linux-stable.git/drivers/md/bcache, branch v5.5

Revert "bcache: fix fifo index swapping condition in journal_pin_cmp()"

2019-11-18T15:35:47+00:00

Coly says:

"Guoju Fang talked to me today, he told me this change was unnecessary
and I was over-thought.

Then I realize fifo_idx() uses a mask to handle the array index overflow
condition, so the index swap in journal_pin_cmp() won't happen. And yes,
Guoju and Kent are correct.

Since you already applied this patch, can you please to remove this
patch from your for-next branch? This single patch does not break
thing, but it is unecessary at this moment."

This reverts commit c0e0954e909c17b43d176ab219fc598964616ae6.

Signed-off-by: Jens Axboe

bcache: don't export symbols

2019-11-13T22:42:51+00:00

None of the exported bcache symbols are actually used anywhere.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Coly Li 
Signed-off-by: Jens Axboe

bcache: remove the extra cflags for request.o

2019-11-13T22:42:50+00:00

There is no block directory this file needs includes from.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Coly Li 
Signed-off-by: Jens Axboe

bcache: at least try to shrink 1 node in bch_mca_scan()

2019-11-13T22:42:50+00:00

In bch_mca_scan(), the number of shrinking btree node is calculated
by code like this,
	unsigned long nr = sc->nr_to_scan;

        nr /= c->btree_pages;
        nr = min_t(unsigned long, nr, mca_can_free(c));
variable sc->nr_to_scan is number of objects (here is bcache B+tree
nodes' number) to shrink, and pointer variable sc is sent from memory
management code as parametr of a callback.

If sc->nr_to_scan is smaller than c->btree_pages, after the above
calculation, variable 'nr' will be 0 and nothing will be shrunk. It is
frequeently observed that only 1 or 2 is set to sc->nr_to_scan and make
nr to be zero. Then bch_mca_scan() will do nothing more then acquiring
and releasing mutex c->bucket_lock.

This patch checkes whether nr is 0 after the above calculation, if 0
is the result then set 1 to variable 'n'. Then at least bch_mca_scan()
will try to shrink a single B+tree node.

Signed-off-by: Coly Li 
Signed-off-by: Jens Axboe

bcache: add idle_max_writeback_rate sysfs interface

2019-11-13T22:42:50+00:00

For writeback mode, if there is no regular I/O request for a while,
the writeback rate will be set to the maximum value (1TB/s for now).
This is good for most of the storage workload, but there are still
people don't what the maximum writeback rate in I/O idle time.

This patch adds a sysfs interface file idle_max_writeback_rate to
permit people to disable maximum writeback rate. Then the minimum
writeback rate can be advised by writeback_rate_minimum in the
bcache device's sysfs interface.

Reported-by: Christian Balzer 
Signed-off-by: Coly Li 
Signed-off-by: Jens Axboe

bcache: add code comments in bch_btree_leaf_dirty()

2019-11-13T22:42:50+00:00

This patch adds code comments in bch_btree_leaf_dirty() to explain
why w->journal should always reference the eldest journal pin of
all the writing bkeys in the btree node. To make the bcache journal
code to be easier to be understood.

Signed-off-by: Coly Li 
Signed-off-by: Jens Axboe

bcache: fix deadlock in bcache_allocator

2019-11-13T22:42:50+00:00

bcache_allocator can call the following:

 bch_allocator_thread()
  -> bch_prio_write()
     -> bch_bucket_alloc()
        -> wait on &ca->set->bucket_wait

But the wake up event on bucket_wait is supposed to come from
bch_allocator_thread() itself => deadlock:

[ 1158.490744] INFO: task bcache_allocato:15861 blocked for more than 10 seconds.
[ 1158.495929]       Not tainted 5.3.0-050300rc3-generic #201908042232
[ 1158.500653] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 1158.504413] bcache_allocato D    0 15861      2 0x80004000
[ 1158.504419] Call Trace:
[ 1158.504429]  __schedule+0x2a8/0x670
[ 1158.504432]  schedule+0x2d/0x90
[ 1158.504448]  bch_bucket_alloc+0xe5/0x370 [bcache]
[ 1158.504453]  ? wait_woken+0x80/0x80
[ 1158.504466]  bch_prio_write+0x1dc/0x390 [bcache]
[ 1158.504476]  bch_allocator_thread+0x233/0x490 [bcache]
[ 1158.504491]  kthread+0x121/0x140
[ 1158.504503]  ? invalidate_buckets+0x890/0x890 [bcache]
[ 1158.504506]  ? kthread_park+0xb0/0xb0
[ 1158.504510]  ret_from_fork+0x35/0x40

Fix by making the call to bch_prio_write() non-blocking, so that
bch_allocator_thread() never waits on itself.

Moreover, make sure to wake up the garbage collector thread when
bch_prio_write() is failing to allocate buckets.

BugLink: https://bugs.launchpad.net/bugs/1784665
BugLink: https://bugs.launchpad.net/bugs/1796292
Signed-off-by: Andrea Righi 
Signed-off-by: Coly Li 
Signed-off-by: Jens Axboe

bcache: add code comment bch_keylist_pop() and bch_keylist_pop_front()

2019-11-13T22:42:50+00:00

This patch adds simple code comments for bch_keylist_pop() and
bch_keylist_pop_front() in bset.c, to make the code more easier to
be understand.

Signed-off-by: Coly Li 
Signed-off-by: Jens Axboe

bcache: deleted code comments for dead code in bch_data_insert_keys()

2019-11-13T22:42:50+00:00

In request.c:bch_data_insert_keys(), there is code comment for a piece
of dead code. This patch deletes the dead code and its code comment
since they are useless in practice.

Signed-off-by: Coly Li 
Signed-off-by: Jens Axboe

bcache: add more accurate error messages in read_super()

2019-11-13T22:42:50+00:00

Previous code only returns "Not a bcache superblock" for both bcache
super block offset and magic error. This patch addss more accurate error
messages,
- for super block unmatched offset:
  "Not a bcache superblock (bad offset)"
- for super block unmatched magic number:
  "Not a bcache superblock (bad magic)"

Signed-off-by: Coly Li 
Signed-off-by: Jens Axboe