linux-toradex.git/drivers/md/raid5-log.h, branch v4.12-rc1

raid5-ppl: use resize_stripes() when enabling or disabling ppl

2017-04-10T19:00:49+00:00

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resize_stripes() can be called after mddev_resume() when ppl is no
longer active.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 
Signed-off-by: Artur Paszkiewicz 
Signed-off-by: Shaohua Li

md/raid5: call bio_endio() directly rather than queueing for later.

2017-03-23T02:16:12+00:00

We currently gather bios that need to be returned into a bio_list
and call bio_endio() on them all together.
The original reason for this was to avoid making the calls while
holding a spinlock.
Locking has changed a lot since then, and that reason is no longer
valid.

So discard return_io() and various return_bi lists, and just call
bio_endio() directly as needed.

Signed-off-by: NeilBrown 
Signed-off-by: Shaohua Li

raid5-ppl: support disk hot add/remove with PPL

2017-03-16T23:55:56+00:00

Add a function to modify the log by removing an rdev when a drive fails
or adding when a spare/replacement is activated as a raid member.

Removing a disk just clears the child log rdev pointer. No new stripes
will be accepted for this child log in ppl_write_stripe() and running io
units will be processed without writing PPL to the device.

Adding a disk sets the child log rdev pointer and writes an empty PPL
header.

Signed-off-by: Artur Paszkiewicz 
Signed-off-by: Shaohua Li

raid5-ppl: Partial Parity Log write logging implementation

2017-03-16T23:55:54+00:00

Implement the calculation of partial parity for a stripe and PPL write
logging functionality. The description of PPL is added to the
documentation. More details can be found in the comments in raid5-ppl.c.

Attach a page for holding the partial parity data to stripe_head.
Allocate it only if mddev has the MD_HAS_PPL flag set.

Partial parity is the xor of not modified data chunks of a stripe and is
calculated as follows:

- reconstruct-write case:
  xor data from all not updated disks in a stripe

- read-modify-write case:
  xor old data and parity from all updated disks in a stripe

Implement it using the async_tx API and integrate into raid_run_ops().
It must be called when we still have access to old data, so do it when
STRIPE_OP_BIODRAIN is set, but before ops_run_prexor5(). The result is
stored into sh->ppl_page.

Partial parity is not meaningful for full stripe write and is not stored
in the log or used for recovery, so don't attempt to calculate it when
stripe has STRIPE_FULL_WRITE.

Put the PPL metadata structures to md_p.h because userspace tools
(mdadm) will also need to read/write PPL.

Warn about using PPL with enabled disk volatile write-back cache for
now. It can be removed once disk cache flushing before writing PPL is
implemented.

Signed-off-by: Artur Paszkiewicz 
Signed-off-by: Shaohua Li

raid5: separate header for log functions

2017-03-16T23:55:54+00:00

Move raid5-cache declarations from raid5.h to raid5-log.h, add inline
wrappers for functions which will be shared with ppl and use them in
raid5 core instead of direct calls to raid5-cache.

Remove unused parameter from r5c_cache_data(), move two duplicated
pr_debug() calls to r5l_init_log().

Signed-off-by: Artur Paszkiewicz 
Signed-off-by: Shaohua Li