Hello Jann,
On 03/20/2018 02:14 AM, Jann Horn wrote:
> The first one happens in
> do_filp_open -> path_openat -> do_last -> handle_truncate -> do_truncate
> -> notify_change -> simple_setattr -> setattr_prepare -> inode_newsize_ok.
>
> Demo:
>
> # dd if=/dev/zero of=/x bs=102400 count=1024
> [...]
> # mkswap /x && swapon /x
> [...]
> # strace dd if=/dev/zero of=/x count=1
> [...]
> open("/x", O_WRONLY|O_CREAT|O_TRUNC, 0666) = -1 ETXTBSY (Text file busy)
> [...]
> # strace dd if=/dev/zero of=/x count=1 conv=notrunc
> [...]
> open("/x", O_WRONLY|O_CREAT, 0666) = 3
> dup2(3, 1) = 1
> close(3) = 0
> read(0, "\0\0\0\0[...]"..., 512) = 512
> write(1, "\0\0\0\0[...]"..., 512) = 512
> [...]
> #
>
> The second one is in kernel_read_file -> deny_write_access.
Thanks, patch applied.
Cheers,
Michael
> Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
> ---
> man2/open.2 | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/man2/open.2 b/man2/open.2
> index 4a43f32e0..858eb2660 100644
> --- a/man2/open.2
> +++ b/man2/open.2
> @@ -1159,6 +1159,17 @@ requested.
> refers to an executable image which is currently being executed and
> write access was requested.
> .TP
> +.B ETXTBSY
> +.I pathname
> +refers to a file that is currently in use as a swap file, and the
> +.B O_TRUNC
> +flag was specified.
> +.TP
> +.B ETXTBSY
> +.I pathname
> +refers to a file that is currently being read by the kernel (e.g. for
> +module/firmware loading), and write access was requested.
> +.TP
> .B EWOULDBLOCK
> The
> .B O_NONBLOCK
>
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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