blk_queue_split() is always called with the last arg being q->bio_split,
where 'q' is the first arg.

Also blk_queue_split() sometimes uses the passed-in 'bs' and sometimes uses
q->bio_split.

This is inconsistent and unnecessary.  Remove the last arg and always use
q->bio_split inside blk_queue_split()
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Credit-to: Javier González <jg@lightnvm.io> (Noticed that lightnvm was missed)
Reviewed-by: NJavier González <javier@cnexlabs.com>
Tested-by: NJavier González <javier@cnexlabs.com>
Signed-off-by: NNeilBrown <neilb@suse.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

his used to be a fall through case, but we shifted code around and I
think we want a break here now.

Fixes: 4e4cbee9 ("block: switch bios to blk_status_t")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Acked-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Replace bi_error with a new bi_status to allow for a clear conversion.
Note that device mapper overloaded bi_error with a private value, which
we'll have to keep arround at least for now and thus propagate to a
proper blk_status_t value.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

Use the same values for use for request completion errors as the return
value from ->queue_rq.  BLK_STS_RESOURCE is special cased to cause
a requeue, and all the others are completed as-is.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

Currently we use nornal Linux errno values in the block layer, and while
we accept any error a few have overloaded magic meanings.  This patch
instead introduces a new  blk_status_t value that holds block layer specific
status codes and explicitly explains their meaning.  Helpers to convert from
and to the previous special meanings are provided for now, but I suspect
we want to get rid of them in the long run - those drivers that have a
errno input (e.g. networking) usually get errnos that don't know about
the special block layer overloads, and similarly returning them to userspace
will usually return somethings that strictly speaking isn't correct
for file system operations, but that's left as an exercise for later.

For now the set of errors is a very limited set that closely corresponds
to the previous overloaded errno values, but there is some low hanging
fruite to improve it.

blk_status_t (ab)uses the sparse __bitwise annotations to allow for sparse
typechecking, so that we can easily catch places passing the wrong values.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

Turn the error paramter into a pointer so that target drivers can change
the value, and make sure only DM_ENDIO_* values are returned from the
methods.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Instead use the special DM_MAPIO_KILL return value to return -EIO just
like we do for the request based path.  Note that dm-log-writes returned
-ENOMEM in a few places, which now becomes -EIO instead.  No consumer
treats -ENOMEM special so this shouldn't be an issue (and it should
use a mempool to start with to make guaranteed progress).
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

This simplifies the code and especially the error passing a bit and
will help with the next patch.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

A few (but not all) dm targets use a special EWOULDBLOCK error code for
failing REQ_RAHEAD requests that fail due to a lack of available resources.
But no one else knows about this magic code, and lower level drivers also
don't generate it when failing read-ahead requests for similar reasons.

So remove this special casing and ignore all additional error handling for
REQ_RAHEAD - if this was a real underlying error we'd get a normal read
once the real read comes in.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NBart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

The new per-cpu counter for writes_pending is initialised in
md_alloc(), which is not called by dm-raid.
So dm-raid fails when md_write_start() is called.

Move the initialization to the personality modules
that need it.  This way it is always initialised when needed,
but isn't unnecessarily initialized (requiring memory allocation)
when the personality doesn't use writes_pending.
Reported-by: NHeinz Mauelshagen <heinzm@redhat.com>
Fixes: 4ad23a97 ("MD: use per-cpu counter for writes_pending")
Signed-off-by: NNeilBrown <neilb@suse.com>
Signed-off-by: NShaohua Li <shli@fb.com>

The md private helper uuid_equal() collides with a generic helper
of the same name.

Rename the md private helper to md_uuid_equal() and do the same for
md_sb_equal().
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NShaohua Li <shli@kernel.org>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

Commit b685d3d6 "block: treat REQ_FUA and REQ_PREFLUSH as
synchronous" removed REQ_SYNC flag from WRITE_{FUA|PREFLUSH|...}
definitions.  generic_make_request_checks() however strips REQ_FUA and
REQ_PREFLUSH flags from a bio when the storage doesn't report volatile
write cache and thus write effectively becomes asynchronous which can
lead to performance regressions

Fix the problem by making sure all bios which are synchronous are
properly marked with REQ_SYNC.

CC: linux-raid@vger.kernel.org
CC: Shaohua Li <shli@kernel.org>
Fixes: b685d3d6
CC: stable@vger.kernel.org
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NShaohua Li <shli@fb.com>

Commit b685d3d6 ("block: treat REQ_FUA and REQ_PREFLUSH as
synchronous") removed REQ_SYNC flag from WRITE_{FUA|PREFLUSH|...}
definitions.  generic_make_request_checks() however strips REQ_FUA and
REQ_PREFLUSH flags from a bio when the storage doesn't report volatile
write cache and thus write effectively becomes asynchronous which can
lead to performance regressions.

Fix the problem by making sure all bios which are synchronous are
properly marked with REQ_SYNC.

Fixes: b685d3d6 ("block: treat REQ_FUA and REQ_PREFLUSH as synchronous")
Cc: stable@vger.kernel.org
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

This makes it possible, with appropriate filesystem support, for a
sysadmin to tell what is affected by the mismatch, and whether
it should be ignored (if it's inside a swap partition, for
instance).

We ratelimit to prevent log flooding: if there are so many
mismatches that ratelimiting is necessary, the individual messages
are relatively unlikely to be important (either the machine is
swapping like crazy or something is very wrong with the disk).
Signed-off-by: NNick Alcock <nick.alcock@oracle.com>
Signed-off-by: NShaohua Li <shli@fb.com>

Previously, the uuid debug statements were printed in little-endian
format, which wasn't consistent in machines that might not be in
little-endian byte order. With this change, the output will be
consistent for all machines with different byte-ordering.
Signed-off-by: NKyungchan Koh <kkc6196@fb.com>
Signed-off-by: NShaohua Li <shli@fb.com>

Commit d224e938 ("drivers/md/dm-ioctl.c: use kvmalloc rather than
opencoded variant") left out the __GFP_HIGH flag when converting from
__vmalloc to kvmalloc.  This can cause the DM ioctl to fail in some low
memory situations where it wouldn't have failed earlier.  Add __GFP_HIGH
back to avoid any potential regression.

Fixes: d224e938 ("drivers/md/dm-ioctl.c: use kvmalloc rather than opencoded variant")
Signed-off-by: NJunaid Shahid <junaids@google.com>
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

DM-Verity has an (undocumented) mode where no salt is used.  This was
never handled directly by the DM-Verity code, instead working due to the
fact that calling crypto_shash_update() with a zero length data is an
implicit noop.

This is no longer the case now that we have switched to
crypto_ahash_update().  Fix the issue by introducing explicit handling
of the no salt use case to DM-Verity.
Signed-off-by: NGilad Ben-Yossef <gilad@benyossef.com>
Reported-by: NMarian Csontos <mcsontos@redhat.com>
Fixes: d1ac3ff0 ("dm verity: switch to using asynchronous hash crypto API")
Tested-by: NMilan Broz <gmazyland@gmail.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

The add_new_disk returns with communication locked if
__sendmsg returns failure, fix it with call unlock_comm
before return.
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
CC: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NGuoqing Jiang <gqjiang@suse.com>
Signed-off-by: NShaohua Li <shli@fb.com>

Currently there is no kmalloc failure check on the allocation of
the background_tracker struct in btracker_create(), and so a NULL return
will lead to a NULL pointer dereference.  Add a NULL check.

Detected by CoverityScan, CID#1416587 ("Dereference null return value")

Fixes: b29d4986 ("dm cache: significant rework to leverage dm-bio-prison-v2")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Change the type of the parameter "retain_bytes" from unsigned to
unsigned long, so that on 64-bit machines the user can set more than
4GiB of data to be retained.

Also, change the type of the variable "count" in the function
"__evict_old_buffers" to unsigned long.  The assignment
"count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];"
could result in unsigned long to unsigned overflow and that could result
in buffers not being freed when they should.

While at it, avoid division in get_retain_buffers().  Division is slow,
we can change it to shift because we have precalculated the log2 of
block size.

Cc: stable@vger.kernel.org
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Since 412445ac ("dm: introduce a new DM_MAPIO_KILL return value"), the
clone_and_map_rq methods must not return errno values, so fix it up
to properly return DM_MAPIO_KILL, instead of the -EIO value that snuck
in due to a conflict between two patches.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Instead just turn the macro into a helper for the warning message.
This removes an unnecessary assignment and will allow the next commit to
fix a place where -EIO is the wrong return value.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

We don't want to bug when receiving a DM_MAPIO_KILL value..

Fixes: 412445ac ("dm: introduce a new DM_MAPIO_KILL return value")
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

When decrementing the reference count for a block, the free count wasn't
being updated if the reference count went to zero.

Cc: stable@vger.kernel.org
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

These calls were the wrong way round in __write_initial_superblock.

Cc: stable@vger.kernel.org
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

If there are no clean blocks to be demoted the writeback will be
triggered at that point.  Preemptively writing back can hurt high IO
load scenarios.
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Drop the MODERATE state since it wasn't buying us much.

Also, in check_migrations(), prepare for the next commit ("dm cache
policy smq: don't do any writebacks unless IDLE") by deferring to the
policy to make the final decision on whether writebacks can be
serviced.
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

IO tracking used to throttle writebacks when the origin device is busy.

Even if all the IO is going to the fast device, writebacks can
significantly degrade performance.  So track all IO to gauge whether the
cache is busy or not.

Otherwise, synthetic IO tests (e.g. fio) that might send all IO to the
fast device wouldn't cause writebacks to get throttled.
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

It causes a lot of churn if the working set's size is close to the fast
device's size.
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

This stops entries bouncing in and out of the cache quickly.
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

If there are no clean entries to demote we really want to writeback
immediately.
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Heavy IO load may mean there are very few clean blocks in the cache, and
we risk demoting entries that get hit a lot.
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

Some bios have no payload (eg, a FLUSH), don't reset the idle_time when
these come in.
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

If an array consists of two drives and the first drive has the bad
block, the read request to the region overlapping the bad block chooses
the same disk (with bad block) as device to read from over and over and
the request gets stuck. If the first disk only partially overlaps with
bad block, it becomes a candidate ("best disk") for shorter range of
sectors. The second disk is capable of reading the entire requested
range and it is updated accordingly, however it is not recorded as a
best device for the request. In the end the request is sent to the first
disk to read entire range of sectors. It fails and is re-tried in a
moment but with the same outcome.

Actually it is quite likely scenario but it had little exposure in my
test until commit 715d40b93b10 ("md/raid1: add failfast handling for
reads.") removed preference for idle disk. Such scenario had been
passing as second disk was always chosen when idle.

Reset a candidate ("best disk") to read from if disk can read entire
range. Do it only if other disk has already been chosen as a candidate
for a smaller range. The head position / disk type logic will select
the best disk to read from - it is fine as disk with bad block won't be
considered for it.
Signed-off-by: NTomasz Majchrzak <tomasz.majchrzak@intel.com>
Signed-off-by: NShaohua Li <shli@fb.com>

Currently, sync of raid456 array cannot make progress when hitting
data in writeback r5cache.

This patch fixes this issue by flushing cached data of the stripe
before processing the sync request. This is achived by:

1. In handle_stripe(), do not set STRIPE_SYNCING if the stripe is
   in write back cache;
2. In r5c_try_caching_write(), handle the stripe in sync with write
   through;
3. In do_release_stripe(), make stripe in sync write out and send
   it to the state machine.

Shaohua: explictly set STRIPE_HANDLE after write out completed
Signed-off-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NShaohua Li <shli@fb.com>

For the raid456 with writeback cache, when journal device failed during
normal operation, it is still possible to persist all data, as all
pending data is still in stripe cache. However, it is necessary to handle
journal failure gracefully.

During journal failures, the following logic handles the graceful shutdown
of journal:
1. raid5_error() marks the device as Faulty and schedules async work
   log->disable_writeback_work;
2. In disable_writeback_work (r5c_disable_writeback_async), the mddev is
   suspended, set to write through, and then resumed. mddev_suspend()
   flushes all cached stripes;
3. All cached stripes need to be flushed carefully to the RAID array.

This patch fixes issues within the process above:
1. In r5c_update_on_rdev_error() schedule disable_writeback_work for
   journal failures;
2. In r5c_disable_writeback_async(), wait for MD_SB_CHANGE_PENDING,
   since raid5_error() updates superblock.
3. In handle_stripe(), allow stripes with data in journal (s.injournal > 0)
   to make progress during log_failed;
4. In delay_towrite(), if log failed only process data in the cache (skip
   new writes in dev->towrite);
5. In __get_priority_stripe(), process loprio_list during journal device
   failures.
6. In raid5_remove_disk(), wait for all cached stripes are flushed before
   calling log_exit().
Signed-off-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NShaohua Li <shli@fb.com>

If we add bios to block plugging list, locking is unnecessry, since the block
unplug is guaranteed not to run at that time.
Reviewed-by: NNeilBrown <neilb@suse.com>
Signed-off-by: NShaohua Li <shli@fb.com>

In r5l_do_submit_io(), it is necessary to check io->split_bio before
submit io->current_bio. This is because, endio of current_bio may
free the whole IO unit, and thus change io->split_bio.
Signed-off-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NShaohua Li <shli@fb.com>

There are complaints that raid0 discard handling is slow. Currently we
divide discard request into chunks and dispatch to underlayer disks. The
block layer will do merge to form big requests. This causes a lot of
request split/merge and uses significant CPU time.

A simple idea is to calculate the range for each raid disk for an IO
request and send a discard request to raid disks, which will avoid the
split/merge completely. Previously Coly tried the approach, but the
implementation was too complex because of raid0 zones. This patch always
split bio in zone boundary and handle bio within one zone. It simplifies
the implementation a lot.
Reviewed-by: NNeilBrown <neilb@suse.com>
Acked-by: NColy Li <colyli@suse.de>
Signed-off-by: NShaohua Li <shli@fb.com>