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authorArtur Paszkiewicz <artur.paszkiewicz@intel.com>2017-03-09 09:59:59 +0100
committerShaohua Li <shli@fb.com>2017-03-16 16:55:54 -0700
commit3418d036c81dcb604b7c7c71b209d5890a8418aa (patch)
treed02a31103e09f82858bf149ebcb511e12ed6065a /drivers/md/raid5.h
parentff875738edd44e3bc892d378deacc50bccc9d70c (diff)
downloadlinux-3418d036c81dcb604b7c7c71b209d5890a8418aa.tar.bz2
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.h10
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;