From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 800FD81AC7 for ; Wed, 21 Feb 2024 20:51:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708548691; cv=none; b=m1LzVaM1YDtMCz5QWrpjxZwkRfhaIgJclSYCz5hXROJ7T9IISHVjsBxK+oovIhHiFezsox4jiqlVR+7cE82gDKblOKvZ/ykFWLGL7RCL+dODACXwmr5E96c6ZhfJ3VUPupT+8URluLso8bHVT8vnMSGQK/ygDxqe1JffTcBuA0Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708548691; c=relaxed/simple; bh=H4aYJ0xBPmrhHURyLchyuM2X1cxBWf9NZciovjM1yF0=; h=Date:To:From:Subject:Message-Id; b=etKs/EIae2bcAPueLOhMVYz4TiDn1iJMvd/97Tvp4bjOY9lwrkkc9i8ONPBOwOKDRTT7cNjoUT8UJu7cQR+cAH+0OzrGspEcHS5wi3gIHZBL6WITTOHaYDzc4cwfcsESW+76wegWdNfBJHPMT1MF2LZ5lW9CTdEYCjagtKpVBeM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=G3JHviX9; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="G3JHviX9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A6B8AC433F1; Wed, 21 Feb 2024 20:51:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1708548690; bh=H4aYJ0xBPmrhHURyLchyuM2X1cxBWf9NZciovjM1yF0=; h=Date:To:From:Subject:From; b=G3JHviX9+ozZhflc/D+H9+5yrtN0kafOxgABhVRgjXEACZG0DpoBYPJEstJMc4FSS 46ltwuL3ZuXT5UV2oAkZdtK8iA7qGzJl6FKrnCOSdjkg3Z8+2JHZWgGmNjvNhWGXE4 ppJGX0gXn4OChh1+/Kj48/GEs80lDc/DxREpjuyk= Date: Wed, 21 Feb 2024 12:51:30 -0800 To: mm-commits@vger.kernel.org,jack@suse.cz,hch@lst.de,dhowells@redhat.com,dchinner@redhat.com,brauner@kernel.org,bfoster@redhat.com,willy@infradead.org,akpm@linux-foundation.org From: Andrew Morton Subject: + writeback-simplify-the-loops-in-write_cache_pages.patch added to mm-unstable branch Message-Id: <20240221205130.A6B8AC433F1@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: writeback: simplify the loops in write_cache_pages() has been added to the -mm mm-unstable branch. Its filename is writeback-simplify-the-loops-in-write_cache_pages.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/writeback-simplify-the-loops-in-write_cache_pages.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: "Matthew Wilcox (Oracle)" Subject: writeback: simplify the loops in write_cache_pages() Date: Thu, 15 Feb 2024 07:36:44 +0100 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. [hch@lst.de: update the commit log per Jan] Link: https://lkml.kernel.org/r/20240215063649.2164017-10-hch@lst.de Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Christoph Hellwig Reviewed-by: Brian Foster Reviewed-by: Jan Kara Acked-by: Dave Chinner Cc: Christian Brauner Cc: David Howells Signed-off-by: Andrew Morton --- mm/page-writeback.c | 83 ++++++++++++++++++++---------------------- 1 file changed, 40 insertions(+), 43 deletions(-) --- a/mm/page-writeback.c~writeback-simplify-the-loops-in-write_cache_pages +++ a/mm/page-writeback.c @@ -2454,6 +2454,7 @@ int write_cache_pages(struct address_spa 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_spa 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; + } + + trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); + + error = writepage(folio, wbc, data); + wbc->nr_to_write -= folio_nr_pages(folio); + + if (error == AOP_WRITEPAGE_ACTIVATE) { + folio_unlock(folio); + error = 0; + } - folio_lock(folio); - if (!folio_prepare_writeback(mapping, wbc, folio)) { - folio_unlock(folio); - continue; - } - - trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); - - error = writepage(folio, wbc, data); - wbc->nr_to_write -= folio_nr_pages(folio); - - 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; } } _ Patches currently in -mm which might be from willy@infradead.org are memcg-convert-mem_cgroup_move_charge_pte_range-to-use-a-folio.patch memcg-return-the-folio-in-union-mc_target.patch memcg-use-a-folio-in-get_mctgt_type.patch memcg-use-a-folio-in-get_mctgt_type_thp.patch mm-add-pfn_swap_entry_folio.patch proc-use-pfn_swap_entry_folio-where-obvious.patch mprotect-use-pfn_swap_entry_folio.patch highmem-add-kernel-doc-for-memcpy__folio.patch rmap-replace-two-calls-to-compound_order-with-folio_order.patch writeback-remove-a-duplicate-prototype-for-tag_pages_for_writeback.patch writeback-factor-folio_prepare_writeback-out-of-write_cache_pages.patch writeback-factor-writeback_get_batch-out-of-write_cache_pages.patch writeback-simplify-the-loops-in-write_cache_pages.patch pagevec-add-ability-to-iterate-a-queue.patch writeback-use-the-folio_batch-queue-iterator.patch writeback-move-the-folio_prepare_writeback-loop-out-of-write_cache_pages.patch writeback-remove-a-use-of-write_cache_pages-from-do_writepages.patch bounds-support-non-power-of-two-config_nr_cpus.patch