Commit 6d3113a1 authored Apr 16, 2020 by Omar Sandoval Committed by David Sterba May 25, 2020

btrfs: fix error handling when submitting direct I/O bio



In btrfs_submit_direct_hook(), if a direct I/O write doesn't span a RAID
stripe or chunk, we submit orig_bio without cloning it. In this case, we
don't increment pending_bios. Then, if btrfs_submit_dio_bio() fails, we
decrement pending_bios to -1, and we never complete orig_bio. Fix it by
initializing pending_bios to 1 instead of incrementing later.

Fixing this exposes another bug: we put orig_bio prematurely and then
put it again from end_io. Fix it by not putting orig_bio.

After this change, pending_bios is really more of a reference count, but
I'll leave that cleanup separate to keep the fix small.

Fixes: e65e1535 ("btrfs: fix panic caused by direct IO")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent 1072c12d

fs/btrfs/inode.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -7939,7 +7939,6 @@ static int btrfs_submit_direct_hook(struct btrfs_dio_private *dip)

		/* bio split */
		ASSERT(geom.len <= INT_MAX);
		atomic_inc(&dip->pending_bios);
		do {
		clone_len = min_t(int, submit_len, geom.len);

		@@ -7989,6 +7988,7 @@ submit:
		if (!status)
		return 0;

		if (bio != orig_bio)
		bio_put(bio);
		out_err:
		dip->errors = 1;
		@@ -8030,7 +8030,7 @@ static void btrfs_submit_direct(struct bio dio_bio, struct inode inode,
		bio->bi_private = dip;
		dip->orig_bio = bio;
		dip->dio_bio = dio_bio;
		atomic_set(&dip->pending_bios, 0);
		atomic_set(&dip->pending_bios, 1);
		io_bio = btrfs_io_bio(bio);
		io_bio->logical = file_offset;

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