From 486c737f7fdc0c3f6464cf27ede811daec2769a1 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Fri, 30 Jun 2023 08:56:40 +0800 Subject: btrfs: raid56: always verify the P/Q contents for scrub [REGRESSION] Commit 75b470332965 ("btrfs: raid56: migrate recovery and scrub recovery path to use error_bitmap") changed the behavior of scrub_rbio(). Initially if we have no error reading the raid bio, we will assign @need_check to true, then finish_parity_scrub() would later verify the content of P/Q stripes before writeback. But after that commit we never verify the content of P/Q stripes and just writeback them. This can lead to unrepaired P/Q stripes during scrub, or already corrupted P/Q copied to the dev-replace target. [FIX] The situation is more complex than the regression, in fact the initial behavior is not 100% correct either. If we have the following rare case, it can still lead to the same problem using the old behavior: 0 16K 32K 48K 64K Data 1: |IIIIIII| | Data 2: | | Parity: | |CCCCCCC| | Where "I" means IO error, "C" means corruption. In the above case, we're scrubbing the parity stripe, then read out all the contents of Data 1, Data 2, Parity stripes. But found IO error in Data 1, which leads to rebuild using Data 2 and Parity and got the correct data. In that case, we would not verify if the Parity is correct for range [16K, 32K). So here we have to always verify the content of Parity no matter if we did recovery or not. This patch would remove the @need_check parameter of finish_parity_scrub() completely, and would always do the P/Q verification before writeback. Fixes: 75b470332965 ("btrfs: raid56: migrate recovery and scrub recovery path to use error_bitmap") CC: stable@vger.kernel.org # 6.2+ Signed-off-by: Qu Wenruo Signed-off-by: David Sterba --- fs/btrfs/raid56.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c index f37b925d587f..0249ea52bb80 100644 --- a/fs/btrfs/raid56.c +++ b/fs/btrfs/raid56.c @@ -71,7 +71,7 @@ static void rmw_rbio_work_locked(struct work_struct *work); static void index_rbio_pages(struct btrfs_raid_bio *rbio); static int alloc_rbio_pages(struct btrfs_raid_bio *rbio); -static int finish_parity_scrub(struct btrfs_raid_bio *rbio, int need_check); +static int finish_parity_scrub(struct btrfs_raid_bio *rbio); static void scrub_rbio_work_locked(struct work_struct *work); static void free_raid_bio_pointers(struct btrfs_raid_bio *rbio) @@ -2404,7 +2404,7 @@ static int alloc_rbio_essential_pages(struct btrfs_raid_bio *rbio) return 0; } -static int finish_parity_scrub(struct btrfs_raid_bio *rbio, int need_check) +static int finish_parity_scrub(struct btrfs_raid_bio *rbio) { struct btrfs_io_context *bioc = rbio->bioc; const u32 sectorsize = bioc->fs_info->sectorsize; @@ -2445,9 +2445,6 @@ static int finish_parity_scrub(struct btrfs_raid_bio *rbio, int need_check) */ clear_bit(RBIO_CACHE_READY_BIT, &rbio->flags); - if (!need_check) - goto writeback; - p_sector.page = alloc_page(GFP_NOFS); if (!p_sector.page) return -ENOMEM; @@ -2516,7 +2513,6 @@ static int finish_parity_scrub(struct btrfs_raid_bio *rbio, int need_check) q_sector.page = NULL; } -writeback: /* * time to start writing. Make bios for everything from the * higher layers (the bio_list in our rbio) and our p/q. Ignore @@ -2699,7 +2695,6 @@ static int scrub_assemble_read_bios(struct btrfs_raid_bio *rbio) static void scrub_rbio(struct btrfs_raid_bio *rbio) { - bool need_check = false; int sector_nr; int ret; @@ -2722,7 +2717,7 @@ static void scrub_rbio(struct btrfs_raid_bio *rbio) * We have every sector properly prepared. Can finish the scrub * and writeback the good content. */ - ret = finish_parity_scrub(rbio, need_check); + ret = finish_parity_scrub(rbio); wait_event(rbio->io_wait, atomic_read(&rbio->stripes_pending) == 0); for (sector_nr = 0; sector_nr < rbio->stripe_nsectors; sector_nr++) { int found_errors; -- cgit v1.2.3