This is the reclaim support for raid5 log. A stripe write will have
following steps:

1. reconstruct the stripe, read data/calculate parity. ops_run_io
prepares to write data/parity to raid disks
2. hijack ops_run_io. stripe data/parity is appending to log disk
3. flush log disk cache
4. ops_run_io run again and do normal operation. stripe data/parity is
written in raid array disks. raid core can return io to upper layer.
5. flush cache of all raid array disks
6. update super block
7. log disk space used by the stripe can be reused

In practice, several stripes consist of an io_unit and we will batch
several io_unit in different steps, but the whole process doesn't
change.

It's possible io return just after data/parity hit log disk, but then
read IO will need read from log disk. For simplicity, IO return happens
at step 4, where read IO can directly read from raid disks.

Currently reclaim run if there is specific reclaimable space (1/4 disk
size or 10G) or we are out of space. Reclaim is just to free log disk
spaces, it doesn't impact data consistency. The size based force reclaim
is to make sure log isn't too big, so recovery doesn't scan log too
much.

Recovery make sure raid disks and log disk have the same data of a
stripe. If crash happens before 4, recovery might/might not recovery
stripe's data/parity depending on if data/parity and its checksum
matches. In either case, this doesn't change the syntax of an IO write.
After step 3, stripe is guaranteed recoverable, because stripe's
data/parity is persistent in log disk. In some cases, log disk content
and raid disks content of a stripe are the same, but recovery will still
copy log disk content to raid disks, this doesn't impact data
consistency. space reuse happens after superblock update and cache
flush.

There is one situation we want to avoid. A broken meta in the middle of
a log causes recovery can't find meta at the head of log. If operations
require meta at the head persistent in log, we must make sure meta
before it persistent in log too. The case is stripe data/parity is in
log and we start write stripe to raid disks (before step 4). stripe
data/parity must be persistent in log before we do the write to raid
disks. The solution is we restrictly maintain io_unit list order. In
this case, we only write stripes of an io_unit to raid disks till the
io_unit is the first one whose data/parity is in log.

The io_unit list order is important for other cases too. For example,
some io_unit are reclaimable and others not. They can be mixed in the
list, we shouldn't reuse space of an unreclaimable io_unit.

Includes fixes to problems which were...
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>

This introduces a simple log for raid5. Data/parity writing to raid
array first writes to the log, then write to raid array disks. If
crash happens, we can recovery data from the log. This can speed up
raid resync and fix write hole issue.

The log structure is pretty simple. Data/meta data is stored in block
unit, which is 4k generally. It has only one type of meta data block.
The meta data block can track 3 types of data, stripe data, stripe
parity and flush block. MD superblock will point to the last valid
meta data block. Each meta data block has checksum/seq number, so
recovery can scan the log correctly. We store a checksum of stripe
data/parity to the metadata block, so meta data and stripe data/parity
can be written to log disk together. otherwise, meta data write must
wait till stripe data/parity is finished.

For stripe data, meta data block will record stripe data sector and
size. Currently the size is always 4k. This meta data record can be made
simpler if we just fix write hole (eg, we can record data of a stripe's
different disks together), but this format can be extended to support
caching in the future, which must record data address/size.

For stripe parity, meta data block will record stripe sector. It's
size should be 4k (for raid5) or 8k (for raid6). We always store p
parity first. This format should work for caching too.

flush block indicates a stripe is in raid array disks. Fixing write
hole doesn't need this type of meta data, it's for caching extension.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>

When a stripe finishes construction, we write the stripe to raid in
ops_run_io normally. With log, we do a bunch of other operations before
the stripe is written to raid. Mainly write the stripe to log disk,
flush disk cache and so on. The operations are still driven by raid5d
and run in the stripe state machine. We introduce a new state for such
stripe (trapped into log). The stripe is in this state from the time it
first enters ops_run_io (finish construction) to the time it is written
to raid. Since we know the state is only for log, we bypass other
check/operation in handle_stripe.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>

Next several patches use some raid5 functions, rename them with raid5
prefix and export out.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>

Journal device stores data in a log structure. We need record the log
start. Here we override md superblock recovery_offset for this purpose.
This field of a journal device is meaningless otherwise.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>

Next patches will use a disk as raid5/6 journaling. We need a new disk
role to present the journal device and add MD_FEATURE_JOURNAL to
feature_map for backward compability.
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>

Add the following two macros for special roles: spare and faulty

MD_DISK_ROLE_SPARE	0xffff
MD_DISK_ROLE_FAULTY	0xfffe

Add MD_DISK_ROLE_MAX	0xff00 as the maximal possible regular role,
and minimal value of special role.
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>

To incorporate --grow feature executed on one node, other nodes need to
acknowledge the change in number of disks. Call update_raid_disks()
to update internal data structures.

This leads to call check_reshape() -> md_allow_write() -> md_update_sb(),
this results in a deadlock. This is done so it can safely allocate memory
(which might trigger writeback which might write to raid1). This is
not required for md with a bitmap.

In the clustered case, we don't perform md_update_sb() in md_allow_write(),
but in do_md_run(). Also we disable safemode for clustered mode.

mddev->recovery_cp need not be set in check_sb_changes() because this
is required only when a node reads another node's bitmap. mddev->recovery_cp
(which is read from sb->resync_offset), is set only if mddev is in_sync.
Since we disabled safemode, in_sync is set to zero.
In a clustered environment, the MD may not be in sync because another
node could be writing to it. So make sure that in_sync is not set in
case of clustered node in __md_stop_writes().
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

The arg isn't used, so its presence is only confusing.
Signed-off-by: NeilBrown <neilb@suse.com>

It is common practice in the kernel to leave out this case.
It isn't needed and adds little if any value.
Signed-off-by: NeilBrown <neilb@suse.com>

Signed-off-by: NeilBrown <neilb@suse.com>

This patches fixes sparse warnings like incorrect type in assignment
(different base types), cast to restricted __le64.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

As cmsg.raid_slot is le32, comparing for >0 is not meaningful.

So introduce cpu-endian 'raid_slot' and only assign to cmsg.raid_slot
when we know value is valid.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NeilBrown <neilb@suse.com>

md-cluster: A better way for METADATA_UPDATED processing

The processing of METADATA_UPDATED message is too simple and prone to
errors. Besides, it would not update the internal data structures as
required.

This set of patches reads the superblock from one of the device of the MD
and checks for changes in the in-memory data structures. If there is a change,
it performs the necessary actions to keep the internal data structures
as it would be in the primary node.

An example is if a devices turns faulty. The algorithm is:

1. The initiator node marks the device as faulty and updates the superblock
2. The initiator node sends METADATA_UPDATED with an advisory  device number to the rest of the nodes.
3. The receiving node on receiving the METADATA_UPDATED message
  3.1 Reads the superblock
  3.2 Detects a device has failed by comparing with memory structure
  3.3 Calls the necessary functions to record the failure and get the device out of the active array.
  3.4 Acknowledges the message.

The patch series also fixes adding the disk which was impacted because of
the changes.

Patches can also be found at
https://github.com/goldwynr/linux branch md-next

Changes since V2:
 - Fix status synchrnoization after --add and --re-add operations
 - Included Guoqing's patches on endian correctness, zeroing cmsg etc
 - Restructure add_new_disk() and cancel()

We shouldn't run related funs of md_cluster_ops in case
metadata_update_start returned failure.
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>

For cluster raid, we should not kick it from array if the disk can't be
remove from array successfully.
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

Signed-off-by: Guoqing Jiang <gqjiang@suse.com>

Signed-off-by: Guoqing Jiang <gqjiang@suse.com>

During the past test, the node occasionally received the msg which is
sent from itself, this case should not happen in theory, but it is
better to avoid it in case something wrong happened.
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

Since slot will be set within _sendmsg, we can remove
the redundant code in resync_info_update.
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>

Signed-off-by: Guoqing Jiang <gqjiang@suse.com>

The receive daemon prints kernel messages for every network message
received. This would fill the kernel message log with unnecessary messages.
Remove the pr_info() messages.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

Adding the disk worked incorrectly with the new reload code. Fix it:

 - No operation should be performed on rdev marked as Candidate
 - After a metadata update operation, kick disk if role is 0xfffe
   else clear Candidate bit and continue with the regular change check.
 - Saving the mode of the lock resource to check if token lock is already
   locked, because it can be called twice while adding a disk. However,
   unlock_comm() must be called only once.
 - add_new_disk() is called by the node initiating the --add operation.
   If it needs to be canceled, call add_new_disk_cancel(). The operation
   is completed by md_update_sb() which will write and unlock the
   communication.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

Resync or recovery must be performed by only one node at a time.
A DLM lock resource, resync_lockres provides the mutual exclusion
so that only one node performs the recovery/resync at a time.

If a node is unable to get the resync_lockres, because recovery is
being performed by another node, it set MD_RECOVER_NEEDED so as
to schedule recovery in the future.

Remove the debug message in resync_info_update()
used during development.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

In a clustered environment, a change such as marking a device faulty,
can be recorded by any of the nodes. This is communicated to all the
nodes and re-recording such a change is unnecessary, and quite often
pretty disruptive.

With this patch, just before the update, we detect for the changes
and if the changes are already in superblock, we abort the update
after clearing all the flags
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

md_reload_sb is too simplistic and it explicitly needs to determine
the changes made by the writing node. However, there are multiple areas
where a simple reload could fail.

Instead, read the superblock of one of the "good" rdevs and update
the necessary information:

- read the superblock into a newly allocated page, by temporarily
  swapping out rdev->sb_page and calling ->load_super.
- if that fails return
- if it succeeds, call check_sb_changes
  1. iterates over list of active devices and checks the matching
   dev_roles[] value.
   	If that is 'faulty', the device must be  marked as faulty
	 - call md_error to mark the device as faulty. Make sure
	   not to set CHANGE_DEVS and wakeup mddev->thread or else
	   it would initiate a resync process, which is the responsibility
	   of the "primary" node.
	 - clear the Blocked bit
	 - Call remove_and_add_spares() to hot remove the device.
	If the device is 'spare':
	 - call remove_and_add_spares() to get the number of spares
	   added in this operation.
	 - Reduce mddev->degraded to mark the array as not degraded.
  2. reset recovery_cp
- read the rest of the rdevs to update recovery_offset. If recovery_offset
  is equal to MaxSector, call spare_active() to set it In_sync

This required that recovery_offset be initialized to MaxSector, as
opposed to zero so as to communicate the end of sync for a rdev.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

remove_and_add_spares() checks for all devices to activate spare.
Change it to activate a specific device if a non-null rdev
argument is passed.

remove_and_add_spares() can be used to activate spares in
slot_store() as well.

For hot_remove_disk(), check if rdev->raid_disk == -1 before
calling remove_and_add_spares()
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

When the suspended_area is deleted, the suspended processes
must be woken up in order to complete their I/O.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

Previously, BITMAP_NEEDS_SYNC message is sent when the resyc
aborts, but it could abort for different reasons, and not all
of reasons require another node to take over the resync ownship.

It is better make BITMAP_NEEDS_SYNC message only be sent when
the node is leaving cluster with dirty bitmap. And we also need
to ensure dlm connection is ok.
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

Suspending the entire device for resync could take too long. Resync
in small chunks.

cluster's resync window (32M) is maintained in r1conf as
cluster_sync_low and cluster_sync_high and processed in
raid1's sync_request(). If the current resync is outside the cluster
resync window:

1. Set the cluster_sync_low to curr_resync_completed.
2. Check if the sync will fit in the new window, if not issue a
   wait_barrier() and set cluster_sync_low to sector_nr.
3. Set cluster_sync_high to cluster_sync_low + resync_window.
4. Send a message to all nodes so they may add it in their suspension
   list.

bitmap_cond_end_sync is modified to allow to force a sync inorder
to get the curr_resync_completed uptodate with the sector passed.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>

Add BITMAP_MAJOR_CLUSTERED as 5, in order to prevent older kernels
to assemble a clustered device.

In order to maximize compatibility, the major version is set to
BITMAP_MAJOR_CLUSTERED *only* if the bitmap is clustered.

Added MD_FEATURE_CLUSTERED in order to return error for older
kernels which would assemble MD even if the bitmap is corrupted.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

process_suspend_info - which handles the RESYNCING request - must not
reply until all writes which were initiated before the request arrived,
have completed.

As a by-product, all process_* functions now take mddev as their
first arguement making it uniform.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

Pull scheduler fix from Thomas Gleixner:
 "Fix a long standing state race in finish_task_switch()"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Fix TASK_DEAD race in finish_task_switch()

Pull perf fix from Thomas Glexiner:
 "Fix build breakage on powerpc in perf tools"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf tools: Fix build break on powerpc due to sample_reg_masks

Pull maintainer email update from Thomas Gleixner:
 "Change Matt Fleming's email address in the maintainers file"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  MAINTAINERS: Change Matt Fleming's email address

Pull irq fixes from Thomas Gleixner:
 "Three trivial commits:

   - Fix a kerneldoc regression

   - Export handle_bad_irq to unbreak a driver in next

   - Add an accessor for the of_node field so refactoring in next does
     not depend on merge ordering"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqdomain: Add an accessor for the of_node field
  genirq: Fix handle_bad_irq kerneldoc comment
  genirq: Export handle_bad_irq

Pull SCSI fixes from James Bottomley:
 "This is a set of three bug fixes, two of which are regressions from
  recent updates (the 3ware one from 4.1 and the device handler fixes
  from 4.2)"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  3w-9xxx: don't unmap bounce buffered commands
  scsi_dh: Use the correct module name when loading device handler
  libiscsi: Fix iscsi_check_transport_timeouts possible infinite loop

Pull md bugfix from Neil Brown:
 "One bug fix for raid1/raid10.

  Very careless bug earler in 4.3-rc, now fixed :-)"

* tag 'md/4.3-rc4-fix' of git://neil.brown.name/md:
  crash in md-raid1 and md-raid10 due to incorrect list manipulation

My Intel email address will soon expire. Replace it with my
personal address so people still know where to send patches.
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1444494136-10333-1-git-send-email-matt@codeblueprint.co.ukSigned-off-by: Ingo Molnar <mingo@kernel.org>