@@ -2894,6 +2894,16 @@ static int btrfs_check_uuid_tree(struct btrfs_fs_info *fs_info)
return 0;
}
+/*
+ * Some options only have meaning at mount time and shouldn't persist across
+ * remounts, or be displayed. Clear these at the end of mount and remount
+ * code paths.
+ */
+void btrfs_clear_oneshot_options(struct btrfs_fs_info *fs_info)
+{
+ btrfs_clear_opt(fs_info->mount_opt, USEBACKUPROOT);
+}
+
/*
* Mounting logic specific to read-write file systems. Shared by open_ctree
* and btrfs_remount when remounting from read-only to read-write.
@@ -3373,7 +3383,7 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
}
if (sb_rdonly(sb))
- return 0;
+ goto clear_oneshot;
if (btrfs_test_opt(fs_info, CLEAR_CACHE) &&
btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) {
@@ -3417,6 +3427,8 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
}
set_bit(BTRFS_FS_OPEN, &fs_info->flags);
+clear_oneshot:
+ btrfs_clear_oneshot_options(fs_info);
return 0;
fail_qgroup:
@@ -50,6 +50,7 @@ struct extent_buffer *btrfs_find_create_tree_block(
struct btrfs_fs_info *fs_info,
u64 bytenr);
void btrfs_clean_tree_block(struct extent_buffer *buf);
+void btrfs_clear_oneshot_options(struct btrfs_fs_info *fs_info);
int btrfs_mount_rw(struct btrfs_fs_info *fs_info);
int __cold open_ctree(struct super_block *sb,
struct btrfs_fs_devices *fs_devices,
@@ -1994,6 +1994,7 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
wake_up_process(fs_info->transaction_kthread);
btrfs_remount_cleanup(fs_info, old_opts);
+ btrfs_clear_oneshot_options(fs_info);
clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
return 0;
Some options only apply during mount time and are cleared at the end of mount. For now, the example is USEBACKUPROOT, but CLEAR_CACHE also fits the bill, and this is a preparation patch for also clearing that option. One subtlety is that the current code only resets USEBACKUPROOT on rw mounts, but the option is meaningfully "consumed" by a ro mount, so it feels appropriate to clear in that case as well. A subsequent read-write remount would not go through open_ctree, which is the only place that checks the option, so the change should be benign. Signed-off-by: Boris Burkov <boris@bur.io> --- fs/btrfs/disk-io.c | 14 +++++++++++++- fs/btrfs/disk-io.h | 1 + fs/btrfs/super.c | 1 + 3 files changed, 15 insertions(+), 1 deletion(-)