Re: [PATCH] msync: fix incorrect fstart calculation

[Eric Whitney <enwlinux@gmail.com>]

I can confirm that this patch corrects the ext4 regressions I reported on
3.16-rc1 for data_journal.

Additionally, it corrects regressions for two other tests I have not yet
reported.  Those tests include generic/263 when running with the
data=journal mount option, and generic/219 (a quota test that doesn't use
fsx) when running with all xfstests-bld scenarios (4k, ext4, nojournal, 1k,
etc.) with the exception of bigalloc.  The generic/219 failure on bigalloc in
3.16-rc1 is not a regression, and was present in earlier releases.

With this patch, ext4 3.16-rc3 regression results on x64_64 should look much
more like 3.15 final.

Thanks guys!
Eric


* Wilcox, Matthew R <matthew.r.wilcox@intel.com>:
> Acked-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
> ________________________________________
> From: Namjae Jeon [namjae.jeon@samsung.com]
> Sent: June 27, 2014 4:38 AM
> To: 'Andrew Morton'
> Cc: linux-mm@kvack.org; linux-ext4; Lukáš Czerner; Wilcox, Matthew R; 'Eric Whitney'; Ashish Sangwan
> Subject: [PATCH] msync: fix incorrect fstart calculation
> 
> Fix a regression caused by Commit 7fc34a62ca mm/msync.c: sync only
> the requested range in msync().
> xfstests generic/075 fail occured on ext4 data=journal mode because
> the intended range was not syncing due to wrong fstart calculation.
> 
> Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
> Cc: Lukáš Czerner <lczerner@redhat.com>
> Reported-by: Eric Whitney <enwlinux@gmail.com>
> Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
> Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
> ---
>  mm/msync.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/msync.c b/mm/msync.c
> index a5c6736..ad97dce 100644
> --- a/mm/msync.c
> +++ b/mm/msync.c
> @@ -78,7 +78,8 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags)
>                         goto out_unlock;
>                 }
>                 file = vma->vm_file;
> -               fstart = start + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
> +               fstart = (start - vma->vm_start) +
> +                        ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
>                 fend = fstart + (min(end, vma->vm_end) - start) - 1;
>                 start = vma->vm_end;
>                 if ((flags & MS_SYNC) && file &&
> --
> 1.7.11-rc0
> 

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