btrfs: add and use helper to assert an inode range is clean

We have four different scenarios where we don't expect to find ordered
extents after locking a file range:

1) During plain fallocate;
2) During hole punching;
3) During zero range;
4) During reflinks (both cloning and deduplication).

This is because in all these cases we follow the pattern:

1) Lock the inode's VFS lock in exclusive mode;

2) Lock the inode's i_mmap_lock in exclusive node, to serialize with
   mmap writes;

3) Flush delalloc in a file range and wait for all ordered extents
   to complete - both done through btrfs_wait_ordered_range();

4) Lock the file range in the inode's io_tree.

So add a helper that asserts that we don't have ordered extents for a
given range. Make the four scenarios listed above use this helper after
locking the respective file range.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/fs/btrfs/reflink.c b/fs/btrfs/reflink.c
index c257bf037cf2..c39f8b3a5a4a 100644
--- a/fs/btrfs/reflink.c
+++ b/fs/btrfs/reflink.c
@@ -614,14 +614,23 @@ static void btrfs_double_extent_unlock(struct inode *inode1, u64 loff1,
 static void btrfs_double_extent_lock(struct inode *inode1, u64 loff1,
 				     struct inode *inode2, u64 loff2, u64 len)
 {
+	u64 range1_end = loff1 + len - 1;
+	u64 range2_end = loff2 + len - 1;
+
 	if (inode1 < inode2) {
 		swap(inode1, inode2);
 		swap(loff1, loff2);
+		swap(range1_end, range2_end);
 	} else if (inode1 == inode2 && loff2 < loff1) {
 		swap(loff1, loff2);
+		swap(range1_end, range2_end);
 	}
-	lock_extent(&BTRFS_I(inode1)->io_tree, loff1, loff1 + len - 1);
-	lock_extent(&BTRFS_I(inode2)->io_tree, loff2, loff2 + len - 1);
+
+	lock_extent(&BTRFS_I(inode1)->io_tree, loff1, range1_end);
+	lock_extent(&BTRFS_I(inode2)->io_tree, loff2, range2_end);
+
+	btrfs_assert_inode_range_clean(BTRFS_I(inode1), loff1, range1_end);
+	btrfs_assert_inode_range_clean(BTRFS_I(inode2), loff2, range2_end);
 }
 
 static void btrfs_double_mmap_lock(struct inode *inode1, struct inode *inode2)