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Commit Graph

110722 Commits

Author SHA1 Message Date
Mikulas Patocka
a481db7846 dm exception store: introduce area_location function
Move this logic to a function, because it will be reused later.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-10-10 13:37:00 +01:00
Jonathan Brassow
f7c83e2e47 dm raid1: kcopyd should stop on error if errors handled
dm-raid1 is setting the 'DM_KCOPYD_IGNORE_ERROR' flag unconditionally
when assigning kcopyd work.  kcopyd is responsible for copying an
assigned section of disk to one or more other disks.  The
'DM_KCOPYD_IGNORE_ERROR' flag affects kcopyd in the following way:

When not set:
kcopyd will immediately stop the copy operation when an error is
encountered.

When set:
kcopyd will try to proceed regardless of errors and try to continue
copying any remaining amount.

Since dm-raid1 tracks regions of the address space that are (or
are not) in sync and it now has the ability to handle these
errors, we can safely enable this optimization.  This optimization
is conditional on whether mirror error handling has been enabled.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-10-10 13:36:59 +01:00
Kiyoshi Ueda
6680073d3e dm mpath: remove is_active from struct dm_path
This patch moves 'is_active' from struct dm_path to struct pgpath
as it does not need exporting.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-10-10 13:36:58 +01:00
Benjamin Marzinski
01460f3520 dm mpath: use more error codes
This patch allows path errors from the multipath ctr function to
propagate up to userspace as errno values from the ioctl() call.

This is in response to
  https://www.redhat.com/archives/dm-devel/2008-May/msg00000.html
and
  https://bugzilla.redhat.com/show_bug.cgi?id=444421

The patch only lets through the errors that it needs to in order to
get the path errors from parse_path().

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-10-10 13:36:57 +01:00
Randy Dunlap
b911e473d2 doc/cdrom: Trvial documentation error, file not present
The sbpcd tester program is not included in the kernel source tree,
so remove the reference to it.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Reported-by: Nick Warne <nick@ukfsn.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-10 08:22:44 +02:00
Roland Dreier
eedd5d0a70 Merge branches 'cma', 'cxgb3', 'ehca', 'ipath', 'ipoib', 'mad', 'misc', 'mlx4', 'mthca' and 'nes' into for-next 2008-10-09 17:41:15 -07:00
Chien Tung
fbcffcc6a0 RDMA/nes: Fix slab corruption
Referencing cm_node after it is freed via rem_ref_cm_node() causes a
slab corruption.  There is no need to set cm_node->cm_id to NULL in
mini_cm_close().

Signed-off-by: Chien Tung <ctung@neteffect.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
2008-10-09 17:41:05 -07:00
Linus Torvalds
3fa8749e58 Linux 2.6.27 2008-10-09 15:13:53 -07:00
Linus Torvalds
efc968d450 Don't allow splice() to files opened with O_APPEND
This is debatable, but while we're debating it, let's disallow the
combination of splice and an O_APPEND destination.

It's not entirely clear what the semantics of O_APPEND should be, and
POSIX apparently expects pwrite() to ignore O_APPEND, for example.  So
we could make up any semantics we want, including the old ones.

But Miklos convinced me that we should at least give it some thought,
and that accepting writes at arbitrary offsets is wrong at least for
IS_APPEND() files (which always have O_APPEND set, even if the reverse
isn't true: you can obviously have O_APPEND set on a regular file).

So disallow O_APPEND entirely for now.  I doubt anybody cares, and this
way we have one less gray area to worry about.

Reported-and-argued-for-by: Miklos Szeredi <miklos@szeredi.hu>
Acked-by: Jens Axboe <ens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-09 14:26:38 -07:00
Linus Torvalds
07f4055418 Merge branch 'hwmon-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6
* 'hwmon-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6:
  hwmon: (abituguru3) Enable DMI probing feature on Abit AT8 32X
  hwmon: (abituguru3) Enable reading from AUX3 fan on Abit AT8 32X
  hwmon: (adt7473) Fix some bogosity in documentation file
  hwmon: Define sysfs interface for energy consumption register
  hwmon: (it87) Prevent power-off on Shuttle SN68PT
  eeepc-laptop: Fix hwmon interface
2008-10-09 12:23:54 -07:00
Linus Torvalds
9283dfed51 Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq:
  [CPUFREQ] correct broken links and email addresses
2008-10-09 12:23:35 -07:00
Matt Mackall
70096a561d SLOB: fix bogus ksize calculation fix
This fixes the previous fix, which was completely wrong on closer
inspection. This version has been manually tested with a user-space
test harness and generates sane values. A nearly identical patch has
been boot-tested.

The problem arose from changing how kmalloc/kfree handled alignment
padding without updating ksize to match. This brings it in sync.

Signed-off-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-09 12:18:27 -07:00
Németh Márton
8d59225720 [CPUFREQ] correct broken links and email addresses
Replace the no longer working links and email address in the
documentation and in source code.

Signed-off-by: Márton Németh <nm127@freemail.hu>
Signed-off-by: Dave Jones <davej@redhat.com>
2008-10-09 13:52:40 -04:00
Alistair John Strachan
5e5cddbc3f hwmon: (abituguru3) Enable DMI probing feature on Abit AT8 32X
Enable driver checking of the DMI product name (when enabled) on
an Abit AT8 32X, instead of falling back to a manual probe. This
eliminates false negatives and eventually will help avoid
unnecessary bus probes on unsupported mainboards.

Signed-off-by: Alistair John Strachan <alistair@devzero.co.uk>
Tested-by: Daniel Exner <dex@dragonslave.de>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-10-09 15:33:59 +02:00
Alistair John Strachan
8748a71e8c hwmon: (abituguru3) Enable reading from AUX3 fan on Abit AT8 32X
The table for the Abit AT8 32X was incorrectly missing an entry
for the sixth ("AUX3") fan. Add this entry, exporting the fan
reading to userspace.

Closes lm-sensors.org ticket #2339.

Signed-off-by: Alistair John Strachan <alistair@devzero.co.uk>
Tested-by: Daniel Exner <dex@dragonslave.de>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-10-09 15:33:59 +02:00
Darrick J. Wong
c73c556c1a hwmon: (adt7473) Fix some bogosity in documentation file
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-10-09 15:33:58 +02:00
Darrick J. Wong
ddedc658fc hwmon: Define sysfs interface for energy consumption register
Describe the sysfs files that were introduced in the ibmaem driver.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-10-09 15:33:58 +02:00
Jean Delvare
98dd22c3e0 hwmon: (it87) Prevent power-off on Shuttle SN68PT
On the Shuttle SN68PT, FAN_CTL2 is apparently not connected to a fan,
but to something else. One user has reported instant system power-off
when changing the PWM2 duty cycle, so we disable it.

I use the board name string as the trigger in case the same board is
ever used in other systems.

This closes lm-sensors ticket #2349:
pwmconfig causes a hard poweroff
http://www.lm-sensors.org/ticket/2349

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-10-09 15:33:58 +02:00
Corentin Chary
04dcd84bc7 eeepc-laptop: Fix hwmon interface
Creates a name file in the sysfs directory, that
is needed for the libsensors library to work.
Also rename fan1_pwm to pwm1 and scale its value as needed.

This fixes bug #11520:
http://bugzilla.kernel.org/show_bug.cgi?id=11520

Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
2008-10-09 15:33:57 +02:00
Randy Dunlap
57d1b5366f block_dev: fix kernel-doc in new functions
Fix kernel-doc in new functions:

Error(mmotm-2008-1002-1617//fs/block_dev.c:895): duplicate section name 'Description'
Error(mmotm-2008-1002-1617//fs/block_dev.c:924): duplicate section name 'Description'
Warning(mmotm-2008-1002-1617//fs/block_dev.c:1282): No description found for parameter 'pathname'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
cc: Andrew Patterson <andrew.patterson@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 10:42:38 +02:00
Jens Axboe
af56394240 block: add some comments around the bio read-write flags
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 09:01:10 +02:00
Denis ChengRq
6feef531f5 block: mark bio_split_pool static
Since all bio_split calls refer the same single bio_split_pool, the bio_split
function can use bio_split_pool directly instead of the mempool_t parameter;

then the mempool_t parameter can be removed from bio_split param list, and
bio_split_pool is only referred in fs/bio.c file, can be marked static.

Signed-off-by: Denis ChengRq <crquan@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:57:05 +02:00
Martin K. Petersen
ad3316bf4e block: Find bio sector offset given idx and offset
Helper function to find the sector offset in a bio given bvec index
and page offset.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:22 +02:00
Martin K. Petersen
b02739b01c block: gendisk integrity wrapper
This is a wrapper for accessing a gendisk's integrity bits.  It allows
the integrity support in MD to be compiled with BLK_DEV_INTEGRITY off.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:22 +02:00
Martin K. Petersen
ad7fce9314 block: Switch blk_integrity_compare from bdev to gendisk
The DM and MD integrity support now depends on being able to use
gendisks instead of block_devices when comparing integrity profiles.
Change function parameters accordingly.

Also update comparison logic so that two NULL profiles are a valid
configuration.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:21 +02:00
Martin K. Petersen
0c032ab889 block: Fix double put in blk_integrity_unregister
- kobject_del already puts the parent.

 - Set integrity profile to NULL to prevent stale data.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:21 +02:00
Martin K. Petersen
74aa8c2cc0 block: Introduce integrity data ownership flag
A filesystem might supply its own integrity metadata.  Introduce a
flag that indicates whether the filesystem or the block layer owns the
integrity buffer.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:21 +02:00
Jens Axboe
b04accc425 block: revert part of d7533ad0e132f92e75c1b2eb7c26387b25a583c1
We need bdev_get_integrity() to support the pending md/dm patches.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:21 +02:00
Alberto Bertogli
8deaf72107 bio.h: Remove unused conditional code
The whole bio_integrity() definition is inside an #ifdef
CONFIG_BLK_DEV_INTEGRITY, there's no need for the conditional code.

Signed-off-by: Alberto Bertogli <albertito@blitiri.com.ar>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:21 +02:00
Kiyoshi Ueda
d00e29fd99 block: remove end_{queued|dequeued}_request()
This patch removes end_queued_request() and end_dequeued_request(),
which are no longer used.

As a results, users of __end_request() became only end_request().
So the actual code in __end_request() is moved to end_request()
and __end_request() is removed.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:21 +02:00
Kiyoshi Ueda
99cd3386f2 block: change elevator to use __blk_end_request()
This patch converts elevator to use __blk_end_request() directly
so that end_{queued|dequeued}_request() can be removed.
Related 'uptodate' arguments is converted to 'error'.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:21 +02:00
Kiyoshi Ueda
7afb3a6e75 gdrom: change to use __blk_end_request()
This patch converts gdrom to use __blk_end_request() directly
so that end_{queued|dequeued}_request() can be removed.

gd.transfer is '1' in error cases and '0' in non-error cases,
so gdrom hasn't been propagating any error code to the block layer.
We can just convert error cases to '-EIO'.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Adrian McMenamin <adrian@mcmen.demon.co.uk>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:21 +02:00
Kiyoshi Ueda
2a9df5055a memstick: change to use __blk_end_request()
This patch converts memstick to use __blk_end_request() directly
so that end_{queued|dequeued}_request() can be removed.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Alex Dubov <oakad@yahoo.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:20 +02:00
Kiyoshi Ueda
8316982ac0 virtio_blk: change to use __blk_end_request()
This patch converts virtio_blk to use __blk_end_request() directly
so that end_{queued|dequeued}_request() can be removed.
Related 'uptodate' argument is converted to 'error'.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:20 +02:00
Jens Axboe
0497b345e7 blktrace: use BLKTRACE_BDEV_SIZE as the name size for setup structure
Define as 32, which is is what BDEVNAME_SIZE is/was as well. This keeps
the user interface the same and gets rid of the difference between
kernel and user api here.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:20 +02:00
Kiyoshi Ueda
ef9e3facdf block: add lld busy state exporting interface
This patch adds an new interface, blk_lld_busy(), to check lld's
busy state from the block layer.
blk_lld_busy() calls down into low-level drivers for the checking
if the drivers set q->lld_busy_fn() using blk_queue_lld_busy().

This resolves a performance problem on request stacking devices below.

Some drivers like scsi mid layer stop dispatching request when
they detect busy state on its low-level device like host/target/device.
It allows other requests to stay in the I/O scheduler's queue
for a chance of merging.

Request stacking drivers like request-based dm should follow
the same logic.
However, there is no generic interface for the stacked device
to check if the underlying device(s) are busy.
If the request stacking driver dispatches and submits requests to
the busy underlying device, the requests will stay in
the underlying device's queue without a chance of merging.
This causes performance problem on burst I/O load.

With this patch, busy state of the underlying device is exported
via q->lld_busy_fn().  So the request stacking driver can check it
and stop dispatching requests if busy.

The underlying device driver must return the busy state appropriately:
    1: when the device driver can't process requests immediately.
    0: when the device driver can process requests immediately,
       including abnormal situations where the device driver needs
       to kill all requests.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:20 +02:00
Elias Oltmanns
336c3d8ce7 block: Fix blk_start_queueing() to not kick a stopped queue
blk_start_queueing() should act like the generic queue unplugging
and kicking and ignore a stopped queue. Such a queue may not be
run until after a call to blk_start_queue().

Signed-off-by: Elias Oltmanns <eo@nebensachen.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:20 +02:00
Sven Schuetz
c0ddffa84a include blktrace_api.h in headers_install
This header file is of interest for user space programming, i.e.
for tools that process blktrace data.

We would like to use it for a tool on-top of blktrace which processes
data provided by blktrace. For this purpose, it would be helpful
if the blktrace API would make it to /usr/include/linux.

The git tree for the blktrace tools comes with its own copy of this header
file. I didn't manage to replace that copy with the file generated
by the patch below yet. A few more cleanups would be needed.
For example, the blktrace ioctl numbers, which are currently defined in
usr/include/fs.h, might need to be moved. Should be feasible, though.

Signed-off-by: Sven Schuetz <sven@linux.vnet.ibm.com>
Signed-off-by: Martin Peschke <mp3@de.ibm.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:19 +02:00
Jens Axboe
e3ba9ae58a block: reserve some tags just for sync IO
By only allowing async IO to consume 3/4 ths of the tag depth, we
always have slots free to serve sync IO. This is important to avoid
having writes fill the entire tag queue, thus starving reads.

Original patch and idea from Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:19 +02:00
Jens Axboe
f7d7b7a7a3 block: as/cfq ssd idle check update
We really need to know about the hardware tagging support as well,
since if the SSD does not do tagging then we still want to idle.
Otherwise have the same dependent sync IO vs flooding async IO
problem as on rotational media.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:19 +02:00
Jens Axboe
8bff7c6b0f libata: set queue SSD flag for SSD devices
SSD devices should give an RPM setting of 1 in word 217 of the ID
page. If we see such a device, tell the block layer about it.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:19 +02:00
Jens Axboe
a68bbddba4 block: add queue flag for SSD/non-rotational devices
We don't want to idle in AS/CFQ if the device doesn't have a seek
penalty. So add a QUEUE_FLAG_NONROT to indicate a non-rotational
device, low level drivers should set this flag upon discovery of
an SSD or similar device type.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:19 +02:00
Keith Wansbrough
9e49184c82 floppy: support arbitrary first-sector numbers
The current floppy_struct allows floppies to number sectors starting
from 0 or 1.  This patch allows arbitrary first-sector numbers - for
example, 0xC1 for Amstrad CPC disks.

This extends the existing 1-bit field (FD_ZEROBASED, bit 2 of stretch)
to 8 bits (FD_SECTMASK, bits 2 to 9).

Currently 0x00 denotes a first sector number of 1, and 0x01 denotes a
first sector number of 0.  We extend this by interpreting FD_SECTMASK
as the first sector number with the LSB flipped.

Signed-off-by: Keith Wansbrough <keith@lochan.org>
Cc: Alain Knaff <alain@linux.lu>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: Karel Zak <kzak@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:19 +02:00
Julia Lawall
061837bc86 drivers/block: Use DIV_ROUND_UP
The kernel.h macro DIV_ROUND_UP performs the computation (((n) + (d) - 1) /
(d)) but is perhaps more readable.

An extract of the semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@haskernel@
@@

#include <linux/kernel.h>

@depends on haskernel@
expression n,d;
@@

(
- (n + d - 1) / d
+ DIV_ROUND_UP(n,d)
|
- (n + (d - 1)) / d
+ DIV_ROUND_UP(n,d)
)

@depends on haskernel@
expression n,d;
@@

- DIV_ROUND_UP((n),d)
+ DIV_ROUND_UP(n,d)

@depends on haskernel@
expression n,d;
@@

- DIV_ROUND_UP(n,(d))
+ DIV_ROUND_UP(n,d)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Cc: <mike.miller@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:19 +02:00
scameron@beardog.cca.cpqcorp.net
905bd78f21 cciss: Fix cciss SCSI rescan code to better notice device changes
Fix cciss SCSI rescan code to better notice device changes.
If you hot-unplug a tape drive, then hot-plug a different
tape drive into the same slot in a storage enclosure,
the cciss driver wouldn't notice anything had changed, as
it was only looking at the LUN address and device type.
Now it looks at the inquiry page 0x83 device identifier,
and vendor and model strings as well.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cca.cpqcorp.net>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:18 +02:00
FUJITA Tomonori
79eb014578 fix an example of scatterlists handling in DMA-API.txt
This example isn't the proper way to handle scatterlists (can't handle
sg chaining).

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:18 +02:00
Kiyoshi Ueda
4ee5eaf451 block: add a queue flag for request stacking support
This patch adds a queue flag to indicate the block device can be
used for request stacking.

Request stacking drivers need to stack their devices on top of
only devices of which q->request_fn is functional.
Since bio stacking drivers (e.g. md, loop) basically initialize
their queue using blk_alloc_queue() and don't set q->request_fn,
the check of (q->request_fn == NULL) looks enough for that purpose.

However, dm will become both types of stacking driver (bio-based and
request-based).  And dm will always set q->request_fn even if the dm
device is bio-based of which q->request_fn is not functional actually.
So we need something else to distinguish the type of the device.
Adding a queue flag is a solution for that.

The reason why dm always sets q->request_fn is to keep
the compatibility of dm user-space tools.
Currently, all dm user-space tools are using bio-based dm without
specifying the type of the dm device they use.
To use request-based dm without changing such tools, the kernel
must decide the type of the dm device automatically.
The automatic type decision can't be done at the device creation time
and needs to be deferred until such tools load a mapping table,
since the actual type is decided by dm target type included in
the mapping table.

So a dm device has to be initialized using blk_init_queue()
so that we can load either type of table.
Then, all queue stuffs are set (e.g. q->request_fn) and we have
no element to distinguish that it is bio-based or request-based,
even after a table is loaded and the type of the device is decided.

By the way, some stuffs of the queue (e.g. request_list, elevator)
are needless when the dm device is used as bio-based.
But the memory size is not so large (about 20[KB] per queue on ia64),
so I hope the memory loss can be acceptable for bio-based dm users.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:18 +02:00
Kiyoshi Ueda
82124d6035 block: add request submission interface
This patch adds blk_insert_cloned_request(), a generic request
submission interface for request stacking drivers.
Request-based dm will use it to submit their clones to underlying
devices.

blk_rq_check_limits() is also added because it is possible that
the lower queue has stronger limitations than the upper queue
if multiple drivers are stacking at request-level.
Not only for blk_insert_cloned_request()'s internal use, the function
will be used by request-based dm when the queue limitation is
modified (e.g. by replacing dm's table).

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:18 +02:00
Kiyoshi Ueda
32fab448e5 block: add request update interface
This patch adds blk_update_request(), which updates struct request
with completing its data part, but doesn't complete the struct
request itself.
Though it looks like end_that_request_first() of older kernels,
blk_update_request() should be used only by request stacking drivers.

Request-based dm will use it in bio->bi_end_io callback to update
the original request when a data part of a cloned request completes.
Followings are additional background information of why request-based
dm needs this interface.

  - Request stacking drivers can't use blk_end_request() directly from
    the lower driver's completion context (bio->bi_end_io or rq->end_io),
    because some device drivers (e.g. ide) may try to complete
    their request with queue lock held, and it may cause deadlock.
    See below for detailed description of possible deadlock:
    <http://marc.info/?l=linux-kernel&m=120311479108569&w=2>

  - To solve that, request-based dm offloads the completion of
    cloned struct request to softirq context (i.e. using
    blk_complete_request() from rq->end_io).

  - Though it is possible to use the same solution from bio->bi_end_io,
    it will delay the notification of bio completion to the original
    submitter.  Also, it will cause inefficient partial completion,
    because the lower driver can't perform the cloned request anymore
    and request-based dm needs to requeue and redispatch it to
    the lower driver again later.  That's not good.

  - So request-based dm needs blk_update_request() to perform the bio
    completion in the lower driver's completion context, which is more
    efficient.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:18 +02:00
Jens Axboe
e3335de940 block: blk_cleanup_queue() should call blk_sync_queue()
When a driver calls blk_cleanup_queue(), the device should be fully idle.
However, the block layer may have pending plugging timers and the IO
schedulers may have pending work in the work queues. So quisce the device
by waiting for the timer and flushing the work queues.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:18 +02:00