fs/btrfs/extent_io.c

881 				      struct btrfs_subpage *prealloc)
903 	/* Already mapped, just free prealloc */
905 		btrfs_free_subpage(prealloc);
909 	if (prealloc)
911 		folio_attach_private(folio, prealloc);
2476  *   delalloc in holes and prealloc extents. And this can lead to a deadlock
2582 	 * when we had a hole or prealloc extent with several delalloc ranges in
2594 			 * a hole or prealloc extent and we have now found a
2621 			 * processing a hole or prealloc extent for which we
2863  * Process a range which is a hole or a prealloc extent in the inode's subvolume
2864  * btree. If @disk_bytenr is 0, we are dealing with a hole, otherwise a prealloc
2902 		 * If this is a prealloc extent we have to report every section
2950 	 * Either we found no delalloc for the whole prealloc extent or we have
2951 	 * a prealloc extent that spans i_size or starts at or after i_size.
3795 	struct btrfs_subpage *prealloc = NULL;
3840 		prealloc = btrfs_alloc_subpage(fs_info, BTRFS_SUBPAGE_METADATA);
3841 		if (IS_ERR(prealloc)) {
3842 			ret = PTR_ERR(prealloc);
3851 		btrfs_free_subpage(prealloc);
3901 		ret = attach_extent_buffer_folio(eb, folio, prealloc);