btrfs: Use xattr handler infrastructure

Use the VFS xattr handler infrastructure and get rid of similar code in
the filesystem.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 63 insertions, 113 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index d540fd70f6c6..4fb8d6e28b21 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -9994,7 +9994,7 @@ static const struct inode_operations btrfs_dir_inode_operations = {
         .setattr        = btrfs_setattr,
         .mknod          = btrfs_mknod,
         .setxattr       = btrfs_setxattr,
-        .getxattr       = btrfs_getxattr,
+        .getxattr       = generic_getxattr,
         .listxattr      = btrfs_listxattr,
         .removexattr    = btrfs_removexattr,
         .permission     = btrfs_permission,
@@ -10071,7 +10071,7 @@ static const struct inode_operations btrfs_file_inode_operations = {
         .getattr        = btrfs_getattr,
         .setattr        = btrfs_setattr,
         .setxattr       = btrfs_setxattr,
-        .getxattr       = btrfs_getxattr,
+        .getxattr       = generic_getxattr,
         .listxattr      = btrfs_listxattr,
         .removexattr    = btrfs_removexattr,
         .permission     = btrfs_permission,
@@ -10085,7 +10085,7 @@ static const struct inode_operations btrfs_special_inode_operations = {
         .setattr        = btrfs_setattr,
         .permission     = btrfs_permission,
         .setxattr       = btrfs_setxattr,
-        .getxattr       = btrfs_getxattr,
+        .getxattr       = generic_getxattr,
         .listxattr      = btrfs_listxattr,
         .removexattr    = btrfs_removexattr,
         .get_acl        = btrfs_get_acl,
@@ -10100,7 +10100,7 @@ static const struct inode_operations btrfs_symlink_inode_operations = {
         .setattr        = btrfs_setattr,
         .permission     = btrfs_permission,
         .setxattr       = btrfs_setxattr,
-        .getxattr       = btrfs_getxattr,
+        .getxattr       = generic_getxattr,
         .listxattr      = btrfs_listxattr,
         .removexattr    = btrfs_removexattr,
         .update_time    = btrfs_update_time,
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index 1fcd7b6e7564..7cbef1a14fe1 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -351,137 +351,89 @@ err:
         return ret;
 }
 
-/*
- * List of handlers for synthetic system.* attributes.  All real ondisk
- * attributes are handled directly.
- */
-const struct xattr_handler *btrfs_xattr_handlers[] = {
-#ifdef CONFIG_BTRFS_FS_POSIX_ACL
-        &posix_acl_access_xattr_handler,
-        &posix_acl_default_xattr_handler,
-#endif
-        NULL,
-};
-
-/*
- * Check if the attribute is in a supported namespace.
- *
- * This is applied after the check for the synthetic attributes in the system
- * namespace.
- */
-static int btrfs_is_valid_xattr(const char *name)
+static int btrfs_xattr_handler_get(const struct xattr_handler *handler,
+                                   struct dentry *dentry, const char *name,
+                                   void *buffer, size_t size)
 {
-        int len = strlen(name);
-        int prefixlen = 0;
-
-        if (!strncmp(name, XATTR_SECURITY_PREFIX,
-                        XATTR_SECURITY_PREFIX_LEN))
-                prefixlen = XATTR_SECURITY_PREFIX_LEN;
-        else if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
-                prefixlen = XATTR_SYSTEM_PREFIX_LEN;
-        else if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
-                prefixlen = XATTR_TRUSTED_PREFIX_LEN;
-        else if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN))
-                prefixlen = XATTR_USER_PREFIX_LEN;
-        else if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
-                prefixlen = XATTR_BTRFS_PREFIX_LEN;
-        else
-                return -EOPNOTSUPP;
-
-        /*
-         * The name cannot consist of just prefix
-         */
-        if (len <= prefixlen)
-                return -EINVAL;
+        struct inode *inode = d_inode(dentry);
 
-        return 0;
+        name = xattr_full_name(handler, name);
+        return __btrfs_getxattr(inode, name, buffer, size);
 }
 
-ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
-                       void *buffer, size_t size)
+static int btrfs_xattr_handler_set(const struct xattr_handler *handler,
+                                   struct dentry *dentry, const char *name,
+                                   const void *buffer, size_t size,
+                                   int flags)
 {
-        int ret;
+        struct inode *inode = d_inode(dentry);
 
-        /*
-         * If this is a request for a synthetic attribute in the system.*
-         * namespace use the generic infrastructure to resolve a handler
-         * for it via sb->s_xattr.
-         */
-        if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
-                return generic_getxattr(dentry, name, buffer, size);
+        name = xattr_full_name(handler, name);
+        return __btrfs_setxattr(NULL, inode, name, buffer, size, flags);
+}
 
-        ret = btrfs_is_valid_xattr(name);
-        if (ret)
-                return ret;
-        return __btrfs_getxattr(d_inode(dentry), name, buffer, size);
+static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler,
+                                        struct dentry *dentry,
+                                        const char *name, const void *value,
+                                        size_t size, int flags)
+{
+        name = xattr_full_name(handler, name);
+        return btrfs_set_prop(d_inode(dentry), name, value, size, flags);
 }
 
+static const struct xattr_handler btrfs_security_xattr_handler = {
+        .prefix = XATTR_SECURITY_PREFIX,
+        .get = btrfs_xattr_handler_get,
+        .set = btrfs_xattr_handler_set,
+};
+
+static const struct xattr_handler btrfs_trusted_xattr_handler = {
+        .prefix = XATTR_TRUSTED_PREFIX,
+        .get = btrfs_xattr_handler_get,
+        .set = btrfs_xattr_handler_set,
+};
+
+static const struct xattr_handler btrfs_user_xattr_handler = {
+        .prefix = XATTR_USER_PREFIX,
+        .get = btrfs_xattr_handler_get,
+        .set = btrfs_xattr_handler_set,
+};
+
+static const struct xattr_handler btrfs_btrfs_xattr_handler = {
+        .prefix = XATTR_BTRFS_PREFIX,
+        .get = btrfs_xattr_handler_get,
+        .set = btrfs_xattr_handler_set_prop,
+};
+
+const struct xattr_handler *btrfs_xattr_handlers[] = {
+        &btrfs_security_xattr_handler,
+#ifdef CONFIG_BTRFS_FS_POSIX_ACL
+        &posix_acl_access_xattr_handler,
+        &posix_acl_default_xattr_handler,
+#endif
+        &btrfs_trusted_xattr_handler,
+        &btrfs_user_xattr_handler,
+        &btrfs_btrfs_xattr_handler,
+        NULL,
+};
+
 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
                    size_t size, int flags)
 {
         struct btrfs_root *root = BTRFS_I(d_inode(dentry))->root;
-        int ret;
 
-        /*
-         * The permission on security.* and system.* is not checked
-         * in permission().
-         */
         if (btrfs_root_readonly(root))
                 return -EROFS;
-
-        /*
-         * If this is a request for a synthetic attribute in the system.*
-         * namespace use the generic infrastructure to resolve a handler
-         * for it via sb->s_xattr.
-         */
-        if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
-                return generic_setxattr(dentry, name, value, size, flags);
-
-        ret = btrfs_is_valid_xattr(name);
-        if (ret)
-                return ret;
-
-        if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
-                return btrfs_set_prop(d_inode(dentry), name,
-                                      value, size, flags);
-
-        if (size == 0)
-                value = "";  /* empty EA, do not remove */
-
-        return __btrfs_setxattr(NULL, d_inode(dentry), name, value, size,
-                                flags);
+        return generic_setxattr(dentry, name, value, size, flags);
 }
 
 int btrfs_removexattr(struct dentry *dentry, const char *name)
 {
         struct btrfs_root *root = BTRFS_I(d_inode(dentry))->root;
-        int ret;
 
-        /*
-         * The permission on security.* and system.* is not checked
-         * in permission().
-         */
         if (btrfs_root_readonly(root))
                 return -EROFS;
-
-        /*
-         * If this is a request for a synthetic attribute in the system.*
-         * namespace use the generic infrastructure to resolve a handler
-         * for it via sb->s_xattr.
-         */
-        if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
-                return generic_removexattr(dentry, name);
-
-        ret = btrfs_is_valid_xattr(name);
-        if (ret)
-                return ret;
-
-        if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
-                return btrfs_set_prop(d_inode(dentry), name,
-                                      NULL, 0, XATTR_REPLACE);
-
-        return __btrfs_setxattr(NULL, d_inode(dentry), name, NULL, 0,
-                                XATTR_REPLACE);
+        return generic_removexattr(dentry, name);
 }
 
 static int btrfs_initxattrs(struct inode *inode,
diff --git a/fs/btrfs/xattr.h b/fs/btrfs/xattr.h
index 5049608d1388..96807b3d22f5 100644
--- a/fs/btrfs/xattr.h
+++ b/fs/btrfs/xattr.h
@@ -28,8 +28,6 @@ extern ssize_t __btrfs_getxattr(struct inode *inode, const char *name,
 extern int __btrfs_setxattr(struct btrfs_trans_handle *trans,
                             struct inode *inode, const char *name,
                             const void *value, size_t size, int flags);
-extern ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
-                void *buffer, size_t size);
 extern int btrfs_setxattr(struct dentry *dentry, const char *name,
                 const void *value, size_t size, int flags);
 extern int btrfs_removexattr(struct dentry *dentry, const char *name);