reiserfs: Expand i_mutex to enclose lookup_one_len

 2.6.30-rc3 introduced some sanity checks in the VFS code to avoid NFS
 bugs by ensuring that lookup_one_len is always called under i_mutex.

 This patch expands the i_mutex locking to enclose lookup_one_len. This was
 always required, but not not enforced in the reiserfs code since it
 does locking around the xattr interactions with the xattr_sem.

 This is obvious enough, and it survived an overnight 50 thread ACL test.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 14 insertions, 18 deletions

diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c
index f83f52bae390..31a3dbb120e1 100644
--- a/fs/reiserfs/xattr.c
+++ b/fs/reiserfs/xattr.c
@@ -120,25 +120,20 @@ static struct dentry *lookup_or_create_dir(struct dentry *parent,
         struct dentry *dentry;
         BUG_ON(!parent);
 
+        mutex_lock_nested(&parent->d_inode->i_mutex, I_MUTEX_XATTR);
         dentry = lookup_one_len(name, parent, strlen(name));
-        if (IS_ERR(dentry))
-                return dentry;
-        else if (!dentry->d_inode) {
+        if (!IS_ERR(dentry) && !dentry->d_inode) {
                 int err = -ENODATA;
 
-                if (xattr_may_create(flags)) {
-                        mutex_lock_nested(&parent->d_inode->i_mutex,
-                                          I_MUTEX_XATTR);
+                if (xattr_may_create(flags))
                         err = xattr_mkdir(parent->d_inode, dentry, 0700);
-                        mutex_unlock(&parent->d_inode->i_mutex);
-                }
 
                 if (err) {
                         dput(dentry);
                         dentry = ERR_PTR(err);
                 }
         }
-
+        mutex_unlock(&parent->d_inode->i_mutex);
         return dentry;
 }
 
@@ -184,6 +179,7 @@ fill_with_dentries(void *buf, const char *name, int namelen, loff_t offset,
 {
         struct reiserfs_dentry_buf *dbuf = buf;
         struct dentry *dentry;
+        WARN_ON_ONCE(!mutex_is_locked(&dbuf->xadir->d_inode->i_mutex));
 
         if (dbuf->count == ARRAY_SIZE(dbuf->dentries))
                 return -ENOSPC;
@@ -349,6 +345,7 @@ static struct dentry *xattr_lookup(struct inode *inode, const char *name,
         if (IS_ERR(xadir))
                 return ERR_CAST(xadir);
 
+        mutex_lock_nested(&xadir->d_inode->i_mutex, I_MUTEX_XATTR);
         xafile = lookup_one_len(name, xadir, strlen(name));
         if (IS_ERR(xafile)) {
                 err = PTR_ERR(xafile);
@@ -360,18 +357,15 @@ static struct dentry *xattr_lookup(struct inode *inode, const char *name,
 
         if (!xafile->d_inode) {
                 err = -ENODATA;
-                if (xattr_may_create(flags)) {
-                        mutex_lock_nested(&xadir->d_inode->i_mutex,
-                                          I_MUTEX_XATTR);
+                if (xattr_may_create(flags))
                         err = xattr_create(xadir->d_inode, xafile,
                                               0700|S_IFREG);
-                        mutex_unlock(&xadir->d_inode->i_mutex);
-                }
         }
 
         if (err)
                 dput(xafile);
 out:
+        mutex_unlock(&xadir->d_inode->i_mutex);
         dput(xadir);
         if (err)
                 return ERR_PTR(err);
@@ -435,6 +429,7 @@ static int lookup_and_delete_xattr(struct inode *inode, const char *name)
         if (IS_ERR(xadir))
                 return PTR_ERR(xadir);
 
+        mutex_lock_nested(&xadir->d_inode->i_mutex, I_MUTEX_XATTR);
         dentry = lookup_one_len(name, xadir, strlen(name));
         if (IS_ERR(dentry)) {
                 err = PTR_ERR(dentry);
@@ -442,14 +437,13 @@ static int lookup_and_delete_xattr(struct inode *inode, const char *name)
         }
 
         if (dentry->d_inode) {
-                mutex_lock_nested(&xadir->d_inode->i_mutex, I_MUTEX_XATTR);
                 err = xattr_unlink(xadir->d_inode, dentry);
-                mutex_unlock(&xadir->d_inode->i_mutex);
                 update_ctime(inode);
         }
 
         dput(dentry);
 out_dput:
+        mutex_unlock(&xadir->d_inode->i_mutex);
         dput(xadir);
         return err;
 }
@@ -906,9 +900,9 @@ static int create_privroot(struct dentry *dentry)
 {
         int err;
         struct inode *inode = dentry->d_parent->d_inode;
-        mutex_lock_nested(&inode->i_mutex, I_MUTEX_XATTR);
+        WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex));
+
         err = xattr_mkdir(inode, dentry, 0700);
-        mutex_unlock(&inode->i_mutex);
         if (err) {
                 dput(dentry);
                 dentry = NULL;
@@ -980,6 +974,7 @@ int reiserfs_xattr_init(struct super_block *s, int mount_flags)
         /* 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)) {
@@ -993,6 +988,7 @@ int reiserfs_xattr_init(struct super_block *s, int mount_flags)
                         }
                 } else
                         err = PTR_ERR(dentry);
+                mutex_unlock(&s->s_root->d_inode->i_mutex);
 
                 if (!err && dentry) {
                         s->s_root->d_op = &xattr_lookup_poison_ops;