When array is degraded, read data landed on failed drives will result in
reading rest of data in a stripe. So a single sequential read would
result in same data being read twice.
This patch is to avoid chunk aligned read for degraded array. The
downside is to involve stripe cache which means associated CPU overhead
and extra memory copy.
Test Results:
Following test are done on a enterprise storage node with Seagate 6T SAS
drives and Xeon E5-2648L CPU (10 cores, 1.9Ghz), 10 disks MD RAID6 8+2,
chunk size 128 KiB.
I use FIO, using direct-io with various bs size, enough queue depth,
tested sequential and 100% random read against 3 array config:
1) optimal, as baseline;
2) degraded;
3) degraded with this patch.
Kernel version is 4.0-rc3.
Each individual test I only did once so there might be some variations,
but we just focus on big trend.
Sequential Read:
bs=(KiB) optimal(MiB/s) degraded(MiB/s) degraded-with-patch (MiB/s)
1024 1608 656 995
512 1624 710 956
256 1635 728 980
128 1636 771 983
64 1612 1119 1000
32 1580 1420 1004
16 1368 688 986
8 768 647 953
4 411 413 850
Random Read:
bs=(KiB) optimal(IOPS) degraded(IOPS) degraded-with-patch (IOPS)
1024 163 160 156
512 274 273 272
256 426 428 424
128 576 592 591
64 726 724 726
32 849 848 837
16 900 970 971
8 927 940 929
4 948 940 955
Some notes:
* In sequential + optimal, as bs size getting smaller, the FIO thread
become CPU bound.
* In sequential + degraded, there's big increase when bs is 64K and
32K, I don't have explanation.
* In sequential + degraded-with-patch, the MD thread mostly become CPU
bound.
If you want to we can discuss specific data point in those data. But in
general it seems with this patch, we have more predictable and in most
cases significant better sequential read performance when array is
degraded, and almost no noticeable impact on random read.
Performance is a complicated thing, the patch works well for this
particular configuration, but may not be universal. For example I
imagine testing on all SSD array may have very different result. But I
personally think in most cases IO bandwidth is more scarce resource than
CPU.
Signed-off-by: Eric Mei <eric.mei@seagate.com>
Signed-off-by: NeilBrown <neilb@suse.de>
The default setting of 256 stripe_heads is probably
much too small for many configurations. So it is best to make it
auto-configure.
Shrinking the cache under memory pressure is easy. The only
interesting part here is that we put a fairly high cost
('seeks') on shrinking the cache as the cost is greater than
just having to read more data, it reduces parallelism.
Growing the cache on demand needs to be done carefully. If we allow
fast growth, that can upset memory balance as lots of dirty memory can
quickly turn into lots of memory queued in the stripe_cache.
It is important for the raid5 block device to appear congested to
allow write-throttling to work.
So we only add stripes slowly. We set a flag when an allocation
fails because all stripes are in use, allocate at a convenient
time when that flag is set, and don't allow it to be set again
until at least one stripe_head has been released for re-use.
This means that a spurt of requests will only cause one stripe_head
to be allocated, but a steady stream of requests will slowly
increase the cache size - until memory pressure puts it back again.
It could take hours to reach a steady state.
The value written to, and displayed in, stripe_cache_size is
used as a minimum. The cache can grow above this and shrink back
down to it. The actual size is not directly visible, though it can
be deduced to some extent by watching stripe_cache_active.
Signed-off-by: NeilBrown <neilb@suse.de>
Rather than adjusting max_nr_stripes whenever {grow,drop}_one_stripe()
succeeds, do it inside the functions.
Also choose the correct hash to handle next inside the functions.
This removes duplication and will help with future new uses of
{grow,drop}_one_stripe.
This also fixes a minor bug where the "md/raid:%md: allocate XXkB"
message always said "0kB".
Signed-off-by: NeilBrown <neilb@suse.de>
Depending on the available coding we allow optimized rmw logic for write
operations. To support easier testing this patch allows manual control
of the rmw/rcw descision through the interface /sys/block/mdX/md/rmw_level.
The configuration can handle three levels of control.
rmw_level=0: Disable rmw for all RAID types. Hardware assisted P/Q
calculation has no implementation path yet to factor in/out chunks of
a syndrome. Enforcing this level can be benefical for slow CPUs with
hardware syndrome support and fast SSDs.
rmw_level=1: Estimate rmw IOs and rcw IOs. Execute rmw only if we will
save IOs. This equals the "old" unpatched behaviour and will be the
default.
rmw_level=2: Execute rmw even if calculated IOs for rmw and rcw are
equal. We might have higher CPU consumption because of calculating the
parity twice but it can be benefical otherwise. E.g. RAID4 with fast
dedicated parity disk/SSD. The option is implemented just to be
forward-looking and will ONLY work with this patch!
Signed-off-by: Markus Stockhausen <stockhausen@collogia.de>
Signed-off-by: NeilBrown <neilb@suse.de>
Glue it altogehter. The raid6 rmw path should work the same as the
already existing raid5 logic. So emulate the prexor handling/flags
and split functions as needed.
1) Enable xor_syndrome() in the async layer.
2) Split ops_run_prexor() into RAID4/5 and RAID6 logic. Xor the syndrome
at the start of a rmw run as we did it before for the single parity.
3) Take care of rmw run in ops_run_reconstruct6(). Again process only
the changed pages to get syndrome back into sync.
4) Enhance set_syndrome_sources() to fill NULL pages if we are in a rmw
run. The lower layers will calculate start & end pages from that and
call the xor_syndrome() correspondingly.
5) Adapt the several places where we ignored Q handling up to now.
Performance numbers for a single E5630 system with a mix of 10 7200k
desktop/server disks. 300 seconds random write with 8 threads onto a
3,2TB (10*400GB) RAID6 64K chunk without spare (group_thread_cnt=4)
bsize rmw_level=1 rmw_level=0 rmw_level=1 rmw_level=0
skip_copy=1 skip_copy=1 skip_copy=0 skip_copy=0
4K 115 KB/s 141 KB/s 165 KB/s 140 KB/s
8K 225 KB/s 275 KB/s 324 KB/s 274 KB/s
16K 434 KB/s 536 KB/s 640 KB/s 534 KB/s
32K 751 KB/s 1,051 KB/s 1,234 KB/s 1,045 KB/s
64K 1,339 KB/s 1,958 KB/s 2,282 KB/s 1,962 KB/s
128K 2,673 KB/s 3,862 KB/s 4,113 KB/s 3,898 KB/s
256K 7,685 KB/s 7,539 KB/s 7,557 KB/s 7,638 KB/s
512K 19,556 KB/s 19,558 KB/s 19,652 KB/s 19,688 Kb/s
Signed-off-by: Markus Stockhausen <stockhausen@collogia.de>
Signed-off-by: NeilBrown <neilb@suse.de>
expansion/resync can grab a stripe when the stripe is in batch list. Since all
stripes in batch list must be in the same state, we can't allow some stripes
run into expansion/resync. So we delay expansion/resync for stripe in batch
list.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
If io error happens in any stripe of a batch list, the batch list will be
split, then normal process will run for the stripes in the list.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
stripe cache is 4k size. Even adjacent full stripe writes are handled in 4k
unit. Idealy we should use big size for adjacent full stripe writes. Bigger
stripe cache size means less stripes runing in the state machine so can reduce
cpu overhead. And also bigger size can cause bigger IO size dispatched to under
layer disks.
With below patch, we will automatically batch adjacent full stripe write
together. Such stripes will be added to the batch list. Only the first stripe
of the list will be put to handle_list and so run handle_stripe(). Some steps
of handle_stripe() are extended to cover all stripes of the list, including
ops_run_io, ops_run_biodrain and so on. With this patch, we have less stripes
running in handle_stripe() and we send IO of whole stripe list together to
increase IO size.
Stripes added to a batch list have some limitations. A batch list can only
include full stripe write and can't cross chunk boundary to make sure stripes
have the same parity disks. Stripes in a batch list must be in the same state
(no written, toread and so on). If a stripe is in a batch list, all new
read/write to add_stripe_bio will be blocked to overlap conflict till the batch
list is handled. The limitations will make sure stripes in a batch list be in
exactly the same state in the life circly.
I did test running 160k randwrite in a RAID5 array with 32k chunk size and 6
PCIe SSD. This patch improves around 30% performance and IO size to under layer
disk is exactly 32k. I also run a 4k randwrite test in the same array to make
sure the performance isn't changed with the patch.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Track overwrite disk count, so we can know if a stripe is a full stripe write.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
A freshly new stripe with write request can be batched. Any time the stripe is
handled or new read is queued, the flag will be cleared.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Use flex_array for scribble data. Next patch will batch several stripes
together, so scribble data should be able to cover several stripes, so this
patch also allocates scribble data for stripes across a chunk.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This option is not well justified and testing suggests that
it hardly ever makes any difference.
The comment suggests there might be a need to wait for non-resync
activity indicated by ->nr_waiting, however raise_barrier()
already waits for all of that.
So just remove it to simplify reasoning about speed limiting.
This allows us to remove a 'FIXME' comment from raid5.c as that
never used the flag.
Signed-off-by: NeilBrown <neilb@suse.de>
When we have more than 1 drive failure, it's possible we start
rebuild one drive while leaving another faulty drive in array.
To determine whether array will be optimal after building, current
code only check whether a drive is missing, which could potentially
lead to data corruption. This patch is to add checking Faulty flag.
Signed-off-by: NeilBrown <neilb@suse.de>
Commit a7854487cd:
md: When RAID5 is dirty, force reconstruct-write instead of read-modify-write.
Causes an RCW cycle to be forced even when the array is degraded.
A degraded array cannot support RCW as that requires reading all data
blocks, and one may be missing.
Forcing an RCW when it is not possible causes a live-lock and the code
spins, repeatedly deciding to do something that cannot succeed.
So change the condition to only force RCW on non-degraded arrays.
Reported-by: Manibalan P <pmanibalan@amiindia.co.in>
Bisected-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Tested-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Fixes: a7854487cd
Cc: stable@vger.kernel.org (v3.7+)
Rather than using mddev_lock() to take the reconfig_mutex
when writing to any md sysfs file, we only take mddev_lock()
in the particular _store() functions that require it.
Admittedly this is most, but it isn't all.
This also allows us to remove special-case handling for new_dev_store
(in md_attr_store).
Signed-off-by: NeilBrown <neilb@suse.de>
It is important that mddev->private isn't freed while
a sysfs attribute function is accessing it.
So use mddev->lock to protect the setting of ->private to NULL, and
take that lock when checking ->private for NULL and de-referencing it
in the sysfs access functions.
This only applies to the read ('show') side of access. Write
access will be handled separately.
Signed-off-by: NeilBrown <neilb@suse.de>
Now that the ->stop function only frees the private data,
rename is accordingly.
Also pass in the private pointer as an arg rather than using
mddev->private. This flexibility will be useful in level_store().
Finally, don't clear ->private. It doesn't make sense to clear
it seeing that isn't what we free, and it is no longer necessary
to clear ->private (it was some time ago before ->to_remove was
introduced).
Setting ->to_remove in ->free() is a bit of a wart, but not a
big problem at the moment.
Signed-off-by: NeilBrown <neilb@suse.de>
Each md personality has a 'stop' operation which does two
things:
1/ it finalizes some aspects of the array to ensure nothing
is accessing the ->private data
2/ it frees the ->private data.
All the steps in '1' can apply to all arrays and so can be
performed in common code.
This is useful as in the case where we change the personality which
manages an array (in level_store()), it would be helpful to do
step 1 early, and step 2 later.
So split the 'step 1' functionality out into a new mddev_detach().
Signed-off-by: NeilBrown <neilb@suse.de>
There is no locking around calls to merge_bvec_fn(), so
it is possible that calls which coincide with a level (or personality)
change could go wrong.
So create a central dispatch point for these functions and use
rcu_read_lock().
If the array is suspended, reject any merge that can be rejected.
If not, we know it is safe to call the function.
Signed-off-by: NeilBrown <neilb@suse.de>
There is currently no locking around calls to the 'congested'
bdi function. If called at an awkward time while an array is
being converted from one level (or personality) to another, there
is a tiny chance of running code in an unreferenced module etc.
So add a 'congested' function to the md_personality operations
structure, and call it with appropriate locking from a central
'mddev_congested'.
When the array personality is changing the array will be 'suspended'
so no IO is processed.
If mddev_congested detects this, it simply reports that the
array is congested, which is a safe guess.
As mddev_suspend calls synchronize_rcu(), mddev_congested can
avoid races by included the whole call inside an rcu_read_lock()
region.
This require that the congested functions for all subordinate devices
can be run under rcu_lock. Fortunately this is the case.
Signed-off-by: NeilBrown <neilb@suse.de>
That last condition is unclear and over cautious.
There are two related issues here.
If a partial write is destined for a missing device, then
either RMW or RCW can work. We must read all the available
block. Only then can the missing blocks be calculated, and
then the parity update performed.
If RMW is not an option, then there is a complication even
without partial writes. If we would need to read a missing
device to perform the reconstruction, then we must first read every
block so the missing device data can be computed.
This is the case for RAID6 (Which currently does not support
RMW) and for times when we don't trust the parity (after a crash)
and so are in the process of resyncing it.
So make these two cases more clear and separate, and perform
the relevant tests more thoroughly.
Signed-off-by: NeilBrown <neilb@suse.de>
Both the last two cases are only relevant if something has failed and
something needs to be written (but not over-written), and if it is OK
to pre-read blocks at this point. So factor out those tests and
explain them.
Signed-off-by: NeilBrown <neilb@suse.de>
Some of the conditions in need_this_block have very straight
forward motivation. Separate those out and document them.
Signed-off-by: NeilBrown <neilb@suse.de>
fetch_block() has a very large and hard to read 'if' condition.
Separate it into its own function so that it can be
made more readable.
Signed-off-by: NeilBrown <neilb@suse.de>
67f455486d introduced a call to
md_wakeup_thread() when adding to the delayed_list. However the md
thread is woken up unconditionally just below.
Remove the unnecessary wakeup call.
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
If a non-page-aligned write is destined for a device which
is missing/faulty, we can deadlock.
As the target device is missing, a read-modify-write cycle
is not possible.
As the write is not for a full-page, a recontruct-write cycle
is not possible.
This should be handled by logic in fetch_block() which notices
there is a non-R5_OVERWRITE write to a missing device, and so
loads all blocks.
However since commit 67f455486d, that code requires
STRIPE_PREREAD_ACTIVE before it will active, and those circumstances
never set STRIPE_PREREAD_ACTIVE.
So: in handle_stripe_dirtying, if neither rmw or rcw was possible,
set STRIPE_DELAYED, which will cause STRIPE_PREREAD_ACTIVE be set
after a suitable delay.
Fixes: 67f455486d
Cc: stable@vger.kernel.org (v3.16+)
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Tested-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
It is critical that fetch_block() and handle_stripe_dirtying()
are consistent in their analysis of what needs to be loaded.
Otherwise raid5 can wait forever for a block that won't be loaded.
Currently when writing to a RAID5 that is resyncing, to a location
beyond the resync offset, handle_stripe_dirtying chooses a
reconstruct-write cycle, but fetch_block() assumes a
read-modify-write, and a lockup can happen.
So treat that case just like RAID6, just as we do in
handle_stripe_dirtying. RAID6 always does reconstruct-write.
This bug was introduced when the behaviour of handle_stripe_dirtying
was changed in 3.7, so the patch is suitable for any kernel since,
though it will need careful merging for some versions.
Cc: stable@vger.kernel.org (v3.7+)
Fixes: a7854487cd
Reported-by: Henry Cai <henryplusplus@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
raid5: fix init_stripe() inconsistencies
1) remove_hash() is not necessary. We will only be called right after
get_free_stripe(). There we have already a call to remove_hash().
2) Tracing prints out the sector of the freed stripe and not the sector
that we want to initialize.
Signed-off-by: NeilBrown <neilb@suse.de>
It has come to my attention (thanks Martin) that 'discard_zeroes_data'
is only a hint. Some devices in some cases don't do what it
says on the label.
The use of DISCARD in RAID5 depends on reads from discarded regions
being predictably zero. If a write to a previously discarded region
performs a read-modify-write cycle it assumes that the parity block
was consistent with the data blocks. If all were zero, this would
be the case. If some are and some aren't this would not be the case.
This could lead to data corruption after a device failure when
data needs to be reconstructed from the parity.
As we cannot trust 'discard_zeroes_data', ignore it by default
and so disallow DISCARD on all raid4/5/6 arrays.
As many devices are trustworthy, and as there are benefits to using
DISCARD, add a module parameter to over-ride this caution and cause
DISCARD to work if discard_zeroes_data is set.
If a site want to enable DISCARD on some arrays but not on others they
should select DISCARD support at the filesystem level, and set the
raid456 module parameter.
raid456.devices_handle_discard_safely=Y
As this is a data-safety issue, I believe this patch is suitable for
-stable.
DISCARD support for RAID456 was added in 3.7
Cc: Shaohua Li <shli@kernel.org>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Heinz Mauelshagen <heinzm@redhat.com>
Cc: stable@vger.kernel.org (3.7+)
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Fixes: 620125f2bf
Signed-off-by: NeilBrown <neilb@suse.de>
During recovery of a double-degraded RAID6 it is possible for
some blocks not to be recovered properly, leading to corruption.
If a write happens to one block in a stripe that would be written to a
missing device, and at the same time that stripe is recovering data
to the other missing device, then that recovered data may not be written.
This patch skips, in the double-degraded case, an optimisation that is
only safe for single-degraded arrays.
Bug was introduced in 2.6.32 and fix is suitable for any kernel since
then. In an older kernel with separate handle_stripe5() and
handle_stripe6() functions the patch must change handle_stripe6().
Cc: stable@vger.kernel.org (2.6.32+)
Fixes: 6c0069c0ae
Cc: Yuri Tikhonov <yur@emcraft.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Reported-by: "Manibalan P" <pmanibalan@amiindia.co.in>
Tested-by: "Manibalan P" <pmanibalan@amiindia.co.in>
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1090423
Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Dan Williams <dan.j.williams@intel.com>
If a stripe in a raid6 array received a write to each data block while
the array is degraded, and if any of these writes to a missing device
are not page-aligned, then a live-lock happens.
In this case the P and Q blocks need to be read so that the part of
the missing block which is *not* being updated by the write can be
constructed. Due to a logic error, these blocks are not loaded, so
the update cannot proceed and the stripe is 'handled' repeatedly in an
infinite loop.
This bug is unlikely as most writes are page aligned. However as it
can lead to a livelock it is suitable for -stable. It was introduced
in 3.16.
Cc: stable@vger.kernel.org (v3.16)
Fixed: 67f455486d
Signed-off-by: NeilBrown <neilb@suse.de>
Mostly performance improvements with a few corner-case bug fixes.
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Merge tag 'md/3.16' of git://neil.brown.name/md
Pull md updates from Neil Brown:
"Assorted md fixes for 3.16
Mostly performance improvements with a few corner-case bug fixes"
* tag 'md/3.16' of git://neil.brown.name/md:
raid5: speedup sync_request processing
md/raid5: deadlock between retry_aligned_read with barrier io
raid5: add an option to avoid copy data from bio to stripe cache
md/bitmap: remove confusing code from filemap_get_page.
raid5: avoid release list until last reference of the stripe
md: md_clear_badblocks should return an error code on failure.
md/raid56: Don't perform reads to support writes until stripe is ready.
md: refuse to change shape of array if it is active but read-only
The raid5 sync_request() processing calls handle_stripe() within the context of
the resync-thread. The resync-thread issues the first set of read requests
and this adds execution latency and slows down the scheduling of the next
sync_request().
The current rebuild/resync speed of raid5 is not much faster than what
rotational HDDs can sustain.
Testing the following patch on a 6-drive array, I can increase the rebuild
speed from 100 MB/s to 175 MB/s.
The sync_request() now just sets STRIPE_HANDLE and releases the stripe. This
creates some more parallelism between the resync-thread and raid5 kernel daemon.
Signed-off-by: Eivind Sarto <esarto@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
A chunk aligned read increases counter active_aligned_reads and
decreases it after sub-device handle it successfully. But when a read
error occurs, the read redispatched by raid5d, and the
active_aligned_reads will not be decreased until we can grab a stripe
head in retry_aligned_read. Now suppose, a barrier io comes, set
conf->quiesce to 2, and wait until both active_stripes and
active_aligned_reads are zero. The retried chunk aligned read gets
stuck at get_active_stripe waiting until conf->quiesce becomes 0.
Retry_aligned_read and barrier io are waiting each other now.
One possible solution is that we ignore conf->quiesce, let the retried
aligned read finish. I reproduced this deadlock and test this patch on
centos6.0
Signed-off-by: NeilBrown <neilb@suse.de>
The stripe cache has two goals:
1. cache data, so next time if data can be found in stripe cache, disk access
can be avoided.
2. stable data. data is copied from bio to stripe cache and calculated parity.
data written to disk is from stripe cache, so if upper layer changes bio data,
data written to disk isn't impacted.
In my environment, I can guarantee 2 will not happen. And BDI_CAP_STABLE_WRITES
can guarantee 2 too. For 1, it's not common too. block plug mechanism will
dispatch a bunch of sequentail small requests together. And since I'm using
SSD, I'm using small chunk size. It's rare case stripe cache is really useful.
So I'd like to avoid the copy from bio to stripe cache and it's very helpful
for performance. In my 1M randwrite tests, avoid the copy can increase the
performance more than 30%.
Of course, this shouldn't be enabled by default. It's reported enabling
BDI_CAP_STABLE_WRITES can harm some workloads before, so I added an option to
control it.
Neilb:
changed BUG_ON to WARN_ON
Removed some assignments from raid5_build_block which are now not needed.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
The (lockless) release_list reduces lock contention, but there is excessive
queueing and dequeuing of stripes on this list. A stripe will currently be
queued on the release_list with a stripe reference count > 1. This can cause
the raid5 kernel thread(s) to dequeue the stripe and decrement the refcount
without doing any other useful processing of the stripe. The are two cases
when the stripe can be put on the release_list multiple times before it is
actually handled by the kernel thread(s).
1) make_request() activates the stripe processing in 4k increments. When a
write request is large enough to span multiple chunks of a stripe_head, the
first 4k chunk adds the stripe to the plug list. The next 4k chunk that is
processed for the same stripe puts the stripe on the release_list with a
refcount=2. This can cause the kernel thread to process and decrement the
stripe before the stripe us unplugged, which again will put it back on the
release_list.
2) Whenever IO is scheduled on a stripe (pre-read and/or write), the stripe
refcount is set to the number of active IO (for each chunk). The stripe is
released as each IO complete, and can be queued and dequeued multiple times
on the release_list, until its refcount finally reached zero.
This simple patch will ensure a stripe is only queued on the release_list when
its refcount=1 and is ready to be handled by the kernel thread(s). I added some
instrumentation to raid5 and counted the number of times striped were queued on
the release_list for a variety of write IO sizes. Without this patch the number
of times stripes got queued on the release_list was 100-500% higher than with
the patch. The excess queuing will increase with the IO size. The patch also
improved throughput by 5-10%.
Signed-off-by: Eivind Sarto <esarto@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
If it is found that we need to pre-read some blocks before a write
can succeed, we normally set STRIPE_DELAYED and don't actually perform
the read until STRIPE_PREREAD_ACTIVE subsequently gets set.
However for a degraded RAID6 we currently perform the reads as soon
as we see that a write is pending. This significantly hurts
throughput.
So:
- when handle_stripe_dirtying find a block that it wants on a device
that is failed, set STRIPE_DELAY, instead of doing nothing, and
- when fetch_block detects that a read might be required to satisfy a
write, only perform the read if STRIPE_PREREAD_ACTIVE is set,
and if we would actually need to read something to complete the write.
This also helps RAID5, though less often as RAID5 supports a
read-modify-write cycle. For RAID5 the read is performed too early
only if the write is not a full 4K aligned write (i.e. no an
R5_OVERWRITE).
Also clean up a couple of horrible bits of formatting.
Reported-by: Patrik Horník <patrik@dsl.sk>
Signed-off-by: NeilBrown <neilb@suse.de>
I hit another BUG_ON with e240c1839d. In __get_priority_stripe(),
stripe count equals to 0 initially. Between atomic_inc and BUG_ON,
get_active_stripe() finds the stripe. So the stripe count isn't 1 any more.
V2: keeps the BUG_ON suggested by Neil.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
For sequential workload (or request size big workload), get_active_stripe can
find cached stripe. In this case, we always hold device_lock, which exposes a
lot of lock contention for such workload. If stripe count isn't 0, we don't
need hold the lock actually, since we just increase its count. And this is the
hot code path for such workload. Unfortunately we must delete the BUG_ON.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
In NUMA machine, prepare_to_wait/finish_wait in make_request exposes a
lot of contention for sequential workload (or big request size
workload). For such workload, each bio includes several stripes. So we
can just do prepare_to_wait/finish_wait once for the whold bio instead
of every stripe. This reduces the lock contention completely for such
workload. Random workload might have the similar lock contention too,
but I didn't see it yet, maybe because my stroage is still not fast
enough.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Subsystems that want to register CPU hotplug callbacks, as well as perform
initialization for the CPUs that are already online, often do it as shown
below:
get_online_cpus();
for_each_online_cpu(cpu)
init_cpu(cpu);
register_cpu_notifier(&foobar_cpu_notifier);
put_online_cpus();
This is wrong, since it is prone to ABBA deadlocks involving the
cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
with CPU hotplug operations).
Interestingly, the raid5 code can actually prevent double initialization and
hence can use the following simplified form of callback registration:
register_cpu_notifier(&foobar_cpu_notifier);
get_online_cpus();
for_each_online_cpu(cpu)
init_cpu(cpu);
put_online_cpus();
A hotplug operation that occurs between registering the notifier and calling
get_online_cpus(), won't disrupt anything, because the code takes care to
perform the memory allocations only once.
So reorganize the code in raid5 this way to fix the deadlock with callback
registration.
Cc: linux-raid@vger.kernel.org
Cc: stable@vger.kernel.org (v2.6.32+)
Fixes: 36d1c6476b
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
[Srivatsa: Fixed the unregister_cpu_notifier() deadlock, added the
free_scratch_buffer() helper to condense code further and wrote the changelog.]
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Pull block IO driver changes from Jens Axboe:
- bcache update from Kent Overstreet.
- two bcache fixes from Nicholas Swenson.
- cciss pci init error fix from Andrew.
- underflow fix in the parallel IDE pg_write code from Dan Carpenter.
I'm sure the 1 (or 0) users of that are now happy.
- two PCI related fixes for sx8 from Jingoo Han.
- floppy init fix for first block read from Jiri Kosina.
- pktcdvd error return miss fix from Julia Lawall.
- removal of IRQF_SHARED from the SEGA Dreamcast CD-ROM code from
Michael Opdenacker.
- comment typo fix for the loop driver from Olaf Hering.
- potential oops fix for null_blk from Raghavendra K T.
- two fixes from Sam Bradshaw (Micron) for the mtip32xx driver, fixing
an OOM problem and a problem with handling security locked conditions
* 'for-3.14/drivers' of git://git.kernel.dk/linux-block: (47 commits)
mg_disk: Spelling s/finised/finished/
null_blk: Null pointer deference problem in alloc_page_buffers
mtip32xx: Correctly handle security locked condition
mtip32xx: Make SGL container per-command to eliminate high order dma allocation
drivers/block/loop.c: fix comment typo in loop_config_discard
drivers/block/cciss.c:cciss_init_one(): use proper errnos
drivers/block/paride/pg.c: underflow bug in pg_write()
drivers/block/sx8.c: remove unnecessary pci_set_drvdata()
drivers/block/sx8.c: use module_pci_driver()
floppy: bail out in open() if drive is not responding to block0 read
bcache: Fix auxiliary search trees for key size > cacheline size
bcache: Don't return -EINTR when insert finished
bcache: Improve bucket_prio() calculation
bcache: Add bch_bkey_equal_header()
bcache: update bch_bkey_try_merge
bcache: Move insert_fixup() to btree_keys_ops
bcache: Convert sorting to btree_keys
bcache: Convert debug code to btree_keys
bcache: Convert btree_iter to struct btree_keys
bcache: Refactor bset_tree sysfs stats
...
Pull core block IO changes from Jens Axboe:
"The major piece in here is the immutable bio_ve series from Kent, the
rest is fairly minor. It was supposed to go in last round, but
various issues pushed it to this release instead. The pull request
contains:
- Various smaller blk-mq fixes from different folks. Nothing major
here, just minor fixes and cleanups.
- Fix for a memory leak in the error path in the block ioctl code
from Christian Engelmayer.
- Header export fix from CaiZhiyong.
- Finally the immutable biovec changes from Kent Overstreet. This
enables some nice future work on making arbitrarily sized bios
possible, and splitting more efficient. Related fixes to immutable
bio_vecs:
- dm-cache immutable fixup from Mike Snitzer.
- btrfs immutable fixup from Muthu Kumar.
- bio-integrity fix from Nic Bellinger, which is also going to stable"
* 'for-3.14/core' of git://git.kernel.dk/linux-block: (44 commits)
xtensa: fixup simdisk driver to work with immutable bio_vecs
block/blk-mq-cpu.c: use hotcpu_notifier()
blk-mq: for_each_* macro correctness
block: Fix memory leak in rw_copy_check_uvector() handling
bio-integrity: Fix bio_integrity_verify segment start bug
block: remove unrelated header files and export symbol
blk-mq: uses page->list incorrectly
blk-mq: use __smp_call_function_single directly
btrfs: fix missing increment of bi_remaining
Revert "block: Warn and free bio if bi_end_io is not set"
block: Warn and free bio if bi_end_io is not set
blk-mq: fix initializing request's start time
block: blk-mq: don't export blk_mq_free_queue()
block: blk-mq: make blk_sync_queue support mq
block: blk-mq: support draining mq queue
dm cache: increment bi_remaining when bi_end_io is restored
block: fixup for generic bio chaining
block: Really silence spurious compiler warnings
block: Silence spurious compiler warnings
block: Kill bio_pair_split()
...
As release_stripe and __release_stripe decrement ->count and then
manipulate ->lru both under ->device_lock, it is important that
get_active_stripe() increments ->count and clears ->lru also under
->device_lock.
However we currently list_del_init ->lru under the lock, but increment
the ->count outside the lock. This can lead to races and list
corruption.
So move the atomic_inc(&sh->count) up inside the ->device_lock
protected region.
Note that we still increment ->count without device lock in the case
where get_free_stripe() was called, and in fact don't take
->device_lock at all in that path.
This is safe because if the stripe_head can be found by
get_free_stripe, then the hash lock assures us the no-one else could
possibly be calling release_stripe() at the same time.
Fixes: 566c09c534
Cc: stable@vger.kernel.org (3.13)
Reported-and-tested-by: Ian Kumlien <ian.kumlien@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Before a write starts we set a bit in the write-intent bitmap.
When the write completes we clear that bit if the write was successful
to all devices. However if the write wasn't fully successful we
should not clear the bit. If the faulty drive is subsequently
re-added, the fact that the bit is still set ensure that we will
re-write the data that is missing.
This logic is mediated by the STRIPE_DEGRADED flag - we only clear the
bitmap bit when this flag is not set.
Currently we correctly set the flag if a write starts when some
devices are failed or missing. But we do *not* set the flag if some
device failed during the write attempt.
This is wrong and can result in clearing the bit inappropriately.
So: set the flag when a write fails.
This bug has been present since bitmaps were introduces, so the fix is
suitable for any -stable kernel.
Reported-by: Ethan Wilson <ethan.wilson@shiftmail.org>
Cc: stable@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
commit 6d183de407
md/raid5: fix newly-broken locking in get_active_stripe.
simplified a BUG_ON, but removed too much so now it sometimes fires
when it shouldn't.
When the STRIPE_EXPANDING flag is set, the stripe_head might be on a
special list while multiple stripe_heads are collected, or it might
not be on any list, even a 'free' list when the refcount is zero. As
long as STRIPE_EXPANDING is set, it will be found and added back to a
list eventually.
So both of the BUG_ONs which test for the ->lru being empty or not
need to avoid the case where STRIPE_EXPANDING is set.
The patch which broke this was marked for -stable, so this patch needs
to be applied to any branch that received 6d183de4
Fixes: 6d183de407
Cc: stable@vger.kernel.org (any release to which above was applied)
Signed-off-by: NeilBrown <neilb@suse.de>
commit 5d8c71f9e5
md: raid5 crash during degradation
Fixed a crash in an overly simplistic way which could leave
R5_WriteError or R5_MadeGood set in the stripe cache for devices
for which it is no longer relevant.
When those devices are removed and spares added the flags are still
set and can cause incorrect behaviour.
commit 14a75d3e07
md/raid5: preferentially read from replacement device if possible.
Fixed the same bug if a more effective way, so we can now revert
the original commit.
Reported-and-tested-by: Alexander Lyakas <alex.bolshoy@gmail.com>
Cc: stable@vger.kernel.org (3.2+ - 3.2 will need a different fix though)
Fixes: 5d8c71f9e5
Signed-off-by: NeilBrown <neilb@suse.de>
Now that we've got code for raid5/6 stripe awareness, bcache just needs
to know about the stripes and when writing partial stripes is expensive
- we probably don't want to enable this optimization for raid1 or 10,
even though they have stripes. So add a flag to queue_limits.
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
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Merge tag 'v3.13-rc6' into for-3.14/core
Needed to bring blk-mq uptodate, since changes have been going in
since for-3.14/core was established.
Fixup merge issues related to the immutable biovec changes.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Conflicts:
block/blk-flush.c
fs/btrfs/check-integrity.c
fs/btrfs/extent_io.c
fs/btrfs/scrub.c
fs/logfs/dev_bdev.c
commit 566c09c534 raid5: relieve lock contention in get_active_stripe()
modified the locking in get_active_stripe() reducing the range
protected by the (highly contended) device_lock.
Unfortunately it reduced the range too much opening up some races.
One race can occur if get_priority_stripe runs between the
test on sh->count and device_lock being taken.
This will mean that sh->lru is not empty while get_active_stripe
thinks ->count is zero resulting in a 'BUG' firing.
Another race happens if __release_stripe is called immediately
after sh->count is tested and found to be non-zero. If STRIPE_HANDLE
is not set, get_active_stripe should increment ->active_stripes
when it increments ->count from 0, but as it didn't think it was 0,
it doesn't.
Extending device_lock to cover the test on sh->count close these
races.
While we are here, fix the two BUG tests:
-If count is zero, then lru really must not be empty, or we've
lock the stripe_head somehow - no other tests are relevant.
-STRIPE_ON_RELEASE_LIST is completely independent of ->lru so
testing it is pointless.
Reported-and-tested-by: Brassow Jonathan <jbrassow@redhat.com>
Reviewed-by: Shaohua Li <shli@kernel.org>
Fixes: 566c09c534
Signed-off-by: NeilBrown <neilb@suse.de>
In alloc_thread_groups, worker_groups is a pointer to an array,
not an array of pointers.
So
worker_groups[i]
is wrong. It should be
&(*worker_groups)[i]
Found-by: coverity
Fixes: 60aaf93385
Reported-by: Ben Hutchings <bhutchings@solarflare.com>
Cc: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
More prep work for immutable biovecs - with immutable bvecs drivers
won't be able to use the biovec directly, they'll need to use helpers
that take into account bio->bi_iter.bi_bvec_done.
This updates callers for the new usage without changing the
implementation yet.
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Ed L. Cashin" <ecashin@coraid.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Lars Ellenberg <drbd-dev@lists.linbit.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Paul Clements <Paul.Clements@steeleye.com>
Cc: Jim Paris <jim@jtan.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Yehuda Sadeh <yehuda@inktank.com>
Cc: Sage Weil <sage@inktank.com>
Cc: Alex Elder <elder@inktank.com>
Cc: ceph-devel@vger.kernel.org
Cc: Joshua Morris <josh.h.morris@us.ibm.com>
Cc: Philip Kelleher <pjk1939@linux.vnet.ibm.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux390@de.ibm.com
Cc: Nagalakshmi Nandigama <Nagalakshmi.Nandigama@lsi.com>
Cc: Sreekanth Reddy <Sreekanth.Reddy@lsi.com>
Cc: support@lsi.com
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Guo Chao <yan@linux.vnet.ibm.com>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
Cc: Selvan Mani <smani@micron.com>
Cc: Sam Bradshaw <sbradshaw@micron.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Quoc-Son Anh <quoc-sonx.anh@intel.com>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Jan Kara <jack@suse.cz>
Cc: linux-m68k@lists.linux-m68k.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: drbd-user@lists.linbit.com
Cc: nbd-general@lists.sourceforge.net
Cc: cbe-oss-dev@lists.ozlabs.org
Cc: xen-devel@lists.xensource.com
Cc: virtualization@lists.linux-foundation.org
Cc: linux-raid@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: DL-MPTFusionLinux@lsi.com
Cc: linux-scsi@vger.kernel.org
Cc: devel@driverdev.osuosl.org
Cc: linux-fsdevel@vger.kernel.org
Cc: cluster-devel@redhat.com
Cc: linux-mm@kvack.org
Acked-by: Geoff Levand <geoff@infradead.org>
Mostly optimisations and obscure bug fixes.
- raid5 gets less lock contention
- raid1 gets less contention between normal-io and resync-io
during resync.
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Merge tag 'md/3.13' of git://neil.brown.name/md
Pull md update from Neil Brown:
"Mostly optimisations and obscure bug fixes.
- raid5 gets less lock contention
- raid1 gets less contention between normal-io and resync-io during
resync"
* tag 'md/3.13' of git://neil.brown.name/md:
md/raid5: Use conf->device_lock protect changing of multi-thread resources.
md/raid5: Before freeing old multi-thread worker, it should flush them.
md/raid5: For stripe with R5_ReadNoMerge, we replace REQ_FLUSH with REQ_NOMERGE.
UAPI: include <asm/byteorder.h> in linux/raid/md_p.h
raid1: Rewrite the implementation of iobarrier.
raid1: Add some macros to make code clearly.
raid1: Replace raise_barrier/lower_barrier with freeze_array/unfreeze_array when reconfiguring the array.
raid1: Add a field array_frozen to indicate whether raid in freeze state.
md: Convert use of typedef ctl_table to struct ctl_table
md/raid5: avoid deadlock when raid5 array has unack badblocks during md_stop_writes.
md: use MD_RECOVERY_INTR instead of kthread_should_stop in resync thread.
md: fix some places where mddev_lock return value is not checked.
raid5: Retry R5_ReadNoMerge flag when hit a read error.
raid5: relieve lock contention in get_active_stripe()
raid5: relieve lock contention in get_active_stripe()
wait: add wait_event_cmd()
md/raid5.c: add proper locking to error path of raid5_start_reshape.
md: fix calculation of stacking limits on level change.
raid5: Use slow_path to release stripe when mddev->thread is null
For R5_ReadNoMerge,it mean this bio can't merge with other bios or
request.It used REQ_FLUSH to achieve this. But REQ_NOMERGE can do the
same work.
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
We currently use kthread_should_stop() in various places in the
sync/reshape code to abort early.
However some places set MD_RECOVERY_INTR but don't immediately call
md_reap_sync_thread() (and we will shortly get another one).
When this happens we are relying on md_check_recovery() to reap the
thread and that only happen when it finishes normally.
So MD_RECOVERY_INTR must lead to a normal finish without the
kthread_should_stop() test.
So replace all relevant tests, and be more careful when the thread is
interrupted not to acknowledge that latest step in a reshape as it may
not be fully committed yet.
Also add a test on MD_RECOVERY_INTR in the 'is_mddev_idle' loop
so we don't wait have to wait for the speed to drop before we can abort.
Signed-off-by: NeilBrown <neilb@suse.de>
Because of block layer merge, one bio fails will cause other bios
which belongs to the same request fails, so raid5_end_read_request
will record all these bios as badblocks.
If retry request with R5_ReadNoMerge flag to avoid bios merge,
badblocks can only record sector which is bad exactly.
test:
hdparm --yes-i-know-what-i-am-doing --make-bad-sector 300000 /dev/sdb
mdadm -C /dev/md0 -l5 -n3 /dev/sd[bcd] --assume-clean
mdadm /dev/md0 -f /dev/sdd
mdadm /dev/md0 -r /dev/sdd
mdadm --zero-superblock /dev/sdd
mdadm /dev/md0 -a /dev/sdd
1. Without this patch:
cat /sys/block/md0/md/rd*/bad_blocks
299776 256
299776 256
2. With this patch:
cat /sys/block/md0/md/rd*/bad_blocks
300000 8
300000 8
Signed-off-by: Bian Yu <bianyu@kedacom.com>
Signed-off-by: NeilBrown <neilb@suse.de>
track empty inactive list count, so md_raid5_congested() can use it to make
decision.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Make this useful helper available for other users.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
get_active_stripe() is the last place we have lock contention. It has two
paths. One is stripe isn't found and new stripe is allocated, the other is
stripe is found.
The first path basically calls __find_stripe and init_stripe. It accesses
conf->generation, conf->previous_raid_disks, conf->raid_disks,
conf->prev_chunk_sectors, conf->chunk_sectors, conf->max_degraded,
conf->prev_algo, conf->algorithm, the stripe_hashtbl and inactive_list. Except
stripe_hashtbl and inactive_list, other fields are changed very rarely.
With this patch, we split inactive_list and add new hash locks. Each free
stripe belongs to a specific inactive list. Which inactive list is determined
by stripe's lock_hash. Note, even a stripe hasn't a sector assigned, it has a
lock_hash assigned. Stripe's inactive list is protected by a hash lock, which
is determined by it's lock_hash too. The lock_hash is derivied from current
stripe_hashtbl hash, which guarantees any stripe_hashtbl list will be assigned
to a specific lock_hash, so we can use new hash lock to protect stripe_hashtbl
list too. The goal of the new hash locks introduced is we can only use the new
locks in the first path of get_active_stripe(). Since we have several hash
locks, lock contention is relieved significantly.
The first path of get_active_stripe() accesses other fields, since they are
changed rarely, changing them now need take conf->device_lock and all hash
locks. For a slow path, this isn't a problem.
If we need lock device_lock and hash lock, we always lock hash lock first. The
tricky part is release_stripe and friends. We need take device_lock first.
Neil's suggestion is we put inactive stripes to a temporary list and readd it
to inactive_list after device_lock is released. In this way, we add stripes to
temporary list with device_lock hold and remove stripes from the list with hash
lock hold. So we don't allow concurrent access to the temporary list, which
means we need allocate temporary list for all participants of release_stripe.
One downside is free stripes are maintained in their inactive list, they can't
across between the lists. By default, we have total 256 stripes and 8 lists, so
each list will have 32 stripes. It's possible one list has free stripe but
other list hasn't. The chance should be rare because stripes allocation are
even distributed. And we can always allocate more stripes for cache, several
mega bytes memory isn't a big deal.
This completely removes the lock contention of the first path of
get_active_stripe(). It slows down the second code path a little bit though
because we now need takes two locks, but since the hash lock isn't contended,
the overhead should be quite small (several atomic instructions). The second
path of get_active_stripe() (basically sequential write or big request size
randwrite) still has lock contentions.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
If raid5_start_reshape errors out, we need to reset all the fields
that were updated (not just some), and need to use the seq_counter
to ensure make_request() doesn't use an inconsitent state.
Signed-off-by: NeilBrown <neilb@suse.de>
When release_stripe() is called in grow_one_stripe(), the
mddev->thread is null. So it will omit one wakeup this thread to
release stripe.
For this condition, use slow_path to release stripe.
Bug was introduced in 3.12
Cc: stable@vger.kernel.org (3.12+)
Fixes: 773ca82fa1
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
SCSI discard will damage discard stripe bio setting, eg, some fields are
changed. If the stripe is reused very soon, we have wrong bios setting. We
remove discard stripe from hash list, so next time the strip will be fully
initialized.
Suitable for backport to 3.7+.
Cc: <stable@vger.kernel.org> (3.7+)
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
SCSI layer will add new payload for discard request. If two bios are merged
to one, the second bio has bi_vcnt 1 which is set in raid5. This will confuse
SCSI and cause oops.
Suitable for backport to 3.7+
Cc: stable@vger.kernel.org (v3.7+)
Reported-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
If there are not enough stripes to handle, we'd better not always
queue all available work_structs. If one worker can only handle small
or even none stripes, it will impact request merge and create lock
contention.
With this patch, the number of work_struct running will depend on
pending stripes number. Note: some statistics info used in the patch
are accessed without locking protection. This should doesn't matter,
we just try best to avoid queue unnecessary work_struct.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Some requests - particularly 'discard' and 'read' are handled
differently depending on whether a reshape is active or not.
It is harmless to assume reshape is active if it isn't but wrong
to act as though reshape is not active when it is.
So when we start reshape - after making clear to all requests that
reshape has started - use mddev_suspend/mddev_resume to flush out all
requests. This will ensure that no requests will be assuming the
absence of reshape once it really starts.
Signed-off-by: NeilBrown <neilb@suse.de>
make_request() access various shape parameters (raid_disks, chunk_size
etc) which might be changed by raid5_start_reshape().
If the later is called at and awkward time during the form, the wrong
stripe_head might be used.
So introduce a 'seqcount' and after finding a stripe_head make sure
there is no reason to expect that we got the wrong one.
Signed-off-by: NeilBrown <neilb@suse.de>
Add a sysfs entry to control running workqueue thread number. If
group_thread_cnt is set to 0, we will disable workqueue offload handling of
stripes.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This is another attempt to create multiple threads to handle raid5 stripes.
This time I use workqueue.
raid5 handles request (especially write) in stripe unit. A stripe is page size
aligned/long and acrosses all disks. Writing to any disk sector, raid5 runs a
state machine for the corresponding stripe, which includes reading some disks
of the stripe, calculating parity, and writing some disks of the stripe. The
state machine is running in raid5d thread currently. Since there is only one
thread, it doesn't scale well for high speed storage. An obvious solution is
multi-threading.
To get better performance, we have some requirements:
a. locality. stripe corresponding to request submitted from one cpu is better
handled in thread in local cpu or local node. local cpu is preferred but some
times could be a bottleneck, for example, parity calculation is too heavy.
local node running has wide adaptability.
b. configurablity. Different setup of raid5 array might need diffent
configuration. Especially the thread number. More threads don't always mean
better performance because of lock contentions.
My original implementation is creating some kernel threads. There are
interfaces to control which cpu's stripe each thread should handle. And
userspace can set affinity of the threads. This provides biggest flexibility
and configurability. But it's hard to use and apparently a new thread pool
implementation is disfavor.
Recent workqueue improvement is quite promising. unbound workqueue will be
bound to numa node. If WQ_SYSFS is set in workqueue, there are sysfs option to
do affinity setting. For example, we can only include one HT sibling in
affinity. Since work is non-reentrant by default, and we can control running
thread number by limiting dispatched work_struct number.
In this patch, I created several stripe worker group. A group is a numa node.
stripes from cpus of one node will be added to a group list. Workqueue thread
of one node will only handle stripes of worker group of the node. In this way,
stripe handling has numa node locality. And as I said, we can control thread
number by limiting dispatched work_struct number.
The work_struct callback function handles several stripes in one run. A typical
work queue usage is to run one unit in each work_struct. In raid5 case, the
unit is a stripe. But we can't do that:
a. Though handling a stripe doesn't need lock because of reference accounting
and stripe isn't in any list, queuing a work_struct for each stripe will make
workqueue lock contended very heavily.
b. blk_start_plug()/blk_finish_plug() should surround stripe handle, as we
might dispatch request. If each work_struct only handles one stripe, such block
plug is meaningless.
This implementation can't do very fine grained configuration. But the numa
binding is most popular usage model, should be enough for most workloads.
Note: since we have only one stripe queue, switching to multi-thread might
decrease request size dispatching down to low level layer. The impact depends
on thread number, raid configuration and workload. So multi-thread raid5 might
not be proper for all setups.
Changes V1 -> V2:
1. remove WQ_NON_REENTRANT
2. disabling multi-threading by default
3. Add more descriptions in changelog
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
patch "make release_stripe lockless" changes the order stripes are released.
Originally I thought block layer can take care of request merge, but it appears
there are still some requests not merged. It's easy to fix the order.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
release_stripe still has big lock contention. We just add the stripe to a llist
without taking device_lock. We let the raid5d thread to do the real stripe
release, which must hold device_lock anyway. In this way, release_stripe
doesn't hold any locks.
The side effect is the released stripes order is changed. But sounds not a big
deal, stripes are never handled in order. And I thought block layer can already
do nice request merge, which means order isn't that important.
I kept the unplug release batch, which is unnecessary with this patch from lock
contention avoid point of view, and actually if we delete it, the stripe_head
release_list and lru can share storage. But the unplug release batch is also
helpful for request merge. We probably can delay wakeup raid5d till unplug, but
I'm still afraid of the case which raid5d is running.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
If a device in a RAID4/5/6 is being replaced while another is being
recovered, then the writes to the replacement device currently don't
happen, resulting in corruption when the replacement completes and the
new drive takes over.
This is because the replacement writes are only triggered when
's.replacing' is set and not when the similar 's.sync' is set (which
is the case during resync and recovery - it means all devices need to
be read).
So schedule those writes when s.replacing is set as well.
In this case we cannot use "STRIPE_INSYNC" to record that the
replacement has happened as that is needed for recording that any
parity calculation is complete. So introduce STRIPE_REPLACED to
record if the replacement has happened.
For safety we should also check that STRIPE_COMPUTE_RUN is not set.
This has a similar effect to the "s.locked == 0" test. The latter
ensure that now IO has been flagged but not started. The former
checks if any parity calculation has been flagged by not started.
We must wait for both of these to complete before triggering the
'replace'.
Add a similar test to the subsequent check for "are we finished yet".
This possibly isn't needed (is subsumed in the STRIPE_INSYNC test),
but it makes it more obvious that the REPLACE will happen before we
think we are finished.
Finally if a NeedReplace device is not UPTODATE then that is an
error. We really must trigger a warning.
This bug was introduced in commit 9a3e1101b8
(md/raid5: detect and handle replacements during recovery.)
which introduced replacement for raid5.
That was in 3.3-rc3, so any stable kernel since then would benefit
from this fix.
Cc: stable@vger.kernel.org (3.3+)
Reported-by: qindehua <13691222965@163.com>
Tested-by: qindehua <qindehua@163.com>
Signed-off-by: NeilBrown <neilb@suse.de>
There is a bug in 'check_reshape' for raid5.c To checks
that the new minimum number of devices is large enough (which is
good), but it does so also after the reshape has started (bad).
This is bad because
- the calculation is now wrong as mddev->raid_disks has changed
already, and
- it is pointless because it is now too late to stop.
So only perform that test when reshape has not been committed to.
Signed-off-by: NeilBrown <neilb@suse.de>
The usage of strict_strtoul() is not preferred, because
strict_strtoul() is obsolete. Thus, kstrtoul() should be
used.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Some tagged for -stable.
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Merge tag 'md-3.10-fixes' of git://neil.brown.name/md
Pull md bugfixes from Neil Brown:
"A few bugfixes for md
Some tagged for -stable"
* tag 'md-3.10-fixes' of git://neil.brown.name/md:
md/raid1,5,10: Disable WRITE SAME until a recovery strategy is in place
md/raid1,raid10: use freeze_array in place of raise_barrier in various places.
md/raid1: consider WRITE as successful only if at least one non-Faulty and non-rebuilding drive completed it.
md: md_stop_writes() should always freeze recovery.
There are cases where the kernel will believe that the WRITE SAME
command is supported by a block device which does not, in fact,
support WRITE SAME. This currently happens for SATA drivers behind a
SAS controller, but there are probably a hundred other ways that can
happen, including drive firmware bugs.
After receiving an error for WRITE SAME the block layer will retry the
request as a plain write of zeroes, but mdraid will consider the
failure as fatal and consider the drive failed. This has the effect
that all the mirrors containing a specific set of data are each
offlined in very rapid succession resulting in data loss.
However, just bouncing the request back up to the block layer isn't
ideal either, because the whole initial request-retry sequence should
be inside the write bitmap fence, which probably means that md needs
to do its own conversion of WRITE SAME to write zero.
Until the failure scenario has been sorted out, disable WRITE SAME for
raid1, raid5, and raid10.
[neilb: added raid5]
This patch is appropriate for any -stable since 3.7 when write_same
support was added.
Cc: stable@vger.kernel.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>
The patch that converted raid5 to use bio_reset() forgot to initialize
bi_vcnt.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
Cc: NeilBrown <neilb@suse.de>
Cc: linux-raid@vger.kernel.org
Tested-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull block core updates from Jens Axboe:
- Major bit is Kents prep work for immutable bio vecs.
- Stable candidate fix for a scheduling-while-atomic in the queue
bypass operation.
- Fix for the hang on exceeded rq->datalen 32-bit unsigned when merging
discard bios.
- Tejuns changes to convert the writeback thread pool to the generic
workqueue mechanism.
- Runtime PM framework, SCSI patches exists on top of these in James'
tree.
- A few random fixes.
* 'for-3.10/core' of git://git.kernel.dk/linux-block: (40 commits)
relay: move remove_buf_file inside relay_close_buf
partitions/efi.c: replace useless kzalloc's by kmalloc's
fs/block_dev.c: fix iov_shorten() criteria in blkdev_aio_read()
block: fix max discard sectors limit
blkcg: fix "scheduling while atomic" in blk_queue_bypass_start
Documentation: cfq-iosched: update documentation help for cfq tunables
writeback: expose the bdi_wq workqueue
writeback: replace custom worker pool implementation with unbound workqueue
writeback: remove unused bdi_pending_list
aoe: Fix unitialized var usage
bio-integrity: Add explicit field for owner of bip_buf
block: Add an explicit bio flag for bios that own their bvec
block: Add bio_alloc_pages()
block: Convert some code to bio_for_each_segment_all()
block: Add bio_for_each_segment_all()
bounce: Refactor __blk_queue_bounce to not use bi_io_vec
raid1: use bio_copy_data()
pktcdvd: Use bio_reset() in disabled code to kill bi_idx usage
pktcdvd: use bio_copy_data()
block: Add bio_copy_data()
...
If we write to a known-bad-block it will be flags as having
a ReadError by analyse_stripe, but the write will proceed anyway
(as it should). Then the read-error handling will kick in an
write again, then re-read.
We don't need that 'write-again', so set R5_ReWrite so it looks like
it has already been done. Then we will just get the re-read, which we
want.
Reported-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
As the function call is the most expensive of these tests it should be
done later in the chain so that it can be avoided in some cases.
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This reverts commit 3a366e614d.
Wanlong Gao reports that it causes a kernel panic on his machine several
minutes after boot. Reverting it removes the panic.
Jens says:
"It's not quite clear why that is yet, so I think we should just revert
the commit for 3.9 final (which I'm assuming is pretty close).
The wifi is crap at the LSF hotel, so sending this email instead of
queueing up a revert and pull request."
Reported-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Requested-by: Jens Axboe <axboe@kernel.dk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tejun writes:
-----
This is the pull request for the earlier patchset[1] with the same
name. It's only three patches (the first one was committed to
workqueue tree) but the merge strategy is a bit involved due to the
dependencies.
* Because the conversion needs features from wq/for-3.10,
block/for-3.10/core is based on rc3, and wq/for-3.10 has conflicts
with rc3, I pulled mainline (rc5) into wq/for-3.10 to prevent those
workqueue conflicts from flaring up in block tree.
* Resolving the issue that Jan and Dave raised about debugging
requires arch-wide changes. The patchset is being worked on[2] but
it'll have to go through -mm after these changes show up in -next,
and not included in this pull request.
The three commits are located in the following git branch.
git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git writeback-workqueue
Pulling it into block/for-3.10/core produces a conflict in
drivers/md/raid5.c between the following two commits.
e3620a3ad5 ("MD RAID5: Avoid accessing gendisk or queue structs when not available")
2f6db2a707 ("raid5: use bio_reset()")
The conflict is trivial - one removes an "if ()" conditional while the
other removes "rbi->bi_next = NULL" right above it. We just need to
remove both. The merged branch is available at
git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git block-test-merge
so that you can use it for verification. The test merge commit has
proper merge description.
While these changes are a bit of pain to route, they make code simpler
and even have, while minute, measureable performance gain[3] even on a
workload which isn't particularly favorable to showing the benefits of
this conversion.
----
Fixed up the conflict.
Conflicts:
drivers/md/raid5.c
Signed-off-by: Jens Axboe <axboe@kernel.dk>
- recent regressions in raid5
- recent regressions in dmraid
- a few instances of CONFIG_MULTICORE_RAID456 linger
Several tagged for -stable
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Merge tag 'md-3.9-fixes' of git://neil.brown.name/md
Pull md fixes from NeilBrown:
"A few bugfixes for md
- recent regressions in raid5
- recent regressions in dmraid
- a few instances of CONFIG_MULTICORE_RAID456 linger
Several tagged for -stable"
* tag 'md-3.9-fixes' of git://neil.brown.name/md:
md: remove CONFIG_MULTICORE_RAID456 entirely
md/raid5: ensure sync and DISCARD don't happen at the same time.
MD: Prevent sysfs operations on uninitialized kobjects
MD RAID5: Avoid accessing gendisk or queue structs when not available
md/raid5: schedule_construction should abort if nothing to do.
Had to shuffle the code around a bit (where bi_rw and bi_end_io were
set), but shouldn't really be anything tricky here
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: NeilBrown <neilb@suse.de>
Bunch of places in the code weren't using it where they could be -
this'll reduce the size of the patch that puts bi_sector/bi_size/bi_idx
into a struct bvec_iter.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: "Ed L. Cashin" <ecashin@coraid.com>
CC: Nick Piggin <npiggin@kernel.dk>
CC: Jiri Kosina <jkosina@suse.cz>
CC: Jim Paris <jim@jtan.com>
CC: Geoff Levand <geoff@infradead.org>
CC: Alasdair Kergon <agk@redhat.com>
CC: dm-devel@redhat.com
CC: Neil Brown <neilb@suse.de>
CC: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Ed Cashin <ecashin@coraid.com>
Just a little convenience macro - main reason to add it now is preparing
for immutable bio vecs, it'll reduce the size of the patch that puts
bi_sector/bi_size/bi_idx into a struct bvec_iter.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: Lars Ellenberg <drbd-dev@lists.linbit.com>
CC: Jiri Kosina <jkosina@suse.cz>
CC: Alasdair Kergon <agk@redhat.com>
CC: dm-devel@redhat.com
CC: Neil Brown <neilb@suse.de>
CC: Martin Schwidefsky <schwidefsky@de.ibm.com>
CC: Heiko Carstens <heiko.carstens@de.ibm.com>
CC: linux-s390@vger.kernel.org
CC: Chris Mason <chris.mason@fusionio.com>
CC: Steven Whitehouse <swhiteho@redhat.com>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
A number of problems can occur due to races between
resync/recovery and discard.
- if sync_request calls handle_stripe() while a discard is
happening on the stripe, it might call handle_stripe_clean_event
before all of the individual discard requests have completed
(so some devices are still locked, but not all).
Since commit ca64cae960
md/raid5: Make sure we clear R5_Discard when discard is finished.
this will cause R5_Discard to be cleared for the parity device,
so handle_stripe_clean_event() will not be called when the other
devices do become unlocked, so their ->written will not be cleared.
This ultimately leads to a WARN_ON in init_stripe and a lock-up.
- If handle_stripe_clean_event() does clear R5_UPTODATE at an awkward
time for resync, it can lead to s->uptodate being less than disks
in handle_parity_checks5(), which triggers a BUG (because it is
one).
So:
- keep R5_Discard on the parity device until all other devices have
completed their discard request
- make sure we don't try to have a 'discard' and a 'sync' action at
the same time.
This involves a new stripe flag to we know when a 'discard' is
happening, and the use of R5_Overlap on the parity disk so when a
discard is wanted while a sync is active, so we know to wake up
the discard at the appropriate time.
Discard support for RAID5 was added in 3.7, so this is suitable for
any -stable kernel since 3.7.
Cc: stable@vger.kernel.org (v3.7+)
Reported-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Tested-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
MD RAID5: Fix kernel oops when RAID4/5/6 is used via device-mapper
Commit a9add5d (v3.8-rc1) added blktrace calls to the RAID4/5/6 driver.
However, when device-mapper is used to create RAID4/5/6 arrays, the
mddev->gendisk and mddev->queue fields are not setup. Therefore, calling
things like trace_block_bio_remap will cause a kernel oops. This patch
conditionalizes those calls on whether the proper fields exist to make
the calls. (Device-mapper will call trace_block_bio_remap on its own.)
This patch is suitable for the 3.8.y stable kernel.
Cc: stable@vger.kernel.org (v3.8+)
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Since commit 1ed850f356
md/raid5: make sure to_read and to_write never go negative.
It has been possible for handle_stripe_dirtying to be called
when there isn't actually any work to do.
It then calls schedule_reconstruction() which will set R5_LOCKED
on the parity block(s) even when nothing else is happening.
This then causes problems in do_release_stripe().
So add checks to schedule_reconstruction() so that if it doesn't
find anything to do, it just aborts.
This bug was introduced in v3.7, so the patch is suitable
for -stable kernels since then.
Cc: stable@vger.kernel.org (v3.7+)
Reported-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
mostly little bugfixes.
Only "feature" is a new RAID10 layout which slightly
improves the number of sets of devices that can concurrently
fail, without data loss.
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Merge tag 'md-3.9' of git://neil.brown.name/md
Pull md updates from NeilBrown:
"Mostly little bugfixes.
Only "feature" is a new RAID10 layout which slightly improves the
number of sets of devices that can concurrently fail, without data
loss."
* tag 'md-3.9' of git://neil.brown.name/md:
md: expedite metadata update when switching read-auto -> active
md: remove CONFIG_MULTICORE_RAID456
md/raid1,raid10: fix deadlock with freeze_array()
md/raid0: improve error message when converting RAID4-with-spares to RAID0
md: raid0: fix error return from create_stripe_zones.
md: fix two bugs when attempting to resize RAID0 array.
DM RAID: Add support for MD's RAID10 "far" and "offset" algorithms
MD RAID10: Improve redundancy for 'far' and 'offset' algorithms (part 2)
MD RAID10: Improve redundancy for 'far' and 'offset' algorithms (part 1)
MD RAID10: Minor non-functional code changes
md: raid1,10: Handle REQ_WRITE_SAME flag in write bios
md: protect against crash upon fsync on ro array
Pull block IO core bits from Jens Axboe:
"Below are the core block IO bits for 3.9. It was delayed a few days
since my workstation kept crashing every 2-8h after pulling it into
current -git, but turns out it is a bug in the new pstate code (divide
by zero, will report separately). In any case, it contains:
- The big cfq/blkcg update from Tejun and and Vivek.
- Additional block and writeback tracepoints from Tejun.
- Improvement of the should sort (based on queues) logic in the plug
flushing.
- _io() variants of the wait_for_completion() interface, using
io_schedule() instead of schedule() to contribute to io wait
properly.
- Various little fixes.
You'll get two trivial merge conflicts, which should be easy enough to
fix up"
Fix up the trivial conflicts due to hlist traversal cleanups (commit
b67bfe0d42: "hlist: drop the node parameter from iterators").
* 'for-3.9/core' of git://git.kernel.dk/linux-block: (39 commits)
block: remove redundant check to bd_openers()
block: use i_size_write() in bd_set_size()
cfq: fix lock imbalance with failed allocations
drivers/block/swim3.c: fix null pointer dereference
block: don't select PERCPU_RWSEM
block: account iowait time when waiting for completion of IO request
sched: add wait_for_completion_io[_timeout]
writeback: add more tracepoints
block: add block_{touch|dirty}_buffer tracepoint
buffer: make touch_buffer() an exported function
block: add @req to bio_{front|back}_merge tracepoints
block: add missing block_bio_complete() tracepoint
block: Remove should_sort judgement when flush blk_plug
block,elevator: use new hashtable implementation
cfq-iosched: add hierarchical cfq_group statistics
cfq-iosched: collect stats from dead cfqgs
cfq-iosched: separate out cfqg_stats_reset() from cfq_pd_reset_stats()
blkcg: make blkcg_print_blkgs() grab q locks instead of blkcg lock
block: RCU free request_queue
blkcg: implement blkg_[rw]stat_recursive_sum() and blkg_[rw]stat_merge()
...
I'm not sure why, but the hlist for each entry iterators were conceived
list_for_each_entry(pos, head, member)
The hlist ones were greedy and wanted an extra parameter:
hlist_for_each_entry(tpos, pos, head, member)
Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.
Besides the semantic patch, there was some manual work required:
- Fix up the actual hlist iterators in linux/list.h
- Fix up the declaration of other iterators based on the hlist ones.
- A very small amount of places were using the 'node' parameter, this
was modified to use 'obj->member' instead.
- Coccinelle didn't handle the hlist_for_each_entry_safe iterator
properly, so those had to be fixed up manually.
The semantic patch which is mostly the work of Peter Senna Tschudin is here:
@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;
type T;
expression a,c,d,e;
identifier b;
statement S;
@@
-T b;
<+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
...+>
[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: Peter Senna Tschudin <peter.senna@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This doesn't seem to actually help and we have an alternate
multi-threading approach waiting in the wings, so just get
rid of this config option and associated code.
As a bonus, we remove one use of CONFIG_EXPERIMENTAL
Cc: Dan Williams <djbw@fb.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: NeilBrown <neilb@suse.de>
bio completion didn't kick block_bio_complete TP. Only dm was
explicitly triggering the TP on IO completion. This makes
block_bio_complete TP useless for tracers which want to know about
bios, and all other bio based drivers skip generating blktrace
completion events.
This patch makes all bio completions via bio_endio() generate
block_bio_complete TP.
* Explicit trace_block_bio_complete() invocation removed from dm and
the trace point is unexported.
* @rq dropped from trace_block_bio_complete(). bios may fly around
w/o queue associated. Verifying and accessing the assocaited queue
belongs to TP probes.
* blktrace now gets both request and bio completions. Make it ignore
bio completions if request completion path is happening.
This makes all bio based drivers generate blktrace completion events
properly and makes the block_bio_complete TP actually useful.
v2: With this change, block_bio_complete TP could be invoked on sg
commands which have bio's with %NULL bi_bdev. Update TP
assignment code to check whether bio->bi_bdev is %NULL before
dereferencing.
Signed-off-by: Tejun Heo <tj@kernel.org>
Original-patch-by: Namhyung Kim <namhyung@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: dm-devel@redhat.com
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Mostly just little fixes. Probably biggest part is
AVX accelerated RAID6 calculations.
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Merge tag 'md-3.8' of git://neil.brown.name/md
Pull md update from Neil Brown:
"Mostly just little fixes. Probably biggest part is AVX accelerated
RAID6 calculations."
* tag 'md-3.8' of git://neil.brown.name/md:
md/raid5: add blktrace calls
md/raid5: use async_tx_quiesce() instead of open-coding it.
md: Use ->curr_resync as last completed request when cleanly aborting resync.
lib/raid6: build proper files on corresponding arch
lib/raid6: Add AVX2 optimized gen_syndrome functions
lib/raid6: Add AVX2 optimized recovery functions
md: Update checkpoint of resync/recovery based on time.
md:Add place to update ->recovery_cp.
md.c: re-indent various 'switch' statements.
md: close race between removing and adding a device.
md: removed unused variable in calc_sb_1_csm.
Pull block driver update from Jens Axboe:
"Now that the core bits are in, here are the driver bits for 3.8. The
branch contains:
- A huge pile of drbd bits that were dumped from the 3.7 merge
window. Following that, it was both made perfectly clear that
there is going to be no more over-the-wall pulls and how the
situation on individual pulls can be improved.
- A few cleanups from Akinobu Mita for drbd and cciss.
- Queue improvement for loop from Lukas. This grew into adding a
generic interface for waiting/checking an even with a specific
lock, allowing this to be pulled out of md and now loop and drbd is
also using it.
- A few fixes for xen back/front block driver from Roger Pau Monne.
- Partition improvements from Stephen Warren, allowing partiion UUID
to be used as an identifier."
* 'for-3.8/drivers' of git://git.kernel.dk/linux-block: (609 commits)
drbd: update Kconfig to match current dependencies
drbd: Fix drbdsetup wait-connect, wait-sync etc... commands
drbd: close race between drbd_set_role and drbd_connect
drbd: respect no-md-barriers setting also when changed online via disk-options
drbd: Remove obsolete check
drbd: fixup after wait_even_lock_irq() addition to generic code
loop: Limit the number of requests in the bio list
wait: add wait_event_lock_irq() interface
xen-blkfront: free allocated page
xen-blkback: move free persistent grants code
block: partition: msdos: provide UUIDs for partitions
init: reduce PARTUUID min length to 1 from 36
block: store partition_meta_info.uuid as a string
cciss: use check_signature()
cciss: cleanup bitops usage
drbd: use copy_highpage
drbd: if the replication link breaks during handshake, keep retrying
drbd: check return of kmalloc in receive_uuids
drbd: Broadcast sync progress no more often than once per second
drbd: don't try to clear bits once the disk has failed
...
Pull trivial branch from Jiri Kosina:
"Usual stuff -- comment/printk typo fixes, documentation updates, dead
code elimination."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (39 commits)
HOWTO: fix double words typo
x86 mtrr: fix comment typo in mtrr_bp_init
propagate name change to comments in kernel source
doc: Update the name of profiling based on sysfs
treewide: Fix typos in various drivers
treewide: Fix typos in various Kconfig
wireless: mwifiex: Fix typo in wireless/mwifiex driver
messages: i2o: Fix typo in messages/i2o
scripts/kernel-doc: check that non-void fcts describe their return value
Kernel-doc: Convention: Use a "Return" section to describe return values
radeon: Fix typo and copy/paste error in comments
doc: Remove unnecessary declarations from Documentation/accounting/getdelays.c
various: Fix spelling of "asynchronous" in comments.
Fix misspellings of "whether" in comments.
eisa: Fix spelling of "asynchronous".
various: Fix spelling of "registered" in comments.
doc: fix quite a few typos within Documentation
target: iscsi: fix comment typos in target/iscsi drivers
treewide: fix typo of "suport" in various comments and Kconfig
treewide: fix typo of "suppport" in various comments
...
handle_stripe_expansion contains:
if (tx) {
async_tx_ack(tx);
dma_wait_for_async_tx(tx);
}
which is very similar to the body of async_tx_quiesce(),
except that the later handles an error from dma_wait_for_async_tx()
(admittedly by panicing, but that decision belongs in the dma
code, not the md code).
So just us async_tx_quiesce().
Acked-by: Dan Williams <djbw@fb.com>
Reported-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: NeilBrown <neilb@suse.de>
New wait_event{_interruptible}_lock_irq{_cmd} macros added. This commit
moves the private wait_event_lock_irq() macro from MD to regular wait
includes, introduces new macro wait_event_lock_irq_cmd() instead of using
the old method with omitting cmd parameter which is ugly and makes a use
of new macros in the MD. It also introduces the _interruptible_ variant.
The use of new interface is when one have a special lock to protect data
structures used in the condition, or one also needs to invoke "cmd"
before putting it to sleep.
All new macros are expected to be called with the lock taken. The lock
is released before sleep and is reacquired afterwards. We will leave the
macro with the lock held.
Note to DM: IMO this should also fix theoretical race on waitqueue while
using simultaneously wait_event_lock_irq() and wait_event() because of
lack of locking around current state setting and wait queue removal.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Cc: Neil Brown <neilb@suse.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
commit 9e44476851
MD: raid5 avoid unnecessary zero page for trim
change raid5 to clear R5_Discard when the complete request is
handled rather than when submitting the per-device discard request.
However it did not clear R5_Discard for the parity device.
This means that if the stripe_head was reused before it expired from
the cache, the setting would be wrong and a hang would result.
Also if the R5_Uptodate bit happens to be set, R5_Discard again
won't be cleared. But R5_Uptodate really should be clear at this point.
So make sure R5_Discard is cleared in all cases, and clear
R5_Uptodate when a 'discard' completes.
Signed-off-by: NeilBrown <neilb@suse.de>
stripe_handle.
The chunk of code in stripe_handle which responds to a
*_result value in reconstruct_state is really the completion
of some processing that happened outside of handle_stripe
(possibly asynchronously) and so should be one of the first
things done in handle_stripe().
After the next patch it will be important that it happens before
handle_stripe_clean_event(), as that will clear some dev->flags
bit that this code tests.
Signed-off-by: NeilBrown <neilb@suse.de>
blkdev_issue_discard currently assumes that the granularity
is a power of 2. So in raid5, round the chosen number up to
avoid embarrassment.
Cc: Shaohua Li <shli@kernel.org>
Signed-off-by: NeilBrown <neilb@suse.de>
"discard" support, some dm-raid improvements and other assorted
bits and pieces.
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Merge tag 'md-3.7' of git://neil.brown.name/md
Pull md updates from NeilBrown:
- "discard" support, some dm-raid improvements and other assorted bits
and pieces.
* tag 'md-3.7' of git://neil.brown.name/md: (29 commits)
md: refine reporting of resync/reshape delays.
md/raid5: be careful not to resize_stripes too big.
md: make sure manual changes to recovery checkpoint are saved.
md/raid10: use correct limit variable
md: writing to sync_action should clear the read-auto state.
Subject: [PATCH] md:change resync_mismatches to atomic64_t to avoid races
md/raid5: make sure to_read and to_write never go negative.
md: When RAID5 is dirty, force reconstruct-write instead of read-modify-write.
md/raid5: protect debug message against NULL derefernce.
md/raid5: add some missing locking in handle_failed_stripe.
MD: raid5 avoid unnecessary zero page for trim
MD: raid5 trim support
md/bitmap:Don't use IS_ERR to judge alloc_page().
md/raid1: Don't release reference to device while handling read error.
raid: replace list_for_each_continue_rcu with new interface
add further __init annotations to crypto/xor.c
DM RAID: Fix for "sync" directive ineffectiveness
DM RAID: Fix comparison of index and quantity for "rebuild" parameter
DM RAID: Add rebuild capability for RAID10
DM RAID: Move 'rebuild' checking code to its own function
...
When a RAID5 is reshaping, conf->raid_disks is increased
before mddev->delta_disks becomes zero.
This can result in check_reshape calling resize_stripes with a
number that is too large. This particularly happens
when md_check_recovery calls ->check_reshape().
If we use ->previous_raid_disks, we don't risk this.
Signed-off-by: NeilBrown <neilb@suse.de>
Now that multiple threads can handle stripes, it is safer to
use an atomic64_t for resync_mismatches, to avoid update races.
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
to_read and to_write are part of the result of analysing
a stripe before handling it.
Their use is to avoid some loops and tests if the values are
known to be zero. Thus it is not a problem if they are a
little bit larger than they should be.
So decrementing them in handle_failed_stripe serves little value, and
due to races it could cause some loops to be skipped incorrectly.
So remove those decrements.
Reported-by: "Jianpeng Ma" <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
The pr_debug in add_stripe_bio could race with something
changing *bip, so it is best to hold the lock until
after the pr_debug.
Reported-by: "Jianpeng Ma" <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
We really should hold the stripe_lock while accessing
'toread' else we could race with add_stripe_bio and corrupt
a list.
Reported-by: "Jianpeng Ma" <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
We want to avoid zero discarded dev page, because it's useless for discard.
But if we don't zero it, another read/write hit such page in the cache and will
get inconsistent data.
To avoid zero the page, we don't set R5_UPTODATE flag after construction is
done. In this way, discard write request is still issued and finished, but read
will not hit the page. If the stripe gets accessed soon, we need reread the
stripe, but since the chance is low, the reread isn't a big deal.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Discard for raid4/5/6 has limitation. If discard request size is
small, we do discard for one disk, but we need calculate parity and
write parity disk. To correctly calculate parity, zero_after_discard
must be guaranteed. Even it's true, we need do discard for one disk
but write another disks, which makes the parity disks wear out
fast. This doesn't make sense. So an efficient discard for raid4/5/6
should discard all data disks and parity disks, which requires the
write pattern to be (A, A+chunk_size, A+chunk_size*2...). If A's size
is smaller than chunk_size, such pattern is almost impossible in
practice. So in this patch, I only handle the case that A's size
equals to chunk_size. That is discard request should be aligned to
stripe size and its size is multiple of stripe size.
Since we can only handle request with specific alignment and size (or
part of the request fitting stripes), we can't guarantee
zero_after_discard even zero_after_discard is true in low level
drives.
The block layer doesn't send down correctly aligned requests even
correct discard alignment is set, so I must filter out.
For raid4/5/6 parity calculation, if data is 0, parity is 0. So if
zero_after_discard is true for all disks, data is consistent after
discard. Otherwise, data might be lost. Let's consider a scenario:
discard a stripe, write data to one disk and write parity disk. The
stripe could be still inconsistent till then depending on using data
from other data disks or parity disks to calculate new parity. If the
disk is broken, we can't restore it. So in this patch, we only enable
discard support if all disks have zero_after_discard.
If discard fails in one disk, we face the similar inconsistent issue
above. The patch will make discard follow the same path as normal
write request. If discard fails, a resync will be scheduled to make
the data consistent. This isn't good to have extra writes, but data
consistency is important.
If a subsequent read/write request hits raid5 cache of a discarded
stripe, the discarded dev page should have zero filled, so the data is
consistent. This patch will always zero dev page for discarded request
stripe. This isn't optimal because discard request doesn't need such
payload. Next patch will avoid it.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Change the thread parameter, so the thread can carry extra info. Next patch
will use it.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
commit b17459c050
raid5: add a per-stripe lock
added a spin_lock to the 'stripe_head' struct.
Unfortunately there are two places where this struct is allocated
but the spin lock was only initialised in one of them.
So add the missing spin_lock_init.
Signed-off-by: NeilBrown <neilb@suse.de>
When a replacement device becomes active, we mark the device that it
replaces as 'faulty' so that it can subsequently get removed.
However 'calc_degraded' only pays attention to the primary device, not
the replacement, so the array appears to become degraded, which is
wrong.
So teach 'calc_degraded' to consider any replacement if a primary
device is faulty.
This is suitable for -stable as an incorrect 'degraded' value can
confuse md and could lead to data corruption.
This is only relevant for 3.3 and later.
Cc: stable@vger.kernel.org
Reported-by: Robin Hill <robin@robinhill.me.uk>
Reported-by: John Drescher <drescherjm@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This reverts commit 895e3c5c58.
While this patch seemed like a good idea and did help some workloads,
it hurts other workloads.
Large sequential O_DIRECT writes were faster,
Small random O_DIRECT writes were slower.
Other changes (batching RAID5 writes) have improved the sequential
writes using a different mechanism, so the net result of this patch
is definitely negative. So revert it.
Reported-by: Shaohua Li <shli@kernel.org>
Tested-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This contains a few patches that depend on
plugging changes in the block layer so needs to wait
for those.
It also contains a Kconfig fix for the new RAID10 support
in dm-raid.
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Merge tag 'md-3.6' of git://neil.brown.name/md
Pull additional md update from NeilBrown:
"This contains a few patches that depend on plugging changes in the
block layer so needed to wait for those.
It also contains a Kconfig fix for the new RAID10 support in dm-raid."
* tag 'md-3.6' of git://neil.brown.name/md:
md/dm-raid: DM_RAID should select MD_RAID10
md/raid1: submit IO from originating thread instead of md thread.
raid5: raid5d handle stripe in batch way
raid5: make_request use batch stripe release
Let raid5d handle stripe in batch way to reduce conf->device_lock locking.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
make_request() does stripe release for every stripe and the stripe usually has
count 1, which makes previous release_stripe() optimization not work. In my
test, this release_stripe() becomes the heaviest pleace to take
conf->device_lock after previous patches applied.
Below patch makes stripe release batch. All the stripes will be released in
unplug. The STRIPE_ON_UNPLUG_LIST bit is to protect concurrent access stripe
lru.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Pull block driver changes from Jens Axboe:
- Making the plugging support for drivers a bit more sane from Neil.
This supersedes the plugging change from Shaohua as well.
- The usual round of drbd updates.
- Using a tail add instead of a head add in the request completion for
ndb, making us find the most completed request more quickly.
- A few floppy changes, getting rid of a duplicated flag and also
running the floppy init async (since it takes forever in boot terms)
from Andi.
* 'for-3.6/drivers' of git://git.kernel.dk/linux-block:
floppy: remove duplicated flag FD_RAW_NEED_DISK
blk: pass from_schedule to non-request unplug functions.
block: stack unplug
blk: centralize non-request unplug handling.
md: remove plug_cnt feature of plugging.
block/nbd: micro-optimization in nbd request completion
drbd: announce FLUSH/FUA capability to upper layers
drbd: fix max_bio_size to be unsigned
drbd: flush drbd work queue before invalidate/invalidate remote
drbd: fix potential access after free
drbd: call local-io-error handler early
drbd: do not reset rs_pending_cnt too early
drbd: reset congestion information before reporting it in /proc/drbd
drbd: report congestion if we are waiting for some userland callback
drbd: differentiate between normal and forced detach
drbd: cleanup, remove two unused global flags
floppy: Run floppy initialization asynchronous
This seemed like a good idea at the time, but after further thought I
cannot see it making a difference other than very occasionally and
testing to try to exercise the case it is most likely to help did not
show any performance difference by removing it.
So remove the counting of active plugs and allow 'pending writes' to
be activated at any time, not just when no plugs are active.
This is only relevant when there is a write-intent bitmap, and the
updating of the bitmap will likely introduce enough delay that
the single-threading of bitmap updates will be enough to collect large
numbers of updates together.
Removing this will make it easier to centralise the unplug code, and
will clear the other for other unplug enhancements which have a
measurable effect.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
'sync' writes set both REQ_SYNC and REQ_NOIDLE.
O_DIRECT writes set REQ_SYNC but not REQ_NOIDLE.
We currently assume that a REQ_SYNC request will not be followed by
more requests and so set STRIPE_PREREAD_ACTIVE to expedite the
request.
This is appropriate for sync requests, but not for O_DIRECT requests.
So make the setting of STRIPE_PREREAD_ACTIVE conditional on REQ_NOIDLE
rather than REQ_SYNC. This is consistent with the documented meaning
of REQ_NOIDLE:
__REQ_NOIDLE, /* don't anticipate more IO after this one */
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Because bios will merge at block-layer,so bios-error may caused by other
bio which be merged into to the same request.
Using this flag,it will find exactly error-sector and not do redundant
operation like re-write and re-read.
V0->V1:Using REQ_FLUSH instead REQ_NOMERGE avoid bio merging at block
layer.
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Add a per-stripe lock to protect stripe specific data. The purpose is to reduce
lock contention of conf->device_lock.
stripe ->toread, ->towrite are protected by per-stripe lock. Accessing bio
list of the stripe is always serialized by this lock, so adding bio to the
lists (add_stripe_bio()) and removing bio from the lists (like
ops_run_biofill()) not race.
If bio in ->read, ->written ... list are not shared by multiple stripes, we
don't need any lock to protect ->read, ->written, because STRIPE_ACTIVE will
protect them. If the bio are shared, there are two protections:
1. bi_phys_segments acts as a reference count
2. traverse the list uses r5_next_bio, which makes traverse never access bio
not belonging to the stripe
Let's have an example:
| stripe1 | stripe2 | stripe3 |
...bio1......|bio2|bio3|....bio4.....
stripe2 has 4 bios, when it's finished, it will decrement bi_phys_segments for
all bios, but only end_bio for bio2 and bio3. bio1->bi_next still points to
bio2, but this doesn't matter. When stripe1 is finished, it will not touch bio2
because of r5_next_bio check. Next time stripe1 will end_bio for bio1 and
stripe3 will end_bio bio4.
before add_stripe_bio() addes a bio to a stripe, we already increament the bio
bi_phys_segments, so don't worry other stripes release the bio.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Neil pointed out the bitmap write optimization in handle_stripe_clean_event()
is unnecessary, because the chance one stripe gets written twice in the mean
time is rare. We can always do a bitmap_startwrite when a write request is
added to a stripe and bitmap_endwrite after write request is done. Delete the
optimization. With it, we can delete some cases of device_lock.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Raid5 overrides bio->bi_phys_segments, accessing it is with device_lock hold,
which is unnecessary, We can make it lockless actually.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
release_stripe() is a place conf->device_lock is heavily contended. We take the
lock even stripe count isn't 1, which isn't required.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
The value returned by "mddev_check_plug" is only valid until the
next 'schedule' as that will unplug things. This could happen at any
call to mempool_alloc.
So just calling mddev_check_plug at the start doesn't really make
sense.
So call it just before, or just after, queuing things for the thread.
As the action that happens at unplug is to wake the thread, this makes
lots of sense.
If we cannot add a plug (which requires a small GFP_ATOMIC alloc) we
wake thread immediately.
RAID5 is a bit different. Requests are queued for the thread and the
thread is woken by release_stripe. So we don't need to wake the
thread on failure.
However the thread doesn't perform certain actions when there is any
active plug, so it is important to install a plug before waking the
thread. So for RAID5 we install the plug *before* queuing the request
and waking the thread.
Without this patch it is possible for raid1 or raid10 to queue a
request without then waking the thread, resulting in the array locking
up.
Also change raid10 to only flush_pending_write when there are not
active plugs, just like raid1.
This patch is suitable for 3.0 or later. I plan to submit it to
-stable, but I'll like to let it spend a few weeks in mainline
first to be sure it is completely safe.
Signed-off-by: NeilBrown <neilb@suse.de>
There isn't locking setting STRIPE_DELAYED and STRIPE_PREREAD_ACTIVE bits, but
the two bits have relationship. A delayed stripe can be moved to hold list only
when preread active stripe count is below IO_THRESHOLD. If a stripe has both
the bits set, such stripe will be in delayed list and preread count not 0,
which will make such stripe never leave delayed list.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
We may not be able to fix a bad block if:
- the array is degraded
- the over-write fails.
In these cases we currently eject the device, but we should
record a bad block if possible.
Signed-off-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Having the 'name' arg optional and defaulting to the current
personality name is no necessary and leads to errors, as when
changing the level of an array we can end up using the
name of the old level instead of the new one.
So make it non-optional and always explicitly pass the name
of the level that the array will be.
Reported-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
commit 43220aa0f2
md/raid5: fix a hang on device failure.
fixed a hang, but introduced a refcounting in-balance so
that if the presence of bad-blocks ever caused an rdev to
be 'blocked' we would increment the refcount on the rdev and
never decrement it.
So added the needed rdev_dec_pending when md_wait_for_blocked_rdev
is not called.
Reported-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
In ops_run_io(), the call to md_wait_for_blocked_rdev will decrement
nr_pending so we lose the reference we hold on the rdev.
So atomic_inc it first to maintain the reference.
This bug was introduced by commit 73e92e51b7
md/raid5. Don't write to known bad block on doubtful devices.
which appeared in 3.0, so patch is suitable for stable kernels since
then.
Cc: stable@vger.kernel.org
Signed-off-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
In chunk_aligned_read() we are adding data_offset before calling
is_badblock. But is_badblock also adds data_offset, so that is bad.
So move the addition of data_offset to after the call to
is_badblock.
This bug was introduced by commit 31c176ecdf
md/raid5: avoid reading from known bad blocks.
which first appeared in 3.0. So that patch is suitable for any
-stable kernel from 3.0.y onwards. However it will need minor
revision for most of those (as the comment didn't appear until
recently).
Cc: stable@vger.kernel.org
Signed-off-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
If a RAID5 has both a failed device and a device marked as
'WantReplacement', then we should preferentially replace the failed
device.
However the current code replaces whichever is found first.
So split into 2 loops, check fail failed/missing first, and only check
for WantReplacement if nothing is failed or missing.
Reported-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
After a reshape which reduced the number of devices we need
to disconnect the extra devices.
The code for this doesn't currently handle 'replacement' devices.
It is very unlikely that such devices will be present, but it is
safest to handle them anyway.
So simplify the handling. Just clear In_sync and leave it
to remove_and_add_spaces (which will be called soon) to do
the real works.
Signed-off-by: NeilBrown <neilb@suse.de>
We always should have allowed this. A raid5 reshape doesn't change
the size of the bitmap, so not need to restrict it.
Also add a test to make sure we don't try to start a reshape on a
failed array.
Signed-off-by: NeilBrown <neilb@suse.de>
Now that bitmaps can be resized, we can allow an array to be resized
while the bitmap is present.
This only covers resizing that involves changing the effective size
of member devices, not resizing that changes the number of devices.
Signed-off-by: NeilBrown <neilb@suse.de>
REQ_SYNC is ignored in current raid5 code. Block layer does use it to do
policy,
for example ioscheduler. This patch adds it.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
The important issue here is incorporating the different in data_offset
into calculations concerning when we might need to over-write data
that is still thought to be valid.
To this end we find the minimum offset difference across all devices
and add that where appropriate.
Signed-off-by: NeilBrown <neilb@suse.de>
As there can now be two different data_offsets - an 'old' and
a 'new' - we need to carefully choose between them.
Signed-off-by: NeilBrown <neilb@suse.de>
