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SubjectRe: [PATCH v2] vfs: don't unnecessarily clone write access for writable fds
On Thu, Jun 11, 2020 at 09:05:34AM -0700, Eric Biggers wrote:
> From: Eric Biggers <>
> There's no need for mnt_want_write_file() to increment mnt_writers when
> the file is already open for writing, provided that
> mnt_drop_write_file() is changed to conditionally decrement it.
> We seem to have ended up in the current situation because
> mnt_want_write_file() used to be paired with mnt_drop_write(), due to
> mnt_drop_write_file() not having been added yet. So originally
> mnt_want_write_file() had to always increment mnt_writers.
> But later mnt_drop_write_file() was added, and all callers of
> mnt_want_write_file() were paired with it. This makes the compatibility
> between mnt_want_write_file() and mnt_drop_write() no longer necessary.
> Therefore, make __mnt_want_write_file() and __mnt_drop_write_file() skip
> incrementing mnt_writers on files already open for writing. This
> removes the only caller of mnt_clone_write(), so remove that too.
> Signed-off-by: Eric Biggers <>

Al, any thoughts on this patch?

- Eric

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