linux.git/drivers/md/raid5.c, branch v2.6.31

md/raid5: Properly remove excess drives after shrinking a raid5/6

2009-08-13T00:41:49+00:00

We were removing the drives, from the array, but not
removing symlinks from /sys/.... and not marking the device
as having been removed.

Signed-off-by: NeilBrown

md/raid5: make sure a reshape restarts at the correct address.

2009-08-13T00:13:00+00:00

This "if" don't allow for the possibility that the number of devices
doesn't change, and so sector_nr isn't set correctly in that case.
So change '>' to '>='.

Signed-off-by: NeilBrown

md/raid5: allow new reshape modes to be restarted in the middle.

2009-08-13T00:06:24+00:00

md/raid5 doesn't allow a reshape to restart if it involves writing
over the same part of disk that it would be reading from.
This happens at the beginning of a reshape that increases the number
of devices, at the end of a reshape that decreases the number of
devices, and continuously for a reshape that does not change the
number of devices.

The current code is correct for the "increase number of devices"
case as the critical section at the start is handled by userspace
performing a backup.

It does not work for reducing the number of devices, or the
no-change case.
For 'reducing', we need to invert the test.  For no-change we cannot
really be sure things will be safe, so simply require the array
to be read-only, which is how the user-space code which carefully
starts such arrays works.

Signed-off-by: NeilBrown

md: Use revalidate_disk to effect changes in size of device.

2009-08-03T00:59:58+00:00

As revalidate_disk calls check_disk_size_change, it will cause
any capacity change of a gendisk to be propagated to the blockdev
inode.  So use that instead of mucking about with locks and
i_size_write.

Also add a call to revalidate_disk in do_md_run and a few other places
where the gendisk capacity is changed.

Signed-off-by: NeilBrown

md: allow raid5_quiesce to work properly when reshape is happening.

2009-08-03T00:59:58+00:00

The ->quiesce method is not supposed to stop resync/recovery/reshape,
just normal IO.
But in raid5 we don't have a way to know which stripes are being
used for normal IO and which for resync etc, so we need to wait for
all stripes to be idle to be sure that all writes have completed.

However reshape keeps at least some stripe busy for an extended period
of time, so a call to raid5_quiesce can block for several seconds
needlessly.
So arrange for reshape etc to pause briefly while raid5_quiesce is
trying to quiesce the array so that the active_stripes count can
drop to zero.

Signed-off-by: NeilBrown

md/raid5: set reshape_position correctly when reshape starts.

2009-08-03T00:59:57+00:00

As the internal reshape_progress counter is the main driver
for reshape, the fact that reshape_position sometimes starts with the
wrong value has minimal effect.  It is visible in sysfs and that
is all.

Signed-off-by: NeilBrown

md/raid6: release spare page at ->stop()

2009-07-31T02:39:15+00:00

Add missing call to safe_put_page from stop() by unifying open coded
raid5_conf_t de-allocation under free_conf().

Cc: 
Signed-off-by: Dan Williams 
Signed-off-by: NeilBrown

md: use interruptible wait when duration is controlled by userspace.

2009-07-01T03:15:35+00:00

User space can set various limits on an md array so that resync waits
when it gets to a certain point, or so that I/O is blocked for a short
while.
When md is waiting against one of these limit, it should use an
interruptible wait so as not to add to the load average, and so are
not to trigger a warning if the wait goes on for too long.

Signed-off-by: NeilBrown

md/raid5: suspend shouldn't affect read requests.

2009-07-01T03:15:35+00:00

md allows write to regions on an array to be suspended temporarily.
This allows user-space to participate is aspects of reshape.
In particular, data can be copied with not risk of a race.
We should not be blocking read requests though, so don't.

Cc: stable@kernel.org
Signed-off-by: NeilBrown

md: Use new topology calls to indicate alignment and I/O sizes

2009-07-01T01:13:45+00:00

Switch MD over to the new disk_stack_limits() function which checks for
aligment and adjusts preferred I/O sizes when stacking.

Also indicate preferred I/O sizes where applicable.

Signed-off-by: Martin K. Petersen 
Signed-off-by: Mike Snitzer 
Signed-off-by: NeilBrown