Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
fs/namespace.c: sanitize descriptions for {__,}lookup_mnt()
Comments regarding "shadow mounts" were stale - no such thing anymore.
Document the locking requirements for __lookup_mnt().
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
+12
-29
+12
-29
fs/namespace.c
+12
-29
fs/namespace.c
···
825
825
}
826
826
827
827
/**
828
-
* __lookup_mnt - find first child mount
828
+
* __lookup_mnt - mount hash lookup
829
829
* @mnt: parent mount
830
-
* @dentry: mountpoint
830
+
* @dentry: dentry of mountpoint
831
831
*
832
-
* If @mnt has a child mount @c mounted @dentry find and return it.
832
+
* If @mnt has a child mount @c mounted on @dentry find and return it.
833
+
* Caller must either hold the spinlock component of @mount_lock or
834
+
* hold rcu_read_lock(), sample the seqcount component before the call
835
+
* and recheck it afterwards.
833
836
*
834
-
* Note that the child mount @c need not be unique. There are cases
835
-
* where shadow mounts are created. For example, during mount
836
-
* propagation when a source mount @mnt whose root got overmounted by a
837
-
* mount @o after path lookup but before @namespace_sem could be
838
-
* acquired gets copied and propagated. So @mnt gets copied including
839
-
* @o. When @mnt is propagated to a destination mount @d that already
840
-
* has another mount @n mounted at the same mountpoint then the source
841
-
* mount @mnt will be tucked beneath @n, i.e., @n will be mounted on
842
-
* @mnt and @mnt mounted on @d. Now both @n and @o are mounted at @mnt
843
-
* on @dentry.
844
-
*
845
-
* Return: The first child of @mnt mounted @dentry or NULL.
837
+
* Return: The child of @mnt mounted on @dentry or %NULL.
846
838
*/
847
839
struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
848
840
{
···
847
855
return NULL;
848
856
}
849
857
850
-
/*
851
-
* lookup_mnt - Return the first child mount mounted at path
858
+
/**
859
+
* lookup_mnt - Return the child mount mounted at given location
860
+
* @path: location in the namespace
852
861
*
853
-
* "First" means first mounted chronologically. If you create the
854
-
* following mounts:
855
-
*
856
-
* mount /dev/sda1 /mnt
857
-
* mount /dev/sda2 /mnt
858
-
* mount /dev/sda3 /mnt
859
-
*
860
-
* Then lookup_mnt() on the base /mnt dentry in the root mount will
861
-
* return successively the root dentry and vfsmount of /dev/sda1, then
862
-
* /dev/sda2, then /dev/sda3, then NULL.
863
-
*
864
-
* lookup_mnt takes a reference to the found vfsmount.
862
+
* Acquires and returns a new reference to mount at given location
863
+
* or %NULL if nothing is mounted there.
865
864
*/
866
865
struct vfsmount *lookup_mnt(const struct path *path)
867
866
{