diff mbox series

[04/24] namei: handle mappings in try_lookup_one_len()

Message ID 20210713111344.1149376-5-brauner@kernel.org (mailing list archive)
State New, archived
Headers show
Series btrfs: support idmapped mounts | expand

Commit Message

Christian Brauner July 13, 2021, 11:13 a.m. UTC 
From: Christian Brauner <christian.brauner@ubuntu.com>

Various filesystems use the try_lookup_one_len() helper to lookup a single path
component relative to a well-known starting point. Allow such filesystems to
support idmapped mounts by enabling try_lookup_one_len() to take the idmap into
account when calling inode_permission(). This change is a required to let btrfs
(and other filesystems) support idmapped mounts.

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
 fs/afs/dynroot.c      | 2 +-
 fs/namei.c            | 7 +++++--
 include/linux/namei.h | 3 ++-
 3 files changed, 8 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/fs/afs/dynroot.c b/fs/afs/dynroot.c
index 6b89d68c8e44..9e96840e6952 100644
--- a/fs/afs/dynroot.c
+++ b/fs/afs/dynroot.c
@@ -315,7 +315,7 @@  void afs_dynroot_rmdir(struct afs_net *net, struct afs_cell *cell)
 	inode_lock(root->d_inode);
 
 	/* Don't want to trigger a lookup call, which will re-add the cell */
-	subdir = try_lookup_one_len(cell->name, root, cell->name_len);
+	subdir = try_lookup_one_len(&init_user_ns, cell->name, root, cell->name_len);
 	if (IS_ERR_OR_NULL(subdir)) {
 		_debug("lookup %ld", PTR_ERR(subdir));
 		goto no_dentry;
diff --git a/fs/namei.c b/fs/namei.c
index 68489c23bc44..0866b88628b9 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2610,6 +2610,7 @@  static int lookup_one_len_common(struct user_namespace *mnt_userns,
 
 /**
  * try_lookup_one_len - filesystem helper to lookup single pathname component
+ * @mnt_userns:	user namespace of the mount the lookup is performed from
  * @name:	pathname component to lookup
  * @base:	base directory to lookup from
  * @len:	maximum length @len should be interpreted to
@@ -2622,14 +2623,16 @@  static int lookup_one_len_common(struct user_namespace *mnt_userns,
  *
  * The caller must hold base->i_mutex.
  */
-struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len)
+struct dentry *try_lookup_one_len(struct user_namespace *mnt_userns,
+				  const char *name, struct dentry *base,
+				  int len)
 {
 	struct qstr this;
 	int err;
 
 	WARN_ON_ONCE(!inode_is_locked(base->d_inode));
 
-	err = lookup_one_len_common(&init_user_ns, name, base, len, &this);
+	err = lookup_one_len_common(mnt_userns, name, base, len, &this);
 	if (err)
 		return ERR_PTR(err);
 
diff --git a/include/linux/namei.h b/include/linux/namei.h
index c177edfb2364..206ea4702d62 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -64,7 +64,8 @@  extern struct dentry *user_path_create(int, const char __user *, struct path *,
 extern void done_path_create(struct path *, struct dentry *);
 extern struct dentry *kern_path_locked(const char *, struct path *);
 
-extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
+extern struct dentry *try_lookup_one_len(struct user_namespace *, const char *,
+					 struct dentry *, int);
 extern struct dentry *lookup_one_len(struct user_namespace *mnt_userns,
 				     const char *, struct dentry *, int);
 extern struct dentry *lookup_one_len_unlocked(struct user_namespace *,