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[PATCH 1/8] vfs - change d_manage() to take a struct path

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  [PATCH 1/8] vfs - change d_manage() to take a struct path Ian Kent <raven@themaw.net> - 2016-10-11 07:40 +0200
    [PATCH 8/8] vfs - remove unused have_submounts() function Ian Kent <raven@themaw.net> - 2016-10-11 07:40 +0200
    [PATCH 7/8] autofs - use path_has_submounts() to fix unreliable  have_submount() checks Ian Kent <raven@themaw.net> - 2016-10-11 07:40 +0200
    [PATCH 5/8] autofs - change autofs4_wait() to take struct path Ian Kent <raven@themaw.net> - 2016-10-11 07:40 +0200
    [PATCH 3/8] vfs - add path_has_submounts() Ian Kent <raven@themaw.net> - 2016-10-11 07:40 +0200
    [PATCH 6/8] autofs - use path_is_mountpoint() to fix unreliable  d_mountpoint() checks Ian Kent <raven@themaw.net> - 2016-10-11 07:40 +0200
    [PATCH 4/8] autofs - change autofs4_expire_wait() to take struct  path Ian Kent <raven@themaw.net> - 2016-10-11 07:40 +0200
    Re: [PATCH 1/8] vfs - change d_manage() to take a struct path ebiederm@xmission.com (Eric W. Biederman) - 2016-10-11 18:10 +0200
      Re: [PATCH 1/8] vfs - change d_manage() to take a struct path Ian Kent <raven@themaw.net> - 2016-10-12 01:50 +0200

#1498610 — [PATCH 1/8] vfs - change d_manage() to take a struct path

For the autofs module to be able to reliably check if a dentry is a
mountpoint in a multiple namespace environment the ->d_manage() dentry
operation will need to take a path argument instead of a dentry.

Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Omar Sandoval <osandov@osandov.com>
---
 Documentation/filesystems/Locking |    2 +-
 Documentation/filesystems/vfs.txt |    2 +-
 fs/autofs4/root.c                 |    5 +++--
 fs/namei.c                        |   13 ++++++-------
 include/linux/dcache.h            |    2 +-
 5 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index fe15682..1949ac4 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -20,7 +20,7 @@ prototypes:
 	void (*d_iput)(struct dentry *, struct inode *);
 	char *(*d_dname)((struct dentry *dentry, char *buffer, int buflen);
 	struct vfsmount *(*d_automount)(struct path *path);
-	int (*d_manage)(struct dentry *, bool);
+	int (*d_manage)(struct path *, bool);
 	struct dentry *(*d_real)(struct dentry *, const struct inode *,
 				 unsigned int);
 
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index bc3b8e0..db70d71 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -934,7 +934,7 @@ struct dentry_operations {
 	void (*d_iput)(struct dentry *, struct inode *);
 	char *(*d_dname)(struct dentry *, char *, int);
 	struct vfsmount *(*d_automount)(struct path *);
-	int (*d_manage)(struct dentry *, bool);
+	int (*d_manage)(struct path *, bool);
 	struct dentry *(*d_real)(struct dentry *, const struct inode *,
 				 unsigned int);
 };
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index a11f731..5cbd4e1 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -32,7 +32,7 @@ static int autofs4_dir_open(struct inode *inode, struct file *file);
 static struct dentry *autofs4_lookup(struct inode *,
 				     struct dentry *, unsigned int);
 static struct vfsmount *autofs4_d_automount(struct path *);
-static int autofs4_d_manage(struct dentry *, bool);
+static int autofs4_d_manage(struct path *, bool);
 static void autofs4_dentry_release(struct dentry *);
 
 const struct file_operations autofs4_root_operations = {
@@ -421,8 +421,9 @@ static struct vfsmount *autofs4_d_automount(struct path *path)
 	return NULL;
 }
 
-static int autofs4_d_manage(struct dentry *dentry, bool rcu_walk)
+static int autofs4_d_manage(struct path *path, bool rcu_walk)
 {
+	struct dentry *dentry = path->dentry;
 	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 	struct autofs_info *ino = autofs4_dentry_ino(dentry);
 	int status;
diff --git a/fs/namei.c b/fs/namei.c
index a7f601c..704766a 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1200,7 +1200,7 @@ static int follow_managed(struct path *path, struct nameidata *nd)
 		if (managed & DCACHE_MANAGE_TRANSIT) {
 			BUG_ON(!path->dentry->d_op);
 			BUG_ON(!path->dentry->d_op->d_manage);
-			ret = path->dentry->d_op->d_manage(path->dentry, false);
+			ret = path->dentry->d_op->d_manage(path, false);
 			if (ret < 0)
 				break;
 		}
@@ -1263,10 +1263,10 @@ int follow_down_one(struct path *path)
 }
 EXPORT_SYMBOL(follow_down_one);
 
-static inline int managed_dentry_rcu(struct dentry *dentry)
+static inline int managed_dentry_rcu(struct path *path)
 {
-	return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ?
-		dentry->d_op->d_manage(dentry, true) : 0;
+	return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ?
+		path->dentry->d_op->d_manage(path, true) : 0;
 }
 
 /*
@@ -1282,7 +1282,7 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
 		 * Don't forget we might have a non-mountpoint managed dentry
 		 * that wants to block transit.
 		 */
-		switch (managed_dentry_rcu(path->dentry)) {
+		switch (managed_dentry_rcu(path)) {
 		case -ECHILD:
 		default:
 			return false;
@@ -1392,8 +1392,7 @@ int follow_down(struct path *path)
 		if (managed & DCACHE_MANAGE_TRANSIT) {
 			BUG_ON(!path->dentry->d_op);
 			BUG_ON(!path->dentry->d_op->d_manage);
-			ret = path->dentry->d_op->d_manage(
-				path->dentry, false);
+			ret = path->dentry->d_op->d_manage(path, false);
 			if (ret < 0)
 				return ret == -EISDIR ? 0 : ret;
 		}
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 5beed7b..798bc04 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -139,7 +139,7 @@ struct dentry_operations {
 	void (*d_iput)(struct dentry *, struct inode *);
 	char *(*d_dname)(struct dentry *, char *, int);
 	struct vfsmount *(*d_automount)(struct path *);
-	int (*d_manage)(struct dentry *, bool);
+	int (*d_manage)(struct path *, bool);
 	struct dentry *(*d_real)(struct dentry *, const struct inode *,
 				 unsigned int);
 } ____cacheline_aligned;

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#1498611 — [PATCH 8/8] vfs - remove unused have_submounts() function

Now that path_has_submounts() has been added have_submounts() is no
longer used so remove it.

Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Omar Sandoval <osandov@osandov.com>
---
 fs/dcache.c            |   33 ---------------------------------
 include/linux/dcache.h |    1 -
 2 files changed, 34 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index 872f04e..719d8b4 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1273,39 +1273,6 @@ static void d_walk(struct dentry *parent, void *data,
 	goto again;
 }
 
-/*
- * Search for at least 1 mount point in the dentry's subdirs.
- * We descend to the next level whenever the d_subdirs
- * list is non-empty and continue searching.
- */
-
-static enum d_walk_ret check_mount(void *data, struct dentry *dentry)
-{
-	int *ret = data;
-	if (d_mountpoint(dentry)) {
-		*ret = 1;
-		return D_WALK_QUIT;
-	}
-	return D_WALK_CONTINUE;
-}
-
-/**
- * have_submounts - check for mounts over a dentry
- * @parent: dentry to check.
- *
- * Return true if the parent or its subdirectories contain
- * a mount point
- */
-int have_submounts(struct dentry *parent)
-{
-	int ret = 0;
-
-	d_walk(parent, &ret, check_mount, NULL);
-
-	return ret;
-}
-EXPORT_SYMBOL(have_submounts);
-
 struct check_mount {
 	struct vfsmount *mnt;
 	unsigned int mounted;
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index e351646..44a9a9b 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -254,7 +254,6 @@ extern struct dentry *d_find_alias(struct inode *);
 extern void d_prune_aliases(struct inode *);
 
 /* test whether we have any submounts in a subdir tree */
-extern int have_submounts(struct dentry *);
 extern int path_has_submounts(struct path *);
 
 /*

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#1498612 — [PATCH 7/8] autofs - use path_has_submounts() to fix unreliable have_submount() checks

From: Ian Kent <ikent@redhat.com>

If an automount mount is clone(2)ed into a file system that is propagation
private, when it later expires in the originating namespace, subsequent
calls to autofs ->d_automount() for that dentry in the original namespace
will return ELOOP until the mount is umounted in the cloned namespace.

Now that a struct path is available where needed use path_has_submounts()
instead of have_submounts() so we don't get false positives when checking
if a dentry is a mount point or contains mounts in the current namespace.

Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Omar Sandoval <osandov@osandov.com>
---
 fs/autofs4/dev-ioctl.c |    2 +-
 fs/autofs4/root.c      |   14 +++++++-------
 fs/autofs4/waitq.c     |   10 +++++++---
 3 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
index 40c69f9..afacdaa 100644
--- a/fs/autofs4/dev-ioctl.c
+++ b/fs/autofs4/dev-ioctl.c
@@ -575,7 +575,7 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp,
 
 		devid = new_encode_dev(dev);
 
-		err = have_submounts(path.dentry);
+		err = path_has_submounts(&path);
 
 		if (follow_down_one(&path))
 			magic = path.dentry->d_sb->s_magic;
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index d7e48fe..c4df881 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -387,16 +387,16 @@ static struct vfsmount *autofs4_d_automount(struct path *path)
 		/*
 		 * It's possible that user space hasn't removed directories
 		 * after umounting a rootless multi-mount, although it
-		 * should. For v5 have_submounts() is sufficient to handle
-		 * this because the leaves of the directory tree under the
-		 * mount never trigger mounts themselves (they have an autofs
-		 * trigger mount mounted on them). But v4 pseudo direct mounts
-		 * do need the leaves to trigger mounts. In this case we
-		 * have no choice but to use the list_empty() check and
+		 * should. For v5 path_has_submounts() is sufficient to
+		 * handle this because the leaves of the directory tree under
+		 * the mount never trigger mounts themselves (they have an
+		 * autofs trigger mount mounted on them). But v4 pseudo direct
+		 * mounts do need the leaves to trigger mounts. In this case
+		 * we have no choice but to use the list_empty() check and
 		 * require user space behave.
 		 */
 		if (sbi->version > 4) {
-			if (have_submounts(dentry)) {
+			if (path_has_submounts(path)) {
 				spin_unlock(&sbi->fs_lock);
 				goto done;
 			}
diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index f757f87..ed05cae 100644
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -250,8 +250,9 @@ autofs4_find_wait(struct autofs_sb_info *sbi, const struct qstr *qstr)
 static int validate_request(struct autofs_wait_queue **wait,
 			    struct autofs_sb_info *sbi,
 			    const struct qstr *qstr,
-			    struct dentry *dentry, enum autofs_notify notify)
+			    struct path *path, enum autofs_notify notify)
 {
+	struct dentry *dentry = path->dentry;
 	struct autofs_wait_queue *wq;
 	struct autofs_info *ino;
 
@@ -314,6 +315,7 @@ static int validate_request(struct autofs_wait_queue **wait,
 	 */
 	if (notify == NFY_MOUNT) {
 		struct dentry *new = NULL;
+		struct path this;
 		int valid = 1;
 
 		/*
@@ -333,7 +335,9 @@ static int validate_request(struct autofs_wait_queue **wait,
 					dentry = new;
 			}
 		}
-		if (have_submounts(dentry))
+		this.mnt = path->mnt;
+		this.dentry = dentry;
+		if (path_has_submounts(&this))
 			valid = 0;
 
 		if (new)
@@ -406,7 +410,7 @@ int autofs4_wait(struct autofs_sb_info *sbi,
 		return -EINTR;
 	}
 
-	ret = validate_request(&wq, sbi, &qstr, dentry, notify);
+	ret = validate_request(&wq, sbi, &qstr, path, notify);
 	if (ret <= 0) {
 		if (ret != -EINTR)
 			mutex_unlock(&sbi->wq_mutex);

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#1498614 — [PATCH 5/8] autofs - change autofs4_wait() to take struct path

From: Ian Kent <ikent@redhat.com>

In order to use the functions path_is_mountpoint() (or its rcu-walk
variant) and path_has_submounts() autofs needs to pass a struct path
in several places.

Now change autofs4_wait() to take a struct path instead of a struct
dentry.

Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Omar Sandoval <osandov@osandov.com>
---
 fs/autofs4/autofs_i.h |    2 +-
 fs/autofs4/expire.c   |    5 +++--
 fs/autofs4/root.c     |   16 ++++++++--------
 fs/autofs4/waitq.c    |    3 ++-
 4 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index 6d72bba..14cef41 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -217,7 +217,7 @@ static inline int autofs_prepare_pipe(struct file *pipe)
 
 /* Queue management functions */
 
-int autofs4_wait(struct autofs_sb_info *, struct dentry *, enum autofs_notify);
+int autofs4_wait(struct autofs_sb_info *, struct path *, enum autofs_notify);
 int autofs4_wait_release(struct autofs_sb_info *, autofs_wqt_t, int);
 void autofs4_catatonic_mode(struct autofs_sb_info *);
 
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index 7eac498..a37ba40 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -526,7 +526,7 @@ int autofs4_expire_wait(struct path *path, int rcu_walk)
 
 		pr_debug("waiting for expire %p name=%pd\n", dentry, dentry);
 
-		status = autofs4_wait(sbi, dentry, NFY_NONE);
+		status = autofs4_wait(sbi, path, NFY_NONE);
 		wait_for_completion(&ino->expire_complete);
 
 		pr_debug("expire done status=%d\n", status);
@@ -593,11 +593,12 @@ int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
 
 	if (dentry) {
 		struct autofs_info *ino = autofs4_dentry_ino(dentry);
+		struct path path = { .mnt = mnt, .dentry = dentry };
 
 		/* This is synchronous because it makes the daemon a
 		 * little easier
 		 */
-		ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
+		ret = autofs4_wait(sbi, &path, NFY_EXPIRE);
 
 		spin_lock(&sbi->fs_lock);
 		/* avoid rapid-fire expire attempts if expiry fails */
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index 35096e3..d47930ad 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -269,17 +269,17 @@ static struct dentry *autofs4_lookup_expiring(struct dentry *dentry,
 	return NULL;
 }
 
-static int autofs4_mount_wait(struct dentry *dentry, bool rcu_walk)
+static int autofs4_mount_wait(struct path *path, bool rcu_walk)
 {
-	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
-	struct autofs_info *ino = autofs4_dentry_ino(dentry);
+	struct autofs_sb_info *sbi = autofs4_sbi(path->dentry->d_sb);
+	struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
 	int status = 0;
 
 	if (ino->flags & AUTOFS_INF_PENDING) {
 		if (rcu_walk)
 			return -ECHILD;
-		pr_debug("waiting for mount name=%pd\n", dentry);
-		status = autofs4_wait(sbi, dentry, NFY_MOUNT);
+		pr_debug("waiting for mount name=%pd\n", path->dentry);
+		status = autofs4_wait(sbi, path, NFY_MOUNT);
 		pr_debug("mount wait done status=%d\n", status);
 	}
 	ino->last_used = jiffies;
@@ -364,7 +364,7 @@ static struct vfsmount *autofs4_d_automount(struct path *path)
 	spin_lock(&sbi->fs_lock);
 	if (ino->flags & AUTOFS_INF_PENDING) {
 		spin_unlock(&sbi->fs_lock);
-		status = autofs4_mount_wait(dentry, 0);
+		status = autofs4_mount_wait(path, 0);
 		if (status)
 			return ERR_PTR(status);
 		goto done;
@@ -405,7 +405,7 @@ static struct vfsmount *autofs4_d_automount(struct path *path)
 		}
 		ino->flags |= AUTOFS_INF_PENDING;
 		spin_unlock(&sbi->fs_lock);
-		status = autofs4_mount_wait(dentry, 0);
+		status = autofs4_mount_wait(path, 0);
 		spin_lock(&sbi->fs_lock);
 		ino->flags &= ~AUTOFS_INF_PENDING;
 		if (status) {
@@ -447,7 +447,7 @@ static int autofs4_d_manage(struct path *path, bool rcu_walk)
 	 * This dentry may be under construction so wait on mount
 	 * completion.
 	 */
-	status = autofs4_mount_wait(dentry, rcu_walk);
+	status = autofs4_mount_wait(path, rcu_walk);
 	if (status)
 		return status;
 
diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 431fd7e..f757f87 100644
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -345,8 +345,9 @@ static int validate_request(struct autofs_wait_queue **wait,
 }
 
 int autofs4_wait(struct autofs_sb_info *sbi,
-		 struct dentry *dentry, enum autofs_notify notify)
+		 struct path *path, enum autofs_notify notify)
 {
+	struct dentry *dentry = path->dentry;
 	struct autofs_wait_queue *wq;
 	struct qstr qstr;
 	char *name;

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#1498615 — [PATCH 3/8] vfs - add path_has_submounts()

From: Ian Kent <ikent@redhat.com>

d_mountpoint() can only be used reliably to establish if a dentry is
not mounted in any namespace. It isn't aware of the possibility there
may be multiple mounts using the given dentry, possibly in a different
namespace.

Add function, path_has_submounts(), that checks is a struct path contains
mounts (or is a mountpoint itself) to handle this case.

Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Omar Sandoval <osandov@osandov.com>
---
 fs/dcache.c            |   35 +++++++++++++++++++++++++++++++++++
 include/linux/dcache.h |    1 +
 2 files changed, 36 insertions(+)

diff --git a/fs/dcache.c b/fs/dcache.c
index 5c7cc95..872f04e 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1306,6 +1306,41 @@ int have_submounts(struct dentry *parent)
 }
 EXPORT_SYMBOL(have_submounts);
 
+struct check_mount {
+	struct vfsmount *mnt;
+	unsigned int mounted;
+};
+
+static enum d_walk_ret path_check_mount(void *data, struct dentry *dentry)
+{
+	struct check_mount *info = data;
+	struct path path = { .mnt = info->mnt, .dentry = dentry };
+
+	if (path_is_mountpoint(&path)) {
+		info->mounted = 1;
+		return D_WALK_QUIT;
+	}
+	return D_WALK_CONTINUE;
+}
+
+/**
+ * path_has_submounts - check for mounts over a dentry in the
+ *                      current namespace.
+ * @parent: path to check.
+ *
+ * Return true if the parent or its subdirectories contain
+ * a mount point in the current namespace.
+ */
+int path_has_submounts(struct path *parent)
+{
+	struct check_mount data = { .mnt = parent->mnt, .mounted = 0 };
+
+	d_walk(parent->dentry, &data, path_check_mount, NULL);
+
+	return data.mounted;
+}
+EXPORT_SYMBOL(path_has_submounts);
+
 /*
  * Called by mount code to set a mountpoint and check if the mountpoint is
  * reachable (e.g. NFS can unhash a directory dentry and then the complete
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 798bc04..e351646 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -255,6 +255,7 @@ extern void d_prune_aliases(struct inode *);
 
 /* test whether we have any submounts in a subdir tree */
 extern int have_submounts(struct dentry *);
+extern int path_has_submounts(struct path *);
 
 /*
  * This adds the entry to the hash queues.

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#1498616 — [PATCH 6/8] autofs - use path_is_mountpoint() to fix unreliable d_mountpoint() checks

From: Ian Kent <ikent@redhat.com>

If an automount mount is clone(2)ed into a file system that is propagation
private, when it later expires in the originating namespace, subsequent
calls to autofs ->d_automount() for that dentry in the original namespace
will return ELOOP until the mount is umounted in the cloned namespace.

Now that a struct path is available where needed use path_is_mountpoint()
instead of d_mountpoint() so we don't get false positives when checking
if a dentry is a mount point in the current namespace.

Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Omar Sandoval <osandov@osandov.com>
---
 fs/autofs4/root.c |   24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index d47930ad..d7e48fe 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -107,12 +107,15 @@ static int autofs4_dir_open(struct inode *inode, struct file *file)
 {
 	struct dentry *dentry = file->f_path.dentry;
 	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
+	struct path path;
 
 	pr_debug("file=%p dentry=%p %pd\n", file, dentry, dentry);
 
 	if (autofs4_oz_mode(sbi))
 		goto out;
 
+	path = file->f_path;
+
 	/*
 	 * An empty directory in an autofs file system is always a
 	 * mount point. The daemon must have failed to mount this
@@ -123,7 +126,7 @@ static int autofs4_dir_open(struct inode *inode, struct file *file)
 	 * it.
 	 */
 	spin_lock(&sbi->lookup_lock);
-	if (!d_mountpoint(dentry) && simple_empty(dentry)) {
+	if (!path_is_mountpoint(&path) && simple_empty(dentry)) {
 		spin_unlock(&sbi->lookup_lock);
 		return -ENOENT;
 	}
@@ -372,15 +375,15 @@ static struct vfsmount *autofs4_d_automount(struct path *path)
 
 	/*
 	 * If the dentry is a symlink it's equivalent to a directory
-	 * having d_mountpoint() true, so there's no need to call back
-	 * to the daemon.
+	 * having path_is_mountpoint() true, so there's no need to call
+	 * back to the daemon.
 	 */
 	if (d_really_is_positive(dentry) && d_is_symlink(dentry)) {
 		spin_unlock(&sbi->fs_lock);
 		goto done;
 	}
 
-	if (!d_mountpoint(dentry)) {
+	if (!path_is_mountpoint(path)) {
 		/*
 		 * It's possible that user space hasn't removed directories
 		 * after umounting a rootless multi-mount, although it
@@ -434,8 +437,13 @@ static int autofs4_d_manage(struct path *path, bool rcu_walk)
 
 	/* The daemon never waits. */
 	if (autofs4_oz_mode(sbi)) {
-		if (!d_mountpoint(dentry))
-			return -EISDIR;
+		if (rcu_walk) {
+			if (!path_is_mountpoint_rcu(path))
+				return -EISDIR;
+		} else {
+			if (!path_is_mountpoint(path))
+				return -EISDIR;
+		}
 		return 0;
 	}
 
@@ -463,7 +471,7 @@ static int autofs4_d_manage(struct path *path, bool rcu_walk)
 
 		if (ino->flags & AUTOFS_INF_WANT_EXPIRE)
 			return 0;
-		if (d_mountpoint(dentry))
+		if (path_is_mountpoint_rcu(path))
 			return 0;
 		inode = d_inode_rcu(dentry);
 		if (inode && S_ISLNK(inode->i_mode))
@@ -490,7 +498,7 @@ static int autofs4_d_manage(struct path *path, bool rcu_walk)
 		 * we can avoid needless calls ->d_automount() and avoid
 		 * an incorrect ELOOP error return.
 		 */
-		if ((!d_mountpoint(dentry) && !simple_empty(dentry)) ||
+		if ((!path_is_mountpoint(path) && !simple_empty(dentry)) ||
 		    (d_really_is_positive(dentry) && d_is_symlink(dentry)))
 			status = -EISDIR;
 	}

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#1498617 — [PATCH 4/8] autofs - change autofs4_expire_wait() to take struct path

From: Ian Kent <ikent@redhat.com>

In order to use the functions path_is_mountpoint() (or it's rcu-walk
variant) and path_has_submounts() autofs needs to pass a struct path
in several places.

Start by changing autofs4_expire_wait() to take a struct path instead
of a struct dentry.

Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Omar Sandoval <osandov@osandov.com>
---
 fs/autofs4/autofs_i.h  |    2 +-
 fs/autofs4/dev-ioctl.c |    2 +-
 fs/autofs4/expire.c    |    3 ++-
 fs/autofs4/root.c      |   12 +++++++-----
 4 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index a1fba42..6d72bba 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -145,7 +145,7 @@ void autofs4_free_ino(struct autofs_info *);
 
 /* Expiration */
 int is_autofs4_dentry(struct dentry *);
-int autofs4_expire_wait(struct dentry *dentry, int rcu_walk);
+int autofs4_expire_wait(struct path *path, int rcu_walk);
 int autofs4_expire_run(struct super_block *, struct vfsmount *,
 		       struct autofs_sb_info *,
 		       struct autofs_packet_expire __user *);
diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
index fc09eb7..40c69f9 100644
--- a/fs/autofs4/dev-ioctl.c
+++ b/fs/autofs4/dev-ioctl.c
@@ -468,7 +468,7 @@ static int autofs_dev_ioctl_requester(struct file *fp,
 	ino = autofs4_dentry_ino(path.dentry);
 	if (ino) {
 		err = 0;
-		autofs4_expire_wait(path.dentry, 0);
+		autofs4_expire_wait(&path, 0);
 		spin_lock(&sbi->fs_lock);
 		param->requester.uid =
 			from_kuid_munged(current_user_ns(), ino->uid);
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index d8e6d42..7eac498 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -495,8 +495,9 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb,
 	return expired;
 }
 
-int autofs4_expire_wait(struct dentry *dentry, int rcu_walk)
+int autofs4_expire_wait(struct path *path, int rcu_walk)
 {
+	struct dentry *dentry = path->dentry;
 	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 	struct autofs_info *ino = autofs4_dentry_ino(dentry);
 	int status;
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index 5cbd4e1..35096e3 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -286,22 +286,24 @@ static int autofs4_mount_wait(struct dentry *dentry, bool rcu_walk)
 	return status;
 }
 
-static int do_expire_wait(struct dentry *dentry, bool rcu_walk)
+static int do_expire_wait(struct path *path, bool rcu_walk)
 {
+	struct dentry *dentry = path->dentry;
 	struct dentry *expiring;
 
 	expiring = autofs4_lookup_expiring(dentry, rcu_walk);
 	if (IS_ERR(expiring))
 		return PTR_ERR(expiring);
 	if (!expiring)
-		return autofs4_expire_wait(dentry, rcu_walk);
+		return autofs4_expire_wait(path, rcu_walk);
 	else {
+		struct path this = { .mnt = path->mnt, .dentry = expiring };
 		/*
 		 * If we are racing with expire the request might not
 		 * be quite complete, but the directory has been removed
 		 * so it must have been successful, just wait for it.
 		 */
-		autofs4_expire_wait(expiring, 0);
+		autofs4_expire_wait(&this, 0);
 		autofs4_del_expiring(expiring);
 		dput(expiring);
 	}
@@ -354,7 +356,7 @@ static struct vfsmount *autofs4_d_automount(struct path *path)
 	 * and the directory was removed, so just go ahead and try
 	 * the mount.
 	 */
-	status = do_expire_wait(dentry, 0);
+	status = do_expire_wait(path, 0);
 	if (status && status != -EAGAIN)
 		return NULL;
 
@@ -438,7 +440,7 @@ static int autofs4_d_manage(struct path *path, bool rcu_walk)
 	}
 
 	/* Wait for pending expires */
-	if (do_expire_wait(dentry, rcu_walk) == -ECHILD)
+	if (do_expire_wait(path, rcu_walk) == -ECHILD)
 		return -ECHILD;
 
 	/*

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#1498998

Ian Kent <raven@themaw.net> writes:

> For the autofs module to be able to reliably check if a dentry is a
> mountpoint in a multiple namespace environment the ->d_manage() dentry
> operation will need to take a path argument instead of a dentry.

Taking a quick look overall I see no issues with this series.  Overall
it seems straight forward.

On the nit side I expect saying const struct path * in the functions
that now take a struct path would be useful.

I suspect it would also be useful to say
	const struct path *path;
        path = &file->f_path;

In the one part of the code where you do that.  Instead of copying the
path out of the struct file.

Overall I expect that will keep down bugs at no reduction in usability.
Just a statement that the struct path won't change when it is passed
to various functions.

Eric

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#1499294

On Tue, 2016-10-11 at 11:04 -0500, Eric W. Biederman wrote:
> Ian Kent <raven@themaw.net> writes:
> 
> > For the autofs module to be able to reliably check if a dentry is a
> > mountpoint in a multiple namespace environment the ->d_manage() dentry
> > operation will need to take a path argument instead of a dentry.
> 
> Taking a quick look overall I see no issues with this series.  Overall
> it seems straight forward.
> 
> On the nit side I expect saying const struct path * in the functions
> that now take a struct path would be useful.
> 
> I suspect it would also be useful to say
> 	const struct path *path;
>         path = &file->f_path;
> 
> In the one part of the code where you do that.  Instead of copying the
> path out of the struct file.
> 
> Overall I expect that will keep down bugs at no reduction in usability.
> Just a statement that the struct path won't change when it is passed
> to various functions.

Thanks Eric, that's a good suggestion for a follow up patch, will do.

Ian

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