From mboxrd@z Thu Jan 1 00:00:00 1970 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 C67F61FC7D5; Wed, 18 Dec 2024 20:05:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734552340; cv=none; b=mRXgMpKaXE/S2y5YydgTitzlKCq4j/sfNi8YObUMHeKX95u5A8dyKHLFSmbrFlRkRMBhJdHqVl1pyEAWBCCIOTfvU9R4mOI0Is4R5HlVTk43JmB4jiSygczHIccit54/lF0IC0FXOH6B3iEW3aYX9LhRoAEDfl6PUhLvFin3STU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734552340; c=relaxed/simple; bh=jwr7VoI8xrDln1LW7FhiygWtBOHRdqVr/6fBs6mNLXY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=dM/nDFTEN713U6syflnTzvHMzPGf+5g/6ohKOlBsUYCEFoSvQNktqMZxRdT9Tw4Q+ytbIkqp66wmnqPBz4FWe6FEVybQZVUBnAfciTtOU9I53tecpHZm1t9Bab4TfCjMG5FOwNQR5dozWubLbOKUL5wfVGpX6YWg+G0JwCPy11Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=R7NGvB9n; arc=none smtp.client-ip=90.155.50.34 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="R7NGvB9n" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=EbdwqBnCPnMA30/eAen6jZBripOiH8JSBeZk3CDGHT0=; b=R7NGvB9nGB2rbrdZXVCuILMXRe 6fmvKr1WgwvzkZhMhJW1PJzMTyEuJsnWTFwEK82TXW4t5hUGJW7Nexip8W/K1+F1Q12BIglQCnyLF SDx+wVu5qUHUgTrgTQ3/tpdPfrIJwQfnAs6JA8eaPfbn+wXalYMY7TLJYsX/0+C6Xc9wMc1dear2s 7qLxZ9KeymLgW3g3D3K53JGnUkcByEVsfIwGZI/BKzd72GsLBSC+/mVU3RFnOp7NYUUaJqqnJ+4Cr Ut9cfQZtp12r2GmgXhlExf2I0wmGOetu+44l4rJptA1C0p/kKg0nEKarItbjCDFvxbUpLQexaLluF il4EFXSg==; Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1tO0IT-00000000ZPU-10Y0; Wed, 18 Dec 2024 20:05:29 +0000 Date: Wed, 18 Dec 2024 20:05:29 +0000 From: Matthew Wilcox To: Luis Chamberlain Cc: hare@suse.de, dave@stgolabs.net, david@fromorbit.com, djwong@kernel.org, kbusch@kernel.org, john.g.garry@oracle.com, hch@lst.de, ritesh.list@gmail.com, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, gost.dev@samsung.com, p.raghav@samsung.com, da.gomez@samsung.com, kernel@pankajraghav.com Subject: Re: [PATCH 0/5] fs/buffer: strack reduction on async read Message-ID: References: <20241218022626.3668119-1-mcgrof@kernel.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241218022626.3668119-1-mcgrof@kernel.org> On Tue, Dec 17, 2024 at 06:26:21PM -0800, Luis Chamberlain wrote: > This splits up a minor enhancement from the bs > ps device support > series into its own series for better review / focus / testing. > This series just addresses the reducing the array size used and cleaning > up the async read to be easier to read and maintain. How about this approach instead -- get rid of the batch entirely? diff --git a/fs/buffer.c b/fs/buffer.c index cc8452f60251..f50ebbc1f518 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -2361,9 +2361,9 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block) { struct inode *inode = folio->mapping->host; sector_t iblock, lblock; - struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; + struct buffer_head *bh, *head; size_t blocksize; - int nr, i; + int i, submitted = 0; int fully_mapped = 1; bool page_error = false; loff_t limit = i_size_read(inode); @@ -2380,7 +2380,6 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block) iblock = div_u64(folio_pos(folio), blocksize); lblock = div_u64(limit + blocksize - 1, blocksize); bh = head; - nr = 0; i = 0; do { @@ -2411,40 +2410,30 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block) if (buffer_uptodate(bh)) continue; } - arr[nr++] = bh; + + lock_buffer(bh); + if (buffer_uptodate(bh)) { + unlock_buffer(bh); + continue; + } + + mark_buffer_async_read(bh); + submit_bh(REQ_OP_READ, bh); + submitted++; } while (i++, iblock++, (bh = bh->b_this_page) != head); if (fully_mapped) folio_set_mappedtodisk(folio); - if (!nr) { - /* - * All buffers are uptodate or get_block() returned an - * error when trying to map them - we can finish the read. - */ - folio_end_read(folio, !page_error); - return 0; - } - - /* Stage two: lock the buffers */ - for (i = 0; i < nr; i++) { - bh = arr[i]; - lock_buffer(bh); - mark_buffer_async_read(bh); - } - /* - * Stage 3: start the IO. Check for uptodateness - * inside the buffer lock in case another process reading - * the underlying blockdev brought it uptodate (the sct fix). + * All buffers are uptodate or get_block() returned an error + * when trying to map them - we must finish the read because + * end_buffer_async_read() will never be called on any buffer + * in this folio. */ - for (i = 0; i < nr; i++) { - bh = arr[i]; - if (buffer_uptodate(bh)) - end_buffer_async_read(bh, 1); - else - submit_bh(REQ_OP_READ, bh); - } + if (!submitted) + folio_end_read(folio, !page_error); + return 0; } EXPORT_SYMBOL(block_read_full_folio);