linux-stable.git/drivers/md/bcache, branch v3.18.28

bcache: Change refill_dirty() to always scan entire disk if necessary

2016-02-10T03:56:17+00:00

[ Upstream commit 627ccd20b4ad3ba836472468208e2ac4dfadbf03 ]

Previously, it would only scan the entire disk if it was starting from
the very start of the disk - i.e. if the previous scan got to the end.

This was broken by refill_full_stripes(), which updates last_scanned so
that refill_dirty was never triggering the searched_from_start path.

But if we change refill_dirty() to always scan the entire disk if
necessary, regardless of what last_scanned was, the code gets cleaner
and we fix that bug too.

Signed-off-by: Kent Overstreet 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

bcache: prevent crash on changing writeback_running

2016-02-10T03:56:17+00:00

[ Upstream commit 8d16ce540c94c9d366eb36fc91b7154d92d6397b ]

Added a safeguard in the shutdown case. At least while not being
attached it is also possible to trigger a kernel bug by writing into
writeback_running. This change  adds the same check before trying to
wake up the thread for that case.

Signed-off-by: Stefan Bader 
Cc: Kent Overstreet 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

bcache: allows use of register in udev to avoid "device_busy" error.

2016-02-10T03:56:17+00:00

[ Upstream commit d7076f21629f8f329bca4a44dc408d94670f49e2 ]

Allows to use register, not register_quiet in udev to avoid "device_busy" error.
The initial patch proposed at https://lkml.org/lkml/2013/8/26/549 by Gabriel de Perthuis
 does not unlock the mutex and hangs the kernel.

See http://thread.gmane.org/gmane.linux.kernel.bcache.devel/2594 for the discussion.

Cc: Denis Bychkov 
Cc: Kent Overstreet 
Cc: Eric Wheeler 
Cc: Gabriel de Perthuis 
Cc: stable@vger.kernel.org

Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

bcache: unregister reboot notifier if bcache fails to unregister device

2016-02-10T03:56:16+00:00

[ Upstream commit 2ecf0cdb2b437402110ab57546e02abfa68a716b ]

In bcache_init() function it forgot to unregister reboot notifier if
bcache fails to unregister a block device.  This commit fixes this.

Signed-off-by: Zheng Liu 
Tested-by: Joshua Schmid 
Tested-by: Eric Wheeler 
Cc: Kent Overstreet 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

bcache: fix a leak in bch_cached_dev_run()

2016-02-10T03:56:16+00:00

[ Upstream commit 4d4d8573a8451acc9f01cbea24b7e55f04a252fe ]

Signed-off-by: Al Viro 
Tested-by: Joshua Schmid 
Tested-by: Eric Wheeler 
Cc: Kent Overstreet 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

bcache: clear BCACHE_DEV_UNLINK_DONE flag when attaching a backing device

2016-02-10T03:56:15+00:00

[ Upstream commit fecaee6f20ee122ad75402c53d8278f9bb142ddc ]

This bug can be reproduced by the following script:

  #!/bin/bash

  bcache_sysfs="/sys/fs/bcache"

  function clear_cache()
  {
  	if [ ! -e $bcache_sysfs ]; then
  		echo "no bcache sysfs"
  		exit
  	fi

  	cset_uuid=$(ls -l $bcache_sysfs|head -n 2|tail -n 1|awk '{print $9}')
  	sudo sh -c "echo $cset_uuid > /sys/block/sdb/sdb1/bcache/detach"
  	sleep 5
  	sudo sh -c "echo $cset_uuid > /sys/block/sdb/sdb1/bcache/attach"
  }

  for ((i=0;i<10;i++)); do
  	clear_cache
  done

The warning messages look like below:
[  275.948611] ------------[ cut here ]------------
[  275.963840] WARNING: at fs/sysfs/dir.c:512 sysfs_add_one+0xb8/0xd0() (Tainted: P        W
---------------   )
[  275.979253] Hardware name: Tecal RH2285
[  275.994106] sysfs: cannot create duplicate filename '/devices/pci0000:00/0000:00:09.0/0000:08:00.0/host4/target4:2:1/4:2:1:0/block/sdb/sdb1/bcache/cache'
[  276.024105] Modules linked in: bcache tcp_diag inet_diag ipmi_devintf ipmi_si ipmi_msghandler
bonding 8021q garp stp llc ipv6 ext3 jbd loop sg iomemory_vsl(P) bnx2 microcode serio_raw i2c_i801
i2c_core iTCO_wdt iTCO_vendor_support i7core_edac edac_core shpchp ext4 jbd2 mbcache megaraid_sas
pata_acpi ata_generic ata_piix dm_mod [last unloaded: scsi_wait_scan]
[  276.072643] Pid: 2765, comm: sh Tainted: P        W  ---------------    2.6.32 #1
[  276.089315] Call Trace:
[  276.105801]  [] ? warn_slowpath_common+0x87/0xc0
[  276.122650]  [] ? warn_slowpath_fmt+0x46/0x50
[  276.139361]  [] ? sysfs_add_one+0xb8/0xd0
[  276.156012]  [] ? sysfs_do_create_link+0x12b/0x170
[  276.172682]  [] ? sysfs_create_link+0x13/0x20
[  276.189282]  [] ? bcache_device_link+0xc1/0x110 [bcache]
[  276.205993]  [] ? bch_cached_dev_attach+0x478/0x4f0 [bcache]
[  276.222794]  [] ? bch_cached_dev_store+0x627/0x780 [bcache]
[  276.239680]  [] ? alloc_pages_current+0xaa/0x110
[  276.256594]  [] ? sysfs_write_file+0xe5/0x170
[  276.273364]  [] ? vfs_write+0xb8/0x1a0
[  276.290133]  [] ? sys_write+0x51/0x90
[  276.306368]  [] ? system_call_fastpath+0x16/0x1b
[  276.322301] ---[ end trace 9f5d4fcdd0c3edfb ]---
[  276.338241] ------------[ cut here ]------------
[  276.354109] WARNING: at /home/wenqing.lz/bcache/bcache/super.c:720
bcache_device_link+0xdf/0x110 [bcache]() (Tainted: P        W  ---------------   )
[  276.386017] Hardware name: Tecal RH2285
[  276.401430] Couldn't create device <-> cache set symlinks
[  276.401759] Modules linked in: bcache tcp_diag inet_diag ipmi_devintf ipmi_si ipmi_msghandler
bonding 8021q garp stp llc ipv6 ext3 jbd loop sg iomemory_vsl(P) bnx2 microcode serio_raw i2c_i801
i2c_core iTCO_wdt iTCO_vendor_support i7core_edac edac_core shpchp ext4 jbd2 mbcache megaraid_sas
pata_acpi ata_generic ata_piix dm_mod [last unloaded: scsi_wait_scan]
[  276.465477] Pid: 2765, comm: sh Tainted: P        W  ---------------    2.6.32 #1
[  276.482169] Call Trace:
[  276.498610]  [] ? warn_slowpath_common+0x87/0xc0
[  276.515405]  [] ? warn_slowpath_fmt+0x46/0x50
[  276.532059]  [] ? bcache_device_link+0xdf/0x110 [bcache]
[  276.548808]  [] ? bch_cached_dev_attach+0x478/0x4f0 [bcache]
[  276.565569]  [] ? bch_cached_dev_store+0x627/0x780 [bcache]
[  276.582418]  [] ? alloc_pages_current+0xaa/0x110
[  276.599341]  [] ? sysfs_write_file+0xe5/0x170
[  276.616142]  [] ? vfs_write+0xb8/0x1a0
[  276.632607]  [] ? sys_write+0x51/0x90
[  276.648671]  [] ? system_call_fastpath+0x16/0x1b
[  276.664756] ---[ end trace 9f5d4fcdd0c3edfc ]---

We forget to clear BCACHE_DEV_UNLINK_DONE flag in bcache_device_attach()
function when we attach a backing device first time.  After detaching this
backing device, this flag will be true and sysfs_remove_link() isn't called in
bcache_device_unlink().  Then when we attach this backing device again,
sysfs_create_link() will return EEXIST error in bcache_device_link().

So the fix is trival and we clear this flag in bcache_device_link().

Signed-off-by: Zheng Liu 
Tested-by: Joshua Schmid 
Tested-by: Eric Wheeler 
Cc: Kent Overstreet 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

bcache: Add a cond_resched() call to gc

2016-02-10T03:56:15+00:00

[ Upstream commit c5f1e5adf956e3ba82d204c7c141a75da9fa449a ]

Signed-off-by: Takashi Iwai 
Tested-by: Eric Wheeler 
Cc: Kent Overstreet 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

bcache: fix a livelock when we cause a huge number of cache misses

2016-02-10T03:56:14+00:00

[ Upstream commit 2ef9ccbfcb90cf84bdba320a571b18b05c41101b ]

Subject :	[PATCH v2] bcache: fix a livelock in btree lock
Date :	Wed, 25 Feb 2015 20:32:09 +0800 (02/25/2015 04:32:09 AM)

This commit tries to fix a livelock in bcache.  This livelock might
happen when we causes a huge number of cache misses simultaneously.

When we get a cache miss, bcache will execute the following path.

->cached_dev_make_request()
  ->cached_dev_read()
    ->cached_lookup()
      ->bch->btree_map_keys()
        ->btree_root()  <------------------------
          ->bch_btree_map_keys_recurse()        |
            ->cache_lookup_fn()                 |
              ->cached_dev_cache_miss()         |
                ->bch_btree_insert_check_key() -|
                  [If btree->seq is not equal to seq + 1, we should return
                   EINTR and traverse btree again.]

In bch_btree_insert_check_key() function we first need to check upgrade
flag (op->lock == -1), and when this flag is true we need to release
read btree->lock and try to take write btree->lock.  During taking and
releasing this write lock, btree->seq will be monotone increased in
order to prevent other threads modify this in cache miss (see btree.h:74).
But if there are some cache misses caused by some requested, we could
meet a livelock because btree->seq is always changed by others.  Thus no
one can make progress.

This commit will try to take write btree->lock if it encounters a race
when we traverse btree.  Although it sacrifice the scalability but we
can ensure that only one can modify the btree.

Signed-off-by: Zheng Liu 
Tested-by: Joshua Schmid 
Tested-by: Eric Wheeler 
Cc: Joshua Schmid 
Cc: Zhu Yanhai 
Cc: Kent Overstreet 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block: disable entropy contributions for nonrot devices

2014-10-04T16:55:32+00:00

Clear QUEUE_FLAG_ADD_RANDOM in all block drivers that set
QUEUE_FLAG_NONROT.

Historically, all block devices have automatically made entropy
contributions.  But as previously stated in commit e2e1a148 ("block: add
sysfs knob for turning off disk entropy contributions"):
    - On SSD disks, the completion times aren't as random as they
      are for rotational drives. So it's questionable whether they
      should contribute to the random pool in the first place.
    - Calling add_disk_randomness() has a lot of overhead.

There are more reliable sources for randomness than non-rotational block
devices.  From a security perspective it is better to err on the side of
caution than to allow entropy contributions from unreliable "random"
sources.

Signed-off-by: Mike Snitzer 
Signed-off-by: Jens Axboe

bcache: Drop unneeded blk_sync_queue() calls

2014-08-04T22:23:04+00:00

this is needed for the queue/block device we created (it's done by
blk_cleanup_queue() which we do call) - but calling it for the block devices we
only opened is pointless.

Change-Id: I53dfded14ed15b9581d10ca8399d5e1b3abbf9f2