Deletion of a subvolume by rmdir(2) has become allowed by the
'commit cd2decf640b1 ("btrfs: Allow rmdir(2) to delete an empty
subvolume")'.
It is a kind of new feature and this commits add new sysfs entry
/sys/fs/btrfs/features/rmdir_subvol
to indicate the feature.
Since the behavior is independent of feature bits of superblock,
new type FEAT_KERNEL is added to struct btrfs_feature_set.
Features of FEAT_KERNEL is supposed to be visible only in /sys/fs/features
and not in /sys/fs/UUID/features.
Signed-off-by: Tomohiro Misono
---
fs/btrfs/ctree.h | 6 ++
fs/btrfs/sysfs.c | 36 +++-
fs/btrfs/sysfs.h | 5 -
include/uapi/linux/btrfs.h | 2 ++
4 files changed, 39 insertions(+), 10 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 954bfb5054b1..c98355a468a9 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -271,6 +271,12 @@ struct btrfs_super_block {
(BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF)
#define BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR 0ULL
+#define BTRFS_FEATURE_KERNEL_SUPP \
+ BTRFS_FEATURE_KERNEL_RMDIR_SUBVOL
+
+#define BTRFS_FEATURE_KERNEL_SAFE_SET 0ULL
+#define BTRFS_FEATURE_KERNEL_SAFE_CLEAR0ULL
+
/*
* A leaf is full of items. offset and size tell us where to find
* the item in the leaf (relative to the start of the data area)
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 217d401fe8ae..ce6ba6b204c3 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -30,20 +30,24 @@ static u64 get_features(struct btrfs_fs_info *fs_info,
return btrfs_super_compat_flags(disk_super);
else if (set == FEAT_COMPAT_RO)
return btrfs_super_compat_ro_flags(disk_super);
- else
+ else if (set == FEAT_INCOMPAT)
return btrfs_super_incompat_flags(disk_super);
+ else
+ return BTRFS_FEATURE_KERNEL_SUPP;
}
static void set_features(struct btrfs_fs_info *fs_info,
enum btrfs_feature_set set, u64 features)
{
struct btrfs_super_block *disk_super = fs_info->super_copy;
+
if (set == FEAT_COMPAT)
btrfs_set_super_compat_flags(disk_super, features);
else if (set == FEAT_COMPAT_RO)
btrfs_set_super_compat_ro_flags(disk_super, features);
- else
+ else if (set == FEAT_INCOMPAT)
btrfs_set_super_incompat_flags(disk_super, features);
+ /* Nothing for FEAT_KERNEL for now */
}
static int can_modify_feature(struct btrfs_feature_attr *fa)
@@ -63,6 +67,10 @@ static int can_modify_feature(struct btrfs_feature_attr *fa)
set = BTRFS_FEATURE_INCOMPAT_SAFE_SET;
clear = BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR;
break;
+ case FEAT_KERNEL:
+ set = BTRFS_FEATURE_KERNEL_SAFE_SET;
+ clear = BTRFS_FEATURE_KERNEL_SAFE_CLEAR;
+ break;
default:
pr_warn("btrfs: sysfs: unknown feature set %d\n",
fa->feature_set);
@@ -110,6 +118,10 @@ static ssize_t btrfs_feature_attr_store(struct kobject
*kobj,
if (sb_rdonly(fs_info->sb))
return -EROFS;
+ /* FEAT_KERNEL features cannot be changed at runtime */
+ if (fa->feature_set == FEAT_KERNEL)
+ return -EINVAL;
+
ret = kstrtoul(skip_spaces(buf), 0, &val);
if (ret)
return ret;
@@ -174,7 +186,10 @@ static umode_t btrfs_feature_visible(struct kobject *kobj,
fa = attr_to_btrfs_feature_attr(attr);
features = get_features(fs_info, fa->feature_set);
- if (can_modify_feature(fa))
+ /* Do not show FEAT_KERNEL features in /sys/fs/UUID/features */
+ if (fa->feature_set == FEAT_KERNEL)
+ mode = 0;
+ else if (can_modify_feature(fa))
mode |= S_IWUSR;
else if (!(features & fa->feature_bit))
mode = 0;
@@ -194,6 +209,7 @@ BTRFS_FEAT_ATTR_INCOMPAT(raid56, RAID56);
BTRFS_FEAT_ATTR_INCOMPAT(skinny_metadata, SKINNY_METADATA);
BTRFS_FEAT_ATTR_INCOMPAT(no_holes, NO_HOLES);
BTRFS_FEAT_ATTR_COMPAT_RO(free_space_tree, FREE_SPACE_TREE);
+BTRFS_FEAT_ATTR_KERNEL(rmdir_subvol, RMDIR_SUBVOL);
static struct attribute *btrfs_supported_feature_attrs[] = {
BTRFS_FEAT_ATTR_PTR(mixed_backref),
@@ -207,6 +223,7 @@ static struct attribute *btrfs_supported_feature_attrs[] = {
BTRFS_FEAT_ATTR_PTR(skinny_metadata),
BTRFS_FEAT_ATTR_PTR(no_holes),
BTRFS_FEAT_ATTR_PTR(free_space_tree),
+ BTRFS_FEAT_ATTR_PTR(rmdir_subvol),
NULL
};
@@ -515,10 +532,11 @@ static inline struct btrfs_fs_info *to_fs_info(struct
kobject *kobj)
#define NUM_FEATURE_BITS 64
#define BTRFS_FEATURE_NAME_MAX 13
-static char
btrfs_unknown_feature_n
