Always lookup priv_root on reiserfs mount and keep it

... even if it's a negative dentry.  That way we can set ->d_op on
root before anyone could race with us.  Simplify d_compare(), while
we are at it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 40 insertions, 52 deletions

diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 0ae6486d9046..d444fe0013a4 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -1842,7 +1842,8 @@ static int reiserfs_fill_super(struct super_block *s, void *data, int silent)
                         goto error;
                 }
 
-                if ((errval = reiserfs_xattr_init(s, s->s_flags))) {
+                if ((errval = reiserfs_lookup_privroot(s)) ||
+                    (errval = reiserfs_xattr_init(s, s->s_flags))) {
                         dput(s->s_root);
                         s->s_root = NULL;
                         goto error;
@@ -1855,7 +1856,8 @@ static int reiserfs_fill_super(struct super_block *s, void *data, int silent)
                         reiserfs_info(s, "using 3.5.x disk format\n");
                 }
 
-                if ((errval = reiserfs_xattr_init(s, s->s_flags))) {
+                if ((errval = reiserfs_lookup_privroot(s)) ||
+                    (errval = reiserfs_xattr_init(s, s->s_flags))) {
                         dput(s->s_root);
                         s->s_root = NULL;
                         goto error;
diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c
index 31a3dbb120e1..2891f789f545 100644
--- a/fs/reiserfs/xattr.c
+++ b/fs/reiserfs/xattr.c
@@ -903,16 +903,19 @@ static int create_privroot(struct dentry *dentry)
         WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex));
 
         err = xattr_mkdir(inode, dentry, 0700);
-        if (err) {
-                dput(dentry);
-                dentry = NULL;
+        if (err || !dentry->d_inode) {
+                reiserfs_warning(dentry->d_sb, "jdm-20006",
+                                 "xattrs/ACLs enabled and couldn't "
+                                 "find/create .reiserfs_priv. "
+                                 "Failing mount.");
+                return -EOPNOTSUPP;
         }
 
-        if (dentry && dentry->d_inode)
-                reiserfs_info(dentry->d_sb, "Created %s - reserved for xattr "
-                              "storage.\n", PRIVROOT_NAME);
+        dentry->d_inode->i_flags |= S_PRIVATE;
+        reiserfs_info(dentry->d_sb, "Created %s - reserved for xattr "
+                      "storage.\n", PRIVROOT_NAME);
 
-        return err;
+        return 0;
 }
 
 static int xattr_mount_check(struct super_block *s)
@@ -944,11 +947,9 @@ static int
 xattr_lookup_poison(struct dentry *dentry, struct qstr *q1, struct qstr *name)
 {
         struct dentry *priv_root = REISERFS_SB(dentry->d_sb)->priv_root;
-        if (name->len == priv_root->d_name.len &&
-            name->hash == priv_root->d_name.hash &&
-            !memcmp(name->name, priv_root->d_name.name, name->len)) {
+        if (container_of(q1, struct dentry, d_name) == priv_root)
                 return -ENOENT;
-        } else if (q1->len == name->len &&
+        if (q1->len == name->len &&
                    !memcmp(q1->name, name->name, name->len))
                 return 0;
         return 1;
@@ -958,6 +959,27 @@ static const struct dentry_operations xattr_lookup_poison_ops = {
         .d_compare = xattr_lookup_poison,
 };
 
+int reiserfs_lookup_privroot(struct super_block *s)
+{
+        struct dentry *dentry;
+        int err = 0;
+
+        /* If we don't have the privroot located yet - go find it */
+        mutex_lock(&s->s_root->d_inode->i_mutex);
+        dentry = lookup_one_len(PRIVROOT_NAME, s->s_root,
+                                strlen(PRIVROOT_NAME));
+        if (!IS_ERR(dentry)) {
+                REISERFS_SB(s)->priv_root = dentry;
+                s->s_root->d_op = &xattr_lookup_poison_ops;
+                if (dentry->d_inode)
+                        dentry->d_inode->i_flags |= S_PRIVATE;
+        } else
+                err = PTR_ERR(dentry);
+        mutex_unlock(&s->s_root->d_inode->i_mutex);
+
+        return err;
+}
+
 /* We need to take a copy of the mount flags since things like
  * MS_RDONLY don't get set until *after* we're called.
  * mount_flags != mount_options */
@@ -969,48 +991,12 @@ int reiserfs_xattr_init(struct super_block *s, int mount_flags)
         err = xattr_mount_check(s);
         if (err)
                 goto error;
-#endif
 
-        /* If we don't have the privroot located yet - go find it */
-        if (!REISERFS_SB(s)->priv_root) {
-                struct dentry *dentry;
-                mutex_lock_nested(&s->s_root->d_inode->i_mutex, I_MUTEX_CHILD);
-                dentry = lookup_one_len(PRIVROOT_NAME, s->s_root,
-                                        strlen(PRIVROOT_NAME));
-                if (!IS_ERR(dentry)) {
-#ifdef CONFIG_REISERFS_FS_XATTR
-                        if (!(mount_flags & MS_RDONLY) && !dentry->d_inode)
-                                err = create_privroot(dentry);
-#endif
-                        if (!dentry->d_inode) {
-                                dput(dentry);
-                                dentry = NULL;
-                        }
-                } else
-                        err = PTR_ERR(dentry);
+        if (!REISERFS_SB(s)->priv_root->d_inode && !(mount_flags & MS_RDONLY)) {
+                mutex_lock(&s->s_root->d_inode->i_mutex);
+                err = create_privroot(REISERFS_SB(s)->priv_root);
                 mutex_unlock(&s->s_root->d_inode->i_mutex);
-
-                if (!err && dentry) {
-                        s->s_root->d_op = &xattr_lookup_poison_ops;
-                        dentry->d_inode->i_flags |= S_PRIVATE;
-                        REISERFS_SB(s)->priv_root = dentry;
-#ifdef CONFIG_REISERFS_FS_XATTR
-                /* xattrs are unavailable */
-                } else if (!(mount_flags & MS_RDONLY)) {
-                        /* If we're read-only it just means that the dir
-                         * hasn't been created. Not an error -- just no
-                         * xattrs on the fs. We'll check again if we
-                         * go read-write */
-                        reiserfs_warning(s, "jdm-20006",
-                                         "xattrs/ACLs enabled and couldn't "
-                                         "find/create .reiserfs_priv. "
-                                         "Failing mount.");
-                        err = -EOPNOTSUPP;
-#endif
-                }
         }
-
-#ifdef CONFIG_REISERFS_FS_XATTR
         if (!err)
                 s->s_xattr = reiserfs_xattr_handlers;