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Fri, 11 Sep 2020 07:17:56 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 51B99ADE4; Fri, 11 Sep 2020 11:18:04 +0000 (UTC) Subject: Re: [PATCH 09/17] btrfs: refactor btrfs_release_extent_buffer_pages() To: Qu Wenruo , linux-btrfs@vger.kernel.org References: <20200908075230.86856-1-wqu@suse.com> <20200908075230.86856-10-wqu@suse.com> From: Nikolay Borisov Autocrypt: addr=nborisov@suse.com; prefer-encrypt=mutual; keydata= xsFNBFiKBz4BEADNHZmqwhuN6EAzXj9SpPpH/nSSP8YgfwoOqwrP+JR4pIqRK0AWWeWCSwmZ T7g+RbfPFlmQp+EwFWOtABXlKC54zgSf+uulGwx5JAUFVUIRBmnHOYi/lUiE0yhpnb1KCA7f u/W+DkwGerXqhhe9TvQoGwgCKNfzFPZoM+gZrm+kWv03QLUCr210n4cwaCPJ0Nr9Z3c582xc bCUVbsjt7BN0CFa2BByulrx5xD9sDAYIqfLCcZetAqsTRGxM7LD0kh5WlKzOeAXj5r8DOrU2 GdZS33uKZI/kZJZVytSmZpswDsKhnGzRN1BANGP8sC+WD4eRXajOmNh2HL4P+meO1TlM3GLl EQd2shHFY0qjEo7wxKZI1RyZZ5AgJnSmehrPCyuIyVY210CbMaIKHUIsTqRgY5GaNME24w7h TyyVCy2qAM8fLJ4Vw5bycM/u5xfWm7gyTb9V1TkZ3o1MTrEsrcqFiRrBY94Rs0oQkZvunqia c+NprYSaOG1Cta14o94eMH271Kka/reEwSZkC7T+o9hZ4zi2CcLcY0DXj0qdId7vUKSJjEep c++s8ncFekh1MPhkOgNj8pk17OAESanmDwksmzh1j12lgA5lTFPrJeRNu6/isC2zyZhTwMWs k3LkcTa8ZXxh0RfWAqgx/ogKPk4ZxOXQEZetkEyTFghbRH2BIwARAQABzSJOaWtvbGF5IEJv cmlzb3YgPG5ib3Jpc292QHN1c2UuZGU+wsF4BBMBAgAiBQJYijkSAhsDBgsJCAcDAgYVCAIJ CgsEFgIDAQIeAQIXgAAKCRBxvoJG5T8oV/B6D/9a8EcRPdHg8uLEPywuJR8URwXzkofT5bZE IfGF0Z+Lt2ADe+nLOXrwKsamhweUFAvwEUxxnndovRLPOpWerTOAl47lxad08080jXnGfYFS Dc+ew7C3SFI4tFFHln8Y22Q9075saZ2yQS1ywJy+TFPADIprAZXnPbbbNbGtJLoq0LTiESnD w/SUC6sfikYwGRS94Dc9qO4nWyEvBK3Ql8NkoY0Sjky3B0vL572Gq0ytILDDGYuZVo4alUs8 LeXS5ukoZIw1QYXVstDJQnYjFxYgoQ5uGVi4t7FsFM/6ykYDzbIPNOx49Rbh9W4uKsLVhTzG BDTzdvX4ARl9La2kCQIjjWRg+XGuBM5rxT/NaTS78PXjhqWNYlGc5OhO0l8e5DIS2tXwYMDY LuHYNkkpMFksBslldvNttSNei7xr5VwjVqW4vASk2Aak5AleXZS+xIq2FADPS/XSgIaepyTV tkfnyreep1pk09cjfXY4A7qpEFwazCRZg9LLvYVc2M2eFQHDMtXsH59nOMstXx2OtNMcx5p8 0a5FHXE/HoXz3p9bD0uIUq6p04VYOHsMasHqHPbsMAq9V2OCytJQPWwe46bBjYZCOwG0+x58 fBFreP/NiJNeTQPOa6FoxLOLXMuVtpbcXIqKQDoEte9aMpoj9L24f60G4q+pL/54ql2VRscK d87BTQRYigc+ARAAyJSq9EFk28++SLfg791xOh28tLI6Yr8wwEOvM3wKeTfTZd+caVb9gBBy wxYhIopKlK1zq2YP7ZjTP1aPJGoWvcQZ8fVFdK/1nW+Z8/NTjaOx1mfrrtTGtFxVBdSCgqBB jHTnlDYV1R5plJqK+ggEP1a0mr/rpQ9dFGvgf/5jkVpRnH6BY0aYFPprRL8ZCcdv2DeeicOO YMobD5g7g/poQzHLLeT0+y1qiLIFefNABLN06Lf0GBZC5l8hCM3Rpb4ObyQ4B9PmL/KTn2FV Xq/c0scGMdXD2QeWLePC+yLMhf1fZby1vVJ59pXGq+o7XXfYA7xX0JsTUNxVPx/MgK8aLjYW hX+TRA4bCr4uYt/S3ThDRywSX6Hr1lyp4FJBwgyb8iv42it8KvoeOsHqVbuCIGRCXqGGiaeX Wa0M/oxN1vJjMSIEVzBAPi16tztL/wQtFHJtZAdCnuzFAz8ue6GzvsyBj97pzkBVacwp3/Mw qbiu7sDz7yB0d7J2tFBJYNpVt/Lce6nQhrvon0VqiWeMHxgtQ4k92Eja9u80JDaKnHDdjdwq FUikZirB28UiLPQV6PvCckgIiukmz/5ctAfKpyYRGfez+JbAGl6iCvHYt/wAZ7Oqe/3Cirs5 KhaXBcMmJR1qo8QH8eYZ+qhFE3bSPH446+5oEw8A9v5oonKV7zMAEQEAAcLBXwQYAQIACQUC WIoHPgIbDAAKCRBxvoJG5T8oV1pyD/4zdXdOL0lhkSIjJWGqz7Idvo0wjVHSSQCbOwZDWNTN JBTP0BUxHpPu/Z8gRNNP9/k6i63T4eL1xjy4umTwJaej1X15H8Hsh+zakADyWHadbjcUXCkg OJK4NsfqhMuaIYIHbToi9K5pAKnV953xTrK6oYVyd/Rmkmb+wgsbYQJ0Ur1Ficwhp6qU1CaJ mJwFjaWaVgUERoxcejL4ruds66LM9Z1Qqgoer62ZneID6ovmzpCWbi2sfbz98+kW46aA/w8r 7sulgs1KXWhBSv5aWqKU8C4twKjlV2XsztUUsyrjHFj91j31pnHRklBgXHTD/pSRsN0UvM26 lPs0g3ryVlG5wiZ9+JbI3sKMfbdfdOeLxtL25ujs443rw1s/PVghphoeadVAKMPINeRCgoJH zZV/2Z/myWPRWWl/79amy/9MfxffZqO9rfugRBORY0ywPHLDdo9Kmzoxoxp9w3uTrTLZaT9M KIuxEcV8wcVjr+Wr9zRl06waOCkgrQbTPp631hToxo+4rA1jiQF2M80HAet65ytBVR2pFGZF zGYYLqiG+mpUZ+FPjxk9kpkRYz61mTLSY7tuFljExfJWMGfgSg1OxfLV631jV1TcdUnx+h3l Sqs2vMhAVt14zT8mpIuu2VNxcontxgVr1kzYA/tQg32fVRbGr449j1gw57BV9i0vww== Message-ID: Date: Fri, 11 Sep 2020 14:17:47 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200908075230.86856-10-wqu@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 8.09.20 г. 10:52 ч., Qu Wenruo wrote: > We have attach_extent_buffer_page() and it get utilized in > btrfs_clone_extent_buffer() and alloc_extent_buffer(). > > But in btrfs_release_extent_buffer_pages() we manually call > detach_page_private(). > > This is fine for current code, but if we're going to support subpage > size, we will do a lot of more work other than just calling > detach_page_private(). > > This patch will extract the main work of btrfs_clone_extent_buffer() Did you mean to type btrfs_release_extent_buffer_pages instead of clone_extent_buffer ? > into detach_extent_buffer_page() so that later subpage size support can > put their own code into them. > > Signed-off-by: Qu Wenruo > --- > fs/btrfs/extent_io.c | 58 +++++++++++++++++++------------------------- > 1 file changed, 25 insertions(+), 33 deletions(-) > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > index 3c8fe40f67fa..1cb41dab7a1d 100644 > --- a/fs/btrfs/extent_io.c > +++ b/fs/btrfs/extent_io.c > @@ -4920,6 +4920,29 @@ int extent_buffer_under_io(const struct extent_buffer *eb) > test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)); > } > > +static void detach_extent_buffer_page(struct extent_buffer *eb, > + struct page *page) > +{ > + bool mapped = !test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags); nit: Now you are performing the atomic op once per page rather than once per-eb. > + > + if (!page) > + return; > + > + if (mapped) > + spin_lock(&page->mapping->private_lock); > + if (PagePrivate(page) && page->private == (unsigned long)eb) { > + BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)); > + BUG_ON(PageDirty(page)); > + BUG_ON(PageWriteback(page)); > + /* We need to make sure we haven't be attached to a new eb. */ > + detach_page_private(page); > + } > + if (mapped) > + spin_unlock(&page->mapping->private_lock); > + /* One for when we allocated the page */ > + put_page(page); > +} > + > /* > * Release all pages attached to the extent buffer. > */ > @@ -4927,43 +4950,12 @@ static void btrfs_release_extent_buffer_pages(struct extent_buffer *eb) > { > int i; > int num_pages; > - int mapped = !test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags); > > BUG_ON(extent_buffer_under_io(eb)); > > num_pages = num_extent_pages(eb); > - for (i = 0; i < num_pages; i++) { > - struct page *page = eb->pages[i]; > - > - if (!page) > - continue; > - if (mapped) > - spin_lock(&page->mapping->private_lock); > - /* > - * We do this since we'll remove the pages after we've > - * removed the eb from the radix tree, so we could race > - * and have this page now attached to the new eb. So > - * only clear page_private if it's still connected to > - * this eb. > - */ > - if (PagePrivate(page) && > - page->private == (unsigned long)eb) { > - BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)); > - BUG_ON(PageDirty(page)); > - BUG_ON(PageWriteback(page)); > - /* > - * We need to make sure we haven't be attached > - * to a new eb. > - */ > - detach_page_private(page); > - } > - > - if (mapped) > - spin_unlock(&page->mapping->private_lock); > - > - /* One for when we allocated the page */ > - put_page(page); > - } > + for (i = 0; i < num_pages; i++) > + detach_extent_buffer_page(eb, eb->pages[i]); > } > > /* >