From a323e8139c3617b2bf975317725d0fd962886d06 Mon Sep 17 00:00:00 2001 From: Zhao Lei Date: Thu, 23 Jul 2015 12:29:49 +0800 Subject: [PATCH] btrfs: Fix scrub panic when leaf crosses stripes Scrub panic in following operation: mkfs.ext4 /dev/vdh btrfs-convert /dev/vdh mount /dev/vdh /mnt/tmp1 btrfs scrub start -B /dev/vdh (panic) Reason: 1: In some case, leaf created by btrfs-convert was splited into 2 strips. 2: Scrub bypassed part of above wrong leaf data, but remain data caused panic in scrub_checksum_tree_block(). For reason 1: we can get following information after some simple operation. a. mkfs.ext4 /dev/vdh btrfs-convert /dev/vdh b. btrfs-debug-tree /dev/vdh we can see following item in extent tree: item 25 key (27054080 METADATA_ITEM 0) itemoff 15083 itemsize 33 Its logical address is [27054080, 27070464) and acrossed 2 strips: [27000832, 27066368) [27066368, 27131904) Will be fixed in btrfs-progs(btrfs-convert, btrfsck, ...) For reason 2: Scrub is trying to do a "bypass" in this case, but the result is "panic", because current code lacks of some condition in bypass, and let some wrong leaf data escaped. This patch fixed above scrub code. Before patch: # btrfs scrub start -B /dev/vdh (panic) After patch: # btrfs scrub start -B /dev/vdh scrub done for 353cec8f-da31-4a94-aa35-be72d997b06e ... # dmesg ... [ 59.088697] BTRFS error (device vdh): scrub: tree block 27054080 spanning stripes, ignored. logical=27000832 [ 59.089929] BTRFS error (device vdh): scrub: tree block 27054080 spanning stripes, ignored. logical=27066368 # Reported-by: Chris Murphy Signed-off-by: Zhao Lei Signed-off-by: Chris Mason --- fs/btrfs/scrub.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 94db0fa5225a..35d49b28a688 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -2881,11 +2881,12 @@ static noinline_for_stack int scrub_raid56_parity(struct scrub_ctx *sctx, flags = btrfs_extent_flags(l, extent); generation = btrfs_extent_generation(l, extent); - if (key.objectid < logic_start && - (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) { - btrfs_err(fs_info, - "scrub: tree block %llu spanning stripes, ignored. logical=%llu", - key.objectid, logic_start); + if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) && + (key.objectid < logic_start || + key.objectid + bytes > + logic_start + map->stripe_len)) { + btrfs_err(fs_info, "scrub: tree block %llu spanning stripes, ignored. logical=%llu", + key.objectid, logic_start); goto next; } again: @@ -3212,8 +3213,10 @@ static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx, flags = btrfs_extent_flags(l, extent); generation = btrfs_extent_generation(l, extent); - if (key.objectid < logical && - (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) { + if ((flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) && + (key.objectid < logical || + key.objectid + bytes > + logical + map->stripe_len)) { btrfs_err(fs_info, "scrub: tree block %llu spanning " "stripes, ignored. logical=%llu", -- 2.20.1