Btrfs: ioctl, don't re-lock extent range when not necessary

In ioctl.c:lock_extent_range(), after locking our target range, the
ordered extent that btrfs_lookup_first_ordered_extent() returns us
may not overlap our target range at all. In this case we would just
unlock our target range, wait for any new ordered extents that overlap
the range to complete, lock again the range and repeat all these steps
until we don't get any ordered extent and the delalloc flag isn't set
in the io tree for our target range.

Therefore just stop if we get an ordered extent that doesn't overlap
our target range and the dealalloc flag isn't set for the range in
the inode's io tree.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index f0b4237cedfc52193c7146fcc71e8ab305982ef2..04ece8fab92164d7ad288890b3ed35888c6f3575 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2700,10 +2700,15 @@ static inline void lock_extent_range(struct inode *inode, u64 off, u64 len)
                lock_extent(&BTRFS_I(inode)->io_tree, off, off + len - 1);
                ordered = btrfs_lookup_first_ordered_extent(inode,
                                                            off + len - 1);
-               if (!ordered &&
+               if ((!ordered ||
+                    ordered->file_offset + ordered->len <= off ||
+                    ordered->file_offset >= off + len) &&
                    !test_range_bit(&BTRFS_I(inode)->io_tree, off,
-                                   off + len - 1, EXTENT_DELALLOC, 0, NULL))
+                                   off + len - 1, EXTENT_DELALLOC, 0, NULL)) {
+                       if (ordered)
+                               btrfs_put_ordered_extent(ordered);
                        break;
+               }
                unlock_extent(&BTRFS_I(inode)->io_tree, off, off + len - 1);
                if (ordered)
                        btrfs_put_ordered_extent(ordered);