DRBD has a concept of request epochs or reorder-domains,
which are separated on the wire by P_BARRIER packets.

Older DRBD is not able to handle zero-sized requests at all,
so we need to map empty flushes to these drbd barriers.

These are the equivalent of empty flushes, and
by default trigger flushes on the receiving side anyways
(unless not supported or explicitly disabled),
so there is no need to handle this differently in newer drbd either.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

Unconditionally announce FLUSH/FUA to upper layers.
If the lower layers on either node do not actually support this,
generic_make_request() will deal with it.

If this causes performance regressions on your setup,
make sure there are no volatile caches involved,
and mount -o nobarrier or equivalent.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

We capped our max_bio_size respectively max_hw_sectors with
min_t(int, lower level limit, our limit);
unfortunately, some drivers, e.g. the kvm virtio block driver, initialize their
limits to "-1U", and that is of course a smaller "int" value than our limit.

Impact: we started to request 16 MB resync requests,
which lead to protocol error and a reconnect loop.

Fix all relevant constants and parameters to be unsigned int.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

If you do back to back wait-sync/invalidate on a Primary in a tight loop,
during application IO load, you could trigger a race:
  kernel: block drbd6: FIXME going to queue 'set_n_write from StartingSync'
	but 'write from resync_finished' still pending?

Fix this by changing the order of the drbd_queue_work() and
the wake_up() in dec_ap_pending(), and adding the additional
drbd_flush_workqueue() before requesting the full sync.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

Occasionally, if we disconnect, we triggered this assert:
  block drbd7: ASSERT FAILED tl_hash[27] == c30b0f04, expected NULL

hlist_del() happens only on master bio completion.

We used to wait for pending IO to complete before freeing tl_hash
on disconnect. We no longer do so, since we learned to "freeze"
IO on disconnect.

If the local disk is too slow, we may reach C_STANDALONE early,
and there are still some requests pending locally when we call
drbd_free_tl_hash().

If we now free the tl_hash, and later the local IO completion completes
the master bio, which then does hlist_del() and clobbers freed memory.

Do hlist_del_init() and hlist_add_fake() before kfree(tl_hash),
so the hlist_del() on master bio completion is harmless.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

In case we want to hard-reset from the local-io-error handler,
we need to call it before notifying the peer or aborting local IO.
Otherwise the peer will advance its data generation UUIDs even
if secondary.

This way, local io error looks like a "regular" node crash,
which reduces the number of different failure cases.
This may be useful in a bigger picture where crashed or otherwise
"misbehaving" nodes are automatically re-deployed.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

Fix asserts like
  block drbd0: in got_BlockAck:4634: rs_pending_cnt = -35 < 0 !

We reset the resync lru cache and related information (rs_pending_cnt),
once we successfully finished a resync or online verify, or if the
replication connection is lost.

We also need to reset it if a resync or online verify is aborted
because a lower level disk failed.

In that case the replication link is still established,
and we may still have packets queued in the network buffers
which want to touch rs_pending_cnt.

We do not have any synchronization mechanism to know for sure when all
such pending resync related packets have been drained.

To avoid this counter to go negative (and violate the ASSERT that it
will always be >= 0), just do not reset it when we lose a disk.

It is good enough to make sure it is re-initialized before the next
resync can start: reset it when we re-attach a disk.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

We cache the congestion status in mdev->congestion_reason whenever
drbd_congested() was called.
Reset this cached info before reporting it when reading /proc/drbd.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

If the drbd worker thread is synchronously waiting for some userland
callback, we don't want some casual pageout to block on us.
Have drbd_congested() report congestion in that case.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

Aborting local requests (not waiting for completion from the lower level
disk) is dangerous: if the master bio has been completed to upper
layers, data pages may be re-used for other things already.
If local IO is still pending and later completes,
this may cause crashes or corrupt unrelated data.

Only abort local IO if explicitly requested.
Intended use case is a lower level device that turned into a tarpit,
not completing io requests, not even doing error completion.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

Sparse complains about this because:
drivers/block/rbd.c:996:20: warning: cast to restricted __le32
drivers/block/rbd.c:996:20: warning: cast from restricted __le16

These are set in osd_req_encode_op() and they are le16.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: NAlex Elder <elder@inktank.com>
(cherry picked from commit 895cfcc8)

ceph_snap_context->snaps is an u64 array
Signed-off-by: NZheng Yan <zheng.z.yan@intel.com>
Reviewed-by: NAlex Elder <elder@inktank.com>
(cherry picked from commit f9f9a190)

The idr_pre_get() function never returns a value < 0.  It returns 0 (no
memory) or 1 (OK).
Reported-by: NSilva Paulo <psdasilva@yahoo.com>
[ Rewrote Silva's patch, but attributing it to Silva anyway  - Linus ]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In commit 070ad7e7 ("floppy: convert to delayed work and
single-thread wq") the 'fd_timeout' timer was converted to a delayed
work.  However, the "del_timer(&fd_timeout)" was lost in the process,
and any previous pending timeouts would stay active when we then
re-queued the timeout.

This resulted in the floppy probe sequence having a (stale) 20s timeout
rather than the intended 3s timeout, and thus made booting with the
floppy driver (but no actual floppy controller) take much longer than it
should.

Of course, there's little reason for most people to compile the floppy
driver into the kernel at all, which is why most people never noticed.

Canceling the delayed work where we used to do the del_timer() fixes the
issue, and makes the floppy probing use the proper new timeout instead.
The three second timeout is still very wasteful, but better than the 20s
one.
Reported-and-tested-by: NAndi Kleen <ak@linux.intel.com>
Reported-and-tested-by: NCalvin Walton <calvin.walton@kepstin.ca>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix a regression introduced by 7eaceacc ("block: remove per-queue
plugging").  In that patch, Jens removed the whole mm_unplug_device()
function, which used to be the trigger to make umem start to work.

We need to implement unplugging to make umem start to work, or I/O will
never be triggered.
Signed-off-by: NTao Guo <Tao.Guo@emc.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Shaohua Li <shli@kernel.org>
Cc: <stable@vger.kernel.org>
Acked-by: NNeilBrown <neilb@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We must not look at mdev->actlog, unless we have a get_ldev() reference.
It also does not make much sense to try to disconnect or pull-ahead of
the peer, if we don't have good local data.

Only even consider congestion policies, if our local disk is D_UP_TO_DATE.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

If a read is aborted due to force-detach of a supposedly unresponsive
local backing device, and retried on the peer, it can happen that the
local request later still completes (hopefully with an error).
As it may already have been completed to upper layers meanwhile,
it must not be retried again now.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

BUG: unable to handle kernel NULL pointer dereference at (null)
...
 [<d1e17561>] ? _drbd_bm_set_bits+0x151/0x240 [drbd]
 [<d1e236f8>] ? receive_bitmap+0x4f8/0xbc0 [drbd]

This fixes an off-by-one error in the receive_bitmap() path,
if run-length encoded bitmap transfer is enabled.

If the bitmap is an exact multiple of PAGE_SIZE, which means the visible
capacity of the drbd device is an exact multiple of 128 MiB (for 4k page
size), and bitmap compression (use-rle) is enabled (which became default
with 8.4), and the very last bit is dirty and reported in an rle
comressed bitmap packet, we ended up trying to kmap_atomic a page pointer
that does not exist (bitmap->bm_pages[last index + 1]).

bug introduced by:
    Date:   Fri Jul 24 15:33:24 2009 +0200
    set bits: optimize for complete last word, fix off-by-one-word corner case

made effective by:
    Date:   Thu Dec 16 00:32:38 2010 +0100
    drbd: get rid of unused debug code

    Long time ago, we had paranoia code in the bitmap that allocated one
    extra word, assigned a magic value, and checked on every occasion that
    the magic value was still unchanged.

    That debug code is unused, the extra long word complicates code a bit.
    Get rid of it.

No-one triggered this bug in the last few years, because a large subset
of our userbase is unaffected:
 * typically the last few blocks of a device are not modified
   frequently, and remain unset
 * use-rle was disabled by default in drbd < 8.4
 * those with slightly "odd" device sizes, or
 * drbd internal meta data (which will skew the device size slightly,
   thus makes it harder to have a bug relevant device size)
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

Part of the ring structure is the 'id' field which is under
control of the frontend. The frontend stamps it with "some"
value (this some in this implementation being a value less
than BLK_RING_SIZE), and when it gets a response expects
said value to be in the response structure. We have a check
for the id field when spolling new requests but not when
de-spolling responses.

We also add an extra check in add_id_to_freelist to make
sure that the 'struct request' was not NULL - as we cannot
pass a NULL to __blk_end_request_all, otherwise that crashes
(and all the operations that the response is dealing with
end up with __blk_end_request_all).

Lastly we also print the name of the operation that failed.

[v1: s/BUG/WARN/ suggested by Stefano]
[v2: Add extra check in add_id_to_freelist]
[v3: Redid op_name per Jan's suggestion]
[v4: add const * and add WARN on failure returns]
Acked-by: NJan Beulich <jbeulich@suse.com>
Acked-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

On module load, creates a debugfs parent 'rssd' in debugfs root. Then for each
device, create a new node with corresponding disk name. Under the new node, two
entries 'registers' and 'flags' are created.

NOTE: These entries were removed from sysfs in the previous patch
Signed-off-by: NAsai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch removes entries 'registers' and 'flags' from sysfs. Updated ABI file
to reflect this change.
Reported-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NAsai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

version.h header file inclusion is no longer required.
Signed-off-by: NSachin Kamat <sachin.kamat@linaro.org>

* Formatted the output of 'registers' entry
* Added "Commands in Q' to output of 'registers' entry
* Added a new entry 'flags'
Signed-off-by: NAsai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Convert macro definitions for flags bits to enum
Signed-off-by: NAsai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

When checking for command completions if the register value is zero, proceed
to next register.
Signed-off-by: NAsai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Fix to support more than one sector in exec_drive_command().
Signed-off-by: NAsai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

'cmd_issue_lock' is for only acquiring a free slot, and it is not used
in interrupt context. So replaced irq version with non-irq version of spinlock.
Signed-off-by: NAsai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Set the following block queue boundary variables
	* max_hw_sectors
	* max_segment_size
Signed-off-by: NAsai Thambi S P <asamymuthupa@micron.com>

Removed setting of q->nr_requests.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If a PIO (IOCTL/internal) command resulted in TFE, signal the wait event or break out of polling.
Signed-off-by: NAsai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

For the ioctl command HDIO_GET_IDENTITY, return the stored copy of IDENTIFY
DATA instead of sending the command to the device - similar to libata.
Signed-off-by: NAsai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This change sets custom timeouts depending on PIO command.
Signed-off-by: NAsai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Fix clearing an incorrect register in mtip_init_port
Signed-off-by: NAsai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We weren't copying the id field so when we sent the response
back to the frontend (especially with a 64-bit host and 32-bit
guest), we ended up using a random value. This lead to the
frontend crashing as it would try to pass to __blk_end_request_all
a NULL 'struct request' (b/c it would use the 'id' to find the
proper 'struct request' in its shadow array) and end up crashing:

BUG: unable to handle kernel NULL pointer dereference at 000000e4
IP: [<c0646d4c>] __blk_end_request_all+0xc/0x40
.. snip..
EIP is at __blk_end_request_all+0xc/0x40
.. snip..
 [<ed95db72>] blkif_interrupt+0x172/0x330 [xen_blkfront]

This fixes the bug by passing in the proper id for the response.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=824641

CC: stable@kernel.org
Tested-by: NWilliam Dauchy <wdauchy@gmail.com>
Acked-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Benchmark shows small performance improvement on fusion io device.

Before:
  seq-read : io=1,024MB, bw=19,982KB/s, iops=39,964, runt= 52475msec
  seq-write: io=1,024MB, bw=20,321KB/s, iops=40,641, runt= 51601msec
  rnd-read : io=1,024MB, bw=15,404KB/s, iops=30,808, runt= 68070msec
  rnd-write: io=1,024MB, bw=14,776KB/s, iops=29,552, runt= 70963msec

After:
  seq-read : io=1,024MB, bw=20,343KB/s, iops=40,685, runt= 51546msec
  seq-write: io=1,024MB, bw=20,803KB/s, iops=41,606, runt= 50404msec
  rnd-read : io=1,024MB, bw=16,221KB/s, iops=32,442, runt= 64642msec
  rnd-write: io=1,024MB, bw=15,199KB/s, iops=30,397, runt= 68991msec
Signed-off-by: NAsias He <asias@redhat.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

If we reset the virtio-blk device before the requests already dispatched
to the virtio-blk driver from the block layer are finised, we will stuck
in blk_cleanup_queue() and the remove will fail.

blk_cleanup_queue() calls blk_drain_queue() to drain all requests queued
before DEAD marking. However it will never success if the device is
already stopped. We'll have q->in_flight[] > 0, so the drain will not
finish.

How to reproduce the race:
1. hot-plug a virtio-blk device
2. keep reading/writing the device in guest
3. hot-unplug while the device is busy serving I/O

Test:
~1000 rounds of hot-plug/hot-unplug test passed with this patch.

Changes in v3:
- Drop blk_abort_queue and blk_abort_request
- Use __blk_end_request_all to complete request dispatched to driver

Changes in v2:
- Drop req_in_flight
- Use virtqueue_detach_unused_buf to get request dispatched to driver
Signed-off-by: NAsias He <asias@redhat.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Block layer now handles O_EXCL in a generic way for block devices.

The semantics is however different for floppy and all other block devices,
as floppy driver contains its own O_EXCL handling.

The semantics for all-but-floppy bdevs is "there can be at most one O_EXCL
open of this file", while for floppy bdev the semantics is "if someone has
the bdev open with O_EXCL, noone else can open it".

There is actual userspace-observable change in behavior because of this
since commit e525fd89 ("block: make blkdev_get/put() handle exclusive
access") -- on kernels containing this commit, mount of /dev/fd0 causes
the fd0 block device be claimed with _EXCL, preventing subsequent
open(/dev/fd0).

Bring things back into shape, i.e.  make it possible, analogically to
other block devices, to mount the floppy and open() it afterwards --
remove the floppy-specific handling and let the generic bdev code O_EXCL
handling take over.
Signed-off-by: NJiri Kosina <jkosina@suse.cz>
Acked-by: NTejun Heo <tj@kernel.org>
Acked-by: NNeilBrown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

There are several races in floppy driver between bottom half
(scheduled_work) and timers (fd_timeout, fd_timer). Due to slowness
of the actual floppy devices, those races are never (at least to my
knowledge) triggered on a bare floppy metal. However on virtualized
(emulated) floppy drives, which are of course magnitudes faster
than the real ones, these races trigger reliably. They usually exhibit
themselves as NULL pointer dereferences during DMA setup, such as

	BUG: unable to handle kernel NULL pointer dereference at 0000000a
	[ ... snip ... ]
	EIP: 0060:[<c02053d5>] EFLAGS: 00010293 CPU: 0
	EAX: ffffe000 EBX: 0000000a ECX: 00000000 EDX: 0000000a
	ESI: c05d2718 EDI: 00000000 EBP: 00000000 ESP: f540fe44
	 DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
	Process swapper (pid: 0, ti=f540e000 task=c082d5a0 task.ti=c0826000)
	Stack:
	 ffffe000 00001ffc 00000000 00000000 00000000 c05d2718 c0708b40 f540fe80
	 c020470f c05d2718 c0708b40 00000000 f540fe80 0000000a f540fee4 00000000
	 c0708b40 f540fee4 00000000 00000000 c020526b 00000000 c05d2718 c0708b40
	Call Trace:
	 [<c020470f>] dump_trace+0xaf/0x110
	 [<c020526b>] show_trace_log_lvl+0x4b/0x60
	 [<c0205298>] show_trace+0x18/0x20
	 [<c05c5811>] dump_stack+0x6d/0x72
	 [<c0248527>] warn_slowpath_common+0x77/0xb0
	 [<c02485f3>] warn_slowpath_fmt+0x33/0x40
	 [<f7ec593c>] setup_DMA+0x14c/0x210 [floppy]
	 [<f7ecaa95>] setup_rw_floppy+0x105/0x190 [floppy]
	 [<c0256d08>] run_timer_softirq+0x168/0x2a0
	 [<c024e762>] __do_softirq+0xc2/0x1c0
	 [<c02042ed>] do_softirq+0x7d/0xb0
	 [<f54d8a00>] 0xf54d89ff

but other instances can be easily seen as well. This can be observed at least under
VMWare, VirtualBox and KVM.

This patch converts all the timers and bottom halfs to be processed in a single
workqueue. This aproach has been already discussed back in 2010 if I remember
correctly, and Acked by Linus [1], but it then never made it to the tree.

This all is based on original idea and code of Stephen Hemminger.  I have
ported original Stepen's code to the current state of the floppy driver, and
performed quite some testing (on real hardware), which didn't reveal any issues
(this includes not only writing and reading data, but also formatting
(unfortunately I didn't find any Double-Density disks any more)). Ability to
handle errors properly (supplying known bad floppies) has also been verified.

[1] http://kerneltrap.org/mailarchive/linux-kernel/2010/6/11/4582092Based-on-patch-by: NStephen Hemminger <shemminger@vyatta.com>
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

This function rereads the entire header and handles any changes in
it, not just changes in snapshots.
Signed-off-by: NJosh Durgin <josh.durgin@dreamhost.com>
Reviewed-by: NAlex Elder <elder@dreamhost.com>
Reviewed-by: NYehuda Sadeh <yehuda@hq.newdream.net>

Snapshot sizes should be the same type as regular image sizes. This
only affects their displayed size in sysfs, not the reported size of
an actual block device sizes.
Signed-off-by: NJosh Durgin <josh.durgin@dreamhost.com>
Reviewed-by: NAlex Elder <elder@dreamhost.com>
Reviewed-by: NYehuda Sadeh <yehuda@hq.newdream.net>