This bit is being used in too many locations while there is still no
good enough explaination for how this bit is used.
Not to mention its name really doesn't make much sense.
So this patch will add my explanation on this bit, considering only
subvolume trees, along with its reloc trees have this bit, to me it
looks like this bit shows whether tree blocks of a root can be shared.
Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
---
fs/btrfs/ctree.h | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 36df977b64d9..61ab6e8c9a18 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -971,6 +971,15 @@ enum {
* is used to tell us when more checks are required
*/
BTRFS_ROOT_IN_TRANS_SETUP,
+
+ /*
+ * Whether tree blocks of a root can be shared.
+ *
+ * All subvolume trees, and their reloc trees, have this bit set.
+ *
+ * While all other trees, including essential trees like root, csum,
+ * extent, chunk trees, and log trees don't have this bit set.
+ */
BTRFS_ROOT_REF_COWS,
BTRFS_ROOT_TRACK_DIRTY,
BTRFS_ROOT_IN_RADIX,
--
2.25.0
