From cf1167d5c1abf3bc42b2a1562bfa7937c05337e2 Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Wed, 20 Sep 2017 17:50:18 -0600 Subject: [PATCH] Btrfs: fix kernel oops while reading compressed data The kernel oops happens at kernel BUG at fs/btrfs/extent_io.c:2104! ... RIP: clean_io_failure+0x263/0x2a0 [btrfs] It's showing that read-repair code is using an improper mirror index. This is due to the fact that compression read's endio hasn't recorded the failed mirror index in %cb->orig_bio. With this, btrfs's read-repair can work properly on reading compressed data. Signed-off-by: Liu Bo Reported-by: Paul Jones Tested-by: Paul Jones Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/compression.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index 883ecc58fd0d..c6aa53c4c102 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -107,6 +107,7 @@ static void end_compressed_bio_read(struct bio *bio) struct inode *inode; struct page *page; unsigned long index; + unsigned int mirror = btrfs_io_bio(bio)->mirror_num; int ret; if (bio->bi_status) @@ -118,6 +119,14 @@ static void end_compressed_bio_read(struct bio *bio) if (!refcount_dec_and_test(&cb->pending_bios)) goto out; + /* + * Record the correct mirror_num in cb->orig_bio so that + * read-repair can work properly. + */ + ASSERT(btrfs_io_bio(cb->orig_bio)); + btrfs_io_bio(cb->orig_bio)->mirror_num = mirror; + cb->mirror_num = mirror; + inode = cb->inode; ret = check_compressed_csum(BTRFS_I(inode), cb, (u64)bio->bi_iter.bi_sector << 9); -- 2.11.0