From facab4d9711e7aa3532cb82643803e8f1b9518e8 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 9 Mar 2016 22:54:00 -0500 Subject: 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 Signed-off-by: Theodore Ts'o --- fs/ext4/inode.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) (limited to 'fs/ext4/inode.c') diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 971892d7c213..1a156ec043a0 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -455,13 +455,13 @@ static void ext4_map_blocks_es_recheck(handle_t *handle, * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping * based files * - * On success, it returns the number of blocks being mapped or allocated. - * if create==0 and the blocks are pre-allocated and unwritten block, - * the result buffer head is unmapped. If the create ==1, it will make sure - * the buffer head is mapped. + * On success, it returns the number of blocks being mapped or allocated. if + * create==0 and the blocks are pre-allocated and unwritten, the resulting @map + * is marked as unwritten. If the create == 1, it will mark @map as mapped. * * It returns 0 if plain look up failed (blocks have not been allocated), in - * that case, buffer head is unmapped + * that case, @map is returned as unmapped but we still do fill map->m_len to + * indicate the length of a hole starting at map->m_lblk. * * It returns the error in case of allocation failure. */ @@ -504,6 +504,11 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode, retval = map->m_len; map->m_len = retval; } else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) { + map->m_pblk = 0; + retval = es.es_len - (map->m_lblk - es.es_lblk); + if (retval > map->m_len) + retval = map->m_len; + map->m_len = retval; retval = 0; } else { BUG_ON(1); -- cgit v1.2.3