fs: add vfs_cmd_create()

Split the steps to create a superblock into a tiny helper. This will
make the next patch easier to follow.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
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-v2-2-95dc4e41b870@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/fsopen.c b/fs/fsopen.c
index fc9d2d9..1de2b35 100644 (file)
--- a/fs/fsopen.c
+++ b/fs/fsopen.c
@@ -209,6 +209,39 @@ err:
        return ret;
 }
 
+static int vfs_cmd_create(struct fs_context *fc)
+{
+       struct super_block *sb;
+       int ret;
+
+       if (fc->phase != FS_CONTEXT_CREATE_PARAMS)
+               return -EBUSY;
+
+       if (!mount_capable(fc))
+               return -EPERM;
+
+       fc->phase = FS_CONTEXT_CREATING;
+
+       ret = vfs_get_tree(fc);
+       if (ret) {
+               fc->phase = FS_CONTEXT_FAILED;
+               return ret;
+       }
+
+       sb = fc->root->d_sb;
+       ret = security_sb_kern_mount(sb);
+       if (unlikely(ret)) {
+               fc_drop_locked(fc);
+               fc->phase = FS_CONTEXT_FAILED;
+               return ret;
+       }
+
+       /* vfs_get_tree() callchains will have grabbed @s_umount */
+       up_write(&sb->s_umount);
+       fc->phase = FS_CONTEXT_AWAITING_MOUNT;
+       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.
@@ -224,23 +257,7 @@ static int vfs_fsconfig_locked(struct fs_context *fc, int cmd,
                return ret;
        switch (cmd) {
        case FSCONFIG_CMD_CREATE:
-               if (fc->phase != FS_CONTEXT_CREATE_PARAMS)
-                       return -EBUSY;
-               if (!mount_capable(fc))
-                       return -EPERM;
-               fc->phase = FS_CONTEXT_CREATING;
-               ret = vfs_get_tree(fc);
-               if (ret)
-                       break;
-               sb = fc->root->d_sb;
-               ret = security_sb_kern_mount(sb);
-               if (unlikely(ret)) {
-                       fc_drop_locked(fc);
-                       break;
-               }
-               up_write(&sb->s_umount);
-               fc->phase = FS_CONTEXT_AWAITING_MOUNT;
-               return 0;
+               return vfs_cmd_create(fc);
        case FSCONFIG_CMD_RECONFIGURE:
                if (fc->phase != FS_CONTEXT_RECONF_PARAMS)
                        return -EBUSY;