1 files changed, 17 insertions, 14 deletions

diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index 2d4c8a3e604e..45ff3d63b758 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -587,19 +587,20 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
 	unhashed = autofs4_lookup_unhashed(sbi, dentry->d_parent, &dentry->d_name);
 	if (!unhashed) {
 		/*
-		 * Mark the dentry incomplete, but add it. This is needed so
-		 * that the VFS layer knows about the dentry, and we can count
-		 * on catching any lookups through the revalidate.
-		 *
-		 * Let all the hard work be done by the revalidate function that
-		 * needs to be able to do this anyway..
-		 *
-		 * We need to do this before we release the directory semaphore.
+		 * Mark the dentry incomplete but don't hash it. We do this
+		 * to serialize our inode creation operations (symlink and
+		 * mkdir) which prevents deadlock during the callback to
+		 * the daemon. Subsequent user space lookups for the same
+		 * dentry are placed on the wait queue while the daemon
+		 * itself is allowed passage unresticted so the create
+		 * operation itself can then hash the dentry. Finally,
+		 * we check for the hashed dentry and return the newly
+		 * hashed dentry.
 		 */
 		dentry->d_op = &autofs4_root_dentry_operations;
 
 		dentry->d_fsdata = NULL;
-		d_add(dentry, NULL);
+		d_instantiate(dentry, NULL);
 	} else {
 		struct autofs_info *ino = autofs4_dentry_ino(unhashed);
 		DPRINTK("rehash %p with %p", dentry, unhashed);
@@ -607,15 +608,17 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
 		 * 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, so just wait for it.
+		 * We need to ensure the AUTOFS_INF_EXPIRING flag is clear
+		 * before continuing as revalidate may fail when calling
+		 * try_to_fill_dentry (returning EAGAIN) if we don't.
 		 */
-		if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
+		while (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
 			DPRINTK("wait for incomplete expire %p name=%.*s",
 				unhashed, unhashed->d_name.len,
 				unhashed->d_name.name);
 			autofs4_wait(sbi, unhashed, NFY_NONE);
 			DPRINTK("request completed");
 		}
-		d_rehash(unhashed);
 		dentry = unhashed;
 	}
 
@@ -658,7 +661,7 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
 	 * for all system calls, but it should be OK for the operations
 	 * we permit from an autofs.
 	 */
-	if (dentry->d_inode && d_unhashed(dentry)) {
+	if (!oz_mode && d_unhashed(dentry)) {
 		/*
 		 * A user space application can (and has done in the past)
 		 * remove and re-create this directory during the callback.
@@ -716,7 +719,7 @@ static int autofs4_dir_symlink(struct inode *dir,
 	strcpy(cp, symname);
 
 	inode = autofs4_get_inode(dir->i_sb, ino);
-	d_instantiate(dentry, inode);
+	d_add(dentry, inode);
 
 	if (dir == dir->i_sb->s_root->d_inode)
 		dentry->d_op = &autofs4_root_dentry_operations;
@@ -844,7 +847,7 @@ static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 		return -ENOSPC;
 
 	inode = autofs4_get_inode(dir->i_sb, ino);
-	d_instantiate(dentry, inode);
+	d_add(dentry, inode);
 
 	if (dir == dir->i_sb->s_root->d_inode)
 		dentry->d_op = &autofs4_root_dentry_operations;