2017-09-14 14:02 GMT+02:00 Jan Kara [off-list ref]:

On Thu 14-09-17 11:50:47, Andreas Gruenbacher wrote:

quoted

@@ -3422,9 +3422,38 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
      map.m_lblk = first_block;
      map.m_len = last_block - first_block + 1;

-     if (!(flags & IOMAP_WRITE)) {
+     if (flags & IOMAP_REPORT) {
              ret = ext4_map_blocks(NULL, inode, &map, 0);
-     } else {
+             if (ret < 0)
+                     return ret;
+
+             if (ret == 0) {
+                     ext4_lblk_t end = map.m_lblk + map.m_len - 1;
+                     struct extent_status es;
+
+                     ext4_es_find_delayed_extent_range(inode, map.m_lblk, end, &es);
+
+                     if (!es.es_len || es.es_lblk > end) {
+                             /* entire range is a hole */
+                     } else if (es.es_lblk > map.m_lblk) {
+                             /* range starts with a hole */
+                             map.m_len = es.es_lblk - map.m_lblk;
+                     } else {
+                             ext4_lblk_t offs = 0;
+
+                             if (es.es_lblk < map.m_lblk)
+                                     offs = map.m_lblk - es.es_lblk;
+                             map.m_lblk = es.es_lblk + offs;
+                             map.m_pblk = ext4_es_pblock(&es) + offs;
+                             map.m_len = es.es_len - offs;
+                             if (ext4_es_is_unwritten(&es))
+                                     map.m_flags |= EXT4_MAP_UNWRITTEN;

This is not possible. If there is unwritten extent at map->m_lblk, then
ext4_map_blocks() could not have possibly returned 0. So just delete this
condition and set map.m_pblk to 0 since delalloc extent has no physical
position.

quoted

+                             if (ext4_es_is_delayed(&es))
+                                     delalloc = true;

Also ext4_es_is_delayed(&es) is guaranteed to be true since you've looked
it up by ext4_es_find_delayed_extent_range(). So just set delalloc = true
unconditionally.

Since map.m_pblk is never used in the delalloc case, we can leave it
undefined above as well.

Otherwise the patch looks good so after fixing up these small issues feel
free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

Thanks,
Andreas