xfs: fix the comment of xfs_extent_busy_update_extent()

Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_extent_busy.c b/fs/xfs/xfs_extent_busy.c
index 85e9f87a..86f559f 100644
--- a/fs/xfs/xfs_extent_busy.c
+++ b/fs/xfs/xfs_extent_busy.c
@@ -147,7 +147,7 @@
  * extent.  If the overlap covers the beginning, the end, or all of the busy
  * extent, the overlapping portion can be made unbusy and used for the
  * allocation.  We can't split a busy extent because we can't modify a
- * transaction/CIL context busy list, but we can update an entries block
+ * transaction/CIL context busy list, but we can update an entry's block
  * number or length.
  *
  * Returns true if the extent can safely be reused, or false if the search