linux.git/block, branch v5.6-rc5

block, bfq: fix overwrite of bfq_group pointer in bfq_find_set_group()

2020-03-06T14:00:58+00:00

The bfq_find_set_group() function takes as input a blkcg (which represents
a cgroup) and retrieves the corresponding bfq_group, then it updates the
bfq internal group hierarchy (see comments inside the function for why
this is needed) and finally it returns the bfq_group.
In the hierarchy update cycle, the pointer holding the correct bfq_group
that has to be returned is mistakenly used to traverse the hierarchy
bottom to top, meaning that in each iteration it gets overwritten with the
parent of the current group. Since the update cycle stops at root's
children (depth = 2), the overwrite becomes a problem only if the blkcg
describes a cgroup at a hierarchy level deeper than that (depth > 2). In
this case the root's child that happens to be also an ancestor of the
correct bfq_group is returned. The main consequence is that processes
contained in a cgroup at depth greater than 2 are wrongly placed in the
group described above by BFQ.

This commits fixes this problem by using a different bfq_group pointer in
the update cycle in order to avoid the overwrite of the variable holding
the original group reference.

Reported-by: Kwon Je Oh 
Signed-off-by: Carlo Nonato 
Signed-off-by: Paolo Valente 
Signed-off-by: Jens Axboe

block: Remove used kblockd_schedule_work_on()

2020-03-02T14:17:31+00:00

Commit ee63cfa7fc19 ("block: add kblockd_schedule_work_on()")
introduced the helper in 2016. Remove it because since then no caller
was added.

Cc: Jens Axboe 
Signed-off-by: Daniel Wagner 
Signed-off-by: Jens Axboe

blk-mq: Remove some unused function arguments

2020-02-26T17:34:41+00:00

The struct blk_mq_hw_ctx pointer argument in blk_mq_put_tag(),
blk_mq_poll_nsecs(), and blk_mq_poll_hybrid_sleep() is unused, so remove
it.

Overall obj code size shows a minor reduction, before:
   text	   data	    bss	    dec	    hex	filename
  27306	   1312	      0	  28618	   6fca	block/blk-mq.o
   4303	    272	      0	   4575	   11df	block/blk-mq-tag.o

after:
  27282	   1312	      0	  28594	   6fb2	block/blk-mq.o
   4311	    272	      0	   4583	   11e7	block/blk-mq-tag.o

Reviewed-by: Johannes Thumshirn 
Reviewed-by: Hannes Reinecke 
Signed-off-by: John Garry 
--
This minor patch had been carried as part of the blk-mq shared tags RFC,
I'd rather not carry it anymore as it required rebasing, so now or never..
Signed-off-by: Jens Axboe

blk-mq: insert passthrough request into hctx->dispatch directly

2020-02-25T01:50:48+00:00

For some reason, device may be in one situation which can't handle
FS request, so STS_RESOURCE is always returned and the FS request
will be added to hctx->dispatch. However passthrough request may
be required at that time for fixing the problem. If passthrough
request is added to scheduler queue, there isn't any chance for
blk-mq to dispatch it given we prioritize requests in hctx->dispatch.
Then the FS IO request may never be completed, and IO hang is caused.

So passthrough request has to be added to hctx->dispatch directly
for fixing the IO hang.

Fix this issue by inserting passthrough request into hctx->dispatch
directly together withing adding FS request to the tail of
hctx->dispatch in blk_mq_dispatch_rq_list(). Actually we add FS request
to tail of hctx->dispatch at default, see blk_mq_request_bypass_insert().

Then it becomes consistent with original legacy IO request
path, in which passthrough request is always added to q->queue_head.

Cc: Dongli Zhang 
Cc: Christoph Hellwig 
Cc: Ewan D. Milne 
Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe

Merge tag 'block-5.6-2020-02-05' of git://git.kernel.dk/linux-block

2020-02-06T06:15:23+00:00

Pull more block updates from Jens Axboe:
 "Some later arrivals, but all fixes at this point:

   - bcache fix series (Coly)

   - Series of BFQ fixes (Paolo)

   - NVMe pull request from Keith with a few minor NVMe fixes

   - Various little tweaks"

* tag 'block-5.6-2020-02-05' of git://git.kernel.dk/linux-block: (23 commits)
  nvmet: update AEN list and array at one place
  nvmet: Fix controller use after free
  nvmet: Fix error print message at nvmet_install_queue function
  brd: check and limit max_part par
  nvme-pci: remove nvmeq->tags
  nvmet: fix dsm failure when payload does not match sgl descriptor
  nvmet: Pass lockdep expression to RCU lists
  block, bfq: clarify the goal of bfq_split_bfqq()
  block, bfq: get a ref to a group when adding it to a service tree
  block, bfq: remove ifdefs from around gets/puts of bfq groups
  block, bfq: extend incomplete name of field on_st
  block, bfq: get extra ref to prevent a queue from being freed during a group move
  block, bfq: do not insert oom queue into position tree
  block, bfq: do not plug I/O for bfq_queues with no proc refs
  bcache: check return value of prio_read()
  bcache: fix incorrect data type usage in btree_flush_write()
  bcache: add readahead cache policy options via sysfs interface
  bcache: explicity type cast in bset_bkey_last()
  bcache: fix memory corruption in bch_cache_accounting_clear()
  xen/blkfront: limit allocated memory size to actual use case
  ...

block, bfq: clarify the goal of bfq_split_bfqq()

2020-02-03T13:58:15+00:00

The exact, general goal of the function bfq_split_bfqq() is not that
apparent. Add a comment to make it clear.

Tested-by: Oleksandr Natalenko 
Signed-off-by: Paolo Valente 
Signed-off-by: Jens Axboe

block, bfq: get a ref to a group when adding it to a service tree

2020-02-03T13:58:15+00:00

BFQ schedules generic entities, which may represent either bfq_queues
or groups of bfq_queues. When an entity is inserted into a service
tree, a reference must be taken, to make sure that the entity does not
disappear while still referred in the tree. Unfortunately, such a
reference is mistakenly taken only if the entity represents a
bfq_queue. This commit takes a reference also in case the entity
represents a group.

Tested-by: Oleksandr Natalenko 
Tested-by: Chris Evich 
Signed-off-by: Paolo Valente 
Signed-off-by: Jens Axboe

block, bfq: remove ifdefs from around gets/puts of bfq groups

2020-02-03T13:58:15+00:00

ifdefs around gets and puts of bfq groups reduce readability, remove them.

Tested-by: Oleksandr Natalenko 
Reported-by: Jens Axboe 
Signed-off-by: Paolo Valente 
Signed-off-by: Jens Axboe

block, bfq: extend incomplete name of field on_st

2020-02-03T13:58:15+00:00

The flag on_st in the bfq_entity data structure is true if the entity
is on a service tree or is in service. Yet the name of the field,
confusingly, does not mention the second, very important case. Extend
the name to mention the second case too.

Tested-by: Oleksandr Natalenko 
Signed-off-by: Paolo Valente 
Signed-off-by: Jens Axboe

block, bfq: get extra ref to prevent a queue from being freed during a group move

2020-02-03T13:58:15+00:00

In bfq_bfqq_move(), the bfq_queue, say Q, to be moved to a new group
may happen to be deactivated in the scheduling data structures of the
source group (and then activated in the destination group). If Q is
referred only by the data structures in the source group when the
deactivation happens, then Q is freed upon the deactivation.

This commit addresses this issue by getting an extra reference before
the possible deactivation, and releasing this extra reference after Q
has been moved.

Tested-by: Chris Evich 
Tested-by: Oleksandr Natalenko 
Signed-off-by: Paolo Valente 
Signed-off-by: Jens Axboe