casaroli commented on code in PR #19512:
URL: https://github.com/apache/nuttx/pull/19512#discussion_r3644857601
##########
fs/vfs/fs_dir.c:
##########
@@ -564,6 +564,22 @@ static int dir_ioctl(FAR struct file *filep, int cmd,
unsigned long arg)
}
else if (cmd != BIOC_FLUSH)
{
+#ifndef CONFIG_DISABLE_MOUNTPOINT
+ /* Not a command the VFS answers for a directory. If this directory
+ * belongs to a mounted volume whose file system offers volume-wide
+ * commands, it is the one route to them that does not require an
+ * unrelated file to be open.
+ */
+
+ if (INODE_IS_MOUNTPT(dir->fd_root) &&
+ dir->fd_root->u.i_mops != NULL &&
+ dir->fd_root->u.i_mops->volume_ioctl != NULL)
+ {
+ return dir->fd_root->u.i_mops->volume_ioctl(dir->fd_root, cmd,
Review Comment:
The dir fd does not point to the real inode. `f_inode` is the static
`g_dir_inode`, so the only way to reach the filesystem is `dir->fd_root` (that
is what I use to call volume_ioctl).
The existing ioctl requires `filep->f_priv` to be the filesystem's open-file
struct. forwarding to ioctl means changing its contract and fixing every
filesystem. Even read-only ones like romfs, where a volume ioctl is meaningless
but whose ioctl asserts and dereferences `f_priv` today just so they don't
crash.
To me the optional method is the smaller and safer version of the same idea.
WDYT?
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