Always lookup priv_root on reiserfs mount and keep it
Al Viro [Sun, 3 May 2009 10:00:05 +0000 (06:00 -0400)]
... 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>

fs/reiserfs/super.c
fs/reiserfs/xattr.c
include/linux/reiserfs_xattr.h

index 0ae6486..d444fe0 100644 (file)
@@ -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;
index 31a3dbb..2891f78 100644 (file)
@@ -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;
 
index dcae01e..fea1a8e 100644 (file)
@@ -38,6 +38,7 @@ struct nameidata;
 int reiserfs_xattr_register_handlers(void) __init;
 void reiserfs_xattr_unregister_handlers(void);
 int reiserfs_xattr_init(struct super_block *sb, int mount_flags);
+int reiserfs_lookup_privroot(struct super_block *sb);
 int reiserfs_delete_xattrs(struct inode *inode);
 int reiserfs_chown_xattrs(struct inode *inode, struct iattr *attrs);