* [PATCH-e2fsprogs] filefrag: fix fm_start in filefrag_fiemap loop
@ 2009-06-02 18:03 Peng Tao
2009-06-02 18:35 ` Andreas Dilger
0 siblings, 1 reply; 4+ messages in thread
From: Peng Tao @ 2009-06-02 18:03 UTC (permalink / raw)
To: linux-ext4; +Cc: tytso, Peng Tao
Signed-off-by: Peng Tao <bergwolf@gmail.com>
---
misc/filefrag.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/misc/filefrag.c b/misc/filefrag.c
index 6bea2cd..7786646 100644
--- a/misc/filefrag.c
+++ b/misc/filefrag.c
@@ -239,7 +239,7 @@ int filefrag_fiemap(int fd, int blk_shift, int *num_extents)
n++;
}
- fiemap->fm_start += fm_ext[i-1].fe_logical +
+ fiemap->fm_start = fm_ext[i-1].fe_logical +
fm_ext[i-1].fe_length;
} while (last == 0);
--
1.6.2.GIT
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH-e2fsprogs] filefrag: fix fm_start in filefrag_fiemap loop
2009-06-02 18:03 [PATCH-e2fsprogs] filefrag: fix fm_start in filefrag_fiemap loop Peng Tao
@ 2009-06-02 18:35 ` Andreas Dilger
2009-06-03 1:21 ` Peng Tao
0 siblings, 1 reply; 4+ messages in thread
From: Andreas Dilger @ 2009-06-02 18:35 UTC (permalink / raw)
To: Peng Tao; +Cc: linux-ext4, tytso
Can you please provide some more details of the problem this solves.
On Jun 03, 2009 02:03 +0800, Peng Tao wrote:
> Signed-off-by: Peng Tao <bergwolf@gmail.com>
> ---
> misc/filefrag.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/misc/filefrag.c b/misc/filefrag.c
> index 6bea2cd..7786646 100644
> --- a/misc/filefrag.c
> +++ b/misc/filefrag.c
> @@ -239,7 +239,7 @@ int filefrag_fiemap(int fd, int blk_shift, int *num_extents)
> n++;
> }
>
> - fiemap->fm_start += fm_ext[i-1].fe_logical +
> + fiemap->fm_start = fm_ext[i-1].fe_logical +
> fm_ext[i-1].fe_length;
> } while (last == 0);
>
> --
> 1.6.2.GIT
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH-e2fsprogs] filefrag: fix fm_start in filefrag_fiemap loop
2009-06-02 18:35 ` Andreas Dilger
@ 2009-06-03 1:21 ` Peng Tao
2009-06-03 21:37 ` Andreas Dilger
0 siblings, 1 reply; 4+ messages in thread
From: Peng Tao @ 2009-06-03 1:21 UTC (permalink / raw)
To: Andreas Dilger; +Cc: linux-ext4, tytso
On Wed, Jun 3, 2009 at 2:35 AM, Andreas Dilger <adilger@sun.com> wrote:
> Can you please provide some more details of the problem this solves.
Sorry for the late reply.
When used with -v and the targeted file has more than 144
extents(double of the length of fm_extents array provided by buf),
filefrag_fiemap loops and calls fiemap ioctl() multiple times to
calculate the actual number of extents in a file. Each call to fiemap
ioctl() uses fm_start as the starting logical offset. The patch fixes
fm_start in each loop( except for the first one) and makes the extent
calculation correct for files with more that 144 extents.
To produce the problem, first run filefrag -v on a highly fragmented
file. Then change the buf size in filefrag_fiemap to make it large
enough to have all the extent mapped in a single loop and run filefrag
-v after recompiling. The former will produce a much smaller extent
count because of the false fm_start used in the loop. And the two will
produce different extent output since the 145th extent.
BTW, should I resend the patch to include the above explanation?
>
> On Jun 03, 2009 02:03 +0800, Peng Tao wrote:
>> Signed-off-by: Peng Tao <bergwolf@gmail.com>
>> ---
>> misc/filefrag.c | 2 +-
>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/misc/filefrag.c b/misc/filefrag.c
>> index 6bea2cd..7786646 100644
>> --- a/misc/filefrag.c
>> +++ b/misc/filefrag.c
>> @@ -239,7 +239,7 @@ int filefrag_fiemap(int fd, int blk_shift, int *num_extents)
>> n++;
>> }
>>
>> - fiemap->fm_start += fm_ext[i-1].fe_logical +
>> + fiemap->fm_start = fm_ext[i-1].fe_logical +
>> fm_ext[i-1].fe_length;
>> } while (last == 0);
>>
>> --
>> 1.6.2.GIT
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
> Cheers, Andreas
> --
> Andreas Dilger
> Sr. Staff Engineer, Lustre Group
> Sun Microsystems of Canada, Inc.
>
>
--
Cheers,
Bergwolf
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH-e2fsprogs] filefrag: fix fm_start in filefrag_fiemap loop
2009-06-03 1:21 ` Peng Tao
@ 2009-06-03 21:37 ` Andreas Dilger
0 siblings, 0 replies; 4+ messages in thread
From: Andreas Dilger @ 2009-06-03 21:37 UTC (permalink / raw)
To: Peng Tao; +Cc: linux-ext4, tytso
On Jun 03, 2009 09:21 +0800, Peng Tao wrote:
> When used with -v and the targeted file has more than 144
> extents(double of the length of fm_extents array provided by buf),
> filefrag_fiemap loops and calls fiemap ioctl() multiple times to
> calculate the actual number of extents in a file. Each call to fiemap
> ioctl() uses fm_start as the starting logical offset. The patch fixes
> fm_start in each loop( except for the first one) and makes the extent
> calculation correct for files with more that 144 extents.
>
> To produce the problem, first run filefrag -v on a highly fragmented
> file. Then change the buf size in filefrag_fiemap to make it large
> enough to have all the extent mapped in a single loop and run filefrag
> -v after recompiling. The former will produce a much smaller extent
> count because of the false fm_start used in the loop. And the two will
> produce different extent output since the 145th extent.
>
> BTW, should I resend the patch to include the above explanation?
Yes, please do. I verified that the code as modified (just '=') is also
present in the Lustre fiemap patch, so I'm not sure how it got += there.
Possibly from an older version of the patch.
> > On Jun 03, 2009 02:03 +0800, Peng Tao wrote:
> >> Signed-off-by: Peng Tao <bergwolf@gmail.com>
> >> ---
> >> misc/filefrag.c | 2 +-
> >> 1 files changed, 1 insertions(+), 1 deletions(-)
> >>
> >> diff --git a/misc/filefrag.c b/misc/filefrag.c
> >> index 6bea2cd..7786646 100644
> >> --- a/misc/filefrag.c
> >> +++ b/misc/filefrag.c
> >> @@ -239,7 +239,7 @@ int filefrag_fiemap(int fd, int blk_shift, int *num_extents)
> >> n++;
> >> }
> >>
> >> - fiemap->fm_start += fm_ext[i-1].fe_logical +
> >> + fiemap->fm_start = fm_ext[i-1].fe_logical +
> >> fm_ext[i-1].fe_length;
> >> } while (last == 0);
> >>
> >> --
> >> 1.6.2.GIT
Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
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2009-06-02 18:03 [PATCH-e2fsprogs] filefrag: fix fm_start in filefrag_fiemap loop Peng Tao
2009-06-02 18:35 ` Andreas Dilger
2009-06-03 1:21 ` Peng Tao
2009-06-03 21:37 ` Andreas Dilger
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