David Howells wrote on Mon, Jan 29, 2024 at 09:49:19AM +0000:
> Fix netfs_unbuffered_write_iter() to return immediately if
> generic_write_checks() returns 0, indicating there's nothing to write.
> Note that netfs_file_write_iter() already does this.
>
> Also, whilst we're at it, put in checks for the size being zero before we
> even take the locks. Note that generic_write_checks() can still reduce the
> size to zero, so we still need that check.
>
> Without this, a warning similar to the following is logged to dmesg:
>
> netfs: Zero-sized write [R=1b6da]
>
> and the syscall fails with EIO, e.g.:
>
> /sbin/ldconfig.real: Writing of cache extension data failed: Input/output error
>
> This can be reproduced on 9p by:
>
> xfs_io -f -c 'pwrite 0 0' /xfstest.test/foo
>
> Fixes: 153a9961b551 ("netfs: Implement unbuffered/DIO write support")
> Reported-by: Eric Van Hensbergen <ericvh@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/ZbQUU6QKmIftKsmo@FV7GG9FTHL/
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> cc: Dominique Martinet <asmadeus@xxxxxxxxxxxxx>
Thanks!
Tested-by: Dominique Martinet <asmadeus@xxxxxxxxxxxxx>
--
Dominique Martinet | Asmadeus
