diff options
author | Artur Paszkiewicz <artur.paszkiewicz@intel.com> | 2017-03-09 09:59:59 +0100 |
---|---|---|
committer | Shaohua Li <shli@fb.com> | 2017-03-16 16:55:54 -0700 |
commit | 3418d036c81dcb604b7c7c71b209d5890a8418aa (patch) | |
tree | d02a31103e09f82858bf149ebcb511e12ed6065a /drivers/md/raid5.h | |
parent | ff875738edd44e3bc892d378deacc50bccc9d70c (diff) |
raid5-ppl: Partial Parity Log write logging implementation
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 <artur.paszkiewicz@intel.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'drivers/md/raid5.h')
-rw-r--r-- | drivers/md/raid5.h | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h index 6dd295a80ee1..ba5b7a3790af 100644 --- a/drivers/md/raid5.h +++ b/drivers/md/raid5.h @@ -224,10 +224,16 @@ struct stripe_head { spinlock_t batch_lock; /* only header's lock is useful */ struct list_head batch_list; /* protected by head's batch lock*/ - struct r5l_io_unit *log_io; + union { + struct r5l_io_unit *log_io; + struct ppl_io_unit *ppl_io; + }; + struct list_head log_list; sector_t log_start; /* first meta block on the journal */ struct list_head r5c; /* for r5c_cache->stripe_in_journal */ + + struct page *ppl_page; /* partial parity of this stripe */ /** * struct stripe_operations * @target - STRIPE_OP_COMPUTE_BLK target @@ -400,6 +406,7 @@ enum { STRIPE_OP_BIODRAIN, STRIPE_OP_RECONSTRUCT, STRIPE_OP_CHECK, + STRIPE_OP_PARTIAL_PARITY, }; /* @@ -696,6 +703,7 @@ struct r5conf { int group_cnt; int worker_cnt_per_group; struct r5l_log *log; + void *log_private; spinlock_t pending_bios_lock; bool batch_bio_dispatch; |