From patchwork Thu Jan 25 08:57:48 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 13530250 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BBC7C1CD16; Thu, 25 Jan 2024 08:58:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706173129; cv=none; b=fxv9CoMJ4300wzO9DW0pjx0cBS+EDv5BO2+OxI0yLu319D3reHhkXGWvNwoZQ6FQ2zjXQMpJYViJHPbJzj//BwHPGX+66PpGBGEWrM+BTszBRmac8Dkz5v5oE7+DeTal37c18ZdcejZrZVWNl72igHgL6SbCTenR0bfKWEC0J44= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706173129; c=relaxed/simple; bh=+QC8WCxfGqhRmoMuzPSArUDy0kgmehhB1gWLDEEcjf8=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=qc6BWA4dgVPWF9n1B5uyBn6s7ml/vV6rSRkeu6R2b+wJTLAaBU7WoKEsvdxEPmE6lJFUGB1pR9XM53+u+OX+n2Lsh49kwJf8k1CtD262QzuY4Z2CZEJN8LSsQrW3yO1C6lN2/kzYJ6rD/Y5OoSitmiG5j3r2RO9I6U20frPEX38= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=m/Q1LhPC; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="m/Q1LhPC" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=uF8JIxjy5aR+l38o23/kghoy+Tugnu4jphYuZf7Sd0E=; b=m/Q1LhPC2/vHTSRu90DWvDptL5 BKQMoE7BL5NkeXAax6P9Yv8CPEYpHoiimUbS48P6z7/UaStZmi3exEaCGCxntBxKnEwJjDTnI5VJP Hf/ZvL0N6tR+UAfkRsSsa0kOyxZryKyVHCuJ+SxCxuef8kZRlV6Ym+mhT7BEBLe/BosuzkrdLBmOZ nsnk9cVwIBEe3hI5Yr0oDGINfAcHWHBX17YJwjH2PzML7Wnv4py4ZII5IEDM6VZuzb+pM1vr/GPre prsVBlnIAvbyHoHFjjv3sboVrNToPf28igDzhaChDmBlBkJfOdLkdbj3l9AHoxNZ8CoaNeULCDXY4 vuN06pFA==; Received: from 2a02-8389-2341-5b80-39d3-4735-9a3c-88d8.cable.dynamic.v6.surfer.at ([2a02:8389:2341:5b80:39d3:4735:9a3c:88d8] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1rSvZG-007QKS-21; Thu, 25 Jan 2024 08:58:39 +0000 From: Christoph Hellwig To: linux-mm@kvack.org Cc: Matthew Wilcox , Jan Kara , David Howells , Brian Foster , Christian Brauner , "Darrick J. Wong" , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Jan Kara , Dave Chinner Subject: [PATCH 09/19] writeback: Simplify the loops in write_cache_pages() Date: Thu, 25 Jan 2024 09:57:48 +0100 Message-Id: <20240125085758.2393327-10-hch@lst.de> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240125085758.2393327-1-hch@lst.de> References: <20240125085758.2393327-1-hch@lst.de> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html From: "Matthew Wilcox (Oracle)" Collapse the two nested loops into one. This is needed as a step towards turning this into an iterator. Note that this drops the "index <= end" check in the previous outer loop and just relies on filemap_get_folios_tag() to return 0 entries when index > end. This actually has a subtle implication when end == -1 because then the returned index will be -1 as well and thus if there is page present on index -1, we could be looping indefinitely. But as the comment in filemap_get_folios_tag documents this as already broken anyway we should not worry about it here either. The fix for that would probably a change to the filemap_get_folios_tag() calling convention. Signed-off-by: Matthew Wilcox (Oracle) [hch: updated the commit log based on feedback from Jan Kara] Signed-off-by: Christoph Hellwig Reviewed-by: Jan Kara Acked-by: Dave Chinner --- mm/page-writeback.c | 94 ++++++++++++++++++++++----------------------- 1 file changed, 46 insertions(+), 48 deletions(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index cec683c7217d2e..d6ac414ddce9ca 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2475,6 +2475,7 @@ int write_cache_pages(struct address_space *mapping, { int error; pgoff_t end; /* Inclusive */ + int i = 0; if (wbc->range_cyclic) { wbc->index = mapping->writeback_index; /* prev offset */ @@ -2489,63 +2490,60 @@ int write_cache_pages(struct address_space *mapping, folio_batch_init(&wbc->fbatch); wbc->err = 0; - while (wbc->index <= end) { - int i; - - writeback_get_batch(mapping, wbc); + for (;;) { + struct folio *folio; + unsigned long nr; + if (i == wbc->fbatch.nr) { + writeback_get_batch(mapping, wbc); + i = 0; + } if (wbc->fbatch.nr == 0) break; - for (i = 0; i < wbc->fbatch.nr; i++) { - struct folio *folio = wbc->fbatch.folios[i]; - unsigned long nr; + folio = wbc->fbatch.folios[i++]; - folio_lock(folio); - if (!folio_prepare_writeback(mapping, wbc, folio)) { - folio_unlock(folio); - continue; - } + folio_lock(folio); + if (!folio_prepare_writeback(mapping, wbc, folio)) { + folio_unlock(folio); + continue; + } - trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); + trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); - error = writepage(folio, wbc, data); - nr = folio_nr_pages(folio); - wbc->nr_to_write -= nr; + error = writepage(folio, wbc, data); + nr = folio_nr_pages(folio); + wbc->nr_to_write -= nr; - /* - * Handle the legacy AOP_WRITEPAGE_ACTIVATE magic return - * value. Eventually all instances should just unlock - * the folio themselves and return 0; - */ - if (error == AOP_WRITEPAGE_ACTIVATE) { - folio_unlock(folio); - error = 0; - } - - if (error && !wbc->err) - wbc->err = error; + /* + * Handle the legacy AOP_WRITEPAGE_ACTIVATE magic return value. + * Eventually all instances should just unlock the folio + * themselves and return 0; + */ + if (error == AOP_WRITEPAGE_ACTIVATE) { + folio_unlock(folio); + error = 0; + } - /* - * For integrity sync we have to keep going until we - * have written all the folios we tagged for writeback - * prior to entering this loop, even if we run past - * wbc->nr_to_write or encounter errors. This is - * because the file system may still have state to clear - * for each folio. We'll eventually return the first - * error encountered. - * - * For background writeback just push done_index past - * this folio so that we can just restart where we left - * off and media errors won't choke writeout for the - * entire file. - */ - if (wbc->sync_mode == WB_SYNC_NONE && - (wbc->err || wbc->nr_to_write <= 0)) { - writeback_finish(mapping, wbc, - folio->index + nr); - return error; - } + if (error && !wbc->err) + wbc->err = error; + + /* + * For integrity sync we have to keep going until we have + * written all the folios we tagged for writeback prior to + * entering this loop, even if we run past wbc->nr_to_write or + * encounter errors. This is because the file system may still + * have state to clear for each folio. We'll eventually return + * the first error encountered. + * + * For background writeback just push done_index past this folio + * so that we can just restart where we left off and media + * errors won't choke writeout for the entire file. + */ + if (wbc->sync_mode == WB_SYNC_NONE && + (wbc->err || wbc->nr_to_write <= 0)) { + writeback_finish(mapping, wbc, folio->index + nr); + return error; } }