From 3418d036c81dcb604b7c7c71b209d5890a8418aa Mon Sep 17 00:00:00 2001 From: Artur Paszkiewicz Date: Thu, 9 Mar 2017 09:59:59 +0100 Subject: 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 Signed-off-by: Shaohua Li --- drivers/md/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/md/Makefile') diff --git a/drivers/md/Makefile b/drivers/md/Makefile index 3cbda1af87a0..4d48714ccc6b 100644 --- a/drivers/md/Makefile +++ b/drivers/md/Makefile @@ -18,7 +18,7 @@ dm-cache-cleaner-y += dm-cache-policy-cleaner.o dm-era-y += dm-era-target.o dm-verity-y += dm-verity-target.o md-mod-y += md.o bitmap.o -raid456-y += raid5.o raid5-cache.o +raid456-y += raid5.o raid5-cache.o raid5-ppl.o # Note: link order is important. All raid personalities # and must come before md.o, as they each initialise -- cgit v1.2.3