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38 commits

Author SHA1 Message Date
Jens Axboe
89c63a8ef3 Merge branch 'stable/for-jens' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen into for-linus 2011-08-23 15:09:13 +02:00
Joe Jin
1bc05b0ae6 xen-blkback: fixed indentation and comments
This patch fixes belows:

1. Fix code style issue.
2. Fix incorrect functions name in comments.

Signed-off-by: Joe Jin <joe.jin@oracle.com>
Cc: Jens Axboe <jaxboe@fusionio.com>
Cc: Ian Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-08-22 11:35:36 -04:00
Joe Jin
6f5986bce5 xen-blkback: Don't disconnect backend until state switched to XenbusStateClosed.
When do block-attach/block-detach test with below steps, umount hangs
in the guest. Furthermore shutdown ends up being stuck when umounting file-systems.

1. start guest.
2. attach new block device by xm block-attach in Dom0.
3. mount new disk in guest.
4. execute xm block-detach to detach the block device in dom0 until timeout
5. Any request to the disk will hung.

Root cause:
This issue is caused when setting backend device's state to
'XenbusStateClosing', which sends to the frontend the XenbusStateClosing
notification. When frontend receives the notification it tries to release
the disk in blkfront_closing(), but at that moment the disk is still in use
by guest, so frontend refuses to close. Specifically it sets the disk state to
XenbusStateClosing and sends the notification to backend - when backend receives the
event, it disconnects the vbd from real device, and sets the vbd device state to
XenbusStateClosing. The backend disconnects the real device/file, and any IO
requests to the disk in guest will end up in ether, leaving disk DEAD and set to
XenbusStateClosing. When the guest wants to disconnect the disk, umount will
hang on blkif_release()->xlvbd_release_gendisk() as it is unable to send any IO
to the disk, which prevents clean system shutdown.

Solution:
Don't disconnect backend until frontend state switched to XenbusStateClosed.

Signed-off-by: Joe Jin <joe.jin@oracle.com>
Cc: Daniel Stodden <daniel.stodden@citrix.com>
Cc: Jens Axboe <jaxboe@fusionio.com>
Cc: Annie Li <annie.li@oracle.com>
Cc: Ian Campbell <Ian.Campbell@eu.citrix.com>
[v1: Modified description a bit]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-08-22 11:35:35 -04:00
Linus Torvalds
8ded371f81 Merge branch 'for-3.1/drivers' of git://git.kernel.dk/linux-block
* 'for-3.1/drivers' of git://git.kernel.dk/linux-block:
  cciss: do not attempt to read from a write-only register
  xen/blkback: Add module alias for autoloading
  xen/blkback: Don't let in-flight requests defer pending ones.
  bsg: fix address space warning from sparse
  bsg: remove unnecessary conditional expressions
  bsg: fix bsg_poll() to return POLLOUT properly
2011-07-25 10:38:18 -07:00
Bastian Blank
a7e9357f10 xen/blkback: Add module alias for autoloading
Add xen-backend:vbd module alias to the xen-blkback module. This allows
automatic loading of the module.

Signed-off-by: Bastian Blank <waldi@debian.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-06-30 12:48:25 -04:00
Daniel Stodden
b4726a9df2 xen/blkback: Don't let in-flight requests defer pending ones.
Running RING_FINAL_CHECK_FOR_REQUESTS from make_response is a bad
idea. It means that in-flight I/O is essentially blocking continued
batches. This essentially kills throughput on frontends which unplug
(or even just notify) early and rightfully assume addtional requests
will be picked up on time, not synchronously.

Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
[v1: Rebased and fixed compile problems]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-06-30 12:48:06 -04:00
Joe Perches
08b8bfc1c6 xen: Add __attribute__((format(printf... where appropriate
Use the compiler to verify printf formats and arguments.

Fix fallout.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-06-30 12:14:40 -04:00
Dan Carpenter
9b83c77121 xen/blkback: potential null dereference in error handling
blkbk->pending_pages can be NULL here so I added a check for it.

Signed-off-by: Dan Carpenter <error27@gmail.com>
[v1: Redid the loop a bit]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-06-01 09:28:21 -04:00
Laszlo Ersek
6464920a6e xen/blkback: don't call vbd_size() if bd_disk is NULL
...because vbd_size() dereferences bd_disk if bd_part is NULL.

Signed-off-by: Laszlo Ersek<lersek@redhat.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-06-01 09:28:20 -04:00
Jan Beulich
8ab521506c xen/blkback: don't fail empty barrier requests
The sector number on empty barrier requests may (will?) be -1, which,
given that it's being treated as unsigned 64-bit quantity, will almost
always exceed the actual (virtual) disk's size.

Inspired by Konrad's "When writting barriers set the sector number to
zero...".

While at it also add overflow checking to the math in vbd_translate().

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-18 11:28:16 -04:00
Laszlo Ersek
496b318eb6 xen/blkback: fix xenbus_transaction_start() hang caused by double xenbus_transaction_end()
vbd_resize() up_read()'s xs_state.suspend_mutex twice in a row via double
xenbus_transaction_end() calls. The next down_read() in
xenbus_transaction_start() (at eg. the next resize attempt) hangs.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=618317

Acked-by: Jan Beulich <jbeulich@novell.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-13 09:45:40 -04:00
Konrad Rzeszutek Wilk
5185432277 xen/blkback: Align the tabs on the structure.
The recent changes caused this field of the structure to be offset a bit.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 18:02:28 -04:00
Konrad Rzeszutek Wilk
cca537af7d xen/blkback: if log_stats is enabled print out the data.
And not depend on the driver being built with -DDEBUG flag.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 17:55:54 -04:00
Konrad Rzeszutek Wilk
5a577e3872 xen/blkback: Add the prefix XEN in the common.h.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 17:55:53 -04:00
Konrad Rzeszutek Wilk
3d814731ba xen/blkback: Prefix 'vbd' with 'xen' in structs and functions.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 17:55:52 -04:00
Konrad Rzeszutek Wilk
30fd150202 xen/blkback: Change structure name blkif_st to xen_blkif.
No need for that '_st' and xen_blkif is more apt.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 17:55:51 -04:00
Konrad Rzeszutek Wilk
325a648604 xen/blkback: Remove the unused typedefs.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 17:55:50 -04:00
Konrad Rzeszutek Wilk
452a6b2bb6 xen/blkback: Move include/xen/blkif.h into drivers/block/xen-blkback/common.h
Not point of the blkif.h file. It is not used by the frontend.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 17:55:49 -04:00
Konrad Rzeszutek Wilk
b0f801273f xen/blkback: Fixing some more of the cleanpatch.pl warnings.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 17:55:48 -04:00
Konrad Rzeszutek Wilk
03e0edf946 xen/blkback: Checkpatch.pl recommend against multiple assigments.
CHECK: multiple assignments should be avoided

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 17:55:47 -04:00
Konrad Rzeszutek Wilk
b9fc02968c xen/blkback: Fix spelling mistakes.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 16:43:21 -04:00
Konrad Rzeszutek Wilk
68c88dd7d3 xen/blkback: Move blkif_get_x86_[32|64]_req to common.h in block/xen-blkback dir.
From the blkif.h header, which was exposed to the frontend.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 16:43:20 -04:00
Konrad Rzeszutek Wilk
72468bfcb8 xen/blkback: Removing the debug_lvl option.
It is not really used for anything.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 16:43:20 -04:00
Konrad Rzeszutek Wilk
22b20f2dff xen/blkback: Use the DRV_PFX in the pr_.. macros.
To make it easier to read.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 16:43:12 -04:00
Konrad Rzeszutek Wilk
1afbd730a3 xen/blkback: Make the DPRINTK uniform.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 16:42:51 -04:00
Konrad Rzeszutek Wilk
ebe8190659 xen/blkback: Change printk/DPRINTK to pr_.. type variant.
And also make them uniform and prefix the message with 'xen-blkback'.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-12 16:42:31 -04:00
Konrad Rzeszutek Wilk
01f37f2d53 xen/blkback: Fixed up comments and converted spaces to tabs.
Suggested-by: Ian Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-11 15:57:09 -04:00
Konrad Rzeszutek Wilk
3d68b39926 xen/blkback: Fix up some of the comments.
They had the wrong data or were in the wrong spot.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-05 13:43:26 -04:00
Konrad Rzeszutek Wilk
fc53bf757e xen/blkback: Squash the checking for operation into dispatch_rw_block_io
We do a check for the operations right before calling dispatch_rw_block_io.
And then we do the same check in dispatch_rw_block_io. This patch
squashes those checks into the 'dispatch_rw_block_io' function.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-05 13:43:25 -04:00
Konrad Rzeszutek Wilk
24f567f952 xen/blkback: Add support for BLKIF_OP_FLUSH_DISKCACHE and drop BLKIF_OP_WRITE_BARRIER.
We drop the support for 'feature-barrier' and add in the support
for the 'feature-flush-cache' if the real backend storage supports
flushing.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-05-05 13:43:24 -04:00
Konrad Rzeszutek Wilk
a19be5f0f0 Revert "xen/blkback: Move the plugging/unplugging to a higher level."
This reverts commit 97961ef46b b/c
we lose about 15% performance if we do the unplugging and the
end of the reading the ring buffer.
2011-04-27 12:40:11 -04:00
Konrad Rzeszutek Wilk
013c3ca184 xen/blkback: Stick REQ_SYNC on WRITEs to deal with CFQ I/O scheduler.
If one runs a simple fio request with random read/write with a
20%/80% ratio, the numbers are incredibly bad when using the CFQ scheduler.

IOmeter       |       |      |          |
64K, randrw   |  NOOP | CFQ  | deadline |
randrwmix=80  |       |      |          |
--------------+-------+------+----------+
blkback       |103/27 |32/10 | 102/27   |
--------------+-------+------+----------+
QEMU qdisk    |103/27 |102/27| 102/27   |

The problem as explained by Vivek Goyal was:

".. that difference is that sync vs async requests. In the case of
a kernel thread submitting IO, [..] all the WRITES might be being
considered as async and will go in a different queue. If you mix those
with some READS, they are always sync and will go in differnet queue.
In presence of sync queue, CFQ will idle and choke up WRITES in
an attempt to improve latencies of READs.

In case of AIO [note: this is what QEMU qdisk is doing] , [..]
it is direct IO and both READS and WRITES will be considered SYNC
and will go in a single queue and no choking of WRITES will take place."

The solution is quite simple, tack on REQ_SYNC (which is
what the WRITE_ODIRECT macro points to) and the numbers go
back up.

Suggested-by: Vivek Goyal <vgoyal@redhat.com
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-04-26 16:24:18 -04:00
Konrad Rzeszutek Wilk
97961ef46b xen/blkback: Move the plugging/unplugging to a higher level.
We used to the plug/unplug on the submit_bio. But that means
if within a stream of WRITE, WRITE, WRITE,...,WRITE we have
one READ, it could stall the pipeline (as the 'submio_bio'
could trigger the unplug_fnc to be called and stall/sync
when doing the READ). Instead we want to move the unplugging
when the whole (or as a much as possible) ring buffer has been
processed. This also eliminates us doing plug/unplug for
each request.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-04-26 13:01:32 -04:00
Konrad Rzeszutek Wilk
8b6bf747d7 xen/blkback: Prefix exposed functions with xen_
And also shorten the name if it has blkback to blkbk.

This results in the symbol table (if compiled in the kernel)
to be much shorter, prettier,  and also easier to search for.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-04-20 11:58:03 -04:00
Konrad Rzeszutek Wilk
42c7841d17 xen-blkback: Inline some of the functions that were moved from vbd/interface.c
Shuffling code around.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-04-20 11:58:02 -04:00
Konrad Rzeszutek Wilk
6cd0388cd6 xen-blkback: Remove from the copyright notice the address.
There is no need for it, as the address is updated constatly
in the root of the Linux kernel.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-04-20 11:58:01 -04:00
Konrad Rzeszutek Wilk
ee9ff8537e xen/blkback: Squash vbd.c,interface.c in blkback.c and xenbus.c respectivly.
Daniel Stodden suggested to eliminate vbd.c and interface.c, inlining the
critical bits where they belong, respectively.

Leaving only blkback.c for the data- and xenbus.c for the control path.

Suggested-by:  Daniel Stodden <daniel.stodden@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-04-20 11:57:59 -04:00
Konrad Rzeszutek Wilk
dfc07b13dc xen/blkback: Move it from drivers/xen to drivers/block
.. and modify the Makefile and Kconfig files appropriately.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-04-18 14:30:26 -04:00