The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 6d3113a193e3385c72240096fe397618ecab6e43 Mon Sep 17 00:00:00 2001
From: Omar Sandoval osandov@fb.com Date: Thu, 16 Apr 2020 14:46:12 -0700 Subject: [PATCH] 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: e65e15355429 ("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
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 259239b33370..b628c319a5b6 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -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);
@@ -7989,7 +7988,8 @@ static int btrfs_submit_direct_hook(struct btrfs_dio_private *dip) if (!status) return 0;
- bio_put(bio); + 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;