When a filesystem is mounted on a nbd device and on a disconnect, because
of kill_bdev(), and resetting bdev size to zero, buffer_head mappings are
getting destroyed under mounted filesystem.

After a bdev size reset(i.e bdev->bd_inode->i_size = 0) on a disconnect,
followed by a sys_umount(),
        generic_shutdown_super()->...
        ->__sync_blockdev()->...
        -blkdev_writepages()->...
        ->do_invalidatepage()->...
        -discard_buffer()   is discarding superblock buffer_head assumed
to be in mapped state by ext4_commit_super().

[mlin: ported to 4.11-rc2]
Signed-off-by: Ratna Manoj Bolla <manoj.br@gmail.com
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

We can't just set the timeout on the tagset, we have to set it on the
queue as it would have been setup already at this point.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

We've been relying on the block layer to assume rq->errors being set
translates into -EIO.  I noticed in testing that sometimes this isn't
true, and really there's not much of a reason to have a counter instead
of just using -EIO.  So set it properly so we don't leak random numbers
to unsuspecting victims.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

We can submit IO in a processes context, which means there can be
pending signals.  This isn't a fatal error for NBD, but it does require
some finesse.  If the signal happens before we transmit anything then we
are ok, just requeue the request and carry on.  However if we've done a
partial transmit we can't allow anything else to be transmitted on this
socket until we transmit the remaining part of the request.  Deal with
this by keeping track of how much we've sent for the current request,
and if we get an ERESTARTSYS during any part of our transmission save
the state of that request and requeue the IO.  If anybody tries to
submit a request that isn't our pending request then requeue that
request until we are able to service the one that is pending.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

This was introduced in the multi-connection patch, we've been leaking
socket's ever since.

Fixes: 9561a7ad ("nbd: add multi-connection support")
cc: stable@vger.kernel.org
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

If we fail to register the blockdev we need to make sure to destroy the
recv workqueue.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

We noticed when trying to do O_DIRECT to an export on the server side
that we were getting requests smaller than the 4k sectorsize of the
device.  This is because the client isn't setting the logical and
physical blocksizes properly for the underlying device.  Fix this up by
setting the queue blocksizes and then calling bd_set_size.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Break the ioctl handling out into helper functions, some of these things
are getting pretty big and unwieldy.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

To prepare for dynamically adding new nbd devices to the system switch
from using an array for the nbd devices and instead use an idr.  This
copies what loop does for keeping track of its devices.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Since we are in the memory reclaim path we need our recv work to be on a
workqueue that has WQ_MEM_RECLAIM set so we can avoid deadlocks.  Also
set WQ_HIGHPRI since we are in the completion path for IO.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Instead of keeping two levels of indirection for requests types, fold it
all into the operations.  The little caveat here is that previously
cmd_type only applied to struct request, while the request and bio op
fields were set to plain REQ_OP_READ/WRITE even for passthrough
operations.

Instead this patch adds new REQ_OP_* for SCSI passthrough and driver
private requests, althought it has to add two for each so that we
can communicate the data in/out nature of the request.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

This is where we do the rest of the request handling, which will
become much simpler soon, too.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

Disconnects don't use block layer requests these days, so all handling
of private requests is dead code.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

A user noticed that write performance was horrible over loopback and we
traced it to an inversion of when we need to set MSG_MORE.  It should be
set when we have more bvec's to send, not when we are on the last bvec.
This patch made the test go from 20 iops to 78k iops.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Fixes: 429a787b ("nbd: fix use-after-free of rq/bio in the xmit path")
Signed-off-by: NJens Axboe <axboe@fb.com>

Additionally, don't assign directly to disk->queue, otherwise
blk_put_queue (called via put_disk) will choke (panic) on the errno
stored there.

Bug found by code inspection after Omar found a similar issue in
virtio_blk.  Compile-tested only.
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

... and don't mess with kmap() - just use BVEC_ITER for those parts.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Step 1 - don't reinintialize ->msg_iter on each iteration.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

This was entirely automated, using the script by Al:

  PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
  sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
        $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.
Requested-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

While doing stress tests we noticed that we'd get a lot of dmesg spam if
we suddenly disconnected the nbd device out of band.  Rate limit the
messages in the io path in order to deal with this.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

If an app exits before running NBD_DO_IT but after adding sockets we can
end up not being allowed to do a new nbd device.  Fix this by making
NBD_CLEAR_SOCK reset the setup_task.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

We have this:

ERROR: "__aeabi_ldivmod" [drivers/block/nbd.ko] undefined!
ERROR: "__divdi3" [drivers/block/nbd.ko] undefined!
nbd.c:(.text+0x247c72): undefined reference to `__divdi3'

due to a recent commit, that did 64-bit division. Use the proper
divider function so that 32-bit compiles don't break.

Fixes: ef77b515 ("nbd: use loff_t for blocksize and nbd_set_size args")
Signed-off-by: NJens Axboe <axboe@fb.com>

If we have large devices (say like the 40t drive I was trying to test with) we
will end up overflowing the int arguments to nbd_set_size and not get the right
size for our device.  Fix this by using loff_t everywhere so I don't have to
think about this again.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Multiple paths don't set it properly, ensure that we do.

Fixes: 9561a7ad ("nbd: add multi-connection support")
Signed-off-by: NJens Axboe <axboe@fb.com>

NBD can become contended on its single connection.  We have to serialize all
writes and we can only process one read response at a time.  Fix this by
allowing userspace to provide multiple connections to a single nbd device.  This
coupled with block-mq drastically increases performance in multi-process cases.
Thanks,
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

For writes, we can get a completion in while we're still iterating
the request and bio chain. If that happens, we're reading freed
memory and we can crash.

Break out after the last segment and avoid having the iterator
read freed memory.
Reviewed-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

'blk_mq_alloc_request()' returns an error pointer in case of error, not
NULL. So test it with IS_ERR.

Fixes: 	fd8383fd ("nbd: convert to blkmq")
Signed-off-by: NChristophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: NJens Axboe <axboe@fb.com>

Commit 0eadf37a ("nbd: allow block mq to deal with timeouts")
changed normal usage of nbd->sock_lock to use spin_lock/spin_unlock
rather than the *_irq variants, but it missed this unlock in an
error path.

Found by Coverity, CID 1373871.
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Markus Pargmann <mpa@pengutronix.de>
Fixes: 0eadf37a ("nbd: allow block mq to deal with timeouts")
Signed-off-by: NJens Axboe <axboe@fb.com>

We take a mutex when sending commands and send stuff over the network, we need
to have queue_rq called asynchronously.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Fixes: fd8383fd ("nbd: convert to blkmq")
Signed-off-by: NJens Axboe <axboe@fb.com>

Instead of rolling our own timer, just utilize the blk mq req timeout and do the
disconnect if any of our commands timeout.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

In preparation for some future changes, change a few of the state bools over to
normal bits to set/clear properly.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

We hit a warning when shutting down the nbd connection because we have irq's
disabled.  We don't really need to do the shutdown under the lock, just clear
the nbd->sock.  So do the shutdown outside of the irq.  This gets rid of the
warning.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

This moves NBD over to using blkmq, which allows us to get rid of the NBD
wide queue lock and the async submit kthread.  We will start with 1 hw
queue for now, but I plan to add multiple tcp connection support in the
future and we'll fix how we set the hwqueue's.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Quentin ran into this bug:

WARNING: CPU: 64 PID: 10085 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x65/0x80
sysfs: cannot create duplicate filename '/devices/virtual/block/nbd3/pid'
Modules linked in: nbd
CPU: 64 PID: 10085 Comm: qemu-nbd Tainted: G      D         4.6.0+ #7
 0000000000000000 ffff8820330bba68 ffffffff814b8791 ffff8820330bbac8
 0000000000000000 ffff8820330bbab8 ffffffff810d04ab ffff8820330bbaa8
 0000001f00000296 0000000000017681 ffff8810380bf000 ffffffffa0001790
Call Trace:
 [<ffffffff814b8791>] dump_stack+0x4d/0x6c
 [<ffffffff810d04ab>] __warn+0xdb/0x100
 [<ffffffff810d0574>] warn_slowpath_fmt+0x44/0x50
 [<ffffffff81218c65>] sysfs_warn_dup+0x65/0x80
 [<ffffffff81218a02>] sysfs_add_file_mode_ns+0x172/0x180
 [<ffffffff81218a35>] sysfs_create_file_ns+0x25/0x30
 [<ffffffff81594a76>] device_create_file+0x36/0x90
 [<ffffffffa0000e8d>] __nbd_ioctl+0x32d/0x9b0 [nbd]
 [<ffffffff814cc8e8>] ? find_next_bit+0x18/0x20
 [<ffffffff810f7c29>] ? select_idle_sibling+0xe9/0x120
 [<ffffffff810f6cd7>] ? __enqueue_entity+0x67/0x70
 [<ffffffff810f9bf0>] ? enqueue_task_fair+0x630/0xe20
 [<ffffffff810efa76>] ? resched_curr+0x36/0x70
 [<ffffffff810f0078>] ? check_preempt_curr+0x78/0x90
 [<ffffffff810f00a2>] ? ttwu_do_wakeup+0x12/0x80
 [<ffffffff810f01b1>] ? ttwu_do_activate.constprop.86+0x61/0x70
 [<ffffffff810f0c15>] ? try_to_wake_up+0x185/0x2d0
 [<ffffffff810f0d6d>] ? default_wake_function+0xd/0x10
 [<ffffffff81105471>] ? autoremove_wake_function+0x11/0x40
 [<ffffffffa0001577>] nbd_ioctl+0x67/0x94 [nbd]
 [<ffffffff814ac0fd>] blkdev_ioctl+0x14d/0x940
 [<ffffffff811b0da2>] ? put_pipe_info+0x22/0x60
 [<ffffffff811d96cc>] block_ioctl+0x3c/0x40
 [<ffffffff811ba08d>] do_vfs_ioctl+0x8d/0x5e0
 [<ffffffff811aa329>] ? ____fput+0x9/0x10
 [<ffffffff810e9092>] ? task_work_run+0x72/0x90
 [<ffffffff811ba627>] SyS_ioctl+0x47/0x80
 [<ffffffff8185f5df>] entry_SYSCALL_64_fastpath+0x17/0x93
---[ end trace 7899b295e4f850c8 ]---

It seems fairly obvious that device_create_file() is not being protected
from being run concurrently on the same nbd.

Quentin found the following relevant commits:

1a2ad211 nbd: add locking to nbd_ioctl
90b8f282 [PATCH] end of methods switch: remove the old ones
d4430d62 [PATCH] beginning of methods conversion
08f85851 [PATCH] move block_device_operations to blkdev.h

It would seem that the race was introduced in the process of moving nbd
from BKL to unlocked ioctls.

By setting nbd->task_recv while the mutex is held, we can prevent other
processes from running concurrently (since nbd->task_recv is also checked
while the mutex is held).
Reported-and-tested-by: NQuentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Markus Pargmann <mpa@pengutronix.de>
Cc: Paul Clements <paul.clements@steeleye.com>
Cc: Pavel Machek <pavel@suse.cz>
Cc: Jens Axboe <axboe@fb.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NVegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

We were passing in &nbd for the private data in debugfs_create_file() for the
flags entry.  We expect it to just be nbd, fix this so we get proper output from
this debugfs entry.
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

This adds a REQ_OP_FLUSH operation that is sent to request_fn
based drivers by the block layer's flush code, instead of
sending requests with the request->cmd_flags REQ_FLUSH bit set.
Signed-off-by: NMike Christie <mchristi@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

The req operation REQ_OP is separated from the rq_flag_bits
definition. This converts the block layer drivers to
use req_op to get the op from the request struct.
Signed-off-by: NMike Christie <mchristi@redhat.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Signed-off-by: NJens Axboe <axboe@fb.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

The do_div() macro now checks its arguments for the correct type,
and refuses anything other than u64, so we get a warning about
nbd_ioctl passing in an loff_t:

drivers/block/nbd.c: In function '__nbd_ioctl':
drivers/block/nbd.c:757:77: error: comparison of distinct pointer types lacks a cast [-Werror]

This changes the nbd code to use div_s64() instead, which takes
a signed argument.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Fixes: 37091fdd ("nbd: Create size change events for userspace")
Signed-off-by: NJens Axboe <axboe@fb.com>

The userspace needs to know when nbd devices are ready for use.
Currently no events are created for the userspace which doesn't work for
systemd.

See the discussion here: https://github.com/systemd/systemd/pull/358

This patch uses a central point to setup the nbd-internal sizes. A ioctl
to set a size does not lead to a visible size change. The size of the
block device will be kept at 0 until nbd is connected. As soon as it
connects, the size will be changed to the real value and a uevent is
created. When disconnecting, the blockdevice is set to 0 size and
another uevent is generated.
Signed-off-by: NMarkus Pargmann <mpa@pengutronix.de>

Make the "Attempted send on closed socket" error messages generated in
nbd_request_handler() ratelimited.

When the nbd socket is shutdown, the nbd_request_handler() function emits
an error message for every request remaining in its queue.  If the queue
is large, this will spam a large amount of messages to the log.  There's
no need for a separate error message for each request, so this patch
ratelimits it.

In the specific case this was found, the system was virtual and the error
messages were logged to the serial port, which overwhelmed it.

Fixes: 4d48a542 ("nbd: fix I/O hang on disconnected nbds")
Signed-off-by: NDan Streetman <dan.streetman@canonical.com>
Signed-off-by: NMarkus Pargmann <mpa@pengutronix.de>