autofs4: track uid and gid of last mount requester

Track the uid and gid of the last process to request a mount for on an
autofs dentry.

[akpm@linux-foundation.org: fix tpyo in comment]
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 6d87bb156326..4b67c2a2d77c 100644
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -457,6 +457,40 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
 
 	status = wq->status;
 
+	/*
+	 * For direct and offset mounts we need to track the requester's
+	 * uid and gid in the dentry info struct. This is so it can be
+	 * supplied, on request, by the misc device ioctl interface.
+	 * This is needed during daemon resatart when reconnecting
+	 * to existing, active, autofs mounts. The uid and gid (and
+	 * related string values) may be used for macro substitution
+	 * in autofs mount maps.
+	 */
+	if (!status) {
+		struct autofs_info *ino;
+		struct dentry *de = NULL;
+
+		/* direct mount or browsable map */
+		ino = autofs4_dentry_ino(dentry);
+		if (!ino) {
+			/* If not lookup actual dentry used */
+			de = d_lookup(dentry->d_parent, &dentry->d_name);
+			if (de)
+				ino = autofs4_dentry_ino(de);
+		}
+
+		/* Set mount requester */
+		if (ino) {
+			spin_lock(&sbi->fs_lock);
+			ino->uid = wq->uid;
+			ino->gid = wq->gid;
+			spin_unlock(&sbi->fs_lock);
+		}
+
+		if (de)
+			dput(de);
+	}
+
 	/* Are we the last process to need status? */
 	mutex_lock(&sbi->wq_mutex);
 	if (!--wq->wait_ctr)