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kmirrord_wq, kcopyd_work and md->wq are created per dm instance and
serve only a single work item from the dm instance, so non-reentrant
workqueues would provide the same ordering guarantees as ordered ones
while allowing CPU affinity and use of the workqueues for other
purposes. Switch them to non-reentrant workqueues.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Convert all create[_singlethread]_work() users to the new
alloc[_ordered]_workqueue(). This conversion is mechanical and
doesn't introduce any behavior change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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kstriped only serves sc->kstriped_ws which runs dm_table_event().
This doesn't need to be executed from an ordered workqueue w/ rescuer.
Drop kstriped and use the system_wq instead. While at it, rename
kstriped_ws to trigger_event so that it's consistent with other dm
modules.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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flush_scheduled_work() is being deprecated. Flush the used work
directly instead. In all dm targets, the only work which uses
system_wq is ->trigger_event.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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dm_snapshot->queued_bios_work isn't used. Remove ->queued_bios[_work]
from dm_snapshot structure, the flush_queued_bios work function and
ksnapd workqueue.
The DM snapshot changes that were going to use the ksnapd workqueue were
either superseded (fix for origin write races) or never completed
(deallocation of invalid snapshot's memory via workqueue).
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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The device-mapper should not send warning messages to syslog
if a device is not found. This can be done by userspace
according to the returned dm-ioctl error code.
So move these messages to debug level and use rate limiting
to not flood syslog.
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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This patch adds a compatible implementation of the block
chaining mode used by the Loop-AES block device encryption
system (http://loop-aes.sourceforge.net/) designed
by Jari Ruusu.
It operates on full 512 byte sectors and uses CBC
with an IV derived from the sector number, the data and
optionally extra IV seed.
This means that after CBC decryption the first block of sector
must be tweaked according to decrypted data.
Loop-AES can use three encryption schemes:
version 1: is plain aes-cbc mode (already compatible)
version 2: uses 64 multikey scheme with own IV generator
version 3: the same as version 2 with additional IV seed
(it uses 65 keys, last key is used as IV seed)
The IV generator is here named lmk (Loop-AES multikey)
and for the cipher specification looks like: aes:64-cbc-lmk
Version 2 and 3 is recognised according to length
of provided multi-key string (which is just hexa encoded
"raw key" used in original Loop-AES ioctl).
Configuration of the device and decoding key string will
be done in userspace (cryptsetup).
(Loop-AES stores keys in gpg encrypted file, raw keys are
output of simple hashing of lines in this file).
Based on an implementation by Max Vozeler:
http://article.gmane.org/gmane.linux.kernel.cryptoapi/3752/
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
CC: Max Vozeler <max@hinterhof.net>
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This patch adds generic multikey handling to be used
in following patch for Loop-AES mode compatibility.
This patch extends mapping table to optional keycount and
implements generic multi-key capability.
With more keys defined the <key> string is divided into
several <keycount> sections and these are used for tfms.
The tfm is used according to sector offset
(sector 0->tfm[0], sector 1->tfm[1], sector N->tfm[N modulo keycount])
(only power of two values supported for keycount here).
Because of tfms per-cpu allocation, this mode can be take
a lot of memory on large smp systems.
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: Max Vozeler <max@hinterhof.net>
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IV (initialisation vector) can in principle depend not only
on sector but also on plaintext data (or other attributes).
Change IV generator interface to work directly with dmreq
structure to allow such dependence in generator.
Also add post() function which is called after the crypto
operation.
This allows tricky modification of decrypted data or IV
internals.
In asynchronous mode the post() can be called after
ctx->sector count was increased so it is needed
to add iv_sector copy directly to dmreq structure.
(N.B. dmreq always include only one sector in scatterlists)
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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If there is enough memory, code can directly submit bio
instead queing this operation in separate thread.
Try to alloc bio clone with GFP_NOWAIT and only if it
fails use separate queue (map function cannot block here).
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Currently dm-crypt does all the encryption work for a single dm-crypt
mapping in a single workqueue. This does not scale well when multiple
CPUs are submitting IO at a high rate. The single CPU running the single
thread cannot keep up with the encryption and encrypted IO performance
tanks.
This patch changes the crypto workqueue to be per CPU. This means
that as long as the IO submitter (or the interrupt target CPUs
for reads) runs on different CPUs the encryption work will be also
parallel.
To avoid a bottleneck on the IO worker I also changed those to be
per-CPU threads.
There is still some shared data, so I suspect some bouncing
cache lines. But I haven't done a detailed study on that yet.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Rename cc->cipher_mode to cc->cipher_string and store the whole of the cipher
information so it can easily be printed when processing the DM_DEV_STATUS ioctl.
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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This patch adds a 'version' field to the 'dm_ulog_request'
structure.
The 'version' field is taken from a portion of the unused
'padding' field in the 'dm_ulog_request' structure. This
was done to avoid changing the size of the structure and
possibly disrupting backwards compatibility.
The version number will help notify user-space daemons
when a change has been made to the kernel/userspace
log API.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Allow the device-mapper log's 'mark' and 'clear' requests to be
grouped and processed in a batch. This can significantly reduce the
amount of traffic going between the kernel and userspace (where the
processing daemon resides).
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Split the 'flush_list', which contained a mix of both 'mark' and 'clear'
requests, into two distinct lists ('mark_list' and 'clear_list').
The device mapper log implementations (used by various DM targets) are
allowed to cache 'mark' and 'clear' requests until a 'flush' is
received. Until now, these cached requests were kept in the same list.
They will now be put into distinct lists to facilitate group processing
of these requests (in the next patch).
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Make kcopyd merge more I/O requests by using device unplugging.
Without this patch, each I/O request is dispatched separately to the device.
If the device supports tagged queuing, there are many small requests sent
to the device. To improve performance, this patch will batch as many requests
as possible, allowing the queue to merge consecutive requests, and send them
to the device at once.
In my tests (15k SCSI disk), this patch improves sequential write throughput:
Sequential write throughput (chunksize of 4k, 32k, 512k)
unpatched: 15.2, 18.5, 17.5 MB/s
patched: 14.4, 22.6, 23.0 MB/s
In most common uses (snapshot or two-way mirror), kcopyd is only used for
two devices, one for reading and the other for writing, thus this optimization
is implemented only for two devices. The optimization may be extended to n-way
mirrors with some code complexity increase.
We keep track of two block devices to unplug (one for read and the
other for write) and unplug them when exiting "do_work" thread. If
there are more devices used (in theory it could happen, in practice it
is rare), we unplug immediately.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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When constructing a mirror log, it is possible for the initial request
to fail for other reasons besides -ESRCH. These must be handled too.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Simplify key size verification (hexadecimal string) and
set key size early in constructor.
(Patch required by later changes.)
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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This patch replaces dm_mutex with _minor_lock in dm_blk_close()
and then removes it.
During the BKL conversion, commit 6e9624b8caec290d28b4c6d9ec75749df6372b87
(block: push down BKL into .open and .release) pushed lock_kernel()
down into dm_blk_open/close calls.
Commit 2a48fc0ab24241755dc93bfd4f01d68efab47f5a
(block: autoconvert trivial BKL users to private mutex) converted it to a
local mutex, but _minor_lock is sufficient.
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Enable discard support in the DM mirror target.
Also change an existing use of 'bvec' to 'addr' in the union.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Allow the uuid of a mapped device to be set after device creation.
Previously the uuid (which is optional) could only be set by
DM_DEV_CREATE. If no uuid was supplied it could not be set later.
Sometimes it's necessary to create the device before the uuid is known,
and in such cases the uuid must be filled in after the creation.
This patch extends DM_DEV_RENAME to accept a uuid accompanied by
a new flag DM_UUID_FLAG. This can only be done once and if no
uuid was previously supplied. It cannot be used to change an
existing uuid.
DM_VERSION_MINOR is also bumped to 19 to indicate this interface
extension is available.
Signed-off-by: Peter Jones <pjones@redhat.com>
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Remove the REQ_SYNC flag to improve write throughput when writing
to the origin with a snapshot on the same device (using the CFQ I/O
scheduler).
Sequential write throughput (chunksize of 4k, 32k, 512k)
unpatched: 8.5, 8.6, 9.3 MB/s
patched: 15.2, 18.5, 17.5 MB/s
Snapshot exception reallocations are triggered by writes that are
usually async, so mark the associated dm_io_request as async as well.
This helps when using the CFQ I/O scheduler because it has separate
queues for sync and async I/O. Async is optimized for throughput; sync
for latency. With this change we're consciously favoring throughput over
latency.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Revert commit 224cb3e981f1b2f9f93dbd49eaef505d17d894c2
dm: Call blk_abort_queue on failed paths
Multipath began to use blk_abort_queue() to allow for
lower latency path deactivation. This was found to
cause list corruption:
the cmd gets blk_abort_queued/timedout run on it and the scsi eh
somehow is able to complete and run scsi_queue_insert while
scsi_request_fn is still trying to process the request.
https://www.redhat.com/archives/dm-devel/2010-November/msg00085.html
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: Mike Anderson <andmike@linux.vnet.ibm.com>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: stable@kernel.org
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No longer needlessly hold md->bdev->bd_inode->i_mutex when changing the
size of a DM device. This additional locking is unnecessary because
i_size_write() is already protected by the existing critical section in
dm_swap_table(). DM already has a reference on md->bdev so the
associated bd_inode may be changed without lifetime concerns.
A negative side-effect of having held md->bdev->bd_inode->i_mutex was
that a concurrent DM device resize and flush (via fsync) would deadlock.
Dropping md->bdev->bd_inode->i_mutex eliminates this potential for
deadlock. The following reproducer no longer deadlocks:
https://www.redhat.com/archives/dm-devel/2009-July/msg00284.html
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: stable@kernel.org
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* 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block: (43 commits)
block: ensure that completion error gets properly traced
blktrace: add missing probe argument to block_bio_complete
block cfq: don't use atomic_t for cfq_group
block cfq: don't use atomic_t for cfq_queue
block: trace event block fix unassigned field
block: add internal hd part table references
block: fix accounting bug on cross partition merges
kref: add kref_test_and_get
bio-integrity: mark kintegrityd_wq highpri and CPU intensive
block: make kblockd_workqueue smarter
Revert "sd: implement sd_check_events()"
block: Clean up exit_io_context() source code.
Fix compile warnings due to missing removal of a 'ret' variable
fs/block: type signature of major_to_index(int) to major_to_index(unsigned)
block: convert !IS_ERR(p) && p to !IS_ERR_NOR_NULL(p)
cfq-iosched: don't check cfqg in choose_service_tree()
fs/splice: Pull buf->ops->confirm() from splice_from_pipe actors
cdrom: export cdrom_check_events()
sd: implement sd_check_events()
sr: implement sr_check_events()
...
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Commit 1a855a0606 (2.6.37-rc4) fixed a problem where devices were
re-added when they shouldn't be but caused a regression in a less
common case that means sometimes devices cannot be re-added when they
should be.
In particular, when re-adding a device to an array without metadata
we should always access the device, but after the above commit we
didn't.
This patch sets the In_sync flag in that case so that the re-add
succeeds.
This patch is suitable for any -stable kernel to which 1a855a0606 was
applied.
Cc: stable@kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
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The "error" field in block_bio_complete is not assigned, leaving the memory area
uninitialized (keeping garbage data). Pass an additional tracepoint argument to
this event to initialize this field.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: Ingo Molnar <mingo@elte.hu>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Li Zefan <lizf@cn.fujitsu.com>
CC: Alan.Brunelle@hp.com
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
cciss: fix cciss_revalidate panic
block: max hardware sectors limit wrapper
block: Deprecate QUEUE_FLAG_CLUSTER and use queue_limits instead
blk-throttle: Correct the placement of smp_rmb()
blk-throttle: Trim/adjust slice_end once a bio has been dispatched
block: check for proper length of iov entries earlier in blk_rq_map_user_iov()
drbd: fix for spin_lock_irqsave in endio callback
drbd: don't recvmsg with zero length
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Implement blk_limits_max_hw_sectors() and make
blk_queue_max_hw_sectors() a wrapper around it.
DM needs this to avoid setting queue_limits' max_hw_sectors and
max_sectors directly. dm_set_device_limits() now leverages
blk_limits_max_hw_sectors() logic to establish the appropriate
max_hw_sectors minimum (PAGE_SIZE). Fixes issue where DM was
incorrectly setting max_sectors rather than max_hw_sectors (which
caused dm_merge_bvec()'s max_hw_sectors check to be ineffective).
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@kernel.org
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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When stacking devices, a request_queue is not always available. This
forced us to have a no_cluster flag in the queue_limits that could be
used as a carrier until the request_queue had been set up for a
metadevice.
There were several problems with that approach. First of all it was up
to the stacking device to remember to set queue flag after stacking had
completed. Also, the queue flag and the queue limits had to be kept in
sync at all times. We got that wrong, which could lead to us issuing
commands that went beyond the max scatterlist limit set by the driver.
The proper fix is to avoid having two flags for tracking the same thing.
We deprecate QUEUE_FLAG_CLUSTER and use the queue limit directly in the
block layer merging functions. The queue_limit 'no_cluster' is turned
into 'cluster' to avoid double negatives and to ease stacking.
Clustering defaults to being enabled as before. The queue flag logic is
removed from the stacking function, and explicitly setting the cluster
flag is no longer necessary in DM and MD.
Reported-by: Ed Lin <ed.lin@promise.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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When we fail to start a raid10 for some reason, we call
md_unregister_thread to kill the thread that was created.
Unfortunately md_thread() will then make one call into the handler
(raid10d) even though md_wakeup_thread has not been called. This is
not safe and as md_unregister_thread is called after mddev->private
has been set to NULL, it will definitely cause a NULL dereference.
So fix this at both ends:
- md_thread should only call the handler if THREAD_WAKEUP has been
set.
- raid10 should call md_unregister_thread before setting things
to NULL just like all the other raid modules do.
This is applicable to 2.6.35 and later.
Cc: stable@kernel.org
Reported-by: "Citizen" <citizen_lee@thecus.com>
Signed-off-by: NeilBrown <neilb@suse.de>
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With v0.90 metadata, a hot-spare does not become a full member of the
array until recovery is complete. So if we re-add such a device to
the array, we know that all of it is as up-to-date as the event count
would suggest, and so it a bitmap-based recovery is possible.
However with v1.x metadata, the hot-spare immediately becomes a full
member of the array, but it record how much of the device has been
recovered. If the array is stopped and re-assembled recovery starts
from this point.
When such a device is hot-added to an array we currently lose the 'how
much is recovered' information and incorrectly included it as a full
in-sync member (after bitmap-based fixup).
This is wrong and unsafe and could corrupt data.
So be more careful about setting saved_raid_disk - which is what
guides the re-adding of devices back into an array.
The new code matches the code in slot_store which does a similar
thing, which is encouraging.
This is suitable for any -stable kernel.
Reported-by: "Dailey, Nate" <Nate.Dailey@stratus.com>
Cc: stable@kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
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As recorded in
https://bugzilla.kernel.org/show_bug.cgi?id=24012
it is possible for a flush request through md to hang. This is due to
an interaction between the recursion avoidance in
generic_make_request, the insistence in md of only having one flush
active at a time, and the possibility of dm (or md) submitting two
flush requests to a device from the one generic_make_request.
If a generic_make_request call into dm causes two flush requests to be
queued (as happens if the dm table has two targets - they get one
each), these two will be queued inside generic_make_request.
Assume they are for the same md device.
The first is processed and causes 1 or more flush requests to be sent
to lower devices. These get queued within generic_make_request too.
Then the second flush to the md device gets handled and it blocks
waiting for the first flush to complete. But it won't complete until
the two lower-device requests complete, and they haven't even been
submitted yet as they are on the generic_make_request queue.
The deadlock can be broken by using a separate thread to submit the
requests to lower devices. md has such a thread readily available:
md_wq.
So use it to submit these requests.
Reported-by: Giacomo Catenazzi <cate@cateee.net>
Tested-by: Giacomo Catenazzi <cate@cateee.net>
Signed-off-by: NeilBrown <neilb@suse.de>
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submit_flushes is called from exactly one place.
Move the code that is before and after that call into
submit_flushes.
This has not functional change, but will make the next patch
smaller and easier to follow.
Signed-off-by: NeilBrown <neilb@suse.de>
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None of the functions called between setting flush_pending to 1, and
atomic_dec_and_test can change flush_pending, or will anything
running in any other thread (as ->flush_bio is not NULL). So the
atomic_dec_and_test will always succeed.
So remove the atomic_sec and the atomic_dec_and_test.
Signed-off-by: NeilBrown <neilb@suse.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc into for-2.6.38/core
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Before 2.6.37, the md layer had a mechanism for catching I/Os with the
barrier flag set, and translating the barrier into barriers for all
the underlying devices. With 2.6.37, I/O barriers have become plain
old flushes, and the md code was updated to reflect this. However,
one piece was left out -- the md layer does not tell the block layer
that it supports flushes or FUA access at all, which results in md
silently dropping flush requests.
Since the support already seems there, just add this one piece of
bookkeeping.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: NeilBrown <neilb@suse.de>
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Commit 4044ba58dd15cb01797c4fd034f39ef4a75f7cc3 supposedly fixed a
problem where if a raid1 with just one good device gets a read-error
during recovery, the recovery would abort and immediately restart in
an infinite loop.
However it depended on raid1_remove_disk removing the spare device
from the array. But that does not happen in this case. So add a test
so that in the 'recovery_disabled' case, the device will be removed.
This suitable for any kernel since 2.6.29 which is when
recovery_disabled was introduced.
Cc: stable@kernel.org
Reported-by: Sebastian Färber <faerber@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
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When trying to grow an array by enlarging component devices,
rdev_size_store() expects the return value of rdev_size_change() to be
in sectors, but the actual value is returned in KBs.
This functionality was broken by commit
dd8ac336c13fd8afdb082ebacb1cddd5cf727889
so this patch is suitable for any kernel since 2.6.30.
Cc: stable@kernel.org
Signed-off-by: Justin Maggard <jmaggard10@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
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event.
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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After recent blkdev_get() modifications, open_by_devnum() and
open_bdev_exclusive() are simple wrappers around blkdev_get().
Replace them with blkdev_get_by_dev() and blkdev_get_by_path().
blkdev_get_by_dev() is identical to open_by_devnum().
blkdev_get_by_path() is slightly different in that it doesn't
automatically add %FMODE_EXCL to @mode.
All users are converted. Most conversions are mechanical and don't
introduce any behavior difference. There are several exceptions.
* btrfs now sets FMODE_EXCL in btrfs_device->mode, so there's no
reason to OR it explicitly on blkdev_put().
* gfs2, nilfs2 and the generic mount_bdev() now set FMODE_EXCL in
sb->s_mode.
* With the above changes, sb->s_mode now always should contain
FMODE_EXCL. WARN_ON_ONCE() added to kill_block_super() to detect
errors.
The new blkdev_get_*() functions are with proper docbook comments.
While at it, add function description to blkdev_get() too.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Joern Engel <joern@lazybastard.org>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jan Kara <jack@suse.cz>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp>
Cc: reiserfs-devel@vger.kernel.org
Cc: xfs-masters@oss.sgi.com
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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Over time, block layer has accumulated a set of APIs dealing with bdev
open, close, claim and release.
* blkdev_get/put() are the primary open and close functions.
* bd_claim/release() deal with exclusive open.
* open/close_bdev_exclusive() are combination of open and claim and
the other way around, respectively.
* bd_link/unlink_disk_holder() to create and remove holder/slave
symlinks.
* open_by_devnum() wraps bdget() + blkdev_get().
The interface is a bit confusing and the decoupling of open and claim
makes it impossible to properly guarantee exclusive access as
in-kernel open + claim sequence can disturb the existing exclusive
open even before the block layer knows the current open if for another
exclusive access. Reorganize the interface such that,
* blkdev_get() is extended to include exclusive access management.
@holder argument is added and, if is @FMODE_EXCL specified, it will
gain exclusive access atomically w.r.t. other exclusive accesses.
* blkdev_put() is similarly extended. It now takes @mode argument and
if @FMODE_EXCL is set, it releases an exclusive access. Also, when
the last exclusive claim is released, the holder/slave symlinks are
removed automatically.
* bd_claim/release() and close_bdev_exclusive() are no longer
necessary and either made static or removed.
* bd_link_disk_holder() remains the same but bd_unlink_disk_holder()
is no longer necessary and removed.
* open_bdev_exclusive() becomes a simple wrapper around lookup_bdev()
and blkdev_get(). It also has an unexpected extra bdev_read_only()
test which probably should be moved into blkdev_get().
* open_by_devnum() is modified to take @holder argument and pass it to
blkdev_get().
Most of bdev open/close operations are unified into blkdev_get/put()
and most exclusive accesses are tested atomically at the open time (as
it should). This cleans up code and removes some, both valid and
invalid, but unnecessary all the same, corner cases.
open_bdev_exclusive() and open_by_devnum() can use further cleanup -
rename to blkdev_get_by_path() and blkdev_get_by_devt() and drop
special features. Well, let's leave them for another day.
Most conversions are straight-forward. drbd conversion is a bit more
involved as there was some reordering, but the logic should stay the
same.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Neil Brown <neilb@suse.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Peter Osterlund <petero2@telia.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Alex Elder <aelder@sgi.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: dm-devel@redhat.com
Cc: drbd-dev@lists.linbit.com
Cc: Leo Chen <leochen@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Joern Engel <joern@logfs.org>
Cc: reiserfs-devel@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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Code to manage symlinks in /sys/block/*/{holders|slaves} are overly
complex with multiple holder considerations, redundant extra
references to all involved kobjects, unused generic kobject holder
support and unnecessary mixup with bd_claim/release functionalities.
Strip it down to what's necessary (single gendisk holder) and make it
use a separate interface. This is a step for cleaning up
bd_claim/release. This patch makes dm-table slightly more complex but
it will be simplified again with further changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Neil Brown <neilb@suse.de>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Cc: dm-devel@redhat.com
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Convert direct reads of an inode's i_size to using i_size_read().
i_size_{read,write} use a seqcount to protect reads from accessing
incomple writes. Concurrent i_size_write()s require mutual exclussion
to protect the seqcount that is used by i_size_{read,write}. But
i_size_read() callers do not need to use additional locking.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: NeilBrown <neilb@suse.de>
Acked-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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The code for searching through the device list to read-balance in
raid1 is rather clumsy and hard to follow. Try to simplify it a bit.
No important functionality change here.
Signed-off-by: NeilBrown <neilb@suse.de>
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Signed-off-by: NeilBrown <neilb@suse.de>
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This structure field (flushing_bio_list) is never used, so remove it.
Signed-off-by: NeilBrown <neilb@suse.de>
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When writing to an 'external' bitmap we don't currently unplug the
device before waiting, so we can get a 3msec delay each time;
So use REQ_UNPLUG to force and unplug.
Signed-off-by: NeilBrown <neilb@suse.de>
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bio_clone and bio_alloc allocate from a common bio pool.
If an md device is stacked with other devices that use this pool, or under
something like swap which uses the pool, then the multiple calls on
the pool can cause deadlocks.
So allocate a local bio pool for each md array and use that rather
than the common pool.
This pool is used both for regular IO and metadata updates.
Signed-off-by: NeilBrown <neilb@suse.de>
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Currently sync_page_io takes a 'bdev'.
Every caller passes 'rdev->bdev'.
We will soon want another field out of the rdev in sync_page_io,
So just pass the rdev instead of the bdev out of it.
Signed-off-by: NeilBrown <neilb@suse.de>
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