linux-toradex.git/block, branch v4.14-rc7

bio_copy_user_iov(): don't ignore ->iov_offset

2017-10-11T03:55:14+00:00

Since "block: support large requests in blk_rq_map_user_iov" we
started to call it with partially drained iter; that works fine
on the write side, but reads create a copy of iter for completion
time.  And that needs to take the possibility of ->iov_iter != 0
into account...

Cc: stable@vger.kernel.org #v4.5+
Signed-off-by: Al Viro

more bio_map_user_iov() leak fixes

2017-10-11T03:54:57+00:00

we need to take care of failure exit as well - pages already
in bio should be dropped by analogue of bio_unmap_pages(),
since their refcounts had been bumped only once per reference
in bio.

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro

fix unbalanced page refcounting in bio_map_user_iov

2017-10-11T03:54:51+00:00

bio_map_user_iov and bio_unmap_user do unbalanced pages refcounting if
IO vector has small consecutive buffers belonging to the same page.
bio_add_pc_page merges them into one, but the page reference is never
dropped.

Cc: stable@vger.kernel.org
Signed-off-by: Vitaly Mayatskikh 
Signed-off-by: Al Viro

bsg-lib: fix use-after-free under memory-pressure

2017-10-04T14:35:04+00:00

When under memory-pressure it is possible that the mempool which backs
the 'struct request_queue' will make use of up to BLKDEV_MIN_RQ count
emergency buffers - in case it can't get a regular allocation. These
buffers are preallocated and once they are also used, they are
re-supplied with old finished requests from the same request_queue (see
mempool_free()).

The bug is, when re-supplying the emergency pool, the old requests are
not again ran through the callback mempool_t->alloc(), and thus also not
through the callback bsg_init_rq(). Thus we skip initialization, and
while the sense-buffer still should be good, scsi_request->cmd might
have become to be an invalid pointer in the meantime. When the request
is initialized in bsg.c, and the user's CDB is larger than BLK_MAX_CDB,
bsg will replace it with a custom allocated buffer, which is freed when
the user's command is finished, thus it dangles afterwards. When next a
command is sent by the user that has a smaller/similar CDB as
BLK_MAX_CDB, bsg will assume that scsi_request->cmd is backed by
scsi_request->__cmd, will not make a custom allocation, and write into
undefined memory.

Fix this by splitting bsg_init_rq() into two functions:
 - bsg_init_rq() is changed to only do the allocation of the
   sense-buffer, which is used to back the bsg job's reply buffer. This
   pointer should never change during the lifetime of a scsi_request, so
   it doesn't need re-initialization.
 - bsg_initialize_rq() is a new function that makes use of
   'struct request_queue's initialize_rq_fn callback (which was
   introduced in v4.12). This is always called before the request is
   given out via blk_get_request(). This function does the remaining
   initialization that was previously done in bsg_init_rq(), and will
   also do it when the request is taken from the emergency-pool of the
   backing mempool.

Fixes: 50b4d485528d ("bsg-lib: fix kernel panic resulting from missing allocation of reply-buffer")
Cc:  # 4.11+
Reviewed-by: Hannes Reinecke 
Reviewed-by: Johannes Thumshirn 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Benjamin Block 
Signed-off-by: Jens Axboe

blk-mq-debugfs: fix device sched directory for default scheduler

2017-10-03T21:58:55+00:00

In blk_mq_debugfs_register(), I remembered to set up the per-hctx sched
directories if a default scheduler was already configured by
blk_mq_sched_init() from blk_mq_init_allocated_queue(), but I didn't do
the same for the device-wide sched directory. Fix it.

Fixes: d332ce091813 ("blk-mq-debugfs: allow schedulers to register debugfs attributes")
Signed-off-by: Omar Sandoval 
Signed-off-by: Jens Axboe

blk-throttle: fix possible io stall when upgrade to max

2017-10-03T21:41:55+00:00

There is a case which will lead to io stall. The case is described as
follows.
/test1
  |-subtest1
/test2
  |-subtest2
And subtest1 and subtest2 each has 32 queued bios already.

Now upgrade to max. In throtl_upgrade_state, it will try to dispatch
bios as follows:
1) tg=subtest1, do nothing;
2) tg=test1, transfer 32 queued bios from subtest1 to test1; no pending
left, no need to schedule next dispatch;
3) tg=subtest2, do nothing;
4) tg=test2, transfer 32 queued bios from subtest2 to test2; no pending
left, no need to schedule next dispatch;
5) tg=/, transfer 8 queued bios from test1 to /, 8 queued bios from
test2 to /, 8 queued bios from test1 to /, and 8 queued bios from test2
to /; note that test1 and test2 each still has 16 queued bios left;
6) tg=/, try to schedule next dispatch, but since disptime is now
(update in tg_update_disptime, wait=0), pending timer is not scheduled
in fact;
7) In throtl_upgrade_state it totally dispatches 32 queued bios and with
32 left. test1 and test2 each has 16 queued bios;
8) throtl_pending_timer_fn sees the left over bios, but could do
nothing, because throtl_select_dispatch returns 0, and test1/test2 has
no pending tg.

The blktrace shows the following:
8,32   0        0     2.539007641     0  m   N throtl upgrade to max
8,32   0        0     2.539072267     0  m   N throtl /test2 dispatch nr_queued=16 read=0 write=16
8,32   7        0     2.539077142     0  m   N throtl /test1 dispatch nr_queued=16 read=0 write=16

So force schedule dispatch if there are pending children.

Reviewed-by: Shaohua Li 
Signed-off-by: Joseph Qi 
Signed-off-by: Jens Axboe

block: fix a crash caused by wrong API

2017-09-25T14:56:05+00:00

part_stat_show takes a part device not a disk, so we should use
part_to_disk.

Fixes: d62e26b3ffd2("block: pass in queue to inflight accounting")
Cc: Bart Van Assche 
Cc: Omar Sandoval 
Signed-off-by: Shaohua Li 
Signed-off-by: Jens Axboe

blktrace: Fix potential deadlock between delete & sysfs ops

2017-09-25T14:56:05+00:00

The lockdep code had reported the following unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(s_active#228);
                               lock(&bdev->bd_mutex/1);
                               lock(s_active#228);
  lock(&bdev->bd_mutex);

 *** DEADLOCK ***

The deadlock may happen when one task (CPU1) is trying to delete a
partition in a block device and another task (CPU0) is accessing
tracing sysfs file (e.g. /sys/block/dm-1/trace/act_mask) in that
partition.

The s_active isn't an actual lock. It is a reference count (kn->count)
on the sysfs (kernfs) file. Removal of a sysfs file, however, require
a wait until all the references are gone. The reference count is
treated like a rwsem using lockdep instrumentation code.

The fact that a thread is in the sysfs callback method or in the
ioctl call means there is a reference to the opended sysfs or device
file. That should prevent the underlying block structure from being
removed.

Instead of using bd_mutex in the block_device structure, a new
blk_trace_mutex is now added to the request_queue structure to protect
access to the blk_trace structure.

Suggested-by: Christoph Hellwig 
Signed-off-by: Waiman Long 
Acked-by: Steven Rostedt (VMware) 

Fix typo in patch subject line, and prune a comment detailing how
the code used to work.

Signed-off-by: Jens Axboe

bsg-lib: don't free job in bsg_prepare_job

2017-09-25T14:56:05+00:00

The job structure is allocated as part of the request, so we should not
free it in the error path of bsg_prepare_job.

Signed-off-by: Christoph Hellwig 
Cc: stable@vger.kernel.org
Reviewed-by: Ming Lei 
Signed-off-by: Jens Axboe

block: directly insert blk-mq request from blk_insert_cloned_request()

2017-09-11T22:43:57+00:00

A NULL pointer crash was reported for the case of having the BFQ IO
scheduler attached to the underlying blk-mq paths of a DM multipath
device.  The crash occured in blk_mq_sched_insert_request()'s call to
e->type->ops.mq.insert_requests().

Paolo Valente correctly summarized why the crash occured with:
"the call chain (dm_mq_queue_rq -> map_request -> setup_clone ->
blk_rq_prep_clone) creates a cloned request without invoking
e->type->ops.mq.prepare_request for the target elevator e.  The cloned
request is therefore not initialized for the scheduler, but it is
however inserted into the scheduler by blk_mq_sched_insert_request."

All said, a request-based DM multipath device's IO scheduler should be
the only one used -- when the original requests are issued to the
underlying paths as cloned requests they are inserted directly in the
underlying dispatch queue(s) rather than through an additional elevator.

But commit bd166ef18 ("blk-mq-sched: add framework for MQ capable IO
schedulers") switched blk_insert_cloned_request() from using
blk_mq_insert_request() to blk_mq_sched_insert_request().  Which
incorrectly added elevator machinery into a call chain that isn't
supposed to have any.

To fix this introduce a blk-mq private blk_mq_request_bypass_insert()
that blk_insert_cloned_request() calls to insert the request without
involving any elevator that may be attached to the cloned request's
request_queue.

Fixes: bd166ef183c2 ("blk-mq-sched: add framework for MQ capable IO schedulers")
Cc: stable@vger.kernel.org
Reported-by: Bart Van Assche 
Tested-by: Mike Snitzer 
Signed-off-by: Jens Axboe