Algorithm:
1. Node 1 issues mdadm --manage /dev/mdX --add /dev/sdYY which issues
ioctl(ADD_NEW_DISC with disc.state set to MD_DISK_CLUSTER_ADD)
2. Node 1 sends NEWDISK with uuid and slot number
3. Other nodes issue kobject_uevent_env with uuid and slot number
(Steps 4,5 could be a udev rule)
4. In userspace, the node searches for the disk, perhaps
using blkid -t SUB_UUID=""
5. Other nodes issue either of the following depending on whether the disk
was found:
ioctl(ADD_NEW_DISK with disc.state set to MD_DISK_CANDIDATE and
disc.number set to slot number)
ioctl(CLUSTERED_DISK_NACK)
6. Other nodes drop lock on no-new-devs (CR) if device is found
7. Node 1 attempts EX lock on no-new-devs
8. If node 1 gets the lock, it sends METADATA_UPDATED after unmarking the disk
as SpareLocal
9. If not (get no-new-dev lock), it fails the operation and sends METADATA_UPDATED
10. Other nodes understand if the device is added or not by reading the superblock again after receiving the METADATA_UPDATED message.
Signed-off-by: Lidong Zhong <lzhong@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
All the interesting information printed by this ioctl
is provided in /proc/mdstat and/or sysfs.
So it isn't needed and isn't used and would be best if it didn't
exist.
Signed-off-by: NeilBrown <neilb@suse.de>
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>
linux/raid/md_p.h is using conditionals depending on endianess and fails
with an error if neither of __BIG_ENDIAN, __LITTLE_ENDIAN or
__BYTE_ORDER are defined, but it doesn't include any header which can
define these constants. This make this header unusable alone.
This patch adds a #include <asm/byteorder.h> at the beginning of this
header to make it usable alone. This is needed to compile klibc on MIPS.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NeilBrown <neilb@suse.de>
In the UAPI header files, __BIG_ENDIAN and __LITTLE_ENDIAN must be
compared against __BYTE_ORDER in preprocessor conditionals where these are
exposed to userspace (that is they're not inside __KERNEL__ conditionals).
However, in the main kernel the norm is to check for
"defined(__XXX_ENDIAN)" rather than comparing against __BYTE_ORDER and
this has incorrectly leaked into the userspace headers.
The definition of struct mdp_superblock_s in linux/raid/md_p.h is wrong in
this way. Note that userspace will likely interpret the ordering of the
fields incorrectly as the big-endian variant on a little-endian machines -
depending on header inclusion order.
[!!!] NOTE [!!!] This patch may adversely change the userspace API. It might
be better to fix the ordering of events_hi, events_lo, cp_events_hi and
cp_events_lo in struct mdp_superblock_s / typedef mdp_super_t.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>
Set up empty UAPI Kbuild files to be populated by the header splitter.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>
Goldwyn Rodrigues