linux-stable.git/drivers/md/md.c, branch linux-2.6.28.y

md: fix deadlock when stopping arrays

2009-05-02T17:57:17+00:00

[backport of 5fd3a17ed456637a224cf4ca82b9ad9d005bc8d4]

Resolve a deadlock when stopping redundant arrays, i.e. ones that
require a call to sysfs_remove_group when shutdown.  The deadlock is
summarized below:

Thread1                Thread2
-------                -------
read sysfs attribute   stop array
                       take mddev lock
                       sysfs_remove_group
sysfs_get_active
wait for mddev lock
                       wait for active

Sysrq-w:
  --------
mdmon         S 00000017  2212  4163      1
  f1982ea8 00000046 2dcf6b85 00000017 c0b23100 f2f83ed0 c0b23100 f2f8413c
  c0b23100 c0b23100 c0b1fb98 f2f8413c 00000000 f2f8413c c0b23100 f2291ecc
  00000002 c0b23100 00000000 00000017 f2f83ed0 f1982eac 00000046 c044d9dd
Call Trace:
  [] ? debug_mutex_add_waiter+0x1d/0x58
  [] __mutex_lock_common+0x1d9/0x338
  [] ? __mutex_lock_common+0x1d9/0x338
  [] mutex_lock_interruptible_nested+0x33/0x3a
  [] ? mddev_lock+0x14/0x16
  [] mddev_lock+0x14/0x16
  [] md_attr_show+0x2a/0x49
  [] sysfs_read_file+0x93/0xf9
mdadm         D 00000017  2812  4177      1
  f0401d78 00000046 430456f8 00000017 f0401d58 f0401d20 c0b23100 f2da2c4c
  c0b23100 c0b23100 c0b1fb98 f2da2c4c 0a10fc36 00000000 c0b23100 f0401d70
  00000003 c0b23100 00000000 00000017 f2da29e0 00000001 00000002 00000000
Call Trace:
  [] schedule_timeout+0x1b/0x95
  [] ? schedule_timeout+0x1b/0x95
  [] ? wait_for_common+0x34/0xdc
  [] ? trace_hardirqs_on_caller+0x18/0x145
  [] ? trace_hardirqs_on+0xb/0xd
  [] wait_for_common+0xa0/0xdc
  [] ? default_wake_function+0x0/0x12
  [] wait_for_completion+0x17/0x19
  [] sysfs_addrm_finish+0x19f/0x1d1
  [] sysfs_hash_and_remove+0x42/0x55
  [] sysfs_remove_group+0x57/0x86
  [] do_md_stop+0x13a/0x499

This has been there for a while, but is easier to trigger now that mdmon
is closely watching sysfs.

Cc: Neil Brown 
Reported-by: Jacek Danecki 
Signed-off-by: Dan Williams 
Signed-off-by: Greg Kroah-Hartman

md: Ensure an md array never has too many devices.

2009-02-12T17:50:24+00:00

commit de01dfadf25bf83cfe3d85c163005c4320532658 upstream.

Each different metadata format supported by md supports a
different maximum number of devices.
We really should be enforcing this maximum in the kernel, but
we aren't quite doing that properly.

We currently only enforce it at the 'hot_add' point, which is an
older interface which is not used by current userspace.

We need to also enforce it at 'add_new_disk' time for active arrays
and at 'do_md_run' time when starting a new array.

So move the test from 'hot_add' into 'bind_rdev_to_array' which is
called from both 'hot_add' and 'add_new_disk, and add a new
test in 'analyse_sbs' which is called from 'do_md_run'.

This bug (or missing feature) has been around "forever" and so
the patch is suitable for any -stable that is currently maintained.

Signed-off-by: NeilBrown 
Signed-off-by: Greg Kroah-Hartman

md: revert the recent addition of a call to the BLKRRPART ioctl.

2008-11-06T06:28:01+00:00

It turns out that it is only safe to call blkdev_ioctl when the device
is actually open (as ->bd_disk is set to NULL on last close).  And it
is quite possible for do_md_stop to be called when the device is not
open.  So discard the call to blkdev_ioctl(BLKRRPART) which was
added in
   commit 934d9c23b4c7e31840a895ba4b7e88d6413c81f3

It is just as easy to call this ioctl from userspace when needed (on
mdadm -S) so leave it out of the kernel

Signed-off-by: NeilBrown

md: destroy partitions and notify udev when md array is stopped.

2008-10-28T06:01:23+00:00

md arrays are not currently destroyed when they are stopped - they
remain in /sys/block.  Last time I tried this I tripped over locking
too much.

A consequence of this is that udev doesn't remove anything from /dev.
This is rather ugly.

As an interim measure until proper device removal can be achieved,
make sure all partitions are removed using the BLKRRPART ioctl, and
send a KOBJ_CHANGE when an md array is stopped.

Signed-off-by: NeilBrown

Merge branch 'for-linus' of git://neil.brown.name/md

2008-10-26T23:42:18+00:00

* 'for-linus' of git://neil.brown.name/md:
  md: allow extended partitions on md devices.
  md: use sysfs_notify_dirent to notify changes to md/dev-xxx/state
  md: use sysfs_notify_dirent to notify changes to md/array_state

[PATCH] pass fmode_t to blkdev_put()

2008-10-21T11:48:58+00:00

Signed-off-by: Al Viro

[PATCH] switch md

2008-10-21T11:48:31+00:00

Signed-off-by: Al Viro

[PATCH] beginning of methods conversion

2008-10-21T11:47:32+00:00

To keep the size of changesets sane we split the switch by drivers;
to keep the damn thing bisectable we do the following:
	1) rename the affected methods, add ones with correct
prototypes, make (few) callers handle both.  That's this changeset.
	2) for each driver convert to new methods.  *ALL* drivers
are converted in this series.
	3) kill the old (renamed) methods.

Note that it _is_ a flagday; all in-tree drivers are converted and by the
end of this series no trace of old methods remain.  The only reason why
we do that this way is to keep the damn thing bisectable and allow per-driver
debugging if anything goes wrong.

New methods:
	open(bdev, mode)
	release(disk, mode)
	ioctl(bdev, mode, cmd, arg)		/* Called without BKL */
	compat_ioctl(bdev, mode, cmd, arg)
	locked_ioctl(bdev, mode, cmd, arg)	/* Called with BKL, legacy */

Signed-off-by: Al Viro

md: allow extended partitions on md devices.

2008-10-21T02:25:32+00:00

The new extended partition support provides a much nicer was
to have partitions on md devices that the 'mdp' alternate major.
We cannot really get rid of 'mdp' at this time, but we can
enable extended partitions as that will probably make life
easier for sysadmins.

Signed-off-by: NeilBrown

md: use sysfs_notify_dirent to notify changes to md/dev-xxx/state

2008-10-21T02:25:28+00:00

The 'state' file for a device reports, for example, when the device
has failed.  Changes should be reported to userspace ASAP without
the possibility of blocking on low-memory.  sysfs_notify does
have that possibility (as it takes a mutex which can be held
across a kmalloc) so use sysfs_notify_dirent instead.

Signed-off-by: NeilBrown