btrfs: handle errors in btrfs_reloc_clone_csums properly

In the cow path we will clone the reloc csums for relocated data
extents, and if there's an error we already have an ordered extent and
rely on the ordered extent finishing to clean everything up.

There's a problem however, we don't mark the ordered extent with an
error, we pretend like everything was just fine.  If we were at the end
of our range we won't actually bubble up this error anywhere, and we
could end up inserting an extent that doesn't have csums where it should
have them.

Fix this by adding a helper to mark the ordered extent with an error,
and then use this when we fail to lookup the csums in
btrfs_reloc_clone_csums.  Use this helper in the other place where we
use the same pattern while we're here.

This will prevent us from erroneously inserting the extent that doesn't
have the required checksums.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/inode.c

@@ -3183,9 +3183,8 @@ int btrfs_finish_one_ordered(struct btrfs_ordered_extent *ordered_extent)
 		 * set the mapping error, so we need to set it if we're the ones
 		 * marking this ordered extent as failed.
 		 */
-		if (ret && !test_and_set_bit(BTRFS_ORDERED_IOERR,
-					     &ordered_extent->flags))
-			mapping_set_error(ordered_extent->inode->i_mapping, -EIO);
+		if (ret)
+			btrfs_mark_ordered_extent_error(ordered_extent);
 
 		if (truncated)
 			unwritten_start += logical_len;

fs/btrfs/ordered-data.c

@@ -294,6 +294,12 @@ void btrfs_add_ordered_sum(struct btrfs_ordered_extent *entry,
 	spin_unlock_irq(&inode->ordered_tree_lock);
 }
 
+void btrfs_mark_ordered_extent_error(struct btrfs_ordered_extent *ordered)
+{
+	if (!test_and_set_bit(BTRFS_ORDERED_IOERR, &ordered->flags))
+		mapping_set_error(ordered->inode->i_mapping, -EIO);
+}
+
 static void finish_ordered_fn(struct btrfs_work *work)
 {
 	struct btrfs_ordered_extent *ordered_extent;

fs/btrfs/ordered-data.h

@@ -203,6 +203,7 @@ bool btrfs_try_lock_ordered_range(struct btrfs_inode *inode, u64 start, u64 end,
 				  struct extent_state **cached_state);
 struct btrfs_ordered_extent *btrfs_split_ordered_extent(
 			struct btrfs_ordered_extent *ordered, u64 len);
+void btrfs_mark_ordered_extent_error(struct btrfs_ordered_extent *ordered);
 int __init ordered_data_init(void);
 void __cold ordered_data_exit(void);
 

fs/btrfs/relocation.c

@@ -4403,8 +4403,10 @@ int btrfs_reloc_clone_csums(struct btrfs_ordered_extent *ordered)
 	ret = btrfs_lookup_csums_list(csum_root, disk_bytenr,
 				      disk_bytenr + ordered->num_bytes - 1,
 				      &list, false);
-	if (ret < 0)
+	if (ret < 0) {
+		btrfs_mark_ordered_extent_error(ordered);
 		return ret;
+	}
 
 	while (!list_empty(&list)) {
 		struct btrfs_ordered_sum *sums =