linux-stable.git/drivers/md, branch v4.1.45

bcache: fix bch_hprint crash and improve output

2017-10-04T11:43:04+00:00

[ Upstream commit 9276717b9e297a62d1151a43d1cd286213f68eb7 ]

Most importantly, solve a crash where %llu was used to format signed
numbers.  This would cause a buffer overflow when reading sysfs
writeback_rate_debug, as only 20 bytes were allocated for this and
%llu writes 20 characters plus a null.

Always use the units mechanism rather than having different output
paths for simplicity.

Also, correct problems with display output where 1.10 was a larger
number than 1.09, by multiplying by 10 and then dividing by 1024 instead
of dividing by 100.  (Remainders of >= 1000 would print as .10).

Minor changes: Always display the decimal point instead of trying to
omit it based on number of digits shown.  Decide what units to use
based on 1000 as a threshold, not 1024 (in other words, always print
at most 3 digits before the decimal point).

Signed-off-by: Michael Lyle 
Reported-by: Dmitry Yu Okunev 
Acked-by: Kent Overstreet 
Reviewed-by: Coly Li 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

bcache: fix for gc and write-back race

2017-10-04T11:43:04+00:00

[ Upstream commit 9baf30972b5568d8b5bc8b3c46a6ec5b58100463 ]

gc and write-back get raced (see the email "bcache get stucked" I sended
before):
gc thread                               write-back thread
|                                       |bch_writeback_thread()
|bch_gc_thread()                        |
|                                       |==>read_dirty()
|==>bch_btree_gc()                      |
|==>btree_root() //get btree root       |
|                //node write locker    |
|==>bch_btree_gc_root()                 |
|                                       |==>read_dirty_submit()
|                                       |==>write_dirty()
|                                       |==>continue_at(cl,
|                                       |               write_dirty_finish,
|                                       |               system_wq);
|                                       |==>write_dirty_finish()//excute
|                                       |               //in system_wq
|                                       |==>bch_btree_insert()
|                                       |==>bch_btree_map_leaf_nodes()
|                                       |==>__bch_btree_map_nodes()
|                                       |==>btree_root //try to get btree
|                                       |              //root node read
|                                       |              //lock
|                                       |-----stuck here
|==>bch_btree_set_root()
|==>bch_journal_meta()
|==>bch_journal()
|==>journal_try_write()
|==>journal_write_unlocked() //journal_full(&c->journal)
|                            //condition satisfied
|==>continue_at(cl, journal_write, system_wq); //try to excute
|                               //journal_write in system_wq
|                               //but work queue is excuting
|                               //write_dirty_finish()
|==>closure_sync(); //wait journal_write execute
|                   //over and wake up gc,
|-------------stuck here
|==>release root node write locker

This patch alloc a separate work-queue for write-back thread to avoid such
race.

(Commit log re-organized by Coly Li to pass checkpatch.pl checking)

Signed-off-by: Tang Junhui 
Acked-by: Coly Li 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

bcache: Correct return value for sysfs attach errors

2017-10-04T11:43:04+00:00

[ Upstream commit 77fa100f27475d08a569b9d51c17722130f089e7 ]

If you encounter any errors in bch_cached_dev_attach it will return
a negative error code.  The variable 'v' which stores the result is
unsigned, thus user space sees a very large value returned for bytes
written which can cause incorrect user space behavior.  Utilize 1
signed variable to use throughout the function to preserve error return
capability.

Signed-off-by: Tony Asleson 
Acked-by: Coly Li 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

bcache: correct cache_dirty_target in __update_writeback_rate()

2017-10-04T11:43:04+00:00

[ Upstream commit a8394090a9129b40f9d90dcb7f4a49d60c727ca6 ]

__update_write_rate() uses a Proportion-Differentiation Controller
algorithm to control writeback rate. A dirty target number is used in
this PD controller to control writeback rate. A larger target number
will make the writeback rate smaller, on the versus, a smaller target
number will make the writeback rate larger.

bcache uses the following steps to calculate the target number,
1) cache_sectors = all-buckets-of-cache-set * buckets-size
2) cache_dirty_target = cache_sectors * cached-device-writeback_percent
3) target = cache_dirty_target *
(sectors-of-cached-device/sectors-of-all-cached-devices-of-this-cache-set)

The calculation at step 1) for cache_sectors is incorrect, which does
not consider dirty blocks occupied by flash only volume.

A flash only volume can be took as a bcache device without cached
device. All data sectors allocated for it are persistent on cache device
and marked dirty, they are not touched by bcache writeback and garbage
collection code. So data blocks of flash only volume should be ignore
when calculating cache_sectors of cache set.

Current code does not subtract dirty sectors of flash only volume, which
results a larger target number from the above 3 steps. And in sequence
the cache device's writeback rate is smaller then a correct value,
writeback speed is slower on all cached devices.

This patch fixes the incorrect slower writeback rate by subtracting
dirty sectors of flash only volumes in __update_writeback_rate().

(Commit log composed by Coly Li to pass checkpatch.pl checking)

Signed-off-by: Tang Junhui 
Reviewed-by: Coly Li 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

bcache: Fix leak of bdev reference

2017-10-04T11:43:04+00:00

[ Upstream commit 4b758df21ee7081ab41448d21d60367efaa625b3 ]

If blkdev_get_by_path() in register_bcache() fails, we try to lookup the
block device using lookup_bdev() to detect which situation we are in to
properly report error. However we never drop the reference returned to
us from lookup_bdev(). Fix that.

Signed-off-by: Jan Kara 
Acked-by: Coly Li 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

bcache: initialize dirty stripes in flash_dev_run()

2017-10-04T11:43:04+00:00

[ Upstream commit 175206cf9ab63161dec74d9cd7f9992e062491f5 ]

bcache uses a Proportion-Differentiation Controller algorithm to control
writeback rate to cached devices. In the PD controller algorithm, dirty
stripes of thin flash device should not be counted in, because flash only
volumes never write back dirty data.

Currently dirty stripe counter for thin flash device is not initialized
when the thin flash device starts. Which means the following calculation
in PD controller will reference an undefined dirty stripes number, and
all cached devices attached to the same cache set where the thin flash
device lies on may have an inaccurate writeback rate.

This patch calles bch_sectors_dirty_init() in flash_dev_run(), to
correctly initialize dirty stripe counter when the thin flash device
starts to run. This patch also does following parameter data type change,
 -void bch_sectors_dirty_init(struct cached_dev *dc);
 +void bch_sectors_dirty_init(struct bcache_device *);
to call this function conveniently in flash_dev_run().

(Commit log is composed by Coly Li)

Signed-off-by: Tang Junhui 
Reviewed-by: Coly Li 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

md/bitmap: disable bitmap_resize for file-backed bitmaps.

2017-10-04T11:42:58+00:00

[ Upstream commit e8a27f836f165c26f867ece7f31eb5c811692319 ]

bitmap_resize() does not work for file-backed bitmaps.
The buffer_heads are allocated and initialized when
the bitmap is read from the file, but resize doesn't
read from the file, it loads from the internal bitmap.
When it comes time to write the new bitmap, the bh is
non-existent and we crash.

The common case when growing an array involves making the array larger,
and that normally means making the bitmap larger.  Doing
that inside the kernel is possible, but would need more code.
It is probably easier to require people who use file-backed
bitmaps to remove them and re-add after a reshape.

So this patch disables the resizing of arrays which have
file-backed bitmaps.  This is better than crashing.

Reported-by: Zhilong Liu 
Fixes: d60b479d177a ("md/bitmap: add bitmap_resize function to allow bitmap resizing.")
Cc: stable@vger.kernel.org (v3.5+).
Signed-off-by: NeilBrown 
Signed-off-by: Shaohua Li 
Signed-off-by: Sasha Levin

md/raid5: add thread_group worker async_tx_issue_pending_all

2017-09-10T20:35:46+00:00

[ Upstream commit 7e96d559634b73a8158ee99a7abece2eacec2668 ]

Since thread_group worker and raid5d kthread are not in sync, if
worker writes stripe before raid5d then requests will be waiting
for issue_pendig.

Issue observed when building raid5 with ext4, in some build runs
jbd2 would get hung and requests were waiting in the HW engine
waiting to be issued.

Fix this by adding a call to async_tx_issue_pending_all in the
raid5_do_work.

Signed-off-by: Ofer Heifetz 
Cc: stable@vger.kernel.org
Signed-off-by: Shaohua Li 
Signed-off-by: Sasha Levin

Raid5 should update rdev->sectors after reshape

2017-09-10T14:59:17+00:00

[ Upstream commit b5d27718f38843a74552e9a93d32e2391fd3999f ]

The raid5 md device is created by the disks which we don't use the total size. For example,
the size of the device is 5G and it just uses 3G of the devices to create one raid5 device.
Then change the chunksize and wait reshape to finish. After reshape finishing stop the raid
and assemble it again. It fails.
mdadm -CR /dev/md0 -l5 -n3 /dev/loop[0-2] --size=3G --chunk=32 --assume-clean
mdadm /dev/md0 --grow --chunk=64
wait reshape to finish
mdadm -S /dev/md0
mdadm -As
The error messages:
[197519.814302] md: loop1 does not have a valid v1.2 superblock, not importing!
[197519.821686] md: md_import_device returned -22

After reshape the data offset is changed. It selects backwards direction in this condition.
In function super_1_load it compares the available space of the underlying device with
sb->data_size. The new data offset gets bigger after reshape. So super_1_load returns -EINVAL.
rdev->sectors is updated in md_finish_reshape. Then sb->data_size is set in super_1_sync based
on rdev->sectors. So add md_finish_reshape in end_reshape.

Signed-off-by: Xiao Ni 
Acked-by: Guoqing Jiang 
Cc: stable@vger.kernel.org
Signed-off-by: Shaohua Li 
Signed-off-by: Sasha Levin

md: don't use flush_signals in userspace processes

2017-09-10T14:59:17+00:00

[ Upstream commit f9c79bc05a2a91f4fba8bfd653579e066714b1ec ]

The function flush_signals clears all pending signals for the process. It
may be used by kernel threads when we need to prepare a kernel thread for
responding to signals. However using this function for an userspaces
processes is incorrect - clearing signals without the program expecting it
can cause misbehavior.

The raid1 and raid5 code uses flush_signals in its request routine because
it wants to prepare for an interruptible wait. This patch drops
flush_signals and uses sigprocmask instead to block all signals (including
SIGKILL) around the schedule() call. The signals are not lost, but the
schedule() call won't respond to them.

Signed-off-by: Mikulas Patocka 
Cc: stable@vger.kernel.org
Acked-by: NeilBrown 
Signed-off-by: Shaohua Li 
Signed-off-by: Sasha Levin