1/ If an array has any read-only devices when it is started,
   the array itself must be read-only
2/ A read-only device cannot be added to an array after it is
   started.
3/ Setting an array to read-write should not succeed
   if any member devices are read-only
Reported-and-Tested-by: Nanda Kishore Chinnaram <Nanda_Kishore_Chinna@dell.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

Since nr_queued is changed, we need to call wake_up here
if the array is already frozen and waiting for condition
"nr_pending == nr_queued + extra" to be true.

And commit 824e47da ("RAID1: avoid unnecessary spin
locks in I/O barrier code") which has already added the
wake_up for raid1.
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

Use __le32 and __le64 instead of u32 and u64.

This fixes klibc build error:
  In file included from /klibc/usr/klibc/../include/sys/md.h:30:0,
                   from /klibc/usr/kinit/do_mounts_md.c:19:
  /linux-next/usr/include/linux/raid/md_p.h:414:51: error: 'u32' undeclared here (not in a function)
    (PPL_HEADER_SIZE - PPL_HDR_RESERVED - 4 * sizeof(u32) - sizeof(u64))
Reported-by: Greg Thelen <gthelen@google.com>
Reported-by: Nigel Croxon <ncroxon@redhat.com>
Tested-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Signed-off-by: Shaohua Li <shli@fb.com>

We know that 'bm_lockres' is NULL here, so 'lockres_free(bm_lockres)' is a
no-op. According to resource handling in case of error a few lines below,
it is likely that 'bitmap_free(bitmap)' was expected instead.

Fixes: b98938d1 ("md-cluster: introduce cluster_check_sync_size")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

md allows a new array device to be created by simply
opening a device file.  This make it difficult to
remove the device and udev is likely to open the device file
as part of processing the REMOVE event.

There is an alternate mechanism for creating arrays
by writing to the new_array module parameter.
When using tools that work with this parameter, it is
best to disable the old semantics.
This new module parameter allows that.
Signed-off-by: NeilBrown <neilb@suse.com>
Acted-by: Coly Li <colyli@suse.de>
Signed-off-by: Shaohua Li <shli@fb.com>

The intention when creating the "new_array" parameter and the
possibility of having array names line "md_HOME" was to transition
away from the old way of creating arrays and to eventually only use
this new way.

The "old" way of creating array is to create a device node in /dev
and then open it.  The act of opening creates the array.
This is problematic because sometimes the device node can be opened
when we don't want to create an array.  This can easily happen
when some rule triggered by udev looks at a device as it is being
destroyed.  The node in /dev continues to exist for a short period
after an array is stopped, and opening it during this time recreates
the array (as an inactive array).

Unfortunately no clear plan for the transition was created.  It is now
time to fix that.

This patch allows devices with numeric names, like "md999" to be
created by writing to "new_array".  This will only work if the minor
number given is not already in use.  This will allow mdadm to
support the creation of arrays with numbers > 511 (currently not
possible) by writing to new_array.
mdadm can, at some point, use this approach to create *all* arrays,
which will allow the transition to only using the new-way.
Signed-off-by: NeilBrown <neilb@suse.com>
Acted-by: Coly Li <colyli@suse.de>
Signed-off-by: Shaohua Li <shli@fb.com>

Allocate both struct ppl_io_unit and its header_page from a shared
mempool to avoid a possible deadlock. Implement allocate and free
functions for the mempool, remove the second pool for allocating
header_page. The header_pages are now freed with their io_units, not
when the ppl bio completes. Also, use GFP_NOWAIT instead of GFP_ATOMIC
for allocating ppl_io_unit because we can handle failed allocations and
there is no reason to utilize emergency reserves.
Suggested-by: NeilBrown <neilb@suse.com>
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Signed-off-by: Shaohua Li <shli@fb.com>

raid0_make_request() should use a private bio_set rather than the
shared fs_bio_set, which is only meant for filesystems to use.

raid0_make_request() shouldn't loop around using the bio_set
multiple times as that can deadlock.

So use mddev->bio_set and pass the tail to generic_make_request()
instead of looping on it.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

linear_make_request() uses fs_bio_set, which is meant for filesystems
to use, and loops, possible allocating  from the same bio set multiple
times.
These behaviors can theoretically cause deadlocks, though as
linear requests are hardly ever split, it is unlikely in practice.

Change to use mddev->bio_set - otherwise unused for linear, and submit
the tail of a split request to generic_make_request() for it to
handle.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

chunk_aligned_read() currently uses fs_bio_set - which is meant for
filesystems to use - and loops if multiple splits are needed, which is
not best practice.
As this is only used for READ requests, not writes, it is unlikely
to cause a problem.  However it is best to be consistent in how
we split bios, and to follow the pattern used in raid1/raid10.

So create a private bioset, bio_split, and use it to perform a single
split, submitting the remainder to generic_make_request() for later
processing.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

handle_read_error() duplicates a lot of the work that raid10_read_request()
does, so it makes sense to just use that function.

handle_read_error() relies on the same r10bio being re-used so that,
in the case of a read-only array, setting IO_BLOCKED in r1bio->devs[].bio
ensures read_balance() won't re-use that device.
So when called from raid10_make_request() we clear that array, but not
when called from handle_read_error().

Two parts of handle_read_error() that need to be preserved are the warning
message it prints, so they are conditionally added to
raid10_read_request().  If the failing rdev can be found, messages
are printed.  Otherwise they aren't.

Not that as rdev_dec_pending() has already been called on the failing
rdev, we need to use rcu_read_lock() to get a new reference from
the conf.  We only use this to get the name of the failing block device.

With this change, we no longer need inc_pending().
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

raid10 splits requests in two different ways for two different
reasons.

First, bio_split() is used to ensure the bio fits with a chunk.
Second, multiple r10bio structures are allocated to represent the
different sections that need to go to different devices, to avoid
known bad blocks.

This can be simplified to just use bio_split() once, and not to use
multiple r10bios.
We delay the split until we know a maximum bio size that can
be handled with a single r10bio, and then split the bio and queue
the remainder for later handling.

As with raid1, we allocate a new bio_set to help with the splitting.
It is not correct to use fs_bio_set in a device driver.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

flush_pending_writes() and raid1_unplug() each contain identical
copies of a fairly large slab of code.  So factor that out into
new flush_bio_list() to simplify maintenance.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

handle_read_error() duplicates a lot of the work that raid1_read_request()
does, so it makes sense to just use that function.
This doesn't quite work as handle_read_error() relies on the same r1bio
being re-used so that, in the case of a read-only array, setting
IO_BLOCKED in r1bio->bios[] ensures read_balance() won't re-use
that device.
So we need to allow a r1bio to be passed to raid1_read_request(), and to
have that function mostly initialise the r1bio, but leave the bios[]
array untouched.

Two parts of handle_read_error() that need to be preserved are the warning
message it prints, so they are conditionally added to raid1_read_request().

Note that this highlights a minor bug on alloc_r1bio().  It doesn't
initalise the bios[] array, so it is possible that old content is there,
which might cause read_balance() to ignore some devices with no good reason.

With this change, we no longer need inc_pending(), or the sectors_handled
arg to alloc_r1bio().

As handle_read_error() is called from raid1d() and allocates memory,
there is tiny chance of a deadlock.  All element of various pools
could be queued waiting for raid1 to handle them, and there may be no
extra memory free.
Achieving guaranteed forward progress would probably require a second
thread and another mempool.  Instead of that complexity, add
__GFP_HIGH to any allocations when read1_read_request() is called
from raid1d.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

This reverts commit 6f880285.
bio_copy_data_partial() is no longer needed.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

Now that we always always pass an offset of 0 and a size
that matches the bio to alloc_behind_master_bio(),
we can remove the offset/size args and simplify the code.

We could probably remove bio_copy_data_partial() too.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

raid1 currently splits requests in two different ways for
two different reasons.

First, bio_split() is used to ensure the bio fits within a
resync accounting region.
Second, multiple r1bios are allocated for each bio to handle
the possiblity of known bad blocks on some devices.

This can be simplified to just use bio_split() once, and not
use multiple r1bios.
We delay the split until we know a maximum bio size that can
be handled with a single r1bio, and then split the bio and
queue the remainder for later handling.

This avoids all loops inside raid1.c request handling.  Just
a single read, or a single set of writes, is submitted to
lower-level devices for each bio that comes from
generic_make_request().

When the bio needs to be split, generic_make_request() will
do the necessary looping and call md_make_request() multiple
times.

raid1_make_request() no longer queues request for raid1 to handle,
so we can remove that branch from the 'if'.

This patch also creates a new private bio_set
(conf->bio_split) for splitting bios.  Using fs_bio_set
is wrong, as it is meant to be used by filesystems, not
block devices.  Using it inside md can lead to deadlocks
under high memory pressure.

Delete unused variable in raid1_write_request() (Shaohua)
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

In case of read-modify-write, partial partity is the same as the result
of ops_run_prexor5(), so we can just copy sh->dev[pd_idx].page into
sh->ppl_page instead of calculating it again.
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Signed-off-by: Shaohua Li <shli@fb.com>

Use resize_stripes() instead of raid5_reset_stripe_cache() to allocate
or free sh->ppl_page at runtime for all stripes in the stripe cache.
raid5_reset_stripe_cache() required suspending the mddev and could
deadlock because of GFP_KERNEL allocations.

Move the 'newsize' check to check_reshape() to allow reallocating the
stripes with the same number of disks. Allocate sh->ppl_page in
alloc_stripe() instead of grow_buffers(). Pass 'struct r5conf *conf' as
a parameter to alloc_stripe() because it is needed to check whether to
allocate ppl_page. Add free_stripe() and use it to free stripes rather
than directly call kmem_cache_free(). Also free sh->ppl_page in
free_stripe().

Set MD_HAS_PPL at the end of ppl_init_log() instead of explicitly
setting it in advance and add another parameter to log_init() to allow
calling ppl_init_log() without the bit set. Don't try to calculate
partial parity or add a stripe to log if it does not have ppl_page set.

Enabling ppl can now be performed without suspending the mddev, because
the log won't be used until new stripes are allocated with ppl_page.
Calling mddev_suspend/resume is still necessary when disabling ppl,
because we want all stripes to finish before stopping the log, but
resize_stripes() can be called after mddev_resume() when ppl is no
longer active.
Suggested-by: NeilBrown <neilb@suse.com>
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Signed-off-by: Shaohua Li <shli@fb.com>

Use a single no_mem_stripes list instead of per member device lists for
handling stripes that need retrying in case of failed io_unit
allocation. Because io_units are allocated from a memory pool shared
between all member disks, the no_mem_stripes list should be checked when
an io_unit for any member is freed. This fixes a deadlock that could
happen if there are stripes in more than one no_mem_stripes list.
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Signed-off-by: Shaohua Li <shli@fb.com>

fix_sync_read_error() modifies a bio on a newly faulty
device by setting bi_end_io to end_sync_write.
This ensure that put_buf() will still call rdev_dec_pending()
as required, but makes sure that subsequent code in
fix_sync_read_error() doesn't try to read from the device.

Unfortunately this interacts badly with sync_request_write()
which assumes that any bio with bi_end_io set to non-NULL
other than end_sync_read is safe to write to.

As the device is now faulty it doesn't make sense to write.
As the bio was recently used for a read, it is "dirty"
and not suitable for immediate submission.
In particular, ->bi_next might be non-NULL, which will cause
generic_make_request() to complain.

Break this interaction by refusing to write to devices
which are marked as Faulty.
Reported-and-tested-by: Michael Wang <yun.wang@profitbricks.com>
Fixes: 2e52d449 ("md/raid1: add failfast handling for reads.")
Cc: stable@vger.kernel.org (v4.10+)
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

md.c: it needs to release the mddev lock before
the array_size_store() returns.

Fixes: ab5a98b1 ("md-cluster: change array_sectors and update size are not supported")
Signed-off-by: Zhilong Liu <zlliu@suse.com>
Reviewed-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

if called md_set_readonly and set MD_CLOSING bit, the mddev cannot
be opened any more due to the MD_CLOING bit wasn't cleared. Thus it
needs to be cleared in md_ioctl after any call to md_set_readonly()
or do_md_stop().
Signed-off-by: NeilBrown <neilb@suse.com>
Fixes: af8d8e6f ("md: changes for MD_STILL_CLOSED flag")
Cc: stable@vger.kernel.org (v4.9+)
Signed-off-by: Zhilong Liu <zlliu@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

We need to set "first = 0' at the end of rdev_for_each
loop, so we can get the array's min_offset_diff correctly
otherwise min_offset_diff just means the last rdev's
offset diff.
Suggested-by: NeilBrown <neilb@suse.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

When recoverying a single missing/failed device in a RAID6,
those stripes where the Q block is on the missing device are
handled a bit differently.  In these cases it is easy to
check that the P block is correct, so we do.  This results
in the P block be destroy.  Consequently the P block needs
to be read a second time in order to compute Q.  This causes
lots of seeks and hurts performance.

It shouldn't be necessary to re-read P as it can be computed
from the DATA.  But we only compute blocks on missing
devices, since c337869d ("md: do not compute parity
unless it is on a failed drive").

So relax the change made in that commit to allow computing
of the P block in a RAID6 which it is the only missing that
block.

This makes RAID6 recovery run much faster as the disk just
"before" the recovering device is no longer seeking
back-and-forth.
Reported-by-tested-by: Brad Campbell <lists2009@fnarfbargle.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

When growing raid5 device on machine with small memory, there is chance that
mdadm will be killed and the following bug report can be observed. The same
bug could also be reproduced in linux-4.10.6.

[57600.075774] BUG: unable to handle kernel NULL pointer dereference at           (null)
[57600.083796] IP: [<ffffffff81a6aa87>] _raw_spin_lock+0x7/0x20
[57600.110378] PGD 421cf067 PUD 4442d067 PMD 0
[57600.114678] Oops: 0002 [#1] SMP
[57600.180799] CPU: 1 PID: 25990 Comm: mdadm Tainted: P           O    4.2.8 #1
[57600.187849] Hardware name: To be filled by O.E.M. To be filled by O.E.M./MAHOBAY, BIOS QV05AR66 03/06/2013
[57600.197490] task: ffff880044e47240 ti: ffff880043070000 task.ti: ffff880043070000
[57600.204963] RIP: 0010:[<ffffffff81a6aa87>]  [<ffffffff81a6aa87>] _raw_spin_lock+0x7/0x20
[57600.213057] RSP: 0018:ffff880043073810  EFLAGS: 00010046
[57600.218359] RAX: 0000000000000000 RBX: 000000000000000c RCX: ffff88011e296dd0
[57600.225486] RDX: 0000000000000001 RSI: ffffe8ffffcb46c0 RDI: 0000000000000000
[57600.232613] RBP: ffff880043073878 R08: ffff88011e5f8170 R09: 0000000000000282
[57600.239739] R10: 0000000000000005 R11: 28f5c28f5c28f5c3 R12: ffff880043073838
[57600.246872] R13: ffffe8ffffcb46c0 R14: 0000000000000000 R15: ffff8800b9706a00
[57600.253999] FS:  00007f576106c700(0000) GS:ffff88011e280000(0000) knlGS:0000000000000000
[57600.262078] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[57600.267817] CR2: 0000000000000000 CR3: 00000000428fe000 CR4: 00000000001406e0
[57600.274942] Stack:
[57600.276949]  ffffffff8114ee35 ffff880043073868 0000000000000282 000000000000eb3f
[57600.284383]  ffffffff81119043 ffff880043073838 ffff880043073838 ffff88003e197b98
[57600.291820]  ffffe8ffffcb46c0 ffff88003e197360 0000000000000286 ffff880043073968
[57600.299254] Call Trace:
[57600.301698]  [<ffffffff8114ee35>] ? cache_flusharray+0x35/0xe0
[57600.307523]  [<ffffffff81119043>] ? __page_cache_release+0x23/0x110
[57600.313779]  [<ffffffff8114eb53>] kmem_cache_free+0x63/0xc0
[57600.319344]  [<ffffffff81579942>] drop_one_stripe+0x62/0x90
[57600.324915]  [<ffffffff81579b5b>] raid5_cache_scan+0x8b/0xb0
[57600.330563]  [<ffffffff8111b98a>] shrink_slab.part.36+0x19a/0x250
[57600.336650]  [<ffffffff8111e38c>] shrink_zone+0x23c/0x250
[57600.342039]  [<ffffffff8111e4f3>] do_try_to_free_pages+0x153/0x420
[57600.348210]  [<ffffffff8111e851>] try_to_free_pages+0x91/0xa0
[57600.353959]  [<ffffffff811145b1>] __alloc_pages_nodemask+0x4d1/0x8b0
[57600.360303]  [<ffffffff8157a30b>] check_reshape+0x62b/0x770
[57600.365866]  [<ffffffff8157a4a5>] raid5_check_reshape+0x55/0xa0
[57600.371778]  [<ffffffff81583df7>] update_raid_disks+0xc7/0x110
[57600.377604]  [<ffffffff81592b73>] md_ioctl+0xd83/0x1b10
[57600.382827]  [<ffffffff81385380>] blkdev_ioctl+0x170/0x690
[57600.388307]  [<ffffffff81195238>] block_ioctl+0x38/0x40
[57600.393525]  [<ffffffff811731c5>] do_vfs_ioctl+0x2b5/0x480
[57600.399010]  [<ffffffff8115e07b>] ? vfs_write+0x14b/0x1f0
[57600.404400]  [<ffffffff811733cc>] SyS_ioctl+0x3c/0x70
[57600.409447]  [<ffffffff81a6ad97>] entry_SYSCALL_64_fastpath+0x12/0x6a
[57600.415875] Code: 00 00 00 00 55 48 89 e5 8b 07 85 c0 74 04 31 c0 5d c3 ba 01 00 00 00 f0 0f b1 17 85 c0 75 ef b0 01 5d c3 90 31 c0 ba 01 00 00 00 <f0> 0f b1 17 85 c0 75 01 c3 55 89 c6 48 89 e5 e8 85 d1 63 ff 5d
[57600.435460] RIP  [<ffffffff81a6aa87>] _raw_spin_lock+0x7/0x20
[57600.441208]  RSP <ffff880043073810>
[57600.444690] CR2: 0000000000000000
[57600.448000] ---[ end trace cbc6b5cc4bf9831d ]---

The problem is that resize_stripes() releases new stripe_heads before assigning new
slab cache to conf->slab_cache. If the shrinker function raid5_cache_scan() gets called
after resize_stripes() starting releasing new stripes but right before new slab cache
being assigned, it is possible that these new stripe_heads will be freed with the old
slab_cache which was already been destoryed and that triggers this bug.
Signed-off-by: Dennis Yang <dennisyang@qnap.com>
Fixes: edbe83ab ("md/raid5: allow the stripe_cache to grow and shrink.")
Cc: stable@vger.kernel.org (4.1+)
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

This patch kills the warning reported on powerpc_pseries,
and actually we don't need the initialization.

	After merging the md tree, today's linux-next build (powerpc
	pseries_le_defconfig) produced this warning:

	drivers/md/raid1.c: In function 'raid1d':
	drivers/md/raid1.c:2172:9: warning: 'page_len$' may be used uninitialized in this function [-Wmaybe-uninitialized]
	     if (memcmp(page_address(ppages[j]),
	         ^
	drivers/md/raid1.c:2160:7: note: 'page_len$' was declared here
	   int page_len[RESYNC_PAGES];
       ^
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>

When journal device of an array fails, the array is forced into read-only
mode. To make the array normal without adding another journal device, we
need to remove journal _feature_ from the array.

This patch allows remove journal _feature_ from an array, For journal
existing journal should be either missing or faulty.

To remove journal feature, it is necessary to remove the journal device
first:

  mdadm --fail /dev/md0 /dev/sdb
  mdadm: set /dev/sdb faulty in /dev/md0
  mdadm --remove /dev/md0 /dev/sdb
  mdadm: hot removed /dev/sdb from /dev/md0

Then the journal feature can be removed by echoing into the sysfs file:

 cat /sys/block/md0/md/consistency_policy
 journal

 echo resync > /sys/block/md0/md/consistency_policy
 cat /sys/block/md0/md/consistency_policy
 resync
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>

The payload->header.type and payload->size are little-endian, so just
convert them to the right byte order.
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Cc: <stable@vger.kernel.org> #v4.10+
Signed-off-by: Shaohua Li <shli@fb.com>

discard request doesn't have data attached, so it's meaningless to
allocate memory and copy from original bio for behind IO. And the copy
is bogus because bio_copy_data_partial can't handle discard request.

We don't support writesame/writezeros request so far.
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>

commit c18a1e09(block: introduce bio_clone_bioset_partial()) introduced
bio_clone_bioset_partial() for raid1 write behind IO. Now the write behind is
rewritten by Ming. We don't need the API any more, so revert the commit.

Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>

All reshape I/O share pages from 1st copy device, so just use that pages
for avoiding direct access to bvec table in handle_reshape_read_error.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>

Now one page array is allocated for each resync bio, and we can
retrieve page from this table directly.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>

Now we allocate one page array for managing resync pages, instead
of using bio's vec table to do that, and the old way is very hacky
and won't work any more if multipage bvec is enabled.

The introduced cost is that we need to allocate (128 + 16) * copies
bytes per r10_bio, and it is fine because the inflight r10_bio for
resync shouldn't be much, as pointed by Shaohua.

Also bio_reset() in raid10_sync_request() and reshape_request()
are removed because all bios are freshly new now in these functions
and not necessary to reset any more.

This patch can be thought as cleanup too.
Suggested-by: Shaohua Li <shli@kernel.org>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>

reshape read request is a bit special and requires one extra
bio which isn't allocated from r10buf_pool.

Refactor the .bi_end_io for read reshape, so that we can use
raid10's resync page mangement approach easily in the following
patches.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>

This patch improve handling of write behind in the following ways:

- introduce behind master bio to hold all write behind pages
- fast clone bios from behind master bio
- avoid to change bvec table directly
- use bio_copy_data() and make code more clean
Suggested-by: Shaohua Li <shli@fb.com>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>

The 'offset' local variable can't be changed inside the loop, so
move it out.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>

Turns out we can use bio_copy_data in raid1's write behind,
and we can make alloc_behind_pages() more clean/efficient,
but we need to partial version of bio_copy_data().
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Reviewed-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>

Avoid to direct access to bvec table.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>

Now one page array is allocated for each resync bio, and we can
retrieve page from this table directly.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>