Btrfs: fix a bug when llseek for delalloc bytes behind prealloc extents

xfstests case 285 complains.

It it because btrfs did not try to find unwritten delalloc
bytes(only dirty pages, not yet writeback) behind prealloc
extents, it ends up finding nothing while we're with SEEK_DATA.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index fa48051484b87192f3d4e14dce90deb40e90f9e6..841cfe3be0e004f304510222e5d2b0a86ec20e2c 100644 (file)
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2309,9 +2309,12 @@ static int find_desired_extent(struct inode *inode, loff_t *offset, int origin)
                                        }
                                }
 
-                               *offset = start;
-                               free_extent_map(em);
-                               break;
+                               if (!test_bit(EXTENT_FLAG_PREALLOC,
+                                             &em->flags)) {
+                                       *offset = start;
+                                       free_extent_map(em);
+                                       break;
+                               }
                        }
                }
 

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 4ddcf79e789419e5526ce7e5c04b3189f5c86481..ac98384b174e68fdc603a284e07c37e64d945b5e 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5623,10 +5623,13 @@ struct extent_map *btrfs_get_extent_fiemap(struct inode *inode, struct page *pag
                return em;
        if (em) {
                /*
-                * if our em maps to a hole, there might
-                * actually be delalloc bytes behind it
+                * if our em maps to
+                * -  a hole or
+                * -  a pre-alloc extent,
+                * there might actually be delalloc bytes behind it.
                 */
-               if (em->block_start != EXTENT_MAP_HOLE)
+               if (em->block_start != EXTENT_MAP_HOLE &&
+                   !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
                        return em;
                else
                        hole_em = em;
@@ -5708,6 +5711,8 @@ struct extent_map *btrfs_get_extent_fiemap(struct inode *inode, struct page *pag
                         */
                        em->block_start = hole_em->block_start;
                        em->block_len = hole_len;
+                       if (test_bit(EXTENT_FLAG_PREALLOC, &hole_em->flags))
+                               set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
                } else {
                        em->start = range_start;
                        em->len = found;