Re: [PATCH] fix intr/nointr to match kernel behavior (ignored)

[NeilBrown <neilb@suse.de>]

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On Thu,  6 Mar 2014 17:02:32 -0500 Jim Rees <rees@umich.edu> wrote:

> Signed-off-by: Jim Rees <rees@umich.edu>
> ---
>  utils/mount/nfs.man | 53 ++++++-----------------------------------------------
>  1 file changed, 6 insertions(+), 47 deletions(-)
> 
> diff --git a/utils/mount/nfs.man b/utils/mount/nfs.man
> index ef09a31..2ab369c 100644
> --- a/utils/mount/nfs.man
> +++ b/utils/mount/nfs.man
> @@ -125,6 +125,12 @@ option may mitigate some of the risks of using the
>  .B soft
>  option.
>  .TP 1.5i
> +.BR intr " / " nointr
> +This option is provided for backward compatibility.
> +It is ignored after kernel 2.6.25.
> +System calls return EINTR if an in-progress NFS operation is interrupted by
> +a signal.

That isn't correct.
"A process that is waiting for a reply for an NFS server can be killed
 by any signal which would normally kill the process.  If a signal would not
 normally kill the process (i.e. it is caught or ignored) then that signal
 will not abort and NFS request".

This is really a fairly horrible semantic.  It makes perfect sense from an
internal implementation perspective and provides good backwards compatibility
and cross-compatibility with other filesystems (where 'read' and 'write'
never ever return EINTR), but it is very hard to document clearly.

NeilBrown


> +.TP 1.5i
>  .BI timeo= n
>  The time in deciseconds (tenths of a second) the NFS client waits for a
>  response before it retries an NFS request.
> @@ -668,30 +674,6 @@ Using the
>  option is also required when mounting exports on NFS servers
>  that do not support the NLM protocol.
>  .TP 1.5i
> -.BR intr " / " nointr
> -Selects whether to allow signals to interrupt file operations
> -on this mount point. If neither option
> -is specified (or if
> -.B nointr
> -is specified),
> -signals do not interrupt NFS file operations. If
> -.B intr
> -is specified, system calls return EINTR if an in-progress NFS operation is interrupted by
> -a signal.
> -.IP
> -Using the
> -.B intr
> -option is preferred to using the
> -.B soft
> -option because it is significantly less likely to result in data corruption.
> -.IP
> -The
> -.BR intr " / " nointr
> -mount option is deprecated after kernel 2.6.25.
> -Only SIGKILL can interrupt a pending NFS operation on these kernels,
> -and if specified, this mount option is ignored to provide backwards
> -compatibility with older kernels.
> -.TP 1.5i
>  .BR cto " / " nocto
>  Selects whether to use close-to-open cache coherence semantics.
>  If neither option is specified (or if
> @@ -807,29 +789,6 @@ The mount request fails if the server's rpcbind service is not available,
>  the server's NFS service is not registered with its rpcbind service,
>  or the server's NFS service is not available on the advertised port.
>  .TP 1.5i
> -.BR intr " / " nointr
> -Selects whether to allow signals to interrupt file operations
> -on this mount point. If neither option is specified (or if
> -.B intr
> -is specified), system calls return EINTR if an in-progress NFS operation
> -is interrupted by a signal.  If
> -.B nointr
> -is specified, signals do not
> -interrupt NFS operations.
> -.IP
> -Using the
> -.B intr
> -option is preferred to using the
> -.B soft
> -option because it is significantly less likely to result in data corruption.
> -.IP
> -The
> -.BR intr " / " nointr
> -mount option is deprecated after kernel 2.6.25.
> -Only SIGKILL can interrupt a pending NFS operation on these kernels,
> -and if specified, this mount option is ignored to provide backwards
> -compatibility with older kernels.
> -.TP 1.5i
>  .BR cto " / " nocto
>  Selects whether to use close-to-open cache coherence semantics
>  for NFS directories on this mount point.


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