reiserfs: fixup xattr_root caching

 The xattr_root caching was broken from my previous patch set. It wouldn't
 cause corruption, but could cause decreased performance due to allocating
 a larger chunk of the journal (~ 27 blocks) than it would actually use.

 This patch loads the xattr root dentry at xattr initialization and creates
 it on-demand. Since we're using the cached dentry, there's no point
 in keeping lookup_or_create_dir around, so that's removed.

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

1 files changed, 46 insertions, 27 deletions

diff --git a/fs/reiserfs/xattr.c b/fs/reiserfs/xattr.c
index 2891f789f545..c77984473db9 100644
--- a/fs/reiserfs/xattr.c
+++ b/fs/reiserfs/xattr.c
@@ -113,36 +113,28 @@ static int xattr_rmdir(struct inode *dir, struct dentry *dentry)
 
 #define xattr_may_create(flags) (!flags || flags & XATTR_CREATE)
 
-/* Returns and possibly creates the xattr dir. */
-static struct dentry *lookup_or_create_dir(struct dentry *parent,
-                                            const char *name, int flags)
+static struct dentry *open_xa_root(struct super_block *sb, int flags)
 {
-        struct dentry *dentry;
-        BUG_ON(!parent);
+        struct dentry *privroot = REISERFS_SB(sb)->priv_root;
+        struct dentry *xaroot;
+        if (!privroot->d_inode)
+                return ERR_PTR(-ENODATA);
 
-        mutex_lock_nested(&parent->d_inode->i_mutex, I_MUTEX_XATTR);
-        dentry = lookup_one_len(name, parent, strlen(name));
-        if (!IS_ERR(dentry) && !dentry->d_inode) {
-                int err = -ENODATA;
+        mutex_lock_nested(&privroot->d_inode->i_mutex, I_MUTEX_XATTR);
 
+        xaroot = dget(REISERFS_SB(sb)->xattr_root);
+        if (!xaroot->d_inode) {
+                int err = -ENODATA;
                 if (xattr_may_create(flags))
-                        err = xattr_mkdir(parent->d_inode, dentry, 0700);
-
+                        err = xattr_mkdir(privroot->d_inode, xaroot, 0700);
                 if (err) {
-                        dput(dentry);
-                        dentry = ERR_PTR(err);
+                        dput(xaroot);
+                        xaroot = ERR_PTR(err);
                 }
         }
-        mutex_unlock(&parent->d_inode->i_mutex);
-        return dentry;
-}
 
-static struct dentry *open_xa_root(struct super_block *sb, int flags)
-{
-        struct dentry *privroot = REISERFS_SB(sb)->priv_root;
-        if (!privroot)
-                return ERR_PTR(-ENODATA);
-        return lookup_or_create_dir(privroot, XAROOT_NAME, flags);
+        mutex_unlock(&privroot->d_inode->i_mutex);
+        return xaroot;
 }
 
 static struct dentry *open_xa_dir(const struct inode *inode, int flags)
@@ -158,10 +150,22 @@ static struct dentry *open_xa_dir(const struct inode *inode, int flags)
                  le32_to_cpu(INODE_PKEY(inode)->k_objectid),
                  inode->i_generation);
 
-        xadir = lookup_or_create_dir(xaroot, namebuf, flags);
+        mutex_lock_nested(&xaroot->d_inode->i_mutex, I_MUTEX_XATTR);
+
+        xadir = lookup_one_len(namebuf, xaroot, strlen(namebuf));
+        if (!IS_ERR(xadir) && !xadir->d_inode) {
+                int err = -ENODATA;
+                if (xattr_may_create(flags))
+                        err = xattr_mkdir(xaroot->d_inode, xadir, 0700);
+                if (err) {
+                        dput(xadir);
+                        xadir = ERR_PTR(err);
+                }
+        }
+
+        mutex_unlock(&xaroot->d_inode->i_mutex);
         dput(xaroot);
         return xadir;
-
 }
 
 /* The following are side effects of other operations that aren't explicitly
@@ -986,19 +990,33 @@ int reiserfs_lookup_privroot(struct super_block *s)
 int reiserfs_xattr_init(struct super_block *s, int mount_flags)
 {
         int err = 0;
+        struct dentry *privroot = REISERFS_SB(s)->priv_root;
 
 #ifdef CONFIG_REISERFS_FS_XATTR
         err = xattr_mount_check(s);
         if (err)
                 goto error;
 
-        if (!REISERFS_SB(s)->priv_root->d_inode && !(mount_flags & MS_RDONLY)) {
+        if (!privroot->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)
+
+        if (privroot->d_inode) {
                 s->s_xattr = reiserfs_xattr_handlers;
+                mutex_lock(&privroot->d_inode->i_mutex);
+                if (!REISERFS_SB(s)->xattr_root) {
+                        struct dentry *dentry;
+                        dentry = lookup_one_len(XAROOT_NAME, privroot,
+                                                strlen(XAROOT_NAME));
+                        if (!IS_ERR(dentry))
+                                REISERFS_SB(s)->xattr_root = dentry;
+                        else
+                                err = PTR_ERR(dentry);
+                }
+                mutex_unlock(&privroot->d_inode->i_mutex);
+        }
 
 error:
         if (err) {
@@ -1008,11 +1026,12 @@ error:
 #endif
 
         /* The super_block MS_POSIXACL must mirror the (no)acl mount option. */
-        s->s_flags = s->s_flags & ~MS_POSIXACL;
 #ifdef CONFIG_REISERFS_FS_POSIX_ACL
         if (reiserfs_posixacl(s))
                 s->s_flags |= MS_POSIXACL;
+        else
 #endif
+                s->s_flags &= ~MS_POSIXACL;
 
         return err;
 }