Re: [PATCH] fs: prevent data-race due to missing inode_lock when calling vfs_getattr

[Al Viro]

On Mon, Nov 18, 2024 at 01:37:19AM +0900, Jeongjun Park wrote:
> Many filesystems lock inodes before calling vfs_getattr, so there is no
> data-race for inodes. However, some functions in fs/stat.c that call
> vfs_getattr do not lock inodes, so the data-race occurs.
> 
> Therefore, we need to apply a patch to remove the long-standing data-race
> for inodes in some functions that do not lock inodes.

Why do we care?  Slapping even a shared lock on a _very_ hot path, with
possible considerable latency, would need more than "theoretically it's
a data race".