ext4: return hole from ext4_map_blocks()
Currently, ext4_map_blocks() just returns 0 when it finds a hole and
allocation is not requested. However we have all the information
available to tell how large the hole actually is and there are callers
of ext4_map_blocks() which would save some block-by-block hole iteration
if they knew this information. So fill in struct ext4_map_blocks even
for holes with the information we have. We keep returning 0 for holes to
maintain backward compatibility of the function.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 7858fc1..2730039 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4374,13 +4374,20 @@
if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
ext4_lblk_t hole_start, hole_len;
+ hole_start = map->m_lblk;
+ hole_len = ext4_ext_determine_hole(inode, path, &hole_start);
/*
* put just found gap into cache to speed up
* subsequent requests
*/
- hole_start = map->m_lblk;
- hole_len = ext4_ext_determine_hole(inode, path, &hole_start);
ext4_ext_put_gap_in_cache(inode, hole_start, hole_len);
+
+ /* Update hole_len to reflect hole size after map->m_lblk */
+ if (hole_start != map->m_lblk)
+ hole_len -= map->m_lblk - hole_start;
+ map->m_pblk = 0;
+ map->m_len = min_t(unsigned int, map->m_len, hole_len);
+
goto out2;
}