2018-11-27 00:37:31

by Pan Bian

Subject: [PATCH V2] xfs: libxfs: move xfs_perag_put late

The function xfs_alloc_get_freelist calls xfs_perag_put to drop the
reference. However, pag->pagf_btreeblks is read and write after the
put operation. This patch moves the put operation late.

Signed-off-by: Pan Bian <[email protected]>
---
V2: correct the commit log
---
fs/xfs/libxfs/xfs_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index e1c0c0d..4be387d 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2435,7 +2435,6 @@ xfs_alloc_get_freelist(
be32_add_cpu(&agf->agf_flcount, -1);
xfs_trans_agflist_delta(tp, -1);
pag->pagf_flcount--;
- xfs_perag_put(pag);

logflags = XFS_AGF_FLFIRST | XFS_AGF_FLCOUNT;
if (btreeblk) {
@@ -2443,6 +2442,7 @@ xfs_alloc_get_freelist(
pag->pagf_btreeblks++;
logflags |= XFS_AGF_BTREEBLKS;
}
+ xfs_perag_put(pag);

xfs_alloc_log_agf(tp, agbp, logflags);
*bnop = bno;
--
2.7.4

2018-11-27 09:17:19

by Carlos Maiolino

Subject: Re: [PATCH V2] xfs: libxfs: move xfs_perag_put late

On Tue, Nov 27, 2018 at 08:33:38AM +0800, Pan Bian wrote:
> The function xfs_alloc_get_freelist calls xfs_perag_put to drop the
> reference. However, pag->pagf_btreeblks is read and write after the
> put operation. This patch moves the put operation late.

I'm not a native English speaker too, but I believe it should be "is read and
written after..."

But, for the code itself, you can add:

Reviewed-by: Carlos Maiolino <[email protected]>

Cheers

>
> Signed-off-by: Pan Bian <[email protected]>
> ---
> V2: correct the commit log
> ---
> fs/xfs/libxfs/xfs_alloc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index e1c0c0d..4be387d 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -2435,7 +2435,6 @@ xfs_alloc_get_freelist(
> be32_add_cpu(&agf->agf_flcount, -1);
> xfs_trans_agflist_delta(tp, -1);
> pag->pagf_flcount--;
> - xfs_perag_put(pag);
>
> logflags = XFS_AGF_FLFIRST | XFS_AGF_FLCOUNT;
> if (btreeblk) {
> @@ -2443,6 +2442,7 @@ xfs_alloc_get_freelist(
> pag->pagf_btreeblks++;
> logflags |= XFS_AGF_BTREEBLKS;
> }
> + xfs_perag_put(pag);
>
> xfs_alloc_log_agf(tp, agbp, logflags);
> *bnop = bno;
> --
> 2.7.4
>
>

--
Carlos

2018-11-27 19:25:58

by Darrick J. Wong

Subject: Re: [PATCH V2] xfs: libxfs: move xfs_perag_put late

On Tue, Nov 27, 2018 at 10:16:02AM +0100, Carlos Maiolino wrote:
> On Tue, Nov 27, 2018 at 08:33:38AM +0800, Pan Bian wrote:
> > The function xfs_alloc_get_freelist calls xfs_perag_put to drop the
> > reference. However, pag->pagf_btreeblks is read and write after the
> > put operation. This patch moves the put operation late.
>
> I'm not a native English speaker too, but I believe it should be "is read and
> written after..."
>
> But, for the code itself, you can add:
>
> Reviewed-by: Carlos Maiolino <[email protected]>
>
> Cheers
>
> >
> > Signed-off-by: Pan Bian <[email protected]>

Looks ok, will amend the changelog on the way in.

Reviewed-by: Darrick J. Wong <[email protected]>

--D

> > ---
> > V2: correct the commit log
> > ---
> > fs/xfs/libxfs/xfs_alloc.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> > index e1c0c0d..4be387d 100644
> > --- a/fs/xfs/libxfs/xfs_alloc.c
> > +++ b/fs/xfs/libxfs/xfs_alloc.c
> > @@ -2435,7 +2435,6 @@ xfs_alloc_get_freelist(
> > be32_add_cpu(&agf->agf_flcount, -1);
> > xfs_trans_agflist_delta(tp, -1);
> > pag->pagf_flcount--;
> > - xfs_perag_put(pag);
> >
> > logflags = XFS_AGF_FLFIRST | XFS_AGF_FLCOUNT;
> > if (btreeblk) {
> > @@ -2443,6 +2442,7 @@ xfs_alloc_get_freelist(
> > pag->pagf_btreeblks++;
> > logflags |= XFS_AGF_BTREEBLKS;
> > }
> > + xfs_perag_put(pag);
> >
> > xfs_alloc_log_agf(tp, agbp, logflags);
> > *bnop = bno;
> > --
> > 2.7.4
> >
> >
>
> --
> Carlos