00
2012-03-26 21:47:19 +02:00
2012-05-12 14:28:14 +02:00
2012-03-26 21:47:19 +02:00
2011-02-23 00:53:26 +00:00
2011-07-01 10:37:15 +02:00
2012-07-02 15:11:12 +02:00
2012-03-27 22:45:26 -04:00
2011-07-21 13:47:54 -07:00
2012-03-20 12:47:48 +01:00
2012-05-07 10:58:57 -06:00
2012-03-20 12:47:47 +01:00
2012-01-03 22:55:17 -05:00
2012-08-06 13:33:21 -07:00
2012-07-19 10:38:32 -04:00
2012-04-09 11:16:55 -07:00
2011-03-31 11:26:23 -03:00
2012-03-08 10:50:35 -08:00
2012-05-31 17:49:32 -07:00
2011-02-17 11:12:40 -08:00
2012-07-31 08:16:42 -05:00
2012-05-31 17:49:30 -07:00
2012-03-08 10:50:35 -08:00
2012-05-11 10:56:56 +01:00
2012-08-22 10:24:41 -04:00
2011-12-27 11:26:41 +02:00
2011-09-16 19:20:20 -04:00
2012-05-29 23:28:41 -04:00
2011-04-25 18:14:10 -07:00
2012-03-15 21:41:34 +01:00
2012-05-09 13:58:06 -07:00
2012-05-22 15:20:28 -04:00
2011-07-26 16:49:47 -07:00
2011-07-26 16:49:47 -07:00
2012-07-29 21:24:13 +04:00
2012-07-09 16:42:24 -04:00
2012-05-26 14:17:30 -04:00
2012-07-30 19:06:52 -04:00
2012-07-30 19:06:52 -04:00
2012-07-10 10:32:06 -05:00
2012-05-21 14:31:48 +01:00
2012-07-31 18:42:43 -07:00
2012-06-20 14:39:36 -07:00
2012-08-30 13:14:48 -04:00
2012-01-06 12:10:26 -08:00
2012-05-14 14:15:32 -07:00
2011-05-26 17:12:37 -07:00
2012-07-12 07:54:46 -07:00
2012-05-12 15:53:42 -04:00
2011-12-13 09:26:45 +00:00
2011-11-02 16:07:02 -07:00
2011-03-31 11:26:23 -03:00
2012-06-15 12:56:57 +02:00
2012-03-20 21:29:38 -04:00
2012-01-03 22:55:07 -05:00
2012-07-19 10:38:32 -04:00
2012-03-28 18:30:03 +01:00
2012-07-30 17:25:20 -07:00
2012-06-01 12:58:52 -04:00
2012-07-02 13:40:06 +03:00
2011-03-31 11:26:23 -03:00
2012-06-05 17:32:30 +02:00
2012-07-16 22:31:34 -07:00
2011-07-26 16:49:47 -07:00
2011-12-13 09:26:45 +00:00
2012-06-13 21:16:42 +02:00
2012-05-14 18:53:19 -04:00
2011-08-16 00:16:49 -07:00
2012-07-23 00:58:46 -07:00
2012-07-22 23:57:55 +04:00
2012-06-18 13:42:03 +02:00
2011-11-02 16:07:02 -07:00
2012-07-31 08:16:24 -06:00
2012-05-22 12:16:16 +09:30
2012-07-31 18:42:50 -07:00
2012-03-28 18:30:03 +01:00
2011-03-31 11:26:23 -03:00
2012-08-04 12:15:37 +04:00
2011-09-14 15:24:51 -04:00
2011-03-31 11:26:23 -03:00