Follow those instructions, and you'll trigger a warning in the
beginning of d_set_d_op():
# mkfs.btrfs /dev/loop3
# mount /dev/loop3 /mnt
# btrfs sub create /mnt/sub
# btrfs sub snap /mnt /mnt/snap
# touch /mnt/snap/sub
touch: cannot touch `tmp': Permission denied
__d_alloc() set d_op to sb->s_d_op (btrfs_dentry_operations), and
then simple_lookup() reset it to simple_dentry_operations, which
triggered the warning.
Signed-off-by: Li Zefan <l...@cn.fujitsu.com>
---
fs/btrfs/inode.c | 14 +++++++++-----
1 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 32214fe..2a623cc 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3908,7 +3908,7 @@ static struct inode *new_simple_dir(struct super_block *s,
BTRFS_I(inode)->dummy_inode = 1;
inode->i_ino = BTRFS_EMPTY_SUBVOL_DIR_OBJECTID;
- inode->i_op = &simple_dir_inode_operations;
+ inode->i_op = &btrfs_dir_ro_inode_operations;
inode->i_fop = &simple_dir_operations;
inode->i_mode = S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
@@ -3979,14 +3979,18 @@ struct inode *btrfs_lookup_dentry(struct inode *dir,
struct dentry *dentry)
static int btrfs_dentry_delete(const struct dentry *dentry)
{
struct btrfs_root *root;
+ struct inode *inode = dentry->d_inode;
- if (!dentry->d_inode && !IS_ROOT(dentry))
- dentry = dentry->d_parent;
+ if (!inode && !IS_ROOT(dentry))
+ inode = dentry->d_parent->d_inode;
- if (dentry->d_inode) {
- root = BTRFS_I(dentry->d_inode)->root;
+ if (inode) {
+ root = BTRFS_I(inode)->root;
if (btrfs_root_refs(&root->root_item) == 0)
return 1;
+
+ if (btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)
+ return 1;
}
return 0;
}
--
1.7.3.1
--
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