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[195.135.220.15]) by mx.google.com with ESMTPS id e12si1354052ejs.54.2019.04.29.14.41.35 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 29 Apr 2019 14:41:35 -0700 (PDT) Received-SPF: pass (google.com: domain of jack@suse.cz designates 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=pass (google.com: domain of jack@suse.cz designates 195.135.220.15 as permitted sender) smtp.mailfrom=jack@suse.cz X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 96A6EABD7; Mon, 29 Apr 2019 21:41:34 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 9167F1E3BEC; Mon, 29 Apr 2019 23:41:32 +0200 (CEST) Date: Mon, 29 Apr 2019 23:41:32 +0200 From: Jan Kara To: Andreas Gruenbacher Cc: cluster-devel@redhat.com, Christoph Hellwig , Bob Peterson , Jan Kara , Dave Chinner , Ross Lagerwall , Mark Syms , Edwin =?iso-8859-1?B?VPZy9ms=?= , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v6 3/4] iomap: Add a page_prepare callback Message-ID: <20190429214132.GD1424@quack2.suse.cz> References: <20190429163239.4874-1-agruenba@redhat.com> <20190429163239.4874-3-agruenba@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190429163239.4874-3-agruenba@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon 29-04-19 18:32:38, Andreas Gruenbacher wrote: > Move the page_done callback into a separate iomap_page_ops structure and > add a page_prepare calback to be called before the next page is written > to. In gfs2, we'll want to start a transaction in page_prepare and end > it in page_done. Other filesystems that implement data journaling will > require the same kind of mechanism. > > Signed-off-by: Andreas Gruenbacher Looks good to me. You can add: Reviewed-by: Jan Kara Honza > --- > fs/gfs2/bmap.c | 22 +++++++++++++++++----- > fs/iomap.c | 36 ++++++++++++++++++++++++++---------- > include/linux/iomap.h | 22 +++++++++++++++++----- > 3 files changed, 60 insertions(+), 20 deletions(-) > > diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c > index 5da4ca9041c0..6b980703bae7 100644 > --- a/fs/gfs2/bmap.c > +++ b/fs/gfs2/bmap.c > @@ -991,15 +991,27 @@ static void gfs2_write_unlock(struct inode *inode) > gfs2_glock_dq_uninit(&ip->i_gh); > } > > -static void gfs2_iomap_journaled_page_done(struct inode *inode, loff_t pos, > - unsigned copied, struct page *page, > - struct iomap *iomap) > +static int gfs2_iomap_page_prepare(struct inode *inode, loff_t pos, > + unsigned len, struct iomap *iomap) > +{ > + return 0; > +} > + > +static void gfs2_iomap_page_done(struct inode *inode, loff_t pos, > + unsigned copied, struct page *page, > + struct iomap *iomap) > { > struct gfs2_inode *ip = GFS2_I(inode); > > - gfs2_page_add_databufs(ip, page, offset_in_page(pos), copied); > + if (page) > + gfs2_page_add_databufs(ip, page, offset_in_page(pos), copied); > } > > +static const struct iomap_page_ops gfs2_iomap_page_ops = { > + .page_prepare = gfs2_iomap_page_prepare, > + .page_done = gfs2_iomap_page_done, > +}; > + > static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos, > loff_t length, unsigned flags, > struct iomap *iomap, > @@ -1077,7 +1089,7 @@ static int gfs2_iomap_begin_write(struct inode *inode, loff_t pos, > } > } > if (!gfs2_is_stuffed(ip) && gfs2_is_jdata(ip)) > - iomap->page_done = gfs2_iomap_journaled_page_done; > + iomap->page_ops = &gfs2_iomap_page_ops; > return 0; > > out_trans_end: > diff --git a/fs/iomap.c b/fs/iomap.c > index b01ed5a28d2c..ee9ce7a06244 100644 > --- a/fs/iomap.c > +++ b/fs/iomap.c > @@ -665,6 +665,7 @@ static int > iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, > struct page **pagep, struct iomap *iomap) > { > + const struct iomap_page_ops *page_ops = iomap->page_ops; > pgoff_t index = pos >> PAGE_SHIFT; > struct page *page; > int status = 0; > @@ -674,9 +675,17 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, > if (fatal_signal_pending(current)) > return -EINTR; > > + if (page_ops && page_ops->page_prepare) { > + status = page_ops->page_prepare(inode, pos, len, iomap); > + if (status) > + return status; > + } > + > page = grab_cache_page_write_begin(inode->i_mapping, index, flags); > - if (!page) > - return -ENOMEM; > + if (!page) { > + status = -ENOMEM; > + goto out_no_page; > + } > > if (iomap->type == IOMAP_INLINE) > iomap_read_inline_data(inode, page, iomap); > @@ -684,15 +693,21 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, > status = __block_write_begin_int(page, pos, len, NULL, iomap); > else > status = __iomap_write_begin(inode, pos, len, page, iomap); > - if (unlikely(status)) { > - unlock_page(page); > - put_page(page); > - page = NULL; > > - iomap_write_failed(inode, pos, len); > - } > + if (unlikely(status)) > + goto out_unlock; > > *pagep = page; > + return 0; > + > +out_unlock: > + unlock_page(page); > + put_page(page); > + iomap_write_failed(inode, pos, len); > + > +out_no_page: > + if (page_ops && page_ops->page_done) > + page_ops->page_done(inode, pos, 0, NULL, iomap); > return status; > } > > @@ -766,6 +781,7 @@ static int > iomap_write_end(struct inode *inode, loff_t pos, unsigned len, > unsigned copied, struct page *page, struct iomap *iomap) > { > + const struct iomap_page_ops *page_ops = iomap->page_ops; > int ret; > > if (iomap->type == IOMAP_INLINE) { > @@ -778,8 +794,8 @@ iomap_write_end(struct inode *inode, loff_t pos, unsigned len, > } > > ret = __generic_write_end(inode, pos, ret, page); > - if (iomap->page_done) > - iomap->page_done(inode, pos, copied, page, iomap); > + if (page_ops) > + page_ops->page_done(inode, pos, copied, page, iomap); > put_page(page); > > if (ret < len) > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > index 0fefb5455bda..2103b94cb1bf 100644 > --- a/include/linux/iomap.h > +++ b/include/linux/iomap.h > @@ -53,6 +53,8 @@ struct vm_fault; > */ > #define IOMAP_NULL_ADDR -1ULL /* addr is not valid */ > > +struct iomap_page_ops; > + > struct iomap { > u64 addr; /* disk offset of mapping, bytes */ > loff_t offset; /* file offset of mapping, bytes */ > @@ -63,12 +65,22 @@ struct iomap { > struct dax_device *dax_dev; /* dax_dev for dax operations */ > void *inline_data; > void *private; /* filesystem private */ > + const struct iomap_page_ops *page_ops; > +}; > > - /* > - * Called when finished processing a page in the mapping returned in > - * this iomap. At least for now this is only supported in the buffered > - * write path. > - */ > +/* > + * When a filesystem sets page_ops in an iomap mapping it returns, page_prepare > + * and page_done will be called for each page written to. This only applies to > + * buffered writes as unbuffered writes will not typically have pages > + * associated with them. > + * > + * When page_prepare succeeds, page_done will always be called to do any > + * cleanup work necessary. In that page_done call, @page will be NULL if the > + * associated page could not be obtained. > + */ > +struct iomap_page_ops { > + int (*page_prepare)(struct inode *inode, loff_t pos, unsigned len, > + struct iomap *iomap); > void (*page_done)(struct inode *inode, loff_t pos, unsigned copied, > struct page *page, struct iomap *iomap); > }; > -- > 2.20.1 > -- Jan Kara SUSE Labs, CR