md supports multiple different RAID level, each being implemented by a
'personality' (which is often in a separate module).

These personalities have fairly artificial 'numbers'.  The numbers
are use to:
 1- provide an index into an array where the various personalities
    are recorded
 2- identify the module (via an alias) which implements are particular
    personality.

Neither of these uses really justify the existence of personality numbers.
The array can be replaced by a linked list which is searched (array lookup
only happens very rarely).  Module identification can be done using an alias
based on level rather than 'personality' number.

The current 'raid5' modules support two level (4 and 5) but only one
personality.  This slight awkwardness (which was handled in the mapping from
level to personality) can be better handled by allowing raid5 to register 2
personalities.

With this change in place, the core md module does not need to have an
exhaustive list of all possible personalities, so other personalities can be
added independently.

This patch also moves the check for chunksize being non-zero into the ->run
routines for the personalities that need it, rather than having it in core-md.
 This has a side effect of allowing 'faulty' and 'linear' not to have a
chunk-size set.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

...because that seems to be the preferred practice these days.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus 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: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Replace multiple kmalloc/memset pairs with kzalloc calls.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Substitute:

  page_cache_get -> get_page
  page_cache_release -> put_page
  PAGE_CACHE_SHIFT -> PAGE_SHIFT
  PAGE_CACHE_SIZE -> PAGE_SIZE
  PAGE_CACHE_MASK -> PAGE_MASK
  __free_page -> put_page

because we aren't using the page cache, we are just using pages.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

With this patch it is possible to poll /proc/mdstat to detect arrays appearing
or disappearing, to detect failures, recovery starting, recovery completing,
and devices being added and removed.

It is similar to the poll-ability of /proc/mounts, though different in that:

We always report that the file is readable (because face it, it is, even if
only for EOF).

We report POLLPRI when there is a change so that select() can detect
it as an exceptional event.  Not only are these exceptional events, but
that is the mechanism that the current 'mdadm' uses to watch for events
(It also polls after a timeout).
(We also report POLLERR like /proc/mounts).

Finally, we only reset the per-file event counter when the start of the file
is read, rather than when poll() returns an event.  This is more robust as it
means that an fd will continue to report activity to poll/select until the
program clearly responds to that activity.

md_new_event takes an 'mddev' which isn't currently used, but it will be soon.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add in correct read-error handling for resync and read-only situations.

When read-only, we don't over-write, so we need to mark the failed drive in
the r10_bio so we don't re-try it.  During resync, we always read all blocks,
so if there is a read error, we simply over-write it with the good block that
we found (assuming we found one).

Note that the recovery case still isn't handled in an interesting way.  There
is nothing useful to do for the 2-copies case.  If there are 3 or more copies,
then we could try reading from one of the non-missing copies, but this is a
bit complicated and very rarely would be used, so I'm leaving it for now.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Largely just a cross-port from raid1.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

We are inadvertently setting the R1BIO_Uptodate bit on read errors when we
decide not to try correcting (because there are no other working devices).
This means that the read error is reported to the client as success.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Where performing a user-requested 'check' or 'repair', we read all readable
devices, and compare the contents.  We only write to blocks which had read
errors, or blocks with content that differs from the first good device found.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Also keep count on the number of errors found.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus 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: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Handling of read errors during resync is separate from handling of read errors
during normal IO in raid1.  A previous patch added support for read errors
during normal IO.  This one adds support for read errors during resync or
recovery.

The key differences are that we don't need to freeze the array, because the
normal handling of resync means that this part of the array will be idle
except for resync, and the read/overwrite/re-read is needed in a separate
piece of code.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

We are dereferencing ->rdev without an rcu lock!
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

On a read-error we suspend the array, then synchronously read the block from
other arrays until we find one where we can read it.  Then we try writing the
good data back everywhere and make sure it works.  If any write or subsequent
read fails, only then do we fail the device out of the array.

To be able to suspend the array, we need to also keep track of how many
requests are queued for handling by raid1d.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This is a simple port of match functionality across from raid5.  If we get a
read error, we don't kick the drive straight away, but try to over-write with
good data first.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus 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: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This is important because bitmap_create uses
  mddev->resync_max_sectors
and that doesn't have a valid value until after the array
has been initialised (with pers->run()).
[It doesn't make a difference for current personalities that
 support bitmaps, but will make a difference for raid10]

This has the added advantage of meaning with can move the thread->timeout
manipulation inside the bitmap.c code instead of sprinkling identical code
throughout all personalities.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

See patch to md.txt for more details
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Resync code:
  A test that isn't needed,
  a 'compute_block' that makes more sense
    elsewhere (And then doesn't need a test),
  a couple of BUG_ONs to confirm the change makes sense.

Printks:
  A few were missing KERN_*

Also fix a typo in a comment..
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

raid10 needs to put up a barrier to new requests while it does resync or other
background recovery.  The code for this is currently open-coded, slighty
obscure by its use of two waitqueues, and not documented.

This patch gathers all the related code into 4 functions, and includes a
comment which (hopefully) explains what is happening.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

raid1 needs to put up a barrier to new requests while it does resync or other
background recovery.  The code for this is currently open-coded, slighty
obscure by its use of two waitqueues, and not documented.

This patch gathers all the related code into 4 functions, and includes a
comment which (hopefully) explains what is happening.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

I've been attempting to set up a (Host)RAID mirror with dm_mirror on
2.6.14.3, and I've been having a strange little problem.  The configuration
in question is a set of 9GB SCSI disks that have 17942584 sectors.  I set
up the dm_mirror table as such:

0 17942528 mirror core 2 2048 nosync 2 8:48 0 8:64 0

If I'm not mistaken, this sets up a 9GB RAID1 mriror with 1MB stripes
across both SCSI disks.  The sector count of the dm device is less than the
size of the disks, so we shouldn't fall off the end.  However, I always get
the messages like this in dmesg when I set up the dm table:

attempt to access beyond end of device
sdd: rw=0, want=17958656, limit=17942584

Clearly, something is trying to read sectors past the end of the drive.  I
traced it down to the __rh_recovery_prepare function in dm-raid1.c, which
gets called when we're putting the mirror set together.  This function
calls the dirty region log's get_resync_work function to see if there's any
resync that needs to be done, and queues up any areas that are out of sync.
 The log's get_resync_work function is actually a pointer to the
core_get_resync_work function in dm-log.c.

The core_get_resync_work function queries a bitset lc->sync_bits to find
out if there are any regions that are out of date (i.e.  the bit is 0),
which is where the problem occurs.  If every bit in lc->sync_bits is 1
(which is the case when we've just configured a new RAID1 with the nosync
option), the find_next_zero_bit does NOT return the size parameter
(lc->region_count in this case), it returns the size parameter rounded up
to the nearest multiple of 32!  I don't know if this is intentional, but
i386 and x86_64 both exhibit this behavior.

In any case, the statement "if (*region == lc->region_count)" looks like
it's supposed to catch the case where are no regions to resync and
return 0.  Since find_next_zero_bit apparently has a habit of returning
a value that's larger than lc->region_count, the enclosed patch changes
the equality test to a greater-than test so that we don't try to resync
areas outside of the RAID1 region.  Seeing as the HostRAID metadata
lives just past the end of the RAID1 data, mucking around in that area
is not a good idea.

I suppose another way to fix this would be to amend find_next_zero_bit so
that it doesn't return values larger than "size", but I don't know if
there's a reason for the current behavior.
Signed-Off-By: NDarrick J. Wong <djwong@us.ibm.com>
Acked-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Zap the memory before freeing it so we don't leave crypto information
around in memory.
Signed-off-by: NStefan Rompf <stefan@loplof.de>
Acked-by: NClemens Fruhwirth <clemens@endorphin.org>
Acked-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch #if 0's the not yet implemented global function kcopyd_cancel().
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Acked-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add ioctl DM_SKIP_LOCKFS_FLAG for userspace to request that lock_fs is
bypassed when suspending a device.

There's no change to the behaviour of existing code that doesn't know about
the new flag.
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Devices only needs syncing when creating snapshots, so make this optional when
suspending a device.
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Rename frozen_bdev to suspended_bdev and move the bdget outside lockfs.  (This
prepares for making lockfs optional.)
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch introduces a new field to the mirror_set (default_mirror) to store
the default mirror.

(A subsequent patch will allow us to change the default mirror in the event of
a failure.)
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Use %llu not %Lu in sscanf/printf format strings.
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch removes an unused #define.
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

More snapshot metadata reading into separate function, to prepare for changing
the place it gets called from.
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

After changing the name of a mapped device, trigger a dm event.  (For
userspace multipath tools.)
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add dm_get_dev() to get a mapped device given its dev_t.
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Abstract dm_find_md() from dm_get_mdptr() to allow use elsewhere.
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Ignore all files generated from *_shipped files, plus a few others.
Signed-off-by: NBrian Gerst <bgerst@didntduck.org>
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>