Commit Graph

519007 Commits

Author SHA1 Message Date
Selvan Mani
98f57c5196 mtip32xx: Fix accessing freed memory
In mtip_pci_remove(), driver data 'dd' is accessed after freeing it. This
is a residue of SRSI code cleanup in the patch 016a41c38821 "mtip32xx: fix
crash on surprise removal of the drive". Removed the bit flags
MTIP_DDF_REMOVE_DONE_BIT and MTIP_PF_SR_CLEANUP_BIT.

Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Vignesh Gunasekaran <vgunasekaran@micron.com>
Signed-off-by: Selvan Mani <smani@micron.com>
Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-24 08:48:46 -06:00
Axel Lin
51ef72bda7 block: nvme-scsi: Catch kcalloc failure
res variable was initialized to -ENOMEM, but it's override by
nvme_trans_copy_from_user(). So current code returns 0 if kcalloc fails.
Fix it to return proper error code.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-20 10:34:07 -06:00
Keith Busch
71feb364e7 NVMe: Fix IO for extended metadata formats
This fixes io submit ioctl handling when using extended metadata
formats. When these formats are used, the user provides a single virtually
contiguous buffer containing both the block and metadata interleaved,
so the metadata size needs to be added to the total length and not mapped
as a separate transfer.

The command is also driver generated, so this patch does not enforce
blk-integrity extensions provide the metadata buffer.

Reported-by: Marcin Dziegielewski <marcin.dziegielewski@intel.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-19 13:16:26 -06:00
Matias Bjørling
e112af0dc9 nvme: don't overwrite req->cmd_flags on sync cmd
In __nvme_submit_sync_cmd, the request direction is overwritten when
the REQ_FAILFAST_DRIVER flag is set.

Signed-off-by: Matias Bjørling <m@bjorling.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Fixes: 75619bfa90 ("NVMe: End sync requests immediately on failure")
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-17 09:36:57 -06:00
Asai Thambi SP
2f17d71dd7 mtip32xx: increase wait time for hba reset
In LUN failure conditions, device takes longer time to complete the hba reset.
Increased wait time from 1 second to 10 seconds.

Signed-off-by: Sam Bradshaw <sbradshaw@micron.com>
Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-16 08:24:53 -06:00
Asai Thambi SP
75787265d6 mtip32xx: fix minor number
When a device is surprise removed and inserted, it is assigned a new minor
number because driver use multiples of 'instance' number. Modified to use the
multiples of 'index' for minor number.

Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-16 08:24:52 -06:00
Asai Thambi SP
284eb9a202 mtip32xx: remove unnecessary sleep in mtip_ftl_rebuild_poll()
Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-16 08:24:50 -06:00
Asai Thambi SP
2132a54472 mtip32xx: fix crash on surprise removal of the drive
pci and block layers have changed a lot compared to when SRSI support was added.
Given the current state of pci and block layers, this driver do not have to do
any specific handling.

Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Selvan Mani <smani@micron.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-16 08:24:49 -06:00
Asai Thambi SP
686d8e0bb5 mtip32xx: Abort I/O during secure erase operation
Currently I/Os are being queued when secure erase operation starts, and issue
them after the operation completes. As all data will be gone when the operation
completes, any queued I/O doesn't make sense. Hence, abort I/O (return -ENODATA)
as soon as the driver receives.

Signed-off-by: Selvan Mani <smani@micron.com>
Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-16 08:24:47 -06:00
Asai Thambi SP
ee04bed690 mtip32xx: fix incorrectly setting MTIP_DDF_SEC_LOCK_BIT
Fix incorrectly setting MTIP_DDF_SEC_LOCK_BIT

Signed-off-by: Selvan Mani <smani@micron.com>
Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-16 08:24:46 -06:00
Asai Thambi SP
a7806fadc5 mtip32xx: remove unused variable 'port->allocated'
Remove unused variable 'port->allocated'

Signed-off-by: Selvan Mani <smani@micron.com>
Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-16 08:24:44 -06:00
Asai Thambi SP
02b48265e7 mtip32xx: fix rmmod issue
put_disk() need to be called after del_gendisk() to free the disk object structure.

Signed-off-by: Selvan Mani <smani@micron.com>
Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-16 08:24:40 -06:00
Geoff Levand
3715a5d014 MAINTAINERS: Update ps3vram block driver
Add myself as co-maintainer of the ps3vram block driver, and add linuxppc-dev
as a relevant mailing list.

I have been acting as maintainer of this driver for the last several years, and
if there is some inquiry regarding it I would like to be notified.

Signed-off-by: Geoff Levand <geoff@infradead.org>
Acked-by: Jim Paris <jim@jtan.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-10 14:06:57 -06:00
Geert Uytterhoeven
de667203fd block/ps3vram: Remove obsolete reference to MTD
The ps3vram driver is a plain block device driver since commit
f507cd2203 ("ps3/block: Replace mtd/ps3vram
by block/ps3vram").

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Geoff Levand <geoff@infradead.org>
Acked-by: Jim Paris <jim@jtan.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-10 14:06:55 -06:00
Geoff Levand
e7bdd17b08 block/ps3vram: Fix sparse warnings
Fix sparse warnings like these:

 drivers/block/ps3vram.c: warning: incorrect type in assignment (different address spaces)
 drivers/block/ps3vram.c:    expected unsigned int [usertype] *ctrl
 drivers/block/ps3vram.c:    got void [noderef] <asn:2>*

Cc: Jim Paris <jim@jtan.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Geoff Levand <geoff@infradead.org>
Acked-by: Jim Paris <jim@jtan.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-10 14:06:53 -06:00
Keith Busch
a5768aa887 NVMe: Automatic namespace rescan
Namespaces may be dynamically allocated and deleted or attached and
detached. This has the driver rescan the device for namespace changes
after each device reset or namespace change asynchronous event.

There could potentially be many detached namespaces that we don't want
polluting /dev/ with unusable block handles, so this will delete disks
if the namespace is not active as indicated by the response from identify
namespace. This also skips adding the disk if no capacity is provisioned
to the namespace in the first place.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-05 10:58:34 -06:00
Jens Axboe
b281ebb817 Merge branch 'for-4.2/core' into for-4.2/drivers 2015-06-05 10:58:28 -06:00
Jens Axboe
3f21c265cd block: add blk_set_queue_dying() to blkdev.h
We export this function and NVMe wants to use it, but for some reason
it was never added to the block header. Do that.

Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-05 10:57:37 -06:00
Jon Derrick
36a7e993ee NVMe: Memory barrier before queue_count is incremented
Protects against reordering and/or preempting which would allow the
kthread to access the queue descriptor before it is set up

Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-05 10:33:34 -06:00
Keith Busch
4cc06521ee NVMe: add sysfs and ioctl controller reset
We need the ability to perform an nvme controller reset as discussed on
the mailing list thread:

  http://lists.infradead.org/pipermail/linux-nvme/2015-March/001585.html

This adds a sysfs entry that when written to will reset perform an NVMe
controller reset if the controller was successfully initialized in the
first place.

This also adds locking around resetting the device in the async probe
method so the driver can't schedule two resets.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Cc: Brandon Schultz <brandon.schulz@hgst.com>
Cc: David Sariel <david.sariel@pmcs.com>

Updated by Jens to:

1) Merge this with the ioctl reset patch from David Sariel. The ioctl
   path now shares the reset code from the sysfs path.

2) Don't flush work if we fail issuing the reset.

Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-05 10:30:08 -06:00
Akinobu Mita
8b70f45e2e null_blk: restart request processing on completion handler
When irqmode=2 (IRQ completion handler is timer) and queue_mode=1
(Block interface to use is rq), the completion handler should restart
request handling for any pending requests on a queue because request
processing stops when the number of commands are queued more than
hw_queue_depth (null_rq_prep_fn returns BLKPREP_DEFER).

Without this change, the following command cannot finish.

	# modprobe null_blk irqmode=2 queue_mode=1 hw_queue_depth=1
	# fio --name=t --rw=read --size=1g --direct=1 \
	  --ioengine=libaio --iodepth=64 --filename=/dev/nullb0

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-01 20:09:05 -06:00
Akinobu Mita
419c21a3b6 null_blk: prevent timer handler running on a different CPU where started
When irqmode=2 (IRQ completion handler is timer), timer handler should
be called on the same CPU where the timer has been started.

Since completion_queues are per-cpu and the completion handler only
touches completion_queue for local CPU, we need to prevent the handler
from running on a different CPU where the timer has been started.
Otherwise, the IO cannot be completed until another completion handler
is executed on that CPU.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-01 20:09:03 -06:00
Keith Busch
42483228d4 NVMe: Remove hctx reliance for multi-namespace
The driver needs to track shared tags to support multiple namespaces
that may be dynamically allocated or deleted. Relying on the first
request_queue's hctx's is not appropriate as we cannot clear outstanding
tags for all namespaces using this handle, nor can the driver easily track
all request_queue's hctx as namespaces are attached/detached. Instead,
this patch uses the nvme_dev's tagset to get the shared tag resources
instead of through a request_queue hctx.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-01 14:36:06 -06:00
Jens Axboe
843e8ddb25 Merge branch 'for-4.2/core' into for-4.2/drivers 2015-06-01 14:36:02 -06:00
Keith Busch
f26cdc8536 blk-mq: Shared tag enhancements
Storage controllers may expose multiple block devices that share hardware
resources managed by blk-mq. This patch enhances the shared tags so a
low-level driver can access the shared resources not tied to the unshared
h/w contexts. This way the LLD can dynamically add and delete disks and
request queues without having to track all the request_queue hctx's to
iterate outstanding tags.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-01 14:35:56 -06:00
Jens Axboe
e548ca4ee4 block: don't honor chunk sizes for data-less IO
We don't need to honor chunk sizes for IO that doesn't carry any
data.

Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-29 13:11:32 -06:00
Jens Axboe
beefa6ba7b block: only honor SG gap prevention for merges that contain data
We can safely merge anything that wont generate an SG list entry,
so if the bio is data-less (discard), don't look at potential
SG gaps.

Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-29 13:10:23 -06:00
Keith Busch
75619bfa90 NVMe: End sync requests immediately on failure
Do not retry failed sync commands so the original status may be seen
without issuing unnecessary retries.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-29 10:10:30 -06:00
Keith Busch
f4ff414aeb NVMe: Use requested sync command timeout
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-29 10:10:29 -06:00
Julia Lawall
f6454b049d block: fix returnvar.cocci warnings
Remove unneeded variable used to store return value.

Generated by: scripts/coccinelle/misc/returnvar.cocci

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-26 14:02:45 -06:00
Keith Busch
a0a931d6a2 NVMe: Fix obtaining command result
Replaces req->sense_len usage, which is not owned by the LLD, to
req->special to contain the command result for driver created commands,
and sets the result unconditionally on completion.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@fb.com>
Fixes: d29ec8241c ("nvme: submit internal commands through the block layer")
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22 14:13:32 -06:00
Christoph Hellwig
5f1b670d0b block, dm: don't copy bios for request clones
Currently dm-multipath has to clone the bios for every request sent
to the lower devices, which wastes cpu cycles and ties down memory.

This patch instead adds a new REQ_CLONE flag that instructs req_bio_endio
to not complete bios attached to a request, which we set on clone
requests similar to bios in a flush sequence.  With this change I/O
errors on a path failure only get propagated to dm-multipath, which
can then either resubmit the I/O or complete the bios on the original
request.

I've done some basic testing of this on a Linux target with ALUA support,
and it survives path failures during I/O nicely.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22 08:58:57 -06:00
Mike Snitzer
326e1dbb57 block: remove management of bi_remaining when restoring original bi_end_io
Commit c4cf5261 ("bio: skip atomic inc/dec of ->bi_remaining for
non-chains") regressed all existing callers that followed this pattern:
 1) saving a bio's original bi_end_io
 2) wiring up an intermediate bi_end_io
 3) restoring the original bi_end_io from intermediate bi_end_io
 4) calling bio_endio() to execute the restored original bi_end_io

The regression was due to BIO_CHAIN only ever getting set if
bio_inc_remaining() is called.  For the above pattern it isn't set until
step 3 above (step 2 would've needed to establish BIO_CHAIN).  As such
the first bio_endio(), in step 2 above, never decremented __bi_remaining
before calling the intermediate bi_end_io -- leaving __bi_remaining with
the value 1 instead of 0.  When bio_inc_remaining() occurred during step
3 it brought it to a value of 2.  When the second bio_endio() was
called, in step 4 above, it should've called the original bi_end_io but
it didn't because there was an extra reference that wasn't dropped (due
to atomic operations being optimized away since BIO_CHAIN wasn't set
upfront).

Fix this issue by removing the __bi_remaining management complexity for
all callers that use the above pattern -- bio_chain() is the only
interface that _needs_ to be concerned with __bi_remaining.  For the
above pattern callers just expect the bi_end_io they set to get called!
Remove bio_endio_nodec() and also remove all bio_inc_remaining() calls
that aren't associated with the bio_chain() interface.

Also, the bio_inc_remaining() interface has been moved local to bio.c.

Fixes: c4cf5261 ("bio: skip atomic inc/dec of ->bi_remaining for non-chains")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22 08:58:55 -06:00
Christoph Hellwig
d29ec8241c nvme: submit internal commands through the block layer
Use block layer queues with an internal cmd_type to submit internally
generated NVMe commands.  This both simplifies the code a lot and allow
for a better structure.  For example now the LighNVM code can construct
commands without knowing the details of the underlying I/O descriptors.
Or a future NVMe over network target could inject commands, as well as
could the SCSI translation and ioctl code be reused for such a beast.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22 08:37:20 -06:00
Christoph Hellwig
772ce43559 nvme: fail SCSI read/write command with unsupported protection bit
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22 08:36:44 -06:00
Christoph Hellwig
9085176848 nvme: report the DPOFUA in MODE_SENSE
NVMe device always support the FUA bit, and the SCSI translations
accepts the DPO bit, which doesn't have much of a meaning for us.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22 08:36:42 -06:00
Christoph Hellwig
cbbb7a2ec6 nvme: simplify and cleanup the READ/WRITE SCSI CDB parsing code
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22 08:36:40 -06:00
Christoph Hellwig
3726897efd nvme: first round at deobsfucating the SCSI translation code
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22 08:36:38 -06:00
Christoph Hellwig
e61b0a86ca nvme: fix scsi translation error handling
Erorr handling for the scsi translation was completely broken, as there
were two different positive error number spaces overlapping.  Fix this
up by removing one of them, and centralizing the generation of the other
positive values in a single place.  Also fix up a few places that didn't
handle the NVMe error codes properly.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22 08:36:36 -06:00
Christoph Hellwig
b90c48d0c1 nvme: split nvme_trans_send_fw_cmd
This function handles two totally different opcodes, so split it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22 08:36:34 -06:00
Christoph Hellwig
e75ec752d7 nvme: store a struct device pointer in struct nvme_dev
Most users want the generic device, so store that in struct nvme_dev
instead of the pci_dev.  This also happens to be a nice step towards
making some code reusable for non-PCI transports.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22 08:36:33 -06:00
Christoph Hellwig
f705f837c5 nvme: consolidate synchronous command submission helpers
Note that we keep the unused timeout argument, but allow callers to
pass 0 instead of a timeout if they want the default.  This will allow
adding a timeout to the pass through path later on.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22 08:36:31 -06:00
Jens Axboe
6a92700758 loop: remove (now) unused 'out' label
gcc, righfully, complains:

drivers/block/loop.c:1369:1: warning: label 'out' defined but not used [-Wunused-label]

Kill it.

Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20 09:54:35 -06:00
Jarod Wilson
a05e578055 s390/block/dasd: remove obsolete while -EBUSY loop
With the mutex_trylock bit gone from blkdev_reread_part(), the retry logic
in dasd_scan_partitions() shouldn't be necessary.

CC: Christoph Hellwig <hch@infradead.org>
CC: Jens Axboe <axboe@kernel.dk>
CC: Tejun Heo <tj@kernel.org>
CC: Alexander Viro <viro@zeniv.linux.org.uk>
CC: Markus Pargmann <mpa@pengutronix.de>
CC: Stefan Weinhuber <wein@de.ibm.com>
CC: Stefan Haberland <stefan.haberland@de.ibm.com>
CC: Sebastian Ott <sebott@linux.vnet.ibm.com>
CC: Fabian Frederick <fabf@skynet.be>
CC: Ming Lei <ming.lei@canonical.com>
CC: David Herrmann <dh.herrmann@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Peter Zijlstra <peterz@infradead.org>
CC: nbd-general@lists.sourceforge.net
CC: linux-s390@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20 09:06:17 -06:00
Ming Lei
6029a06c88 block: dasd_genhd: convert to blkdev_reread_part
Also remove the obsolete comment.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20 09:06:15 -06:00
Ming Lei
9dcd137953 block: nbd: convert to blkdev_reread_part()
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20 09:06:13 -06:00
Ming Lei
06f0e9e68c block: loop: fix another reread part failure
loop_clr_fd() can be run piggyback with lo_release(), and
under this situation, reread partition may always fail because
bd_mutex has been held already.

This patch detects the situation by the reference count, and
call __blkdev_reread_part() to avoid acquiring the lock again.

In the meantime, this patch switches to new kernel APIs
of blkdev_reread_part() and __blkdev_reread_part().

Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20 09:06:11 -06:00
Ming Lei
f893366795 block: loop: don't hold lo_ctl_mutex in lo_open
The lo_ctl_mutex is held for running all ioctl handlers, and
in some ioctl handlers, ioctl_by_bdev(BLKRRPART) is called for
rereading partitions, which requires bd_mutex.

So it is easy to cause failure because trylock(bd_mutex) may
fail inside blkdev_reread_part(), and follows the lock context:

blkid or other application:
	->open()
		->mutex_lock(bd_mutex)
		->lo_open()
			->mutex_lock(lo_ctl_mutex)

losetup(set fd ioctl):
	->mutex_lock(lo_ctl_mutex)
	->ioctl_by_bdev(BLKRRPART)
		->trylock(bd_mutex)

This patch trys to eliminate the ABBA lock dependency by removing
lo_ctl_mutext in lo_open() with the following approach:

1) make lo_refcnt as atomic_t and avoid acquiring lo_ctl_mutex in lo_open():
	- for open vs. add/del loop, no any problem because of loop_index_mutex
	- freeze request queue during clr_fd, so I/O can't come until
	  clearing fd is completed, like the effect of holding lo_ctl_mutex
	  in lo_open
	- both open() and release() have been serialized by bd_mutex already

2) don't hold lo_ctl_mutex for decreasing/checking lo_refcnt in
lo_release(), then lo_ctl_mutex is only required for the last release.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20 09:06:09 -06:00
Jens Axboe
b816d45fd5 Merge branch 'for-4.2/core' into for-4.2/drivers
We need the blkdev_reread_part() changes for drivers to adapt.
2015-05-20 09:05:57 -06:00
Ming Lei
b04a5636a6 block: replace trylock with mutex_lock in blkdev_reread_part()
The only possible problem of using mutex_lock() instead of trylock
is about deadlock.

If there aren't any locks held before calling blkdev_reread_part(),
deadlock can't be caused by this conversion.

If there are locks held before calling blkdev_reread_part(),
and if these locks arn't required in open, close handler and I/O
path, deadlock shouldn't be caused too.

Both user space's ioctl(BLKRRPART) and md_setup_drive() from
init/do_mounts_md.c belongs to the 1st case, so the conversion is safe
for the two cases.

For loop, the previous patches in this pathset has fixed the ABBA lock
dependency, so the conversion is OK.

For nbd, tx_lock is held when calling the function:

	- both open and release won't hold the lock
	- when blkdev_reread_part() is run, I/O thread has been stopped
	already, so tx_lock won't be acquired in I/O path at that time.
	- so the conversion won't cause deadlock for nbd

For dasd, both dasd_open(), dasd_release() and request function don't
acquire any mutex/semphone, so the conversion should be safe.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Jarod Wilson <jarod@redhat.com>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20 09:05:45 -06:00