* [PATCH] xfs: fix off-by-one on max nr_pages in xfs_find_get_desired_pgoff()
@ 2017-05-21 7:59 Eryu Guan
2017-05-23 8:36 ` Jan Kara
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Eryu Guan @ 2017-05-21 7:59 UTC (permalink / raw)
To: linux-xfs; +Cc: Eryu Guan
xfs_find_get_desired_pgoff() is used to search for offset of hole or
data in page range [index, end] (both inclusive), and the max number
of pages to search should be at least one, if end == index.
Otherwise the only page is missed and no hole or data is found,
which is not correct.
When block size is smaller than page size, this can be demonstrated
by preallocating a file with size smaller than page size and writing
data to the last block. E.g. run this xfs_io command on a 1k block
size XFS on x86_64 host.
# xfs_io -fc "falloc 0 3k" -c "pwrite 2k 1k" \
-c "seek -d 0" /mnt/xfs/testfile
wrote 1024/1024 bytes at offset 2048
1 KiB, 1 ops; 0.0000 sec (33.675 MiB/sec and 34482.7586 ops/sec)
Whence Result
DATA EOF
Data at offset 2k was missed, and lseek(2) returned ENXIO.
This is unconvered by generic/285 subtest 07 and 08 on ppc64 host,
where pagesize is 64k. Because a recent change to generic/285
reduced the preallocated file size to smaller than 64k.
Cc: stable@vger.kernel.org # v3.7+
Signed-off-by: Eryu Guan <eguan@redhat.com>
---
fs/xfs/xfs_file.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 35703a8..aefa213 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1049,7 +1049,7 @@ xfs_find_get_desired_pgoff(
unsigned nr_pages;
unsigned int i;
- want = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
+ want = min_t(pgoff_t, end - index, PAGEVEC_SIZE - 1) + 1;
nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
want);
/*
--
2.9.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] xfs: fix off-by-one on max nr_pages in xfs_find_get_desired_pgoff()
2017-05-21 7:59 [PATCH] xfs: fix off-by-one on max nr_pages in xfs_find_get_desired_pgoff() Eryu Guan
@ 2017-05-23 8:36 ` Jan Kara
2017-05-23 12:35 ` Brian Foster
2017-05-23 15:33 ` Darrick J. Wong
2 siblings, 0 replies; 6+ messages in thread
From: Jan Kara @ 2017-05-23 8:36 UTC (permalink / raw)
To: Eryu Guan; +Cc: linux-xfs
On Sun 21-05-17 15:59:39, Eryu Guan wrote:
> xfs_find_get_desired_pgoff() is used to search for offset of hole or
> data in page range [index, end] (both inclusive), and the max number
> of pages to search should be at least one, if end == index.
> Otherwise the only page is missed and no hole or data is found,
> which is not correct.
>
> When block size is smaller than page size, this can be demonstrated
> by preallocating a file with size smaller than page size and writing
> data to the last block. E.g. run this xfs_io command on a 1k block
> size XFS on x86_64 host.
>
> # xfs_io -fc "falloc 0 3k" -c "pwrite 2k 1k" \
> -c "seek -d 0" /mnt/xfs/testfile
> wrote 1024/1024 bytes at offset 2048
> 1 KiB, 1 ops; 0.0000 sec (33.675 MiB/sec and 34482.7586 ops/sec)
> Whence Result
> DATA EOF
>
> Data at offset 2k was missed, and lseek(2) returned ENXIO.
>
> This is unconvered by generic/285 subtest 07 and 08 on ppc64 host,
> where pagesize is 64k. Because a recent change to generic/285
> reduced the preallocated file size to smaller than 64k.
>
> Cc: stable@vger.kernel.org # v3.7+
> Signed-off-by: Eryu Guan <eguan@redhat.com>
Looks good. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>
BTW, this was actually introduced by my recent SEEK_HOLE fixes so Darrick,
please put this in one batch with them. Thanks!
Honza
> ---
> fs/xfs/xfs_file.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 35703a8..aefa213 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -1049,7 +1049,7 @@ xfs_find_get_desired_pgoff(
> unsigned nr_pages;
> unsigned int i;
>
> - want = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
> + want = min_t(pgoff_t, end - index, PAGEVEC_SIZE - 1) + 1;
> nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
> want);
> /*
> --
> 2.9.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] xfs: fix off-by-one on max nr_pages in xfs_find_get_desired_pgoff()
2017-05-21 7:59 [PATCH] xfs: fix off-by-one on max nr_pages in xfs_find_get_desired_pgoff() Eryu Guan
2017-05-23 8:36 ` Jan Kara
@ 2017-05-23 12:35 ` Brian Foster
2017-05-23 13:00 ` Eryu Guan
2017-05-23 15:33 ` Darrick J. Wong
2 siblings, 1 reply; 6+ messages in thread
From: Brian Foster @ 2017-05-23 12:35 UTC (permalink / raw)
To: Eryu Guan; +Cc: linux-xfs
On Sun, May 21, 2017 at 03:59:39PM +0800, Eryu Guan wrote:
> xfs_find_get_desired_pgoff() is used to search for offset of hole or
> data in page range [index, end] (both inclusive), and the max number
> of pages to search should be at least one, if end == index.
> Otherwise the only page is missed and no hole or data is found,
> which is not correct.
>
> When block size is smaller than page size, this can be demonstrated
> by preallocating a file with size smaller than page size and writing
> data to the last block. E.g. run this xfs_io command on a 1k block
> size XFS on x86_64 host.
>
> # xfs_io -fc "falloc 0 3k" -c "pwrite 2k 1k" \
> -c "seek -d 0" /mnt/xfs/testfile
> wrote 1024/1024 bytes at offset 2048
> 1 KiB, 1 ops; 0.0000 sec (33.675 MiB/sec and 34482.7586 ops/sec)
> Whence Result
> DATA EOF
>
Ok, so this does look like a different problem.
> Data at offset 2k was missed, and lseek(2) returned ENXIO.
>
> This is unconvered by generic/285 subtest 07 and 08 on ppc64 host,
> where pagesize is 64k. Because a recent change to generic/285
> reduced the preallocated file size to smaller than 64k.
>
> Cc: stable@vger.kernel.org # v3.7+
> Signed-off-by: Eryu Guan <eguan@redhat.com>
Could we fold this patch into Jan's patch 2 or vice versa (retaining
Eryu's commit log and credit)?
> ---
> fs/xfs/xfs_file.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 35703a8..aefa213 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -1049,7 +1049,7 @@ xfs_find_get_desired_pgoff(
> unsigned nr_pages;
> unsigned int i;
>
> - want = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
> + want = min_t(pgoff_t, end - index, PAGEVEC_SIZE - 1) + 1;
Kind of a nit, but could we do the following?
want = min_t(pgoff_t, end - index + 1, PAGEVEC_SIZE);
It seems more clear to me given that end would be inclusive after Jan's
patch.
Brian
> nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
> want);
> /*
> --
> 2.9.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] xfs: fix off-by-one on max nr_pages in xfs_find_get_desired_pgoff()
2017-05-23 12:35 ` Brian Foster
@ 2017-05-23 13:00 ` Eryu Guan
2017-05-23 13:27 ` Brian Foster
0 siblings, 1 reply; 6+ messages in thread
From: Eryu Guan @ 2017-05-23 13:00 UTC (permalink / raw)
To: Brian Foster; +Cc: linux-xfs
On Tue, May 23, 2017 at 08:35:39AM -0400, Brian Foster wrote:
> On Sun, May 21, 2017 at 03:59:39PM +0800, Eryu Guan wrote:
> > xfs_find_get_desired_pgoff() is used to search for offset of hole or
> > data in page range [index, end] (both inclusive), and the max number
> > of pages to search should be at least one, if end == index.
> > Otherwise the only page is missed and no hole or data is found,
> > which is not correct.
> >
> > When block size is smaller than page size, this can be demonstrated
> > by preallocating a file with size smaller than page size and writing
> > data to the last block. E.g. run this xfs_io command on a 1k block
> > size XFS on x86_64 host.
> >
> > # xfs_io -fc "falloc 0 3k" -c "pwrite 2k 1k" \
> > -c "seek -d 0" /mnt/xfs/testfile
> > wrote 1024/1024 bytes at offset 2048
> > 1 KiB, 1 ops; 0.0000 sec (33.675 MiB/sec and 34482.7586 ops/sec)
> > Whence Result
> > DATA EOF
> >
>
> Ok, so this does look like a different problem.
>
> > Data at offset 2k was missed, and lseek(2) returned ENXIO.
> >
> > This is unconvered by generic/285 subtest 07 and 08 on ppc64 host,
> > where pagesize is 64k. Because a recent change to generic/285
> > reduced the preallocated file size to smaller than 64k.
> >
> > Cc: stable@vger.kernel.org # v3.7+
> > Signed-off-by: Eryu Guan <eguan@redhat.com>
>
> Could we fold this patch into Jan's patch 2 or vice versa (retaining
> Eryu's commit log and credit)?
>
> > ---
> > fs/xfs/xfs_file.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> > index 35703a8..aefa213 100644
> > --- a/fs/xfs/xfs_file.c
> > +++ b/fs/xfs/xfs_file.c
> > @@ -1049,7 +1049,7 @@ xfs_find_get_desired_pgoff(
> > unsigned nr_pages;
> > unsigned int i;
> >
> > - want = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
> > + want = min_t(pgoff_t, end - index, PAGEVEC_SIZE - 1) + 1;
>
> Kind of a nit, but could we do the following?
>
> want = min_t(pgoff_t, end - index + 1, PAGEVEC_SIZE);
>
> It seems more clear to me given that end would be inclusive after Jan's
> patch.
I thought about it too, but I searched for other places doing the same
calculation and they are all comparing (end-index) with (PAGEVEC_SIZE-1)
then plus one, e.g. mm/truncate.c::invalidate_inode_pages2_range(). I
guess it's meant to prevent (end - index + 1) from overflowing, i.e.
(end(ULONG_MAX) - index(0) + 1).
Thanks for the review!
Eryu
>
> Brian
>
> > nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
> > want);
> > /*
> > --
> > 2.9.4
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] xfs: fix off-by-one on max nr_pages in xfs_find_get_desired_pgoff()
2017-05-23 13:00 ` Eryu Guan
@ 2017-05-23 13:27 ` Brian Foster
0 siblings, 0 replies; 6+ messages in thread
From: Brian Foster @ 2017-05-23 13:27 UTC (permalink / raw)
To: Eryu Guan; +Cc: linux-xfs
On Tue, May 23, 2017 at 09:00:28PM +0800, Eryu Guan wrote:
> On Tue, May 23, 2017 at 08:35:39AM -0400, Brian Foster wrote:
> > On Sun, May 21, 2017 at 03:59:39PM +0800, Eryu Guan wrote:
> > > xfs_find_get_desired_pgoff() is used to search for offset of hole or
> > > data in page range [index, end] (both inclusive), and the max number
> > > of pages to search should be at least one, if end == index.
> > > Otherwise the only page is missed and no hole or data is found,
> > > which is not correct.
> > >
> > > When block size is smaller than page size, this can be demonstrated
> > > by preallocating a file with size smaller than page size and writing
> > > data to the last block. E.g. run this xfs_io command on a 1k block
> > > size XFS on x86_64 host.
> > >
> > > # xfs_io -fc "falloc 0 3k" -c "pwrite 2k 1k" \
> > > -c "seek -d 0" /mnt/xfs/testfile
> > > wrote 1024/1024 bytes at offset 2048
> > > 1 KiB, 1 ops; 0.0000 sec (33.675 MiB/sec and 34482.7586 ops/sec)
> > > Whence Result
> > > DATA EOF
> > >
> >
> > Ok, so this does look like a different problem.
> >
> > > Data at offset 2k was missed, and lseek(2) returned ENXIO.
> > >
> > > This is unconvered by generic/285 subtest 07 and 08 on ppc64 host,
> > > where pagesize is 64k. Because a recent change to generic/285
> > > reduced the preallocated file size to smaller than 64k.
> > >
> > > Cc: stable@vger.kernel.org # v3.7+
> > > Signed-off-by: Eryu Guan <eguan@redhat.com>
> >
> > Could we fold this patch into Jan's patch 2 or vice versa (retaining
> > Eryu's commit log and credit)?
> >
> > > ---
> > > fs/xfs/xfs_file.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> > > index 35703a8..aefa213 100644
> > > --- a/fs/xfs/xfs_file.c
> > > +++ b/fs/xfs/xfs_file.c
> > > @@ -1049,7 +1049,7 @@ xfs_find_get_desired_pgoff(
> > > unsigned nr_pages;
> > > unsigned int i;
> > >
> > > - want = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
> > > + want = min_t(pgoff_t, end - index, PAGEVEC_SIZE - 1) + 1;
> >
> > Kind of a nit, but could we do the following?
> >
> > want = min_t(pgoff_t, end - index + 1, PAGEVEC_SIZE);
> >
> > It seems more clear to me given that end would be inclusive after Jan's
> > patch.
>
> I thought about it too, but I searched for other places doing the same
> calculation and they are all comparing (end-index) with (PAGEVEC_SIZE-1)
> then plus one, e.g. mm/truncate.c::invalidate_inode_pages2_range(). I
> guess it's meant to prevent (end - index + 1) from overflowing, i.e.
> (end(ULONG_MAX) - index(0) + 1).
>
Ah, I see. Disregard this comment then, thanks!
Brian
> Thanks for the review!
>
> Eryu
>
> >
> > Brian
> >
> > > nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
> > > want);
> > > /*
> > > --
> > > 2.9.4
> > >
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > > the body of a message to majordomo@vger.kernel.org
> > > More majordomo info at http://vger.kernel.org/majordomo-info.html
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] xfs: fix off-by-one on max nr_pages in xfs_find_get_desired_pgoff()
2017-05-21 7:59 [PATCH] xfs: fix off-by-one on max nr_pages in xfs_find_get_desired_pgoff() Eryu Guan
2017-05-23 8:36 ` Jan Kara
2017-05-23 12:35 ` Brian Foster
@ 2017-05-23 15:33 ` Darrick J. Wong
2 siblings, 0 replies; 6+ messages in thread
From: Darrick J. Wong @ 2017-05-23 15:33 UTC (permalink / raw)
To: Eryu Guan; +Cc: linux-xfs
On Sun, May 21, 2017 at 03:59:39PM +0800, Eryu Guan wrote:
> xfs_find_get_desired_pgoff() is used to search for offset of hole or
> data in page range [index, end] (both inclusive), and the max number
> of pages to search should be at least one, if end == index.
> Otherwise the only page is missed and no hole or data is found,
> which is not correct.
>
> When block size is smaller than page size, this can be demonstrated
> by preallocating a file with size smaller than page size and writing
> data to the last block. E.g. run this xfs_io command on a 1k block
> size XFS on x86_64 host.
>
> # xfs_io -fc "falloc 0 3k" -c "pwrite 2k 1k" \
> -c "seek -d 0" /mnt/xfs/testfile
> wrote 1024/1024 bytes at offset 2048
> 1 KiB, 1 ops; 0.0000 sec (33.675 MiB/sec and 34482.7586 ops/sec)
> Whence Result
> DATA EOF
>
> Data at offset 2k was missed, and lseek(2) returned ENXIO.
>
> This is unconvered by generic/285 subtest 07 and 08 on ppc64 host,
"uncovered", will fix it when I commit and push to testbox.
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> where pagesize is 64k. Because a recent change to generic/285
> reduced the preallocated file size to smaller than 64k.
>
> Cc: stable@vger.kernel.org # v3.7+
> Signed-off-by: Eryu Guan <eguan@redhat.com>
> ---
> fs/xfs/xfs_file.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 35703a8..aefa213 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -1049,7 +1049,7 @@ xfs_find_get_desired_pgoff(
> unsigned nr_pages;
> unsigned int i;
>
> - want = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
> + want = min_t(pgoff_t, end - index, PAGEVEC_SIZE - 1) + 1;
> nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
> want);
> /*
> --
> 2.9.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2017-05-23 15:33 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2017-05-21 7:59 [PATCH] xfs: fix off-by-one on max nr_pages in xfs_find_get_desired_pgoff() Eryu Guan
2017-05-23 8:36 ` Jan Kara
2017-05-23 12:35 ` Brian Foster
2017-05-23 13:00 ` Eryu Guan
2017-05-23 13:27 ` Brian Foster
2017-05-23 15:33 ` Darrick J. Wong
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