The patch titled
Subject: vfs: merge path_is_mountpoint() and path_is_mountpoint_rcu()
has been added to the -mm tree. Its filename is
vfs-merge-path_is_mountpoint-and-path_is_mountpoint_rcu.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/vfs-merge-path_is_mountpoint-and-path_is_mountpoint_rcu.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/vfs-merge-path_is_mountpoint-and-path_is_mountpoint_rcu.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Ian Kent <ikent@xxxxxxxxxx>
Subject: vfs: merge path_is_mountpoint() and path_is_mountpoint_rcu()
Forgetting that the rcu lock allows nesting I added a superfluous rcu
version of path_is_mountpoint().
Merge it and the rcu version, make the common case (d_mountpoint()
returning true) inline and change the path parameter to a const.
Also move the function definition to include/linux/mount.h as it seems a
more sensible place for it.
Link: http://lkml.kernel.org/r/148029910861.27779.4517883721395202453.stgit@xxxxxxxxxxxxxxxx
Signed-off-by: Ian Kent <raven@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Omar Sandoval <osandov@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/autofs4/root.c | 11 ++--------
fs/namespace.c | 41 +++++++++++++---------------------------
include/linux/fs.h | 2 -
include/linux/mount.h | 11 ++++++++++
4 files changed, 28 insertions(+), 37 deletions(-)
diff -puN fs/autofs4/root.c~vfs-merge-path_is_mountpoint-and-path_is_mountpoint_rcu fs/autofs4/root.c
--- a/fs/autofs4/root.c~vfs-merge-path_is_mountpoint-and-path_is_mountpoint_rcu
+++ a/fs/autofs4/root.c
@@ -437,13 +437,8 @@ static int autofs4_d_manage(struct path
/* The daemon never waits. */
if (autofs4_oz_mode(sbi)) {
- if (rcu_walk) {
- if (!path_is_mountpoint_rcu(path))
- return -EISDIR;
- } else {
- if (!path_is_mountpoint(path))
- return -EISDIR;
- }
+ if (!path_is_mountpoint(path))
+ return -EISDIR;
return 0;
}
@@ -471,7 +466,7 @@ static int autofs4_d_manage(struct path
if (ino->flags & AUTOFS_INF_WANT_EXPIRE)
return 0;
- if (path_is_mountpoint_rcu(path))
+ if (path_is_mountpoint(path))
return 0;
inode = d_inode_rcu(dentry);
if (inode && S_ISLNK(inode->i_mode))
diff -puN fs/namespace.c~vfs-merge-path_is_mountpoint-and-path_is_mountpoint_rcu fs/namespace.c
--- a/fs/namespace.c~vfs-merge-path_is_mountpoint-and-path_is_mountpoint_rcu
+++ a/fs/namespace.c
@@ -1159,12 +1159,23 @@ struct vfsmount *mntget(struct vfsmount
}
EXPORT_SYMBOL(mntget);
-static bool __path_is_mountpoint(struct path *path)
+/* __path_is_mountpoint() - Check if path is a mount in the current
+ * namespace.
+ *
+ * d_mountpoint() can only be used reliably to establish if a dentry is
+ * not mounted in any namespace and that common case is handled inline.
+ * d_mountpoint() isn't aware of the possibility there may be multiple
+ * mounts using a given dentry in a different namespace. This function
+ * checks if the passed in path is a mountpoint rather than the dentry
+ * alone.
+ */
+bool __path_is_mountpoint(const struct path *path)
{
struct mount *mount;
struct vfsmount *mnt;
unsigned seq;
+ rcu_read_lock();
do {
seq = read_seqbegin(&mount_lock);
mount = __lookup_mnt(path->mnt, path->dentry);
@@ -1172,35 +1183,11 @@ static bool __path_is_mountpoint(struct
} while (mnt &&
!(mnt->mnt_flags & MNT_SYNC_UMOUNT) &&
read_seqretry(&mount_lock, seq));
-
- return mnt != NULL;
-}
-
-/* Check if path is a mount in current namespace */
-bool path_is_mountpoint(struct path *path)
-{
- bool res;
-
- if (!d_mountpoint(path->dentry))
- return false;
-
- rcu_read_lock();
- res = __path_is_mountpoint(path);
rcu_read_unlock();
- return res;
-}
-EXPORT_SYMBOL(path_is_mountpoint);
-
-/* Check if path is a mount in current namespace */
-bool path_is_mountpoint_rcu(struct path *path)
-{
- if (!d_mountpoint(path->dentry))
- return false;
-
- return __path_is_mountpoint(path);
+ return mnt != NULL;
}
-EXPORT_SYMBOL(path_is_mountpoint_rcu);
+EXPORT_SYMBOL(__path_is_mountpoint);
struct vfsmount *mnt_clone_internal(struct path *path)
{
diff -puN include/linux/fs.h~vfs-merge-path_is_mountpoint-and-path_is_mountpoint_rcu include/linux/fs.h
--- a/include/linux/fs.h~vfs-merge-path_is_mountpoint-and-path_is_mountpoint_rcu
+++ a/include/linux/fs.h
@@ -2134,8 +2134,6 @@ extern int vfs_ustat(dev_t, struct kstat
extern int freeze_super(struct super_block *super);
extern int thaw_super(struct super_block *super);
extern bool our_mnt(struct vfsmount *mnt);
-extern bool path_is_mountpoint(struct path *);
-extern bool path_is_mountpoint_rcu(struct path *);
extern int current_umask(void);
diff -puN include/linux/mount.h~vfs-merge-path_is_mountpoint-and-path_is_mountpoint_rcu include/linux/mount.h
--- a/include/linux/mount.h~vfs-merge-path_is_mountpoint-and-path_is_mountpoint_rcu
+++ a/include/linux/mount.h
@@ -15,6 +15,8 @@
#include <linux/spinlock.h>
#include <linux/seqlock.h>
#include <linux/atomic.h>
+#include <linux/path.h>
+#include <linux/dcache.h>
struct super_block;
struct vfsmount;
@@ -98,4 +100,13 @@ extern dev_t name_to_dev_t(const char *n
extern unsigned int sysctl_mount_max;
+extern bool __path_is_mountpoint(const struct path *path);
+static inline bool path_is_mountpoint(const struct path *path)
+{
+ if (!d_mountpoint(path->dentry))
+ return 0;
+
+ return __path_is_mountpoint(path);
+}
+
#endif /* _LINUX_MOUNT_H */
_
Patches currently in -mm which might be from ikent@xxxxxxxxxx are
vfs-change-d_manage-to-take-a-struct-path.patch
vfs-add-path_is_mountpoint-helper.patch
vfs-add-path_has_submounts.patch
autofs-change-autofs4_expire_wait-to-take-struct-path.patch
autofs-change-autofs4_wait-to-take-struct-path.patch
autofs-use-path_is_mountpoint-to-fix-unreliable-d_mountpoint-checks.patch
autofs-use-path_has_submounts-to-fix-unreliable-have_submount-checks.patch
vfs-remove-unused-have_submounts-function.patch
vfs-merge-path_is_mountpoint-and-path_is_mountpoint_rcu.patch
autofs-make-struct-path-const-in-autofs4_dir_open.patch
autofs-change-struct-path-to-const-in-autofs4_expire_wait-and-autofs4_wait.patch
vfs-change-struct-path-to-const-in-d_manage.patch
vfs-constify-path-parameter-of-path_has_submounts.patch
autofs-dont-hold-spin-lock-over-direct-mount-expire.patch
vfs-make-may_umount_tree-mount-propogation-aware.patch
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