kernel/git/stable/linux.git/drivers/md/md.c, branch linux-2.6.31.y

md: Fix unfortunate interaction with evms

2010-01-06T22:26:28+00:00

commit cbd1998377504df005302ac90d49db72a48552a6 upstream. evms configures md arrays by: open device send ioctl close device for each different ioctl needed. Since 2.6.29, the device can disappear after the 'close' unless a significant configuration has happened to the device. The change made by "SET_ARRAY_INFO" can too minor to stop the device from disappearing, but important enough that losing the change is bad. So: make sure SET_ARRAY_INFO sets mddev->ctime, and keep the device active as long as ctime is non-zero (it gets zeroed with lots of other things when the array is stopped). This is suitable for -stable kernels since 2.6.29. Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman

md/bitmap: protect against bitmap removal while being updated.

2009-12-18T21:43:25+00:00

commit aa5cbd103887011b4830355f88fb055f9ad2d556 upstream. A write intent bitmap can be removed from an array while the array is active. When this happens, all IO is suspended and flushed before the bitmap is removed. However it is possible that bitmap_daemon_work is still running to clear old bits from the bitmap. If it is, it can dereference the bitmap after it has been freed. So introduce a new mutex to protect bitmap_daemon_work and get it before destroying a bitmap. This is suitable for any current -stable kernel. Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman

md: don't clear endpoint for resync when resync is interrupted.

2009-12-08T18:20:56+00:00

commit 24395a85d8efe6eee477ea35c73d045a8dd7a3a1 upstream. If a 'sync_max' has been set (via sysfs), it is wrong to clear it until a resync (or reshape or recovery ...) actually reached that point. So if a resync is interrupted (e.g. by device failure), leave 'resync_max' unchanged. This is particularly important for 'reshape' operations that do not change the size of the array. For such operations mdadm needs to monitor the reshape taking rolling backups of the section being reshaped. If resync_max gets cleared, the reshape can get ahead of mdadm and then the backups that mdadm creates are useless. This is suitable for 2.6.31.y stable kernels. Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman

Fix new incorrect error return from do_md_stop.

2009-08-18T00:35:26+00:00

Recent commit c8c00a6915a2e3d10416e8bdd3138429beb96210 changed the exit paths in do_md_stop and was not quite careful enough. There is one path were 'err' now needs to be cleared but it isn't. So setting an array to readonly (with mdadm --readonly) will work, but will incorrectly report and error: ENXIO. Signed-off-by: NeilBrown

md: allow upper limit for resync/reshape to be set when array is read-only

2009-08-13T00:41:50+00:00

Normally we only allow the upper limit for a reshape to be decreased when the array not performing a sync/recovery/reshape, otherwise there could be races. But if an array is part-way through a reshape when it is assembled the reshape is started immediately leaving no window to set an upper bound. If the array is started read-only, the reshape will be suspended until the array becomes writable, so that provides a window during which it is perfectly safe to reduce the upper limit of a reshape. So: allow the upper limit (sync_max) to be reduced even if the reshape thread is running, as long as the array is still read-only. Signed-off-by: NeilBrown

md: never advance 'events' counter by more than 1.

2009-08-12T23:54:02+00:00

When assembling arrays, md allows two devices to have different event counts as long as the difference is only '1'. This is to cope with a system failure between updating the metadata on two difference devices. However there are currently times when we update the event count by 2. This was done to keep the event count even when the array is clean and odd when it is dirty, which allows us to avoid writing common update to spare devices and so allow those spares to go to sleep. This is bad for the above reason. So change it to never increase by two. This means that the alignment between 'odd/even' and 'clean/dirty' might take a little longer to attain, but that is only a small cost. The spares will get a few more updates but that will still be spared (;-) most updates and can still go to sleep. Prior to this patch there was a small chance that after a crash an array would fail to assemble due to the overly large event count mismatch. Signed-off-by: NeilBrown

Remove deadlock potential in md_open

2009-08-10T02:50:52+00:00

A recent commit: commit 449aad3e25358812c43afc60918c5ad3819488e7 introduced the possibility of an A-B/B-A deadlock between bd_mutex and reconfig_mutex. __blkdev_get holds bd_mutex while calling md_open which takes reconfig_mutex, do_md_run is always called with reconfig_mutex held, and it now takes bd_mutex in the call the revalidate_disk. This potential deadlock was not caught by lockdep due to the use of mutex_lock_interruptible_nexted which was introduced by commit d63a5a74dee87883fda6b7d170244acaac5b05e8 do avoid a warning of an impossible deadlock. It is quite possible to split reconfig_mutex in to two locks. One protects the array data structures while it is being reconfigured, the other ensures that an array is never even partially open while it is being deactivated. In particular, the second lock prevents an open from completing between the time when do_md_stop checks if there are any active opens, and the time when the array is either set read-only, or when ->pers is set to NULL. So we can be certain that no IO is in flight as the array is being destroyed. So create a new lock, open_mutex, just to ensure exclusion between 'open' and 'stop'. This avoids the deadlock and also avoids the lockdep warning mentioned in commit d63a5a74d Reported-by: "Mike Snitzer" Reported-by: "H. Peter Anvin" Signed-off-by: NeilBrown

md: Use revalidate_disk to effect changes in size of device.

2009-08-03T00:59:58+00:00

As revalidate_disk calls check_disk_size_change, it will cause any capacity change of a gendisk to be propagated to the blockdev inode. So use that instead of mucking about with locks and i_size_write. Also add a call to revalidate_disk in do_md_run and a few other places where the gendisk capacity is changed. Signed-off-by: NeilBrown

md: Handle growth of v1.x metadata correctly.

2009-08-03T00:59:57+00:00

The v1.x metadata does not have a fixed size and can grow when devices are added. If it grows enough to require an extra sector of storage, we need to update the 'sb_size' to match. Without this, md can write out an incomplete superblock with a bad checksum, which will be rejected when trying to re-assemble the array. Cc: stable@kernel.org Signed-off-by: NeilBrown

md: avoid array overflow with bad v1.x metadata

2009-08-03T00:59:56+00:00

We trust the 'desc_nr' field in v1.x metadata enough to use it as an index in an array. This isn't really safe. So range-check the value first. Signed-off-by: NeilBrown