From patchwork Sat Feb 3 07:11:42 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 13543894 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 E836252F7A; Sat, 3 Feb 2024 07:12:38 +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=1706944360; cv=none; b=u2bVxp5Pk9OW/pScTl5/LFSmFvfQ7TWn2MpJPQxFqDupUuZ9qyrKStiz80alvHmGGfmu8sXGnJdt0s6fMj2faeT30pgWNLC7lL7FmoD5jwjyhbauhGJ2rzns6Plx1g1wyMGmEBEtXV9T/7bdHTkk8RQZRnCWcyAa1h+LVyg0U9Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706944360; c=relaxed/simple; bh=wQIP+N3XvRn+eYb7iTMjcVZ9jDHU0guNE2DI5QJg/zQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Fl7ABjXMutSr9Wuq8e7t6uDTIT2BK46P672SdZlGXuhI2le0mptmu6Veax7GtPk/k7EdiWWTgsvs+5tpGp0VgRk16kS+koDVjfhUpMONgRbPELM37mC2XElNnbWgAFctHbbKREcHQ6lO/arMQT28gxzsaxQXJD7ML1rR16aXqgY= 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=BZP6RRlB; 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="BZP6RRlB" 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=YJszH51EwdW2rUwhJ/fmC9DInqYvSSbYnjASxDZKqZ0=; b=BZP6RRlBDDpDvPXciqWZlZGJn5 oC+v7sIzJvcs21tF8kJfjVZUxi+rlyNMkbXo9XyOmN+I4iFNmzmF8RE4x6Adbipm2iFwKH0YFjQdA 9/nlcT5ORYA4i24NEohIRXfYMQHGG+tKQIlh8qPq1VUBvrwNdgJLkGI3T+hb+i9GBglSUhcAxX9Xq 01aj7FFKMTuwF5eQBQl5BVoEFAIoOLYL7DjnFNlp/5NFpxywbU++nEGUH4m1TKZzgN5N+mKnfs/jO LXaUZ4bnnWLEsSjwcWKrbME/Fb2QcL2hF3E4KWQ0BaYNZfCcRv1Ee/5ZlvfFK9xbwIOfldgQwV1Gx JYbz3wYA==; Received: from [89.144.222.32] (helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.97.1 #2 (Red Hat Linux)) id 1rWACZ-0000000FkAd-0VnK; Sat, 03 Feb 2024 07:12:35 +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 08/13] writeback: Simplify the loops in write_cache_pages() Date: Sat, 3 Feb 2024 08:11:42 +0100 Message-Id: <20240203071147.862076-9-hch@lst.de> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240203071147.862076-1-hch@lst.de> References: <20240203071147.862076-1-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: Brian Foster Reviewed-by: Jan Kara Acked-by: Dave Chinner --- mm/page-writeback.c | 75 ++++++++++++++++++++++----------------------- 1 file changed, 36 insertions(+), 39 deletions(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 23363ed712f646..d7ab42def43035 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2454,6 +2454,7 @@ int write_cache_pages(struct address_space *mapping, int error; struct folio *folio; pgoff_t end; /* Inclusive */ + int i = 0; if (wbc->range_cyclic) { wbc->index = mapping->writeback_index; /* prev offset */ @@ -2467,53 +2468,49 @@ int write_cache_pages(struct address_space *mapping, folio_batch_init(&wbc->fbatch); - while (wbc->index <= end) { - int i; - - writeback_get_batch(mapping, wbc); - + for (;;) { + 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++) { - folio = wbc->fbatch.folios[i]; + 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); - wbc->nr_to_write -= folio_nr_pages(folio); + error = writepage(folio, wbc, data); + wbc->nr_to_write -= folio_nr_pages(folio); - if (error == AOP_WRITEPAGE_ACTIVATE) { - folio_unlock(folio); - error = 0; - } + if (error == AOP_WRITEPAGE_ACTIVATE) { + folio_unlock(folio); + error = 0; + } - /* - * For integrity writeback we have to keep going until - * we have written all the folios we tagged for - * writeback above, even if we run past wbc->nr_to_write - * or encounter errors. - * We stash away the first error we encounter in - * wbc->saved_err so that it can be retrieved when we're - * done. This is because the file system may still have - * state to clear for each folio. - * - * For background writeback we exit as soon as we run - * past wbc->nr_to_write or encounter the first error. - */ - if (wbc->sync_mode == WB_SYNC_ALL) { - if (error && !ret) - ret = error; - } else { - if (error || wbc->nr_to_write <= 0) - goto done; - } + /* + * For integrity writeback we have to keep going until we have + * written all the folios we tagged for writeback above, even if + * we run past wbc->nr_to_write or encounter errors. + * We stash away the first error we encounter in wbc->saved_err + * so that it can be retrieved when we're done. This is because + * the file system may still have state to clear for each folio. + * + * For background writeback we exit as soon as we run past + * wbc->nr_to_write or encounter the first error. + */ + if (wbc->sync_mode == WB_SYNC_ALL) { + if (error && !ret) + ret = error; + } else { + if (error || wbc->nr_to_write <= 0) + goto done; } }