diff options
| -rw-r--r-- | fs/btrfs/ioctl.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 717f34f977d5..d8539979b44f 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -3041,11 +3041,21 @@ static int btrfs_cmp_data_prepare(struct inode *src, u64 loff, cmp->src_pages = src_pgarr; cmp->dst_pages = dst_pgarr; - ret = gather_extent_pages(src, cmp->src_pages, cmp->num_pages, loff); + /* + * If deduping ranges in the same inode, locking rules make it mandatory + * to always lock pages in ascending order to avoid deadlocks with + * concurrent tasks (such as starting writeback/delalloc). + */ + if (src == dst && dst_loff < loff) { + swap(src_pgarr, dst_pgarr); + swap(loff, dst_loff); + } + + ret = gather_extent_pages(src, src_pgarr, cmp->num_pages, loff); if (ret) goto out; - ret = gather_extent_pages(dst, cmp->dst_pages, cmp->num_pages, dst_loff); + ret = gather_extent_pages(dst, dst_pgarr, cmp->num_pages, dst_loff); out: if (ret) |