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;