From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 6569152F27F for ; Tue, 13 Oct 2026 18:23:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791915790; cv=none; b=GmtUO0arYHKHHiEoX5AWXgMWhSEIbhqLz6D/N1Aj9VumZAqwoR71ojeTgptP7OD2fawxCz1/bP8Rr+yaKG+bvoCVRgzeYwRd1PNznf03g4xBkhLzkvxUY4KjQ6hOk2zGq2Ur+N9Km+dSXe2kwmm7tr1Vs4bW2wOa70nJPomf37U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791915790; c=relaxed/simple; bh=j82rZcOehlmmwffgpfYLs6NCdm3rsPnM3KEHIVIQZKk=; h=Date:To:From:Subject:Message-Id; b=E9nkyIiXX4baIvwhS6nQOuzjmJxdXFHF05bhoB8bT/u/tDI1yidapqXI+ECMToY5VmMxtqsIsMYjRG2KbcQWLEHMUTqLS2Lh4txmCDko/qmfqC30amvNRgFOonnlEiMpgiN9kUWbzQeqkdnTJm+pctLYU5+CS0ir29fFnsAqy4A= 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=wiO642fM; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="wiO642fM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D07C01F000FF; Tue, 13 Oct 2026 18:23:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1791915788; bh=IpHNyvUBVW6mLZhEebxbSzb4N0hNlC+n7KuXu7mLMFs=; h=Date:To:From:Subject; b=wiO642fMqgyXxk2mqIlJGMtOuZrsOb78gnFFN42GsOyPiO/vPOcfLCzWwPK9t7x/Y 9PES/QB3Vo2U07P7215keHGQCuamHYjtz70UZpsEo5KUq/I7oroGpGK0zPdd91AjGh ADxp0zb3Lf2UYgIfm6eXm6d3tIs+gsND4c1EYAao= Date: Tue, 13 Oct 2026 11:23:08 -0700 To: mm-commits@vger.kernel.org,hirofumi@mail.parknet.co.jp,matheus.aalmeida@inf.ufrgs.br,akpm@linux-foundation.org From: Andrew Morton Subject: + fat-allocate-multiple-clusters-in-fallocate.patch added to mm-nonmm-unstable branch Message-Id: <20261013182308.D07C01F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: fat: allocate multiple clusters in fallocate has been added to the -mm mm-nonmm-unstable branch. Its filename is fat-allocate-multiple-clusters-in-fallocate.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fat-allocate-multiple-clusters-in-fallocate.patch This patch will later appear in the mm-nonmm-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 various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Matheus Alves de Almeida Subject: fat: allocate multiple clusters in fallocate Date: Mon, 12 Oct 2026 14:11:06 -0300 The fat_fallocate() code currently does many 1-cluster allocations when growing a file in the FALLOC_FL_KEEP_SIZE path. Make it allocate everything with one call instead. Benchmarking was done under QEMU/KVM with a virtio-blk device using cache=none. Each result is the arithmetic mean of the listed samples. start = now_ns(); for (unsigned int i = 0; i < count; i++) fallocate(fds[i], FALLOC_FL_KEEP_SIZE, 0, bytes); elapsed = now_ns() - start; FAT32 with 512-byte clusters using count=16 files: length mounted sync? before after improvement samples 256MiB no 2.328s 0.175s 13.2x 10 16MiB no 149.659ms 14.036ms 10.7x 10 16MiB yes 747.993s 3.445s 217.1x 3 1MiB yes 46.63s 0.333s 140.1x 10 FAT32 with 512-byte clusters using count=128 files: length mounted sync? before after improvement samples 1MiB no 90.873ms 4.686ms 19.4x 10 16KiB no 1.287ms 0.241ms 5.3x 10 128KiB yes 47.284s 0.350s 135x 10 4KiB yes 1.98s 0.144s 13.7x 10 FAT32 with 4096-byte clusters using count=16 files: length mounted sync? before after improvement samples 256MiB no 295.392ms 24.733ms 11.9x 10 16MiB no 20.509ms 1.404ms 14.6x 10 16MiB yes 92.489s 0.348s 265.4x 10 1MiB yes 5.837s 0.048s 121.3x 10 The improvement is especially large on synchronous mounts, where the new code can batch FAT updates instead of synchronously handling each cluster allocation separately. Link: https://lore.kernel.org/20261012171106.146243-4-matheus.aalmeida@inf.ufrgs.br Signed-off-by: Matheus Alves de Almeida Signed-off-by: Andrew Morton Acked-by: OGAWA Hirofumi --- fs/fat/file.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) --- a/fs/fat/file.c~fat-allocate-multiple-clusters-in-fallocate +++ a/fs/fat/file.c @@ -290,12 +290,10 @@ static long fat_fallocate(struct file *f nr_cluster = (mm_bytes + (sbi->cluster_size - 1)) >> sbi->cluster_bits; - /* Start the allocation.We are not zeroing out the clusters */ - while (nr_cluster-- > 0) { - err = fat_add_clusters(inode, 1); - if (err) - goto error; - } + /* Allocate the clusters. We are not zeroing them out */ + err = fat_add_clusters(inode, nr_cluster); + if (err) + goto error; } else { if ((offset + len) <= i_size_read(inode)) goto error; _ Patches currently in -mm which might be from matheus.aalmeida@inf.ufrgs.br are fat-remove-cluster-allocation-size-limit.patch fat-support-adding-multiple-clusters.patch fat-allocate-multiple-clusters-in-fallocate.patch