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author | Jan Kara <jack@suse.cz> | 2016-03-09 22:54:00 -0500 |
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committer | Theodore Ts'o <tytso@mit.edu> | 2016-03-09 22:54:00 -0500 |
commit | facab4d9711e7aa3532cb82643803e8f1b9518e8 (patch) | |
tree | 5c0f800db5aeb1fca6842c81cd3821ae847fcc0d /fs/ext4/inode.c | |
parent | 140a52508a68387e22486659ff9eaa89a24f6e40 (diff) | |
download | op-kernel-dev-facab4d9711e7aa3532cb82643803e8f1b9518e8.zip op-kernel-dev-facab4d9711e7aa3532cb82643803e8f1b9518e8.tar.gz |
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>
Diffstat (limited to 'fs/ext4/inode.c')
-rw-r--r-- | fs/ext4/inode.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 971892d..1a156ec 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); |