kernel/git/stable/linux-stable.git/drivers/md/raid5.c, branch linux-2.6.35.y

md/raid5: fix raid5_set_bi_hw_segments

2011-08-01T20:54:56+00:00

commit 9b2dc8b665932a8e681a7ab3237f60475e75e161 upstream. The @bio->bi_phys_segments consists of active stripes count in the lower 16 bits and processed stripes count in the upper 16 bits. So logical-OR operator should be bitwise one. This bug has been present since 2.6.27 and the fix is suitable for any -stable kernel since then. Fortunately the bad code is only used on error paths and is relatively unlikely to be hit. Signed-off-by: Namhyung Kim Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman Signed-off-by: Andi Kleen

md/raid5: don't include 'spare' drives when reshaping to fewer devices.

2010-06-24T03:36:04+00:00

There are few situations where it would make any sense to add a spare when reducing the number of devices in an array, but it is conceivable: A 6 drive RAID6 with two missing devices could be reshaped to a 5 drive RAID6, and a spare could become available just in time for the reshape, but not early enough to have been recovered first. 'freezing' recovery can make this easy to do without any races. However doing such a thing is a bad idea. md will not record the partially-recovered state of the 'spare' and when the reshape finished it will think that the spare is still spare. Easiest way to avoid this confusion is to simply disallow it. Signed-off-by: NeilBrown

md/raid5: add a missing 'continue' in a loop.

2010-06-24T03:35:49+00:00

As the comment says, the tail of this loop only applies to devices that are not fully in sync, so if In_sync was set, we should avoid the rest of the loop. This bug will hardly ever cause an actual problem. The worst it can do is allow an array to be assembled that is dirty and degraded, which is not generally a good idea (without warning the sysadmin first). This will only happen if the array is RAID4 or a RAID5/6 in an intermediate state during a reshape and so has one drive that is all 'parity' - no data - while some other device has failed. This is certainly possible, but not at all common. Signed-off-by: NeilBrown

md/raid5: Allow recovered part of partially recovered devices to be in-sync

2010-06-24T03:35:39+00:00

During a recovery of reshape the early part of some devices might be in-sync while the later parts are not. We we know we are looking at an early part it is good to treat that part as in-sync for stripe calculations. This is particularly important for a reshape which suffers device failure. Treating the data as in-sync can mean the difference between data-safety and data-loss. Signed-off-by: NeilBrown

md/raid5: More careful check for "has array failed".

2010-06-24T03:35:27+00:00

When we are reshaping an array, the device failure combinations that cause us to decide that the array as failed are more subtle. In particular, any 'spare' will be fully in-sync in the section of the array that has already been reshaped, thus failures that affect only that section are less critical. So encode this subtlety in a new function and call it as appropriate. The case that showed this problem was a 4 drive RAID5 to 8 drive RAID6 conversion where the last two devices failed. This resulted in: good good good good incomplete good good failed failed while converting a 5-drive RAID6 to 8 drive RAID5 The incomplete device causes the whole array to look bad, bad as it was actually good for the section that had been converted to 8-drives, all the data was actually safe. Reported-by: Terry Morris Signed-off-by: NeilBrown

md: Don't update ->recovery_offset when reshaping an array to fewer devices.

2010-06-24T03:35:18+00:00

When an array is reshaped to have fewer devices, the reshape proceeds from the end of the devices to the beginning. If a device happens to be non-In_sync (which is possible but rare) we would normally update the ->recovery_offset as the reshape progresses. However that would be wrong as the recover_offset records that the early part of the device is in_sync, while in fact it would only be the later part that is in_sync, and in any case the offset number would be measured from the wrong end of the device. Relatedly, if after a reshape a spare is discovered to not be recoverred all the way to the end, not allow spare_active to incorporate it in the array. This becomes relevant in the following sample scenario: A 4 drive RAID5 is converted to a 6 drive RAID6 in a combined operation. The RAID5->RAID6 conversion will cause a 5 drive to be included as a spare, then the 5drive -> 6drive reshape will effectively rebuild that spare as it progresses. The 6th drive is treated as in_sync the whole time as there is never any case that we might consider reading from it, but must not because there is no valid data. If we interrupt this reshape part-way through and reverse it to return to a 5-drive RAID6 (or event a 4-drive RAID5), we don't want to update the recovery_offset - as that would be wrong - and we don't want to include that spare as active in the 5-drive RAID6 when the reversed reshape completed and it will be mostly out-of-sync still. Signed-off-by: NeilBrown

md/raid5: avoid oops when number of devices is reduced then increased.

2010-06-24T03:35:02+00:00

The entries in the stripe_cache maintained by raid5 are enlarged when we increased the number of devices in the array, but not shrunk when we reduce the number of devices. So if entries are added after reducing the number of devices, we much ensure to initialise the whole entry, not just the part that is currently relevant. Otherwise if we enlarge the array again, we will reference uninitialised values. As grow_buffers/shrink_buffer now want to use a count that is stored explicity in the raid_conf, they should get it from there rather than being passed it as a parameter. Signed-off-by: NeilBrown

md: convert cpu notifier to return encapsulate errno value

2010-05-27T16:12:48+00:00

By the previous modification, the cpu notifier can return encapsulate errno value. This converts the cpu notifiers for raid5. Signed-off-by: Akinobu Mita Cc: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge commit '3ff195b011d7decf501a4d55aeed312731094796' into for-linus

2010-05-21T22:31:36+00:00

Conflicts: drivers/md/md.c - Resolved conflict in md_update_sb - Added extra 'NULL' arg to new instance of sysfs_get_dirent. Signed-off-by: NeilBrown

md/raid6: Fix raid-6 read-error correction in degraded state

2010-05-18T05:28:00+00:00

Fix: Raid-6 was not trying to correct a read-error when in singly-degraded state and was instead dropping one more device, going to doubly-degraded state. This patch fixes this behaviour. Tested-by: Janos Haar Signed-off-by: Gabriele A. Trombetti Reported-by: Janos Haar Signed-off-by: NeilBrown Cc: stable@kernel.org