linux.git/drivers/md/raid10.c, branch v3.3-rc2

md/raid10: If there is a spare and a want_replacement device, start replacement.

2011-12-22T23:17:56+00:00

When attempting to add a spare to a RAID10 array, also consider
adding it as a replacement for a want_replacement device.

Signed-off-by: NeilBrown

md/raid10: recognise replacements when assembling array.

2011-12-22T23:17:55+00:00

If a Replacement is seen, file it as such.

If we see two replacements (or two normal devices) for the one slot,
abort.

Signed-off-by: NeilBrown

md/raid10: Allow replacement device to be replace old drive.

2011-12-22T23:17:55+00:00

When recovery finish and spare_active is called, check for a
replace that might have just become fully synced and mark it
as such, marking the original as failed.

Then when the original is removed, move the replacement into
its position.

This means that 'replacement' and spontaneously become NULL in some
situations.  Make sure we check for those.
It also means that 'rdev' and 'replacement' could appear to be
identical - check for that too.

Signed-off-by: NeilBrown

md/raid10: handle recovery of replacement devices.

2011-12-22T23:17:55+00:00

If there is a replacement device, then recover to it,
reading from any drives - maybe the one being replaced, maybe not.

Signed-off-by: NeilBrown

md/raid10: Handle replacement devices during resync.

2011-12-22T23:17:55+00:00

If we need to resync an array which has replacement devices,
we always write any block checked to every replacement.

If the resync was bitmap-based resync we will then complete the
replacement normally.
If it was a full resync, we mark the replacements as fully recovered
when the resync finishes so no further recovery is needed.

Signed-off-by: NeilBrown

md/raid10: writes should get directed to replacement as well as original.

2011-12-22T23:17:55+00:00

When writing, we need to submit two writes, one to the original,
and one to the replacements - if there is a replacement.

If the write to the replacement results in a write error we just
fail the device.  We only try to record write errors to the
original.

This only handles writing new data.  Writing for resync/recovery
will come later.

Signed-off-by: NeilBrown

md/raid10: allow removal of failed replacement devices.

2011-12-22T23:17:54+00:00

Enhance raid10_remove_disk to be able to remove ->replacement
as well as ->rdev

Signed-off-by: NeilBrown

md/raid10: preferentially read from replacement device if possible.

2011-12-22T23:17:54+00:00

When reading (for array reads, not for recovery etc) we read from the
replacement device if it has recovered far enough.
This requires storing the chosen rdev in the 'r10_bio' so we can make
sure to drop the ref on the right device when the read finishes.

Signed-off-by: NeilBrown

md/raid10: change read_balance to return an rdev

2011-12-22T23:17:54+00:00

It makes more sense to return an rdev than just an index as
read_balance() gets a reference to the rdev and so returning
the pointer make this more idiomatic.

This will be needed in a future patch when we might return
a 'replacement' rdev instead of the main rdev.

Signed-off-by: NeilBrown

md/raid10: prepare data structures for handling replacement.

2011-12-22T23:17:54+00:00

Allow each slot in the RAID10 to have 2 devices, the want_replacement
and the replacement.

Also an r10bio to have 2 bios, and for resync/recovery allocate the
second bio if there are any replacement devices.

Signed-off-by: NeilBrown