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  1. 06 9月, 2017 10 次提交
    • D
      bcache: silence static checker warning · da22f0ee
      由 Dan Carpenter 提交于 
      In olden times, closure_return() used to have a hidden return built in.
We removed the hidden return but forgot to add a new return here.  If
"c" were NULL we would oops on the next line, but fortunately "c" is
never NULL.  Let's just remove the if statement.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: NColy Li <colyli@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      da22f0ee
    • T
      bcache: fix for gc and write-back race · 9baf3097
      由 Tang Junhui 提交于 
      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: NTang Junhui <tang.junhui@zte.com.cn>
Acked-by: NColy Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      9baf3097
    • T
      bcache: increase the number of open buckets · 89b1fc54
      由 Tang Junhui 提交于 
      In currently, we only alloc 6 open buckets for each cache set,
but in usually, we always attach about 10 or so backend devices for
each cache set, and the each bcache device are always accessed by
about 10 or so threads in top application layer. So 6 open buckets
are too few, It has led to that each of the same thread write data
to different buckets, which would cause low efficiency write-back,
and also cause buckets inefficient, and would be Very easy to run
out of.

I add debug message in bch_open_buckets_alloc() to print alloc bucket
info, and test with ten bcache devices with a cache set, and each
bcache device is accessed by ten threads.

From the debug message, we can see that, after the modification, One
bucket is more likely to assign to the same thread, and the data from
the same thread are more likely to write the same bucket. Usually the
same thread always write/read the same backend device, so it is good
for write-back and also promote the usage efficiency of buckets.
Signed-off-by: NTang Junhui <tang.junhui@zte.com.cn>
Reviewed-by: NColy Li <colyli@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      89b1fc54
    • T
      bcache: Correct return value for sysfs attach errors · 77fa100f
      由 Tony Asleson 提交于 
      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: NTony Asleson <tasleson@redhat.com>
Acked-by: NColy Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      77fa100f
    • T
      bcache: correct cache_dirty_target in __update_writeback_rate() · a8394090
      由 Tang Junhui 提交于 
      __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: NTang Junhui <tang.junhui@zte.com.cn>
Reviewed-by: NColy Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      a8394090
    • T
      bcache: gc does not work when triggering by manual command · 0b43f49d
      由 Tang Junhui 提交于 
      I try to execute the following command to trigger gc thread:
[root@localhost internal]# echo 1 > trigger_gc
But it does not work, I debug the code in gc_should_run(), It works only
if in invalidating or sectors_to_gc < 0. So set sectors_to_gc to -1 to
meet the condition when we trigger gc by manual command.

(Code comments aded by Coly Li)
Signed-off-by: NTang Junhui <tang.junhui@zte.com.cn>
Reviewed-by: NColy Li <colyli@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      0b43f49d
    • B
      bcache: Don't reinvent the wheel but use existing llist API · 09b3efec
      由 Byungchul Park 提交于 
      Although llist provides proper APIs, they are not used. Make them used.
Signed-off-by: NByungchul Park <byungchul.park@lge.com>
Acked-by: NColy Li <colyli@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      09b3efec
    • T
      bcache: do not subtract sectors_to_gc for bypassed IO · 69daf03a
      由 Tang Junhui 提交于 
      Since bypassed IOs use no bucket, so do not subtract sectors_to_gc to
trigger gc thread.
Signed-off-by: Ntang.junhui <tang.junhui@zte.com.cn>
Acked-by: NColy Li <colyli@suse.de>
Reviewed-by: NEric Wheeler <bcache@linux.ewheeler.net>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      69daf03a
    • T
      bcache: fix sequential large write IO bypass · c81ffa32
      由 Tang Junhui 提交于 
      Sequential write IOs were tested with bs=1M by FIO in writeback cache
mode, these IOs were expected to be bypassed, but actually they did not.
We debug the code, and find in check_should_bypass():
    if (!congested &&
        mode == CACHE_MODE_WRITEBACK &&
        op_is_write(bio_op(bio)) &&
        (bio-＞bi_opf & REQ_SYNC))
        goto rescale
that means, If in writeback mode, a write IO with REQ_SYNC flag will not
be bypassed though it is a sequential large IO, It's not a correct thing
to do actually, so this patch remove these codes.
Signed-off-by: Ntang.junhui <tang.junhui@zte.com.cn>
Reviewed-by: NKent Overstreet <kent.overstreet@gmail.com>
Reviewed-by: NEric Wheeler <bcache@linux.ewheeler.net>
Cc: stable@vger.kernel.org
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      c81ffa32
    • J
      bcache: Fix leak of bdev reference · 4b758df2
      由 Jan Kara 提交于 
      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: NJan Kara <jack@suse.cz>
Acked-by: NColy Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      4b758df2
  3. 02 9月, 2017 2 次提交
  5. 01 9月, 2017 7 次提交
  7. 30 8月, 2017 6 次提交
  9. 29 8月, 2017 15 次提交