Commit Graph

773 Commits

Author SHA1 Message Date
Adrian Bunk
e03f1a8422 dm-raid1.c: fix NULL dereferences
This patch fixes two NULL dereferences introduced by commit
06386bbfd2 and spotted by the Coverity
checker.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-19 15:52:27 -08:00
Jan Blunck
cf28b4863f d_path: Make d_path() use a struct path
d_path() is used on a <dentry,vfsmount> pair.  Lets use a struct path to
reflect this.

[akpm@linux-foundation.org: fix build in mm/memory.c]
Signed-off-by: Jan Blunck <jblunck@suse.de>
Acked-by: Bryan Wu <bryan.wu@analog.com>
Acked-by: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-14 21:17:09 -08:00
Jan Blunck
c32c2f63a9 d_path: Make seq_path() use a struct path argument
seq_path() is always called with a dentry and a vfsmount from a struct path.
Make seq_path() take it directly as an argument.

Signed-off-by: Jan Blunck <jblunck@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-14 21:17:08 -08:00
Jan Blunck
1d957f9bf8 Introduce path_put()
* Add path_put() functions for releasing a reference to the dentry and
  vfsmount of a struct path in the right order

* Switch from path_release(nd) to path_put(&nd->path)

* Rename dput_path() to path_put_conditional()

[akpm@linux-foundation.org: fix cifs]
Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: <linux-fsdevel@vger.kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-14 21:13:33 -08:00
Jan Blunck
4ac9137858 Embed a struct path into struct nameidata instead of nd->{dentry,mnt}
This is the central patch of a cleanup series. In most cases there is no good
reason why someone would want to use a dentry for itself. This series reflects
that fact and embeds a struct path into nameidata.

Together with the other patches of this series
- it enforced the correct order of getting/releasing the reference count on
  <dentry,vfsmount> pairs
- it prepares the VFS for stacking support since it is essential to have a
  struct path in every place where the stack can be traversed
- it reduces the overall code size:

without patch series:
   text    data     bss     dec     hex filename
5321639  858418  715768 6895825  6938d1 vmlinux

with patch series:
   text    data     bss     dec     hex filename
5320026  858418  715768 6894212  693284 vmlinux

This patch:

Switch from nd->{dentry,mnt} to nd->path.{dentry,mnt} everywhere.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix cifs]
[akpm@linux-foundation.org: fix smack]
Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-14 21:13:33 -08:00
Al Viro
39ed7adb17 dm-raid1 breakage on 64bit
test_and_set_bit() on address of uint32_t is a Bad Idea(tm)...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-13 08:16:34 -08:00
Jonathan Brassow
af195ac82e dm raid1: report fault status
This patch adds extra information to the mirror status output, so that
it can be determined which device(s) have failed.  For each mirror device,
a character is printed indicating the most severe error encountered.  The
characters are:
 *    A => Alive - No failures
 *    D => Dead - A write failure occurred leaving mirror out-of-sync
 *    S => Sync - A sychronization failure occurred, mirror out-of-sync
 *    R => Read - A read failure occurred, mirror data unaffected
This allows userspace to properly reconfigure the mirror set.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:39 +00:00
Jonathan Brassow
06386bbfd2 dm raid1: handle read failures
This patch gives the ability to respond-to/record device failures
that happen during read operations.  It also adds the ability to
read from mirror devices that are not the primary if they are
in-sync.

There are essentially two read paths in mirroring; the direct path
and the queued path.  When a read request is mapped, if the region
is 'in-sync' the direct path is taken; otherwise the queued path
is taken.

If the direct path is taken, we must record bio information so that
if the read fails we can retry it.  We then discover the status of
a direct read through mirror_end_io.  If the read has failed, we will
mark the device from which the read was attempted as failed (so we
don't try to read from it again), restore the bio and try again.

If the queued path is taken, we discover the results of the read
from 'read_callback'.  If the device failed, we will mark the device
as failed and attempt the read again if there is another device
where this region is known to be 'in-sync'.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:37 +00:00
Jonathan Brassow
b80aa7a0c2 dm raid1: fix EIO after log failure
This patch adds the ability to requeue write I/O to
core device-mapper when there is a log device failure.

If a write to the log produces and error, the pending writes are
put on the "failures" list.  Since the log is marked as failed,
they will stay on the failures list until a suspend happens.

Suspends come in two phases, presuspend and postsuspend.  We must
make sure that all the writes on the failures list are requeued
in the presuspend phase (a requirement of dm core).  This means
that recovery must be complete (because writes may be delayed
behind it) and the failures list must be requeued before we
return from presuspend.

The mechanisms to ensure recovery is complete (or stopped) was
already in place, but needed to be moved from postsuspend to
presuspend.  We rely on 'flush_workqueue' to ensure that the
mirror thread is complete and therefore, has requeued all writes
in the failures list.

Because we are using flush_workqueue, we must ensure that no
additional 'queue_work' calls will produce additional I/O
that we need to requeue (because once we return from
presuspend, we are unable to do anything about it).  'queue_work'
is called in response to the following functions:
- complete_resync_work = NA, recovery is stopped
- rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it
                           is ready to recover the region
                           (recovery is stopped) or it needs
                           to clear the region in the log*
                           **this doesn't get called while
                           suspending**
- rh_recovery_end = NA, recovery is stopped
- rh_recovery_start = NA, recovery is stopped
- write_callback = 1) Writes w/o failures simply call
                   bio_endio -> mirror_end_io -> rh_dec
                   (see rh_dec above)
                   2) Writes with failures are put on
                   the failures list and queue_work is
                   called**
                   ** write_callbacks don't happen
                   during suspend **
- do_failures = NA, 'queue_work' not called if suspending
- add_mirror (initialization) = NA, only done on mirror creation
- queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue
              is called.  2) No more I/Os are being issued.
              3) Re-attempted READs can still be handled.
              (Write completions are handled through rh_dec/
              write_callback - mention above - and do not
              use queue_bio.)

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:35 +00:00
Jonathan Brassow
8f0205b798 dm raid1: handle recovery failures
This patch adds the calls to 'fail_mirror' if an error occurs during
mirror recovery (aka resynchronization).  'fail_mirror' is responsible
for recording the type of error by mirror device and ensuring an event
gets raised for the purpose of notifying userspace.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:32 +00:00
Jonathan Brassow
72f4b31410 dm raid1: handle write failures
This patch gives mirror the ability to handle device failures
during normal write operations.

The 'write_callback' function is called when a write completes.
If all the writes failed or succeeded, we report failure or
success respectively.  If some of the writes failed, we call
fail_mirror; which increments the error count for the device, notes
the type of error encountered (DM_RAID1_WRITE_ERROR),  and
selects a new primary (if necessary).  Note that the primary
device can never change while the mirror is not in-sync (IOW,
while recovery is happening.)  This means that the scenario
where a failed write changes the primary and gives
recovery_complete a chance to misread the primary never happens.
The fact that the primary can change has necessitated the change
to the default_mirror field.  We need to protect against reading
garbage while the primary changes.  We then add the bio to a new
list in the mirror set, 'failures'.  For every bio in the 'failures'
list, we call a new function, '__bio_mark_nosync', where we mark
the region 'not-in-sync' in the log and properly set the region
state as, RH_NOSYNC.  Userspace must also be notified of the
failure.  This is done by 'raising an event' (dm_table_event()).
If fail_mirror is called in process context the event can be raised
right away.  If in interrupt context, the event is deferred to the
kmirrord thread - which raises the event if 'event_waiting' is set.

Backwards compatibility is maintained by ignoring errors if
the DM_FEATURES_HANDLE_ERRORS flag is not present.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:29 +00:00
Milan Broz
d74f81f8ad dm snapshot: combine consecutive exceptions in memory
Provided sector_t is 64 bits, reduce the in-memory footprint of the
snapshot exception table by the simple method of using unused bits of
the chunk number to combine consecutive entries.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:27 +00:00
Brian Wood
4f7f5c675f dm: stripe enhanced status return
This patch adds additional information to the status line. It is added at the
end of the returned text so it will not interfere with existing
implementations using this data. The addition of this information will allow
for a common return interface to match that returned with the dm-raid1.c
status line (with Jonathan Brassow's patches).

Here is a sample of what is returned with a mirror "status" call:
isw_eeaaabgfg_mirror: 0 488390920 mirror 2 8:16 8:32 3727/3727 1 AA 1 core

Here's what's returned with this patch for a stripe "status" call:
isw_dheeijjdej_stripe: 0 976783872 striped 2 8:16 8:32 1 AA

Signed-off-by: Brian Wood <brian.j.wood@intel.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:24 +00:00
Brian Wood
a25eb9446a dm: stripe trigger event on failure
This patch adds the stripe_end_io function to process errors that might
occur after an IO operation. As part of this there are a number of
enhancements made to record and trigger events:

- New atomic variable in struct stripe to record the number of
errors each stripe volume device has experienced (could be used
later with uevents to report back directly to userspace)

- New workqueue/work struct setup to process the trigger_event function

- New end_io function. It is here that testing for BIO error conditions
take place. It determines the exact stripe that cause the error,
records this in the new atomic variable, and calls the queue_work() function

- New trigger_event function to process failure events. This
calls dm_table_event()

Signed-off-by: Brian Wood <brian.j.wood@intel.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:22 +00:00
Jonathan Brassow
fb8b284806 dm log: auto load modules
If the log type is not recognised, attempt to load the module
'dm-log-<type>.ko'.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:19 +00:00
Milan Broz
304f3f6a58 dm: move deferred bio flushing to workqueue
Add a single-thread workqueue for each mapped device
and move flushing of the lists of pushback and deferred bios
to this new workqueue.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:17 +00:00
Milan Broz
3a7f6c990a dm crypt: use async crypto
dm-crypt: Use crypto ablkcipher interface

Move encrypt/decrypt core to async crypto call.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:14 +00:00
Milan Broz
95497a9600 dm crypt: prepare async callback fn
dm-crypt: Use crypto ablkcipher interface

Prepare callback function for async crypto operation.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:12 +00:00
Milan Broz
43d6903482 dm crypt: add completion for async
dm-crypt: Use crypto ablkcipher interface
Prepare completion for async crypto request.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:09 +00:00
Milan Broz
ddd42edfd8 dm crypt: add async request mempool
dm-crypt: Use crypto ablkcipher interface

Introduce mempool for async crypto requests.

cc->req is used mainly during synchronous operations
(to prevent allocation and deallocation of the same object).

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:07 +00:00
Milan Broz
01482b7671 dm crypt: extract scatterlist processing
dm-crypt: Use crypto ablkcipher interface

Move scatterlists to separate dm_crypt_struct and
pick out block processing from crypt_convert.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:04 +00:00
Milan Broz
899c95d36c dm crypt: tidy io ref counting
Make io reference counting more obvious.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:11:02 +00:00
Milan Broz
84131db689 dm crypt: introduce crypt_write_io_loop
Introduce crypt_write_io_loop().

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:59 +00:00
Milan Broz
dec1cedf9d dm crypt: abstract crypt_write_done
Process write request in separate function and queue
final bio through io workqueue.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:57 +00:00
Milan Broz
0c395b0f8d dm crypt: store sector mapping in dm_crypt_io
Add sector into dm_crypt_io instead of using local variable.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:54 +00:00
Alasdair G Kergon
395b167ca0 dm crypt: move queue functions
Reorder kcryptd functions for clarity.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:52 +00:00
Milan Broz
4e4eef64e2 dm crypt: adjust io processing functions
Rename functions to follow calling convention.
Prepare write io error processing function skeleton.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:49 +00:00
Milan Broz
ee7a491e62 dm crypt: tidy crypt_endio
Simplify crypt_endio function.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:46 +00:00
Milan Broz
5742fd7775 dm crypt: move error setting outside crypt_dec_pending
Move error code setting outside of crypt_dec_pending function.
Use -EIO if crypt_convert_scatterlist() fails.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:43 +00:00
Milan Broz
fcd369daa3 dm crypt: remove unnecessary crypt_context write parm
Remove write attribute from convert_context and use bio flag instead.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:41 +00:00
Milan Broz
53017030e2 dm crypt: move convert_context inside dm_crypt_io
Move convert_context inside dm_crypt_io.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:38 +00:00
Alasdair G Kergon
009cd09042 dm mpath: add missing static
A static declaration missing.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:35 +00:00
Alasdair G Kergon
0149e57fed dm: targets no longer experimental
Drop the EXPERIMENTAL tag from well-established device-mapper targets, so
the newer ones stand out better.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:32 +00:00
Milan Broz
46125c1c90 dm: refactor dm_suspend completion wait
Move completion wait to separate function

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:30 +00:00
Milan Broz
94d6351e14 dm: split dm_suspend io_lock hold into two
Change io_locking to allow processing flush in separate thread.

Because we have DMF_BLOCK_IO already set, any possible
new ios are queued in dm_requests now.

In the case of interrupting previous wait there can be more
ios queued (we unlocked io_lock for a while) but this is safe.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:27 +00:00
Milan Broz
73d410c013 dm: tidy dm_suspend
Tidy dm_suspend function

 - change return value logic in dm_suspend
 - use atomic_read only once.
 - move DMF_BLOCK_IO clearing into one place

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:25 +00:00
Milan Broz
6d6f10df89 dm: refactor deferred bio_list processing
Refactor deferred bio_list processing.

 - use separate _merge_pushback_list function
 - move deferred bio list pick up to flush function
 - use bio_list_pop instead of bio_list_get
 - simplify noflush flag use

No real functional change in this patch.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:22 +00:00
Milan Broz
6ed7ade896 dm: tidy alloc_dev labels
Tidy labels in alloc_dev to make later patches more clear.

No functional change in this patch.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:19 +00:00
Andrew Morton
a26ffd4aa9 dm ioctl: use uninitialized_var
drivers/md/dm-ioctl.c:1405: warning: 'param' may be used uninitialized in this function

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:16 +00:00
Andrew Morton
69a2ce72a4 dm: table use uninitialized_var
drivers/md/dm-table.c: In function 'dm_get_device':
drivers/md/dm-table.c:478: warning: 'dev' may be used uninitialized in this function

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:14 +00:00
Andrew Morton
e48b9db251 dm snapshot: use uninitialized_var
drivers/md/dm-exception-store.c: In function 'persistent_read_metadata':
drivers/md/dm-exception-store.c:452: warning: 'new_snapshot' may be used uninitialized in this function

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:11 +00:00
Daniel Walker
e61290a4a2 dm: convert suspend_lock semaphore to mutex
Replace semaphore with mutex.

Signed-off-by: Daniel Walker <dwalker@mvista.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:08 +00:00
Robert P. J. Day
8defd83084 dm snapshot: use rounddown_pow_of_two
Since the source file already includes the log2.h header file, it
seems pointless to re-invent the necessary routine.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:06 +00:00
Jun'ichi Nomura
82d601dc07 dm: table remove unused total
"total = 0" does nothing.

Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:10:04 +00:00
Paul Jimenez
afb24528f9 dm: table use list_for_each
This patch is some minor janitorish cleanup, using some macros
from linux/list.h (already #included via dm.h) to improve
readability.

Signed-off-by: Paul Jimenez <pj@place.org>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:09:59 +00:00
Milan Broz
76c072b48e dm ioctl: move compat code
Move compat_ioctl handling into dm-ioctl.c.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:09:56 +00:00
Alasdair G Kergon
27238b2bea dm ioctl: remove lock_kernel
Remove lock_kernel() from the device-mapper ioctls - there should
be sufficient internal locking already where required.

Also remove some superfluous casts.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:09:53 +00:00
Alasdair G Kergon
b9249e5568 dm: mark function lists static
Add a couple of statics.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:09:51 +00:00
Milan Broz
7e5c1e830b dm: add missing memory barrier to dm_suspend
Add memory barrier to fix atomic_read of pending value.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 02:09:49 +00:00
NeilBrown
6ed3003c19 md: fix an occasional deadlock in raid5
raid5's 'make_request' function calls generic_make_request on underlying
devices and if we run out of stripe heads, it could end up waiting for one of
those requests to complete.  This is bad as recursive calls to
generic_make_request go on a queue and are not even attempted until
make_request completes.

So: don't make any generic_make_request calls in raid5 make_request until all
waiting has been done.  We do this by simply setting STRIPE_HANDLE instead of
calling handle_stripe().

If we need more stripe_heads, raid5d will get called to process the pending
stripe_heads which will call generic_make_request from a

This change by itself causes a performance hit.  So add a change so that
raid5_activate_delayed is only called at unplug time, never in raid5.  This
seems to bring back the performance numbers.  Calling it in raid5d was
sometimes too soon...

Neil said:

  How about we queue it for 2.6.25-rc1 and then about when -rc2 comes out,
  we queue it for 2.6.24.y?

Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Tested-by: dean gaudet <dean@arctic.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-06 10:41:19 -08:00