Commit cf1167d5 authored Sep 20, 2017 by Liu Bo Committed by David Sterba Sep 26, 2017

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 <bo.li.liu@oracle.com>
Reported-by: Paul Jones <paul@pauljones.id.au>
Tested-by: Paul Jones <paul@pauljones.id.au>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent bd7d63c2

fs/btrfs/compression.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -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);

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