Re: [PATCH] madvise.2: madvise(, , MADV_REMOVE) supports ext4, ocfs2 and xfs as well

["Michael Kerrisk (man-pages)" <mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Hello Jan,

On 10/07/2014 04:03 PM, Jan Chaloupka wrote:
> As from upstream commit:
> 
> commit 3f31d07571eeea18a7d34db9af21d2285b807a17
> Author: Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> Date:   Tue May 29 15:06:40 2012 -0700
> 
>     mm/fs: route MADV_REMOVE to FALLOC_FL_PUNCH_HOLE
> 
>     Now tmpfs supports hole-punching via fallocate(), switch madvise_remove()
>     to use do_fallocate() instead of vmtruncate_range(): which extends
>     madvise(,,MADV_REMOVE) support from tmpfs to ext4, ocfs2 and xfs.
> 
> madvise(,,MADV_REMOVE) support was extended by ext4, ocfs2 and xfs.
> 
> bug report: https://bugzilla.redhat.com/show_bug.cgi?id=1120294
> 
> Justification from Rafael Aquini:
> Well, that code is committed in kernel since v3.5 (2012) and it surely is
> the expected behaviour since. It seems to me that madvise(2) man page text
> for MADV_REMOVE just got out-of-date in that regard.
> 
> This patch mentions this support in madvise.2 man page.

The intent of this patch seems correct, but I think the details
need fixing. See below.


> Signed-off-by: Jan Chaloupka <jchaloup-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
>  man2/madvise.2 |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/man2/madvise.2 b/man2/madvise.2
> index 032ead7..44698ec 100644
> --- a/man2/madvise.2
> +++ b/man2/madvise.2
> @@ -98,12 +98,12 @@ either in reloading of the memory contents from the underlying mapped file
>  or zero-fill-on-demand pages for mappings
>  without an underlying file.
>  .TP
> -.BR MADV_REMOVE " (since Linux 2.6.16)"
> +.BR MADV_REMOVE " (since Linux 3.5)"

I think the above should not change.

>  Free up a given range of pages
>  and its associated backing store.
>  Currently,
>  .\" 2.6.18-rc5
> -only shmfs/tmpfs supports this; other filesystems return with the
> +only shmfs/tmpfs, ext4, ocfs2 and xfs supports this; other filesystems return with the

I think the above line should be:

    only shmfs/tmpfs and (since Linux 3.5) ext4, ocfs2 and xfs supports this;
    other filesystems return with the

See what I mean? Could you fix and resubmit please?

Cheers,

Michael


-- 
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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