[PATCH] utils/mount/nfs.man: add noalignwrite

[PATCH] utils/mount/nfs.man: add noalignwrite

[Dan Aloni]

Signed-off-by: Dan Aloni <dan.aloni@vastdata.com>
---
 utils/mount/nfs.man | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/utils/mount/nfs.man b/utils/mount/nfs.man
index eab4692a87de..744411688641 100644
--- a/utils/mount/nfs.man
+++ b/utils/mount/nfs.man
@@ -618,6 +618,17 @@ option is not specified,
 the default behavior depends on the kernel version,
 but is usually equivalent to
 .BR "xprtsec=none" .
+.TP 1.5i
+.BI noalignwrite
+This option disables the default behavior of extending write operations to full
+page boundaries.
+.IP
+Normally, the NFS client rounds non-aligned writes up to the system page size,
+which can lead to "lost writes" when multiple clients write concurrently
+to distinct non-overlapping regions. Use this option when your
+applications perform non-aligned writes and you can guarantee that file
+regions do not overlap, thus avoiding the need for file locking.
+.IP
 .SS "Options for NFS versions 2 and 3 only"
 Use these options, along with the options in the above subsection,
 for NFS versions 2 and 3 only.
-- 
2.47.0

Re: [PATCH] utils/mount/nfs.man: add noalignwrite

[Jeff Layton]

On Mon, 2025-03-10 at 14:04 +0200, Dan Aloni wrote:
> Signed-off-by: Dan Aloni <dan.aloni@vastdata.com>
> ---
>  utils/mount/nfs.man | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/utils/mount/nfs.man b/utils/mount/nfs.man
> index eab4692a87de..744411688641 100644
> --- a/utils/mount/nfs.man
> +++ b/utils/mount/nfs.man
> @@ -618,6 +618,17 @@ option is not specified,
>  the default behavior depends on the kernel version,
>  but is usually equivalent to
>  .BR "xprtsec=none" .
> +.TP 1.5i
> +.BI noalignwrite
> +This option disables the default behavior of extending write operations to full
> +page boundaries.
> +.IP
> +Normally, the NFS client rounds non-aligned writes up to the system page size,

Isn't that only true for buffered writes? That should probably be made
clear if so.

> +which can lead to "lost writes" when multiple clients write concurrently
> +to distinct non-overlapping regions. Use this option when your
> +applications perform non-aligned writes and you can guarantee that file
> +regions do not overlap, thus avoiding the need for file locking.
> +.IP
>  .SS "Options for NFS versions 2 and 3 only"
>  Use these options, along with the options in the above subsection,
>  for NFS versions 2 and 3 only.

-- 
Jeff Layton <jlayton@kernel.org>

[PATCH v2] utils/mount/nfs.man: add noalignwrite

[Dan Aloni]

Signed-off-by: Dan Aloni <dan.aloni@vastdata.com>
---
 utils/mount/nfs.man | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/utils/mount/nfs.man b/utils/mount/nfs.man
index eab4692a87de..b5c5913bf315 100644
--- a/utils/mount/nfs.man
+++ b/utils/mount/nfs.man
@@ -618,6 +618,17 @@ option is not specified,
 the default behavior depends on the kernel version,
 but is usually equivalent to
 .BR "xprtsec=none" .
+.TP 1.5i
+.BI noalignwrite
+This option disables the default behavior of extending buffered write operations
+to full page boundaries.
+.IP
+Normally, the NFS client rounds non-aligned buffered writes up to the system
+page size, which can lead to "lost writes" when multiple clients write
+concurrently to distinct non-overlapping regions. Use this option when your
+applications perform non-aligned buffered writes and you can guarantee that file
+regions do not overlap, thus avoiding the need for file locking.
+.IP
 .SS "Options for NFS versions 2 and 3 only"
 Use these options, along with the options in the above subsection,
 for NFS versions 2 and 3 only.
-- 
2.47.0

Re: [PATCH v2] utils/mount/nfs.man: add noalignwrite

[Steve Dickson]

On 3/10/25 8:52 AM, Dan Aloni wrote:
> Signed-off-by: Dan Aloni <dan.aloni@vastdata.com>
Committed... (tag: nfs-utils-2-8-3-rc8)

steved
> ---
>   utils/mount/nfs.man | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/utils/mount/nfs.man b/utils/mount/nfs.man
> index eab4692a87de..b5c5913bf315 100644
> --- a/utils/mount/nfs.man
> +++ b/utils/mount/nfs.man
> @@ -618,6 +618,17 @@ option is not specified,
>   the default behavior depends on the kernel version,
>   but is usually equivalent to
>   .BR "xprtsec=none" .
> +.TP 1.5i
> +.BI noalignwrite
> +This option disables the default behavior of extending buffered write operations
> +to full page boundaries.
> +.IP
> +Normally, the NFS client rounds non-aligned buffered writes up to the system
> +page size, which can lead to "lost writes" when multiple clients write
> +concurrently to distinct non-overlapping regions. Use this option when your
> +applications perform non-aligned buffered writes and you can guarantee that file
> +regions do not overlap, thus avoiding the need for file locking.
> +.IP
>   .SS "Options for NFS versions 2 and 3 only"
>   Use these options, along with the options in the above subsection,
>   for NFS versions 2 and 3 only.