From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-177.mta0.migadu.com (out-177.mta0.migadu.com [91.218.175.177]) (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 096023AEF47 for ; Thu, 25 Jun 2026 16:03:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782403442; cv=none; b=Ye8ceefbYT/McaCg9oSQ9ABqEx1SIi1r6E7h8a5xBrHN2mGppSLJXCMbAQA/0UUSPJf881emuKyeeYdDUYU4YsVbg6P/8tdG+e282jU+0Eq8DMWilPXZWB4WgyI/d3M7R194zG5ZI+CUzRjqvHQQ/RWQL/KWLrV6jOiQSIMS8Dk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782403442; c=relaxed/simple; bh=dkaFwtpfgso/SCGPqZMg16AuwE+RKpcfHl4peWjNbfI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LT4g5ywV1PGVLvZSj2qGoUaOC1jWBmUY/vgsCwyugVuo9me9+4yL2ckD/raTg1nvUWq9u+ylgvKV3rpOMTZTTihMXtUMxpunpjAJUk48RRAihDhGmX2x60RTVnIh/a7zQKSMBosN/9ZLEcxyOTlLBeks92amewqTJaOdnKBaPtk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=pO1Q77zn; arc=none smtp.client-ip=91.218.175.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="pO1Q77zn" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1782403435; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=iv8yTdHfG4Kdkj3HOItwRLcEUjghrTsNd56hf6kZ590=; b=pO1Q77znyDJ43tlZogSPkSDhGRBEZaGJpPIBWFbc/l5k7s9Y8QNN8a88Dt368na1AXakxk xSar+Ed6782imO3UTENWiePnhDf8St1OAq+lFWuHr2S91POqEtWe93OLt7bMYpIpwAcRFA sBTYrI8xYgiqKixJe8CZn2Gu537o4KU= From: Huiwen He To: smfrench@gmail.com, linkinjeon@kernel.org, pc@manguebit.org, ronniesahlberg@gmail.com, sprasad@microsoft.com, tom@talpey.com, bharathsm@microsoft.com, senozhatsky@chromium.org, dhowells@redhat.com, metze@samba.org, chenxiaosong@kylinos.cn Cc: linux-cifs@vger.kernel.org Subject: [PATCH v3 7/9] smb/client: reduce fallocate zero buffer allocation Date: Fri, 26 Jun 2026 00:01:52 +0800 Message-ID: <20260625160154.104450-8-huiwen.he@linux.dev> In-Reply-To: <20260625160154.104450-1-huiwen.he@linux.dev> References: <20260625160154.104450-1-huiwen.he@linux.dev> Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT From: Huiwen He The fallocate emulation allocates a 1 MiB zero-filled buffer even though each SMB2_write request is limited to SMB2_MAX_BUFFER_SIZE, which is 64 KiB. A high-order 1 MiB allocation is more likely to fail on a fragmented system. Allocate only the smaller of the requested range and SMB2_MAX_BUFFER_SIZE, and reuse that zero-filled buffer for every write request. Also reject a successful write that makes no progress to avoid looping indefinitely. This reduces the contiguous allocation required by fallocate emulation without changing the written data or range semantics. Signed-off-by: Huiwen He Reviewed-by: ChenXiaoSong --- fs/smb/client/smb2ops.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c index a260e85ad1c8..5f2e4a0722a6 100644 --- a/fs/smb/client/smb2ops.c +++ b/fs/smb/client/smb2ops.c @@ -3543,7 +3543,7 @@ static int smb3_simple_fallocate_write_range(unsigned int xid, char *buf) { struct cifs_io_parms io_parms = {0}; - int nbytes; + unsigned int nbytes; int rc = 0; struct kvec iov[2]; @@ -3564,9 +3564,10 @@ static int smb3_simple_fallocate_write_range(unsigned int xid, rc = SMB2_write(xid, &io_parms, &nbytes, iov, 1); if (rc) break; + if (!nbytes) + return -EIO; if (nbytes > len) return -EINVAL; - buf += nbytes; off += nbytes; len -= nbytes; } @@ -3596,7 +3597,7 @@ static int smb3_simple_fallocate_range(unsigned int xid, if (rc) goto out; - buf = kzalloc(1024 * 1024, GFP_KERNEL); + buf = kzalloc(min_t(loff_t, len, SMB2_MAX_BUFFER_SIZE), GFP_KERNEL); if (buf == NULL) { rc = -ENOMEM; goto out; -- 2.43.0