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SubjectRe: [f2fs-dev] [PATCH 2/3] f2fs crypto: use bounce pages from mempool first
Hi Chao,

On Mon, May 25, 2015 at 06:00:47PM +0800, Chao Yu wrote:
> Hi Jaegeuk,
>
> > -----Original Message-----
> > From: Jaegeuk Kim [mailto:jaegeuk@kernel.org]
> > Sent: Friday, May 22, 2015 8:40 AM
> > To: linux-kernel@vger.kernel.org; linux-fsdevel@vger.kernel.org;
> > linux-f2fs-devel@lists.sourceforge.net
> > Cc: Jaegeuk Kim
> > Subject: [f2fs-dev] [PATCH 2/3] f2fs crypto: use bounce pages from mempool first
> >
> > If a lot of write streams are triggered, alloc_page and __free_page are
> > costly called, resulting in high memory pressure.
> >
> > In order to avoid that, let's reuse mempool pages for writeback pages.
> >
> > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> > ---
> > fs/f2fs/crypto.c | 16 ++++------------
> > 1 file changed, 4 insertions(+), 12 deletions(-)
> >
> > diff --git a/fs/f2fs/crypto.c b/fs/f2fs/crypto.c
> > index 2c7819a..2ceee68 100644
> > --- a/fs/f2fs/crypto.c
> > +++ b/fs/f2fs/crypto.c
> > @@ -408,20 +408,12 @@ struct page *f2fs_encrypt(struct inode *inode,
> > return (struct page *)ctx;
> >
> > /* The encryption operation will require a bounce page. */
> > - ciphertext_page = alloc_page(GFP_NOFS);
> > + ciphertext_page = mempool_alloc(f2fs_bounce_page_pool, GFP_NOFS);
> > if (!ciphertext_page) {
> > - /*
> > - * This is a potential bottleneck, but at least we'll have
> > - * forward progress.
> > - */
> > - ciphertext_page = mempool_alloc(f2fs_bounce_page_pool,
> > - GFP_NOFS);
> > - if (WARN_ON_ONCE(!ciphertext_page))
> > - ciphertext_page = mempool_alloc(f2fs_bounce_page_pool,
> > - GFP_NOFS | __GFP_WAIT);
> > - ctx->flags &= ~F2FS_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
> > - } else {
> > + ciphertext_page = alloc_page(GFP_NOFS);
>
> Using alloc_page(GFP_NOFS | __GFP_WAIT) to avoid failure?

#define GFP_NOFS (__GFP_WAIT | __GFP_IO)

Thanks,

>
> Thanks,
>
> > ctx->flags |= F2FS_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
> > + } else {
> > + ctx->flags &= ~F2FS_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
> > }
> > ctx->flags |= F2FS_WRITE_PATH_FL;
> > ctx->w.bounce_page = ciphertext_page;
> > --
> > 2.1.1
> >
> >
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> > Linux-f2fs-devel@lists.sourceforge.net
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