1 files changed, 14 insertions, 7 deletions

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 41734202796f..2ef78aa1d3f6 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -449,15 +449,17 @@ xfs_prepare_ioend(
 }
 
 /*
- * If the page has delalloc blocks on it, we need to punch them out before we
- * invalidate the page.  If we don't, we leave a stale delalloc mapping on the
- * inode that can trip up a later direct I/O read operation on the same region.
+ * If the folio has delalloc blocks on it, the caller is asking us to punch them
+ * out. If we don't, we can leave a stale delalloc mapping covered by a clean
+ * page that needs to be dirtied again before the delalloc mapping can be
+ * converted. This stale delalloc mapping can trip up a later direct I/O read
+ * operation on the same region.
  *
- * We prevent this by truncating away the delalloc regions on the page.  Because
+ * We prevent this by truncating away the delalloc regions on the folio. Because
  * they are delalloc, we can do this without needing a transaction. Indeed - if
  * we get ENOSPC errors, we have to be able to do this truncation without a
- * transaction as there is no space left for block reservation (typically why we
- * see a ENOSPC in writeback).
+ * transaction as there is no space left for block reservation (typically why
+ * we see a ENOSPC in writeback).
  */
 static void
 xfs_discard_folio(
@@ -475,8 +477,13 @@ xfs_discard_folio(
 		"page discard on page "PTR_FMT", inode 0x%llx, pos %llu.",
 			folio, ip->i_ino, pos);
 
+	/*
+	 * The end of the punch range is always the offset of the the first
+	 * byte of the next folio. Hence the end offset is only dependent on the
+	 * folio itself and not the start offset that is passed in.
+	 */
 	error = xfs_bmap_punch_delalloc_range(ip, pos,
-			round_up(pos, folio_size(folio)));
+				folio_pos(folio) + folio_size(folio));
 
 	if (error && !xfs_is_shutdown(mp))
 		xfs_alert(mp, "page discard unable to remove delalloc mapping.");