The remainder of this batch implements raid5 reshaping. Currently the only
shape change that is supported is added a device, but it is envisioned that
changing the chunksize and layout will also be supported, as well as changing
the level (e.g. 1->5, 5->6).
The reshape process naturally has to move all of the data in the array, and so
should be used with caution. It is believed to work, and some testing does
support this, but wider testing would be great for increasing my confidence.
You will need a version of mdadm newer than 2.3.1 to make use of raid5 growth.
This is because mdadm need to take a copy of a 'critical section' at the
start of the array incase there is a crash at an awkward moment. On restart,
mdadm will restore the critical section and allow reshape to continue.
I hope to release a 2.4-pre by early next week - it still needs a little more
polishing.
This patch:
Previously the array of disk information was included in the raid5 'conf'
structure which was allocated to an appropriate size. This makes it awkward
to change the size of that array. So we split it off into a separate
kmalloced array which will require a little extra indexing, but is much easier
to grow.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
- replace open-coded hash chain with hlist macros
- Fix hash-table size at one page - it is already quite generous, so there
will never be a need to use multiple pages, so no need for __get_free_pages
No functional change.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
There is this "FIXME" comment with a typo in it!! that been annoying me for
days, so I just had to remove it.
conf->disks[i].rdev should only be accessed if
- we know we hold a reference or
- the mddev->reconfig_sem is down or
- we have a rcu_readlock
handle_stripe was referencing rdev in three places without any of these. For
the first two, get an rcu_readlock. For the last, the same access
(md_sync_acct call) is made a little later after the rdev has been claimed
under and rcu_readlock, if R5_Syncio is set. So just use that access...
However R5_Syncio isn't really needed as the 'syncing' variable contains the
same information. So use that instead.
Issues, comment, and fix are identical in raid5 and raid6.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
raid6 currently does not check the P/Q syndromes when doing a resync, it just
calculates the correct value and writes it. Doing the check can reduce writes
(often to 0) for a resync, and it is needed to properly implement the
echo check > sync_action
operation.
This patch implements the appropriate checks and tidies up some related code.
It also allows raid6 user-requested resync to bypass the intent bitmap.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
There isn't really a need for raid5 attributes to be an a subdirectory,
so this patch moves them from
/sys/block/mdX/md/raid5/attribute
to
/sys/block/mdX/md/attribute
This suggests that all md personalities should co-operate about
namespace usage, but that shouldn't be a problem.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
/sys/block/mdX/md/raid5/
contains raid5-related attributes.
Currently
stripe_cache_size
is number of entries in stripe cache, and is settable.
stripe_cache_active
is number of active entries, and in only readable.
Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch changes the behaviour of raid5 when it gets a read error.
Instead of just failing the device, it tried to find out what should have
been there, and writes it over the bad block. For some media-errors, this
has a reasonable chance of fixing the error. If the write succeeds, and a
subsequent read succeeds as well, raid5 decided the address is OK and
conitnues.
Instead of failing a drive on read-error, we attempt to re-write the block,
and then re-read. If that all works, we allow the device to remain in the
array.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Most awkward part of this is delaying write requests until bitmap updates have
been flushed.
To achieve this, we have a sequence number (seq_flush) which is incremented
each time the raid5 is unplugged.
If the raid thread notices that this has changed, it flushes bitmap changes,
and assigned the value of seq_flush to seq_write.
When a write request arrives, it is given the number from seq_write, and that
write request may not complete until seq_flush is larger than the saved seq
number.
We have a new queue for storing stripes which are waiting for a bitmap flush
and an extra flag for stripes to record if the write was 'degraded' and so
should not clear the a bit in the bitmap.
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
