From patchwork Fri Dec 15 20:02:34 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 13494847 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 DBBE45639E; Fri, 15 Dec 2023 20:02:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="CgLipEpS" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=y2LTUl+ZxJP8korj46ZIojz6qFBZmH/UltM1ueD//bY=; b=CgLipEpSQeL7n3K7h5qv//dI1J Hyxu1SNcuc6KE8jhGSWFs58vYD3Ub89XHd7GA8EZWVff0bnCAQ2AUPlYAcWmRslUjziZa2Txj/tdR lZb6urewEhwHsr+FYouUuqEuHYuh6LVjV4L23AiWMXhDxMJGDXScMgR0BKTTWz/qXkwG/ZCxdq8Ir lPuibOk7rQWaudaDIcmh+imazfOubEGNxtJd+4tg2i92riw+HuTk67lZpzaAQ5j8acssDeDrM1W2d RQEqLCazr3B5+hkCZ5B8FYOaHepMoxpgtSmO8YS/auXztCf+iqOwvANUpuLNAb3LtykX77pNzIHHZ PDjxz1zg==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1rEEOV-0038iK-3c; Fri, 15 Dec 2023 20:02:47 +0000 From: "Matthew Wilcox (Oracle)" To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , Christoph Hellwig , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org Subject: [PATCH 03/14] fs: Reduce stack usage in __mpage_writepage Date: Fri, 15 Dec 2023 20:02:34 +0000 Message-Id: <20231215200245.748418-4-willy@infradead.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20231215200245.748418-1-willy@infradead.org> References: <20231215200245.748418-1-willy@infradead.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Some architectures support a very large PAGE_SIZE, so instead of the 8 pointers we see with a 4kB PAGE_SIZE, we can see 128 pointers with 64kB or so many on Hexagon that it trips compiler warnings about exceeding stack frame size. All we're doing with this array is checking for block contiguity, which we can as well do by remembering the address of the first block in the page and checking this block is at the appropriate offset from that address. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig --- fs/mpage.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/fs/mpage.c b/fs/mpage.c index 630f4a7c7d03..84b02098e7a5 100644 --- a/fs/mpage.c +++ b/fs/mpage.c @@ -466,7 +466,7 @@ static int __mpage_writepage(struct folio *folio, struct writeback_control *wbc, const unsigned blocks_per_page = PAGE_SIZE >> blkbits; sector_t last_block; sector_t block_in_file; - sector_t blocks[MAX_BUF_PER_PAGE]; + sector_t first_block; unsigned page_block; unsigned first_unmapped = blocks_per_page; struct block_device *bdev = NULL; @@ -504,10 +504,12 @@ static int __mpage_writepage(struct folio *folio, struct writeback_control *wbc, if (!buffer_dirty(bh) || !buffer_uptodate(bh)) goto confused; if (page_block) { - if (bh->b_blocknr != blocks[page_block-1] + 1) + if (bh->b_blocknr != first_block + page_block) goto confused; + } else { + first_block = bh->b_blocknr; } - blocks[page_block++] = bh->b_blocknr; + page_block++; boundary = buffer_boundary(bh); if (boundary) { boundary_block = bh->b_blocknr; @@ -556,10 +558,12 @@ static int __mpage_writepage(struct folio *folio, struct writeback_control *wbc, boundary_bdev = map_bh.b_bdev; } if (page_block) { - if (map_bh.b_blocknr != blocks[page_block-1] + 1) + if (map_bh.b_blocknr != first_block + page_block) goto confused; + } else { + first_block = map_bh.b_blocknr; } - blocks[page_block++] = map_bh.b_blocknr; + page_block++; boundary = buffer_boundary(&map_bh); bdev = map_bh.b_bdev; if (block_in_file == last_block) @@ -591,7 +595,7 @@ static int __mpage_writepage(struct folio *folio, struct writeback_control *wbc, /* * This page will go to BIO. Do we need to send this BIO off first? */ - if (bio && mpd->last_block_in_bio != blocks[0] - 1) + if (bio && mpd->last_block_in_bio != first_block - 1) bio = mpage_bio_submit_write(bio); alloc_new: @@ -599,7 +603,7 @@ static int __mpage_writepage(struct folio *folio, struct writeback_control *wbc, bio = bio_alloc(bdev, BIO_MAX_VECS, REQ_OP_WRITE | wbc_to_write_flags(wbc), GFP_NOFS); - bio->bi_iter.bi_sector = blocks[0] << (blkbits - 9); + bio->bi_iter.bi_sector = first_block << (blkbits - 9); wbc_init_bio(wbc, bio); } @@ -627,7 +631,7 @@ static int __mpage_writepage(struct folio *folio, struct writeback_control *wbc, boundary_block, 1 << blkbits); } } else { - mpd->last_block_in_bio = blocks[blocks_per_page - 1]; + mpd->last_block_in_bio = first_block + blocks_per_page - 1; } goto out;