goto next;
/*
+ * Our start offset might be in the middle of an existing extent
+ * map, so take that into account.
+ */
+ range_len = em->len - (cur - em->start);
+ /*
+ * If this range of the extent map is already flagged for delalloc,
+ * skip it, because:
+ *
+ * 1) We could deadlock later, when trying to reserve space for
+ * delalloc, because in case we can't immediately reserve space
+ * the flusher can start delalloc and wait for the respective
+ * ordered extents to complete. The deadlock would happen
+ * because we do the space reservation while holding the range
+ * locked, and starting writeback, or finishing an ordered
+ * extent, requires locking the range;
+ *
+ * 2) If there's delalloc there, it means there's dirty pages for
+ * which writeback has not started yet (we clean the delalloc
+ * flag when starting writeback and after creating an ordered
+ * extent). If we mark pages in an adjacent range for defrag,
+ * then we will have a larger contiguous range for delalloc,
+ * very likely resulting in a larger extent after writeback is
+ * triggered (except in a case of free space fragmentation).
+ */
+ if (test_range_bit(&inode->io_tree, cur, cur + range_len - 1,
+ EXTENT_DELALLOC, 0, NULL))
+ goto next;
+
+ /*
* For do_compress case, we want to compress all valid file
* extents, thus no @extent_thresh or mergeable check.
*/
goto add;
/* Skip too large extent */
- if (em->len >= extent_thresh)
+ if (range_len >= extent_thresh)
goto next;
next_mergeable = defrag_check_next_extent(&inode->vfs_inode, em,