Merge tag 'for-5.5-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
 "A few fixes for btrfs:

   - blkcg accounting problem with compression that could stall writes

   - setting up blkcg bio for compression crashes due to NULL bdev
     pointer

   - fix possible infinite loop in writeback for nocow files (here
     possible means almost impossible, 13 things that need to happen to
     trigger it)"

* tag 'for-5.5-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  Btrfs: fix infinite loop during nocow writeback due to race
  btrfs: fix compressed write bio blkcg attribution
  btrfs: punt all bios created in btrfs_submit_compressed_write()

Author: torvalds

fs/btrfs/compression.c

@@ -447,7 +447,7 @@ blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
 
 	if (blkcg_css) {
 		bio->bi_opf |= REQ_CGROUP_PUNT;
-		bio_associate_blkg_from_css(bio, blkcg_css);
+		kthread_associate_blkcg(blkcg_css);
 	}
 	refcount_set(&cb->pending_bios, 1);
 
@@ -491,6 +491,8 @@ blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
 			bio->bi_opf = REQ_OP_WRITE | write_flags;
 			bio->bi_private = cb;
 			bio->bi_end_io = end_compressed_bio_write;
+			if (blkcg_css)
+				bio->bi_opf |= REQ_CGROUP_PUNT;
 			bio_add_page(bio, page, PAGE_SIZE, 0);
 		}
 		if (bytes_left < PAGE_SIZE) {
@@ -517,6 +519,9 @@ blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
 		bio_endio(bio);
 	}
 
+	if (blkcg_css)
+		kthread_associate_blkcg(NULL);
+
 	return 0;
 }
 

fs/btrfs/inode.c

@@ -1479,10 +1479,10 @@ static noinline int run_delalloc_nocow(struct inode *inode,
 			disk_num_bytes =
 				btrfs_file_extent_disk_num_bytes(leaf, fi);
 			/*
-			 * If extent we got ends before our range starts, skip
-			 * to next extent
+			 * If the extent we got ends before our current offset,
+			 * skip to the next extent.
 			 */
-			if (extent_end <= start) {
+			if (extent_end <= cur_offset) {
 				path->slots[0]++;
 				goto next_slot;
 			}