btrfs: don't clear qgroup reserved bit in release_folio

The EXTENT_QGROUP_RESERVED bit is used to "lock" regions of the file for
duplicate reservations. That is two writes to that range in one
transaction shouldn't create two reservations, as the reservation will
only be freed once when the write finally goes down. Therefore, it is
never OK to clear that bit without freeing the associated qgroup
reserve. At this point, we don't want to be freeing the reserve, so mask
off the bit.

CC: [email protected] # 5.15+
Reviewed-by: Qu Wenruo <[email protected]>
Signed-off-by: Boris Burkov <[email protected]>
Signed-off-by: David Sterba <[email protected]>

Author: boryas

fs/btrfs/extent_io.c

@@ -2302,7 +2302,8 @@ static int try_release_extent_state(struct extent_io_tree *tree,
 		ret = 0;
 	} else {
 		u32 clear_bits = ~(EXTENT_LOCKED | EXTENT_NODATASUM |
-				   EXTENT_DELALLOC_NEW | EXTENT_CTLBITS);
+				   EXTENT_DELALLOC_NEW | EXTENT_CTLBITS |
+				   EXTENT_QGROUP_RESERVED);
 
 		/*
 		 * At this point we can safely clear everything except the