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Wed, 19 Feb 2020 03:29:10 +0000 Received: from dread.disaster.area (pa49-179-138-28.pa.nsw.optusnet.com.au [49.179.138.28]) by mail104.syd.optusnet.com.au (Postfix) with ESMTPS id C4ADA7EB4FD; Wed, 19 Feb 2020 14:29:02 +1100 (AEDT) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1j4G2m-0005Wz-JP; Wed, 19 Feb 2020 14:29:00 +1100 Date: Wed, 19 Feb 2020 14:29:00 +1100 From: Dave Chinner To: Matthew Wilcox Message-ID: <20200219032900.GE10776@dread.disaster.area> References: <20200217184613.19668-1-willy@infradead.org> <20200217184613.19668-31-willy@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200217184613.19668-31-willy@infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=X6os11be c=1 sm=1 tr=0 a=zAxSp4fFY/GQY8/esVNjqw==:117 a=zAxSp4fFY/GQY8/esVNjqw==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=kj9zAlcOel0A:10 a=l697ptgUJYAA:10 a=JfrnYn6hAAAA:8 a=7-415B0cAAAA:8 a=D_ITGRzz0ucxF3CW0B0A:9 a=m4Eakf-3O-CBJR1D:21 a=uIsSIQHDIO17Gszz:21 a=CjuIK1q_8ugA:10 a=1CNFftbPRP8L7MoqJWF3:22 a=biEYGPWJfzWAr4FL6Ov7:22 X-Headers-End: 1j4G2v-00HAK7-92 Subject: Re: [f2fs-dev] [PATCH v6 17/19] iomap: Restructure iomap_readpages_actor X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-mm@kvack.org, ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-btrfs@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On Mon, Feb 17, 2020 at 10:46:11AM -0800, Matthew Wilcox wrote: > From: "Matthew Wilcox (Oracle)" > > By putting the 'have we reached the end of the page' condition at the end > of the loop instead of the beginning, we can remove the 'submit the last > page' code from iomap_readpages(). Also check that iomap_readpage_actor() > didn't return 0, which would lead to an endless loop. > > Signed-off-by: Matthew Wilcox (Oracle) > --- > fs/iomap/buffered-io.c | 25 ++++++++++++------------- > 1 file changed, 12 insertions(+), 13 deletions(-) > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index cb3511eb152a..44303f370b2d 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -400,15 +400,9 @@ iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length, > void *data, struct iomap *iomap, struct iomap *srcmap) > { > struct iomap_readpage_ctx *ctx = data; > - loff_t done, ret; > + loff_t ret, done = 0; > > - for (done = 0; done < length; done += ret) { > - if (ctx->cur_page && offset_in_page(pos + done) == 0) { > - if (!ctx->cur_page_in_bio) > - unlock_page(ctx->cur_page); > - put_page(ctx->cur_page); > - ctx->cur_page = NULL; > - } > + while (done < length) { > if (!ctx->cur_page) { > ctx->cur_page = iomap_next_page(inode, ctx->pages, > pos, length, &done); > @@ -418,6 +412,15 @@ iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length, > } > ret = iomap_readpage_actor(inode, pos + done, length - done, > ctx, iomap, srcmap); > + if (WARN_ON(ret == 0)) > + break; This error case now leaks ctx->cur_page.... > + done += ret; > + if (offset_in_page(pos + done) == 0) { > + if (!ctx->cur_page_in_bio) > + unlock_page(ctx->cur_page); > + put_page(ctx->cur_page); > + ctx->cur_page = NULL; > + } > } > > return done; > @@ -451,11 +454,7 @@ iomap_readpages(struct address_space *mapping, struct list_head *pages, > done: > if (ctx.bio) > submit_bio(ctx.bio); > - if (ctx.cur_page) { > - if (!ctx.cur_page_in_bio) > - unlock_page(ctx.cur_page); > - put_page(ctx.cur_page); > - } > + BUG_ON(ctx.cur_page); And so will now trigger both a warn and a bug.... Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel