NeilBrown f466722ca6 md: Change handling of save_raid_disk and metadata update during recovery. ... Since commit d70ed2e4fa MD: Allow restarting an interrupted incremental recovery. we don't write out the metadata to devices while they are recovering. This had a good reason, but has unfortunate consequences. This patch changes things to make them work better. At issue is what happens if the array is shut down while a recovery is happening, particularly a bitmap-guided recovery. Ideally the recovery should pick up where it left off. However the metadata cannot represent the state "A recovery is in process which is guided by the bitmap". Before the above mentioned commit, we wrote metadata to the device which said "this is being recovered and it is up to <here>". So after a restart, a full recovery (not bitmap-guided) would happen from where-ever it was up to. After the commit the metadata wasn't updated so it still said "This device is fully in sync with <this> event count". That leads to a bitmap-based recovery following the whole bitmap, which should be a lot less work than a full recovery from some starting point. So this was an improvement. However updates some metadata but not all leads to other problems. In particular, the metadata written to the fully-up-to-date device record that the array has all devices present (even though some are recovering). So on restart, mdadm wants to find all devices and expects them to have current event counts. Obviously it doesn't (some have old event counts) so (when assembling with --incremental) it waits indefinitely for the rest of the expected devices. It really is wrong to not update all the metadata together. Do that is bound to cause confusion. Instead, we should make it possible to record the truth in the metadata. i.e. we need to be able to record that a device is being recovered based on the bitmap. We already have a Feature flag to say that recovery is happening. We now add another one to say that it is a bitmap-based recovery. With this we can remove the code that disables the write-out of metadata on some devices. So this patch: - moves the setting of 'saved_raid_disk' from add_new_disk to the validate_super methods. This makes sure it is always set properly, both when adding a new device to an array, and when assembling an array from a collection of devices. - Adds a metadata flag MD_FEATURE_RECOVERY_BITMAP which is only used if MD_FEATURE_RECOVERY_OFFSET is set, and record that a bitmap-based recovery is allowed. This is only present in v1.x metadata. v0.90 doesn't support devices which are in the middle of recovery at all. - Only skips writing metadata to Faulty devices. - Also allows rdev state to be set to "-insync" via sysfs. This can be used for external-metadata arrays. When the 'role' is set the device is assumed to be in-sync. If, after setting the role, we set the state to "-insync", the role is moved to saved_raid_disk which effectively says the device is partly in-sync with that slot and needs a bitmap recovery. Cc: Andrei Warkentin <andreiw@vmware.com> Signed-off-by: NeilBrown <neilb@suse.de>		2014-01-14 16:44:21 +11:00
..
acpi	ACPI / driver core: Store an ACPI device pointer in struct acpi_dev_node	2013-11-14 23:14:43 +01:00
asm-generic	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial	2013-11-15 16:47:22 -08:00
clocksource	drivers: clocksource: add support for ARM architected timer event stream	2013-09-26 09:48:00 +01:00
crypto	keys: change asymmetric keys to use common hash definitions	2013-10-25 17:15:18 -04:00
drm	Merge branch 'ttm-fixes-3.13' of git://people.freedesktop.org/~thomash/linux into drm-fixes	2013-11-21 18:46:56 +10:00
dt-bindings	For the 3.13 merge window we have a couple of new drivers for the AMS	2013-11-15 16:37:40 -08:00
keys	KEYS: Separate the kernel signature checking keyring from module signing	2013-09-25 17:17:01 +01:00
kvm
linux	PCI updates for v3.13:	2013-11-22 10:53:47 -08:00
math-emu
media	Merge branch 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux	2013-11-18 15:50:07 -08:00
memory
misc
net	genetlink: fix genl_set_err() group ID	2013-11-21 13:09:43 -05:00
pcmcia
ras
rdma	Merge branches 'cma', 'cxgb4', 'flowsteer', 'ipoib', 'misc', 'mlx4', 'mlx5', 'nes', 'ocrdma', 'qib' and 'srp' into for-next	2013-11-17 08:22:19 -08:00
rxrpc
scsi	Main batch of InfiniBand/RDMA changes for 3.13:	2013-11-18 15:36:04 -08:00
sound	Merge remote-tracking branch 'asoc/topic/twl4030' into asoc-next	2013-11-08 10:43:40 +00:00
target	target_core_alua: Store supported ALUA states	2013-11-20 11:26:37 -08:00
trace	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs	2013-11-22 08:38:55 -08:00
uapi	md: Change handling of save_raid_disk and metadata update during recovery.	2014-01-14 16:44:21 +11:00
video	fbdev changes for 3.13	2013-11-14 14:44:20 +09:00
xen	Features:	2013-11-15 13:34:37 +09:00
Kbuild