fs: add vfs_cmd_reconfigure()

Split the steps to reconfigure a superblock into a tiny helper instead
of open-coding it in the switch.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Aleksa Sarai <cyphar@cyphar.com>
Message-Id: <20230802-vfs-super-exclusive-v2-3-95dc4e41b870@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/fsopen.c b/fs/fsopen.c
index 1de2b35..a69b7c9 100644 (file)
--- a/fs/fsopen.c
+++ b/fs/fsopen.c
@@ -242,6 +242,34 @@ static int vfs_cmd_create(struct fs_context *fc)
        return 0;
 }
 
+static int vfs_cmd_reconfigure(struct fs_context *fc)
+{
+       struct super_block *sb;
+       int ret;
+
+       if (fc->phase != FS_CONTEXT_RECONF_PARAMS)
+               return -EBUSY;
+
+       fc->phase = FS_CONTEXT_RECONFIGURING;
+
+       sb = fc->root->d_sb;
+       if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) {
+               fc->phase = FS_CONTEXT_FAILED;
+               return -EPERM;
+       }
+
+       down_write(&sb->s_umount);
+       ret = reconfigure_super(fc);
+       up_write(&sb->s_umount);
+       if (ret) {
+               fc->phase = FS_CONTEXT_FAILED;
+               return ret;
+       }
+
+       vfs_clean_context(fc);
+       return 0;
+}
+
 /*
  * Check the state and apply the configuration.  Note that this function is
  * allowed to 'steal' the value by setting param->xxx to NULL before returning.
@@ -249,7 +277,6 @@ static int vfs_cmd_create(struct fs_context *fc)
 static int vfs_fsconfig_locked(struct fs_context *fc, int cmd,
                               struct fs_parameter *param)
 {
-       struct super_block *sb;
        int ret;
 
        ret = finish_clean_context(fc);
@@ -259,21 +286,7 @@ static int vfs_fsconfig_locked(struct fs_context *fc, int cmd,
        case FSCONFIG_CMD_CREATE:
                return vfs_cmd_create(fc);
        case FSCONFIG_CMD_RECONFIGURE:
-               if (fc->phase != FS_CONTEXT_RECONF_PARAMS)
-                       return -EBUSY;
-               fc->phase = FS_CONTEXT_RECONFIGURING;
-               sb = fc->root->d_sb;
-               if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) {
-                       ret = -EPERM;
-                       break;
-               }
-               down_write(&sb->s_umount);
-               ret = reconfigure_super(fc);
-               up_write(&sb->s_umount);
-               if (ret)
-                       break;
-               vfs_clean_context(fc);
-               return 0;
+               return vfs_cmd_reconfigure(fc);
        default:
                if (fc->phase != FS_CONTEXT_CREATE_PARAMS &&
                    fc->phase != FS_CONTEXT_RECONF_PARAMS)
@@ -281,8 +294,6 @@ static int vfs_fsconfig_locked(struct fs_context *fc, int cmd,
 
                return vfs_parse_fs_param(fc, param);
        }
-       fc->phase = FS_CONTEXT_FAILED;
-       return ret;
 }
 
 /**