Some code waits for a metadata update by:
1. flagging that it is needed (MD_CHANGE_DEVS or MD_CHANGE_CLEAN)
2. setting MD_CHANGE_PENDING and waking the management thread
3. waiting for MD_CHANGE_PENDING to be cleared
If the first two are done without locking, the code in md_update_sb()
which checks if it needs to repeat might test if an update is needed
before step 1, then clear MD_CHANGE_PENDING after step 2, resulting
in the wait returning early.
So make sure all places that set MD_CHANGE_PENDING are atomicial, and
bit_clear_unless (suggested by Neil) is introduced for the purpose.
Cc: Martin Kepplinger <martink@posteo.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: <linux-kernel@vger.kernel.org>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
In case md runs underneath the dm-raid target, the mddev does not have
a request queue or gendisk, thus avoid accesses.
This patch adds a missing conditional to the raid5 personality.
Signed-of-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Shaohua Li <shli@fb.com>
If device has R5_LOCKED set, it's legit device has R5_SkipCopy set and page !=
orig_page. After R5_LOCKED is clear, handle_stripe_clean_event will clear the
SkipCopy flag and set page to orig_page. So the warning is unnecessary.
Reported-by: Joey Liao <joeyliao@qnap.com>
Signed-off-by: Shaohua Li <shli@fb.com>
The raid456_cpu_notify() hotplug callback lacks handling of the
CPU_UP_CANCELED case. That means if CPU_UP_PREPARE fails, the scratch
buffer is leaked.
Add handling for CPU_UP_CANCELED[_FROZEN] hotplug notifier transitions
to free the scratch buffer.
CC: Shaohua Li <shli@kernel.org>
CC: linux-raid@vger.kernel.org
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Shaohua Li <shli@fb.com>
Neil recently fixed an obscure race in break_stripe_batch_list. Debug would be
quite convenient if we know the stripe state. This is what this patch does.
Signed-off-by: Shaohua Li <shli@fb.com>
break_stripe_batch_list breaks up a batch and copies some flags from
the batch head to the members, preserving others.
It doesn't preserve or copy STRIPE_PREREAD_ACTIVE. This is not
normally a problem as STRIPE_PREREAD_ACTIVE is cleared when a
stripe_head is added to a batch, and is not set on stripe_heads
already in a batch.
However there is no locking to ensure one thread doesn't set the flag
after it has just been cleared in another. This does occasionally happen.
md/raid5 maintains a count of the number of stripe_heads with
STRIPE_PREREAD_ACTIVE set: conf->preread_active_stripes. When
break_stripe_batch_list clears STRIPE_PREREAD_ACTIVE inadvertently
this could becomes incorrect and will never again return to zero.
md/raid5 delays the handling of some stripe_heads until
preread_active_stripes becomes zero. So when the above mention race
happens, those stripe_heads become blocked and never progress,
resulting is write to the array handing.
So: change break_stripe_batch_list to preserve STRIPE_PREREAD_ACTIVE
in the members of a batch.
URL: https://bugzilla.kernel.org/show_bug.cgi?id=108741
URL: https://bugzilla.redhat.com/show_bug.cgi?id=1258153
URL: http://thread.gmane.org/5649C0E9.2030204@zoner.cz
Reported-by: Martin Svec <martin.svec@zoner.cz> (and others)
Tested-by: Tom Weber <linux@junkyard.4t2.com>
Fixes: 1b956f7a8f ("md/raid5: be more selective about distributing flags across batch.")
Cc: stable@vger.kernel.org (v4.1 and later)
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Revert commit
e9e4c377e2f563(md/raid5: per hash value and exclusive wait_for_stripe)
The problem is raid5_get_active_stripe waits on
conf->wait_for_stripe[hash]. Assume hash is 0. My test release stripes
in this order:
- release all stripes with hash 0
- raid5_get_active_stripe still sleeps since active_stripes >
max_nr_stripes * 3 / 4
- release all stripes with hash other than 0. active_stripes becomes 0
- raid5_get_active_stripe still sleeps, since nobody wakes up
wait_for_stripe[0]
The system live locks. The problem is active_stripes isn't a per-hash
count. Revert the patch makes the live lock go away.
Cc: stable@vger.kernel.org (v4.2+)
Cc: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Cc: NeilBrown <neilb@suse.de>
Signed-off-by: Shaohua Li <shli@fb.com>
check_reshape() is called from raid5d thread. raid5d thread shouldn't
call mddev_suspend(), because mddev_suspend() waits for all IO finish
but IO is handled in raid5d thread, we could easily deadlock here.
This issue is introduced by
738a273 ("md/raid5: fix allocation of 'scribble' array.")
Cc: stable@vger.kernel.org (v4.1+)
Reported-and-tested-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
'max_discard_sectors' is in sectors, while 'stripe' is in bytes.
This fixes the problem where DISCARD would get disabled on some larger
RAID5 configurations (6 or more drives in my testing), while it worked
as expected with smaller configurations.
Fixes: 620125f2bf ("MD: raid5 trim support")
Cc: stable@vger.kernel.org v3.7+
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Add support for journal disk hot add/remove. Mostly trival checks in md
part. The raid5 part is a little tricky. For hot-remove, we can't wait
pending write as it's called from raid5d. The wait will cause deadlock.
We simplily fail the hot-remove. A hot-remove retry can success
eventually since if journal disk is faulty all pending write will be
failed and finish. For hot-add, since an array supporting journal but
without journal disk will be marked read-only, we are safe to hot add
journal without stopping IO (should be read IO, while journal only
handles write IO).
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
The stripe_add_to_batch_list() function is called only if
stripe_can_batch() returned true, so there is no need for double check.
Signed-off-by: Roman Gushchin <klamm@yandex-team.ru>
Cc: Neil Brown <neilb@suse.com>
Cc: linux-raid@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.com>
Two major components to this update.
1/ the clustered-raid1 support from SUSE is nearly
complete. There are a few outstanding issues being
worked on. Maybe half a dozen patches will bring
this to a usable state.
2/ The first stage of journalled-raid5 support from
Facebook makes an appearance. With a journal
device configured (typically NVRAM or SSD), the
"RAID5 write hole" should be closed - a crash
during degraded operations cannot result in data
corruption.
The next stage will be to use the journal as a
write-behind cache so that latency can be reduced
and in some cases throughput increased by
performing more full-stripe writes.
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Merge tag 'md/4.4' of git://neil.brown.name/md
Pull md updates from Neil Brown:
"Two major components to this update.
1) The clustered-raid1 support from SUSE is nearly complete. There
are a few outstanding issues being worked on. Maybe half a dozen
patches will bring this to a usable state.
2) The first stage of journalled-raid5 support from Facebook makes an
appearance. With a journal device configured (typically NVRAM or
SSD), the "RAID5 write hole" should be closed - a crash during
degraded operations cannot result in data corruption.
The next stage will be to use the journal as a write-behind cache
so that latency can be reduced and in some cases throughput
increased by performing more full-stripe writes.
* tag 'md/4.4' of git://neil.brown.name/md: (66 commits)
MD: when RAID journal is missing/faulty, block RESTART_ARRAY_RW
MD: set journal disk ->raid_disk
MD: kick out journal disk if it's not fresh
raid5-cache: start raid5 readonly if journal is missing
MD: add new bit to indicate raid array with journal
raid5-cache: IO error handling
raid5: journal disk can't be removed
raid5-cache: add trim support for log
MD: fix info output for journal disk
raid5-cache: use bio chaining
raid5-cache: small log->seq cleanup
raid5-cache: new helper: r5_reserve_log_entry
raid5-cache: inline r5l_alloc_io_unit into r5l_new_meta
raid5-cache: take rdev->data_offset into account early on
raid5-cache: refactor bio allocation
raid5-cache: clean up r5l_get_meta
raid5-cache: simplify state machine when caches flushes are not needed
raid5-cache: factor out a helper to run all stripes for an I/O unit
raid5-cache: rename flushed_ios to finished_ios
raid5-cache: free I/O units earlier
...
Set journal disk ->raid_disk to >=0, I choose raid_disks + 1 instead of
0, because we already have a disk with ->raid_disk 0 and this causes
sysfs entry creation conflict. A lot of places assumes disk with
->raid_disk >=0 is normal raid disk, so we add check for journal disk.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
If raid array is expected to have journal (eg, journal is set in MD
superblock feature map) and the array is started without journal disk,
start the array readonly.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
There are 3 places the raid5-cache dispatches IO. The discard IO error
doesn't matter, so we ignore it. The superblock write IO error can be
handled in MD core. The remaining are log write and flush. When the IO
error happens, we mark log disk faulty and fail all write IO. Read IO is
still allowed to run. Userspace will get a notification too and
corresponding daemon can choose setting raid array readonly for example.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
raid5-cache uses journal disk rdev->bdev, rdev->mddev in several places.
Don't allow journal disk disappear magically. On the other hand, we do
need to update superblock for other disks to bump up ->events, so next
time journal disk will be identified as stale.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Move reclaim stop to quiesce handling, where is safer for this stuff.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
With log enabled, bio is written to raid disks after the bio is settled
down in log disk. The recovery guarantees we can recovery the bio data
from log disk, so we we skip FLUSH IO.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Before we write stripe data to raid disks, we must guarantee stripe data
is settled down in log disk. To do this, we flush log disk cache and
wait the flush finish. That wait introduces sleep time in raid5d thread
and impact performance. This patch moves the log disk cache flush
process to the stripe handling state machine, which can remove the wait
in raid5d.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
If cache(log) support is enabled, don't allow resize/reshape in current
stage. In the future, we can flush all data from cache(log) to raid
before resize/reshape and then allow resize/reshape.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
With log enabled, r5l_write_stripe will add the stripe to log. With
batch, several stripes are linked together. The stripes must be in the
same state. While with log, the log/reclaim unit is stripe, we can't
guarantee the several stripes are in the same state. Disabling batch for
log now.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
After commit 566c09c534 ("raid5: relieve lock contention in get_active_stripe()")
__find_stripe() is called under conf->hash_locks + hash.
But handle_stripe_clean_event() calls remove_hash() under
conf->device_lock.
Under some cirscumstances the hash chain can be circuited,
and we get an infinite loop with disabled interrupts and locked hash
lock in __find_stripe(). This leads to hard lockup on multiple CPUs
and following system crash.
I was able to reproduce this behavior on raid6 over 6 ssd disks.
The devices_handle_discard_safely option should be set to enable trim
support. The following script was used:
for i in `seq 1 32`; do
dd if=/dev/zero of=large$i bs=10M count=100 &
done
neilb: original was against a 3.x kernel. I forward-ported
to 4.3-rc. This verison is suitable for any kernel since
Commit: 59fc630b8b ("RAID5: batch adjacent full stripe write")
(v4.1+). I'll post a version for earlier kernels to stable.
Signed-off-by: Roman Gushchin <klamm@yandex-team.ru>
Fixes: 566c09c534 ("raid5: relieve lock contention in get_active_stripe()")
Signed-off-by: NeilBrown <neilb@suse.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: <stable@vger.kernel.org> # 3.13 - 4.2
This is the reclaim support for raid5 log. A stripe write will have
following steps:
1. reconstruct the stripe, read data/calculate parity. ops_run_io
prepares to write data/parity to raid disks
2. hijack ops_run_io. stripe data/parity is appending to log disk
3. flush log disk cache
4. ops_run_io run again and do normal operation. stripe data/parity is
written in raid array disks. raid core can return io to upper layer.
5. flush cache of all raid array disks
6. update super block
7. log disk space used by the stripe can be reused
In practice, several stripes consist of an io_unit and we will batch
several io_unit in different steps, but the whole process doesn't
change.
It's possible io return just after data/parity hit log disk, but then
read IO will need read from log disk. For simplicity, IO return happens
at step 4, where read IO can directly read from raid disks.
Currently reclaim run if there is specific reclaimable space (1/4 disk
size or 10G) or we are out of space. Reclaim is just to free log disk
spaces, it doesn't impact data consistency. The size based force reclaim
is to make sure log isn't too big, so recovery doesn't scan log too
much.
Recovery make sure raid disks and log disk have the same data of a
stripe. If crash happens before 4, recovery might/might not recovery
stripe's data/parity depending on if data/parity and its checksum
matches. In either case, this doesn't change the syntax of an IO write.
After step 3, stripe is guaranteed recoverable, because stripe's
data/parity is persistent in log disk. In some cases, log disk content
and raid disks content of a stripe are the same, but recovery will still
copy log disk content to raid disks, this doesn't impact data
consistency. space reuse happens after superblock update and cache
flush.
There is one situation we want to avoid. A broken meta in the middle of
a log causes recovery can't find meta at the head of log. If operations
require meta at the head persistent in log, we must make sure meta
before it persistent in log too. The case is stripe data/parity is in
log and we start write stripe to raid disks (before step 4). stripe
data/parity must be persistent in log before we do the write to raid
disks. The solution is we restrictly maintain io_unit list order. In
this case, we only write stripes of an io_unit to raid disks till the
io_unit is the first one whose data/parity is in log.
The io_unit list order is important for other cases too. For example,
some io_unit are reclaimable and others not. They can be mixed in the
list, we shouldn't reuse space of an unreclaimable io_unit.
Includes fixes to problems which were...
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
This introduces a simple log for raid5. Data/parity writing to raid
array first writes to the log, then write to raid array disks. If
crash happens, we can recovery data from the log. This can speed up
raid resync and fix write hole issue.
The log structure is pretty simple. Data/meta data is stored in block
unit, which is 4k generally. It has only one type of meta data block.
The meta data block can track 3 types of data, stripe data, stripe
parity and flush block. MD superblock will point to the last valid
meta data block. Each meta data block has checksum/seq number, so
recovery can scan the log correctly. We store a checksum of stripe
data/parity to the metadata block, so meta data and stripe data/parity
can be written to log disk together. otherwise, meta data write must
wait till stripe data/parity is finished.
For stripe data, meta data block will record stripe data sector and
size. Currently the size is always 4k. This meta data record can be made
simpler if we just fix write hole (eg, we can record data of a stripe's
different disks together), but this format can be extended to support
caching in the future, which must record data address/size.
For stripe parity, meta data block will record stripe sector. It's
size should be 4k (for raid5) or 8k (for raid6). We always store p
parity first. This format should work for caching too.
flush block indicates a stripe is in raid array disks. Fixing write
hole doesn't need this type of meta data, it's for caching extension.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
When a stripe finishes construction, we write the stripe to raid in
ops_run_io normally. With log, we do a bunch of other operations before
the stripe is written to raid. Mainly write the stripe to log disk,
flush disk cache and so on. The operations are still driven by raid5d
and run in the stripe state machine. We introduce a new state for such
stripe (trapped into log). The stripe is in this state from the time it
first enters ops_run_io (finish construction) to the time it is written
to raid. Since we know the state is only for log, we bypass other
check/operation in handle_stripe.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Next several patches use some raid5 functions, rename them with raid5
prefix and export out.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Suspending the entire device for resync could take too long. Resync
in small chunks.
cluster's resync window (32M) is maintained in r1conf as
cluster_sync_low and cluster_sync_high and processed in
raid1's sync_request(). If the current resync is outside the cluster
resync window:
1. Set the cluster_sync_low to curr_resync_completed.
2. Check if the sync will fit in the new window, if not issue a
wait_barrier() and set cluster_sync_low to sector_nr.
3. Set cluster_sync_high to cluster_sync_low + resync_window.
4. Send a message to all nodes so they may add it in their suspension
list.
bitmap_cond_end_sync is modified to allow to force a sync inorder
to get the curr_resync_completed uptodate with the sector passed.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Remove unneeded NULL test.
The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)
// <smpl>
@@ expression x; @@
-if (x != NULL)
\(kmem_cache_destroy\|mempool_destroy\|dma_pool_destroy\)(x);
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NeilBrown <neilb@suse.com>
When need_this_block probably shouldn't be called when there
are more than 2 failed devices, we really don't want it to try
indexing beyond the end of the failed_num[] of fdev[] arrays.
So limit the loops to at most 2 iterations.
Reported-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.de>
handle_failed_stripe() makes the stripe fail, eg, all IO will return
with a failure, but it doesn't update stripe_head_state. Later
handle_stripe() has special handling for raid6 for handle_stripe_fill().
That check before handle_stripe_fill() doesn't skip the failed stripe
and we get a kernel crash in need_this_block. This patch clear the
analysis state to make sure no functions wrongly called after
handle_failed_stripe()
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Pull core block updates from Jens Axboe:
"This first core part of the block IO changes contains:
- Cleanup of the bio IO error signaling from Christoph. We used to
rely on the uptodate bit and passing around of an error, now we
store the error in the bio itself.
- Improvement of the above from myself, by shrinking the bio size
down again to fit in two cachelines on x86-64.
- Revert of the max_hw_sectors cap removal from a revision again,
from Jeff Moyer. This caused performance regressions in various
tests. Reinstate the limit, bump it to a more reasonable size
instead.
- Make /sys/block/<dev>/queue/discard_max_bytes writeable, by me.
Most devices have huge trim limits, which can cause nasty latencies
when deleting files. Enable the admin to configure the size down.
We will look into having a more sane default instead of UINT_MAX
sectors.
- Improvement of the SGP gaps logic from Keith Busch.
- Enable the block core to handle arbitrarily sized bios, which
enables a nice simplification of bio_add_page() (which is an IO hot
path). From Kent.
- Improvements to the partition io stats accounting, making it
faster. From Ming Lei.
- Also from Ming Lei, a basic fixup for overflow of the sysfs pending
file in blk-mq, as well as a fix for a blk-mq timeout race
condition.
- Ming Lin has been carrying Kents above mentioned patches forward
for a while, and testing them. Ming also did a few fixes around
that.
- Sasha Levin found and fixed a use-after-free problem introduced by
the bio->bi_error changes from Christoph.
- Small blk cgroup cleanup from Viresh Kumar"
* 'for-4.3/core' of git://git.kernel.dk/linux-block: (26 commits)
blk: Fix bio_io_vec index when checking bvec gaps
block: Replace SG_GAPS with new queue limits mask
block: bump BLK_DEF_MAX_SECTORS to 2560
Revert "block: remove artifical max_hw_sectors cap"
blk-mq: fix race between timeout and freeing request
blk-mq: fix buffer overflow when reading sysfs file of 'pending'
Documentation: update notes in biovecs about arbitrarily sized bios
block: remove bio_get_nr_vecs()
fs: use helper bio_add_page() instead of open coding on bi_io_vec
block: kill merge_bvec_fn() completely
md/raid5: get rid of bio_fits_rdev()
md/raid5: split bio for chunk_aligned_read
block: remove split code in blkdev_issue_{discard,write_same}
btrfs: remove bio splitting and merge_bvec_fn() calls
bcache: remove driver private bio splitting code
block: simplify bio_add_page()
block: make generic_make_request handle arbitrarily sized bios
blk-cgroup: Drop unlikely before IS_ERR(_OR_NULL)
block: don't access bio->bi_error after bio_put()
block: shrink struct bio down to 2 cache lines again
...
When a write to one of the devices of a RAID5/6 fails, the failure is
recorded in the metadata of the other devices so that after a restart
the data on the failed drive wont be trusted even if that drive seems
to be working again (maybe a cable was unplugged).
Similarly when we record a bad-block in response to a write failure,
we must not let the write complete until the bad-block update is safe.
Currently there is no interlock between the write request completing
and the metadata update. So it is possible that the write will
complete, the app will confirm success in some way, and then the
machine will crash before the metadata update completes.
This is an extremely small hole for a racy to fit in, but it is
theoretically possible and so should be closed.
So:
- set MD_CHANGE_PENDING when requesting a metadata update for a
failed device, so we can know with certainty when it completes
- queue requests that completed when MD_CHANGE_PENDING is set to
only be processed after the metadata update completes
- call raid_end_bio_io() on bios in that queue when the time comes.
Signed-off-by: NeilBrown <neilb@suse.com>
It is possible (though unlikely) for a reshape to be
interrupted between the time that end_reshape is called
and the time when raid5_finish_reshape is called.
This can leave conf->reshape_progress set to MaxSector,
but mddev->reshape_position not.
This combination confused reshape_request() when ->reshape_backwards.
As conf->reshape_progress is so high, it seems the reshape hasn't
really begun. But assuming MaxSector is a valid address only
leads to sorrow.
So ensure reshape_position and reshape_progress both agree,
and add an extra check in reshape_request() just in case they don't.
Signed-off-by: NeilBrown <neilb@suse.com>
While it generally shouldn't happen, it is not impossible for
curr_resync_completed to exceed resync_max.
This can particularly happen when reshaping RAID5 - the current
status isn't copied to curr_resync_completed promptly, so when it
is, it can exceed resync_max.
This happens when the reshape is 'frozen', resync_max is set low,
and reshape is re-enabled.
Taking a difference between two unsigned numbers is always dangerous
anyway, so add a test to behave correctly if
curr_resync_completed > resync_max
Signed-off-by: NeilBrown <neilb@suse.com>
This code is calculating:
writepos, which is the furthest along address (device-space) that we
*will* be writing to
readpos, which is the earliest address that we *could* possible read
from, and
safepos, which is the earliest address in the 'old' section that we
might read from after a crash when the reshape position is
recovered from metadata.
The first is a precise calculation, so clipping at zero doesn't
make sense. As the reshape position is now guaranteed to always be
a multiple of reshape_sectors and as we already BUG_ON when
reshape_progress is zero, there is no point in this min_t() call.
The readpos and safepos are worst case - actual value depends on
precise geometry. That worst case could be negative, which is only
a problem because we are storing the value in an unsigned.
So leave the min_t() for those.
Signed-off-by: NeilBrown <neilb@suse.com>
When reshaping, we work in units of the largest chunk size.
If changing from a larger to a smaller chunk size, that means we
reshape more than one stripe at a time. So the required alignment
of reshape_position needs to take into account both the old
and new chunk size.
This means that both 'here_new' and 'here_old' are calculated with
respect to the same (maximum) chunk size, so testing if they are the
same when delta_disks is zero becomes pointless.
Signed-off-by: NeilBrown <neilb@suse.com>
The chunk_sectors and new_chunk_sectors fields of mddev can be changed
any time (via sysfs) that the reconfig mutex can be taken. So raid5
keeps internal copies in 'conf' which are stable except for a short
locked moment when reshape stops/starts.
So any access that does not hold reconfig_mutex should use the 'conf'
values, not the 'mddev' values.
Several don't.
This could result in corruption if new values were written at awkward
times.
Also use min() or max() rather than open-coding.
Signed-off-by: NeilBrown <neilb@suse.com>
These aren't really needed when no reshape is happening,
but it is safer to have them always set to a meaningful value.
The next patch will use ->prev_chunk_sectors without checking
if a reshape is happening (because that makes the code simpler),
and this patch makes that safe.
Signed-off-by: NeilBrown <neilb@suse.com>
md/raid5 only updates ->reshape_position (which is stored in
metadata and is authoritative) occasionally, but particularly
when getting closed to ->resync_max as it must be correct
when ->resync_max is reached.
When mdadm tries to stop an array which is reshaping it will:
- freeze the reshape,
- set resync_max to where the reshape has reached.
- unfreeze the reshape.
When this happens, the reshape is aborted and then restarted.
The restart doesn't check that resync_max is close, and so doesn't
update ->reshape_position like it should.
This results in the reshape stopping, but ->reshape_position being
incorrect.
So on that first call to reshape_request, make sure ->reshape_position
is updated if needed.
Signed-off-by: NeilBrown <neilb@suse.com>
As generic_make_request() is now able to handle arbitrarily sized bios,
it's no longer necessary for each individual block driver to define its
own ->merge_bvec_fn() callback. Remove every invocation completely.
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lars Ellenberg <drbd-dev@lists.linbit.com>
Cc: drbd-user@lists.linbit.com
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Yehuda Sadeh <yehuda@inktank.com>
Cc: Sage Weil <sage@inktank.com>
Cc: Alex Elder <elder@kernel.org>
Cc: ceph-devel@vger.kernel.org
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: dm-devel@redhat.com
Cc: Neil Brown <neilb@suse.de>
Cc: linux-raid@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Acked-by: NeilBrown <neilb@suse.de> (for the 'md' bits)
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
[dpark: also remove ->merge_bvec_fn() in dm-thin as well as
dm-era-target, and resolve merge conflicts]
Signed-off-by: Dongsu Park <dpark@posteo.net>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Remove bio_fits_rdev() as sufficient merge_bvec_fn() handling is now
performed by blk_queue_split() in md_make_request().
Cc: Neil Brown <neilb@suse.de>
Cc: linux-raid@vger.kernel.org
Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
[dpark: add more description in commit message]
Signed-off-by: Dongsu Park <dpark@posteo.net>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
If a read request fits entirely in a chunk, it will be passed directly to the
underlying device (providing it hasn't failed of course). If it doesn't fit,
the slightly less efficient path that uses the stripe_cache is used.
Requests that get to the stripe cache are always completely split up as
necessary.
So with RAID5, ripping out the merge_bvec_fn doesn't cause it to stop work,
but could cause it to take the less efficient path more often.
All that is needed to manage this is for 'chunk_aligned_read' do some bio
splitting, much like the RAID0 code does.
Cc: Neil Brown <neilb@suse.de>
Cc: linux-raid@vger.kernel.org
Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
I have a report of drop_one_stripe() called from
raid5_cache_scan() apparently finding ->max_nr_stripes == 0.
This should not be allowed.
So add a test to keep max_nr_stripes above min_nr_stripes.
Also use a 'mask' rather than a 'mod' in drop_one_stripe
to ensure 'hash' is valid even if max_nr_stripes does reach zero.
Fixes: edbe83ab4c ("md/raid5: allow the stripe_cache to grow and shrink.")
Cc: stable@vger.kernel.org (4.1 - please release with 2d5b569b66)
Reported-by: Tomas Papan <tomas.papan@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Some places use helpers now, others don't. We only have the 'is set'
helper, add helpers for setting and clearing flags too.
It was a bit of a mess of atomic vs non-atomic access. With
BIO_UPTODATE gone, we don't have any risk of concurrent access to the
flags. So relax the restriction and don't make any of them atomic. The
flags that do have serialization issues (reffed and chained), we
already handle those separately.
Signed-off-by: Jens Axboe <axboe@fb.com>
Currently we have two different ways to signal an I/O error on a BIO:
(1) by clearing the BIO_UPTODATE flag
(2) by returning a Linux errno value to the bi_end_io callback
The first one has the drawback of only communicating a single possible
error (-EIO), and the second one has the drawback of not beeing persistent
when bios are queued up, and are not passed along from child to parent
bio in the ever more popular chaining scenario. Having both mechanisms
available has the additional drawback of utterly confusing driver authors
and introducing bugs where various I/O submitters only deal with one of
them, and the others have to add boilerplate code to deal with both kinds
of error returns.
So add a new bi_error field to store an errno value directly in struct
bio and remove the existing mechanisms to clean all this up.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
