From ef340fccbe982a14588ed15eb3a20b2e5b78a3e1 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Thu, 2 Jun 2022 15:51:19 +0800 Subject: [PATCH] btrfs: raid56: avoid double for loop inside __raid56_parity_recover() The double for loop can be easily converted to single for loop as we're really iterating the sectors in their bytenr order. The only exception is the full stripe skip, however that can also easily be done inside the loop. Add an ASSERT() along with a comment for that specific case. Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/raid56.c | 39 +++++++++++++++++++-------------------- 1 file changed, 19 insertions(+), 20 deletions(-) diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c index c63845c036df..ae4556b98060 100644 --- a/fs/btrfs/raid56.c +++ b/fs/btrfs/raid56.c @@ -2115,8 +2115,7 @@ static int __raid56_parity_recover(struct btrfs_raid_bio *rbio) int bios_to_read = 0; struct bio_list bio_list; int ret; - int sectornr; - int stripe; + int total_sector_nr; struct bio *bio; bio_list_init(&bio_list); @@ -2132,29 +2131,29 @@ static int __raid56_parity_recover(struct btrfs_raid_bio *rbio) * stripe cache, it is possible that some or all of these * pages are going to be uptodate. */ - for (stripe = 0; stripe < rbio->real_stripes; stripe++) { + for (total_sector_nr = 0; total_sector_nr < rbio->nr_sectors; + total_sector_nr++) { + int stripe = total_sector_nr / rbio->stripe_nsectors; + int sectornr = total_sector_nr % rbio->stripe_nsectors; + struct sector_ptr *sector; + if (rbio->faila == stripe || rbio->failb == stripe) { atomic_inc(&rbio->error); + /* Skip the current stripe. */ + ASSERT(sectornr == 0); + total_sector_nr += rbio->stripe_nsectors - 1; continue; } + /* The RMW code may have already read this page in. */ + sector = rbio_stripe_sector(rbio, stripe, sectornr); + if (sector->uptodate) + continue; - for (sectornr = 0; sectornr < rbio->stripe_nsectors; sectornr++) { - struct sector_ptr *sector; - - /* - * the rmw code may have already read this - * page in - */ - sector = rbio_stripe_sector(rbio, stripe, sectornr); - if (sector->uptodate) - continue; - - ret = rbio_add_io_sector(rbio, &bio_list, sector, - stripe, sectornr, rbio->stripe_len, - REQ_OP_READ); - if (ret < 0) - goto cleanup; - } + ret = rbio_add_io_sector(rbio, &bio_list, sector, stripe, + sectornr, rbio->stripe_len, + REQ_OP_READ); + if (ret < 0) + goto cleanup; } bios_to_read = bio_list_size(&bio_list); -- GitLab