From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-188.mta0.migadu.com (out-188.mta0.migadu.com [91.218.175.188]) (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 501ED48A2C3 for ; Wed, 1 Jul 2026 15:22:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782919368; cv=none; b=F62owmBhRIcEq4RdM7JpLErT3SOJvDlzg5whM11PU2+VJwO3e8F1HUH0lHCXyyAWjdrAbY7IRa2tA80j0E8Glz1YkHPAXcHu0MmIeja5IJSyC/pDNSKb7DngaboypbdF1sJDcF9GTPKb8K+93bshFqX2AloJwHyOMH5432DR/gY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782919368; c=relaxed/simple; bh=PJeuIBVyHEUB9iEtpBqd5iUDfkHhsFzodLbTo0Uzfv0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=F1araScHuL+wsNCRJxQChSsKIBQ9PVzCoK/UJFLRr9/tBEELGdNawG1hOi6+3yc7Bj06nby8p5i76jHTqDU4VGYUBO/I0L12Gg9xGaZ3S5imsoehUUv7/jX5nCTa2TubJYLlZruTygEyT+ovEG69WbqdkhmTXyeFG6ZyB/+egVs= 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=gNBIOwXe; arc=none smtp.client-ip=91.218.175.188 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="gNBIOwXe" 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=1782919365; 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=DdrPFOM9ZnxBG1aKBzq415lF8gBqBb64jDm9SlnGFHU=; b=gNBIOwXeR7N7+a/MwvwQnj6CA5Vddtx7Y8qITcpvuEjlYgaV+Hp8FG80cVPxKOKkvv6WNl O/1RgZ/MEJD1BoJQVgMYGMUmNXXA4PPAVZMJqFd4fHORi0hzPccZOfoUSDOLw4bIZB6f98 +lRFUqM5+a2uwtLKrp6+D/faCLJJEVI= 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 v6 2/5] smb/client: reduce fallocate zero buffer allocation Date: Wed, 1 Jul 2026 23:21:54 +0800 Message-ID: <20260701152157.822207-3-huiwen.he@linux.dev> In-Reply-To: <20260701152157.822207-1-huiwen.he@linux.dev> References: <20260701152157.822207-1-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 cc8e0595e504..23505ae9bd81 100644 --- a/fs/smb/client/smb2ops.c +++ b/fs/smb/client/smb2ops.c @@ -3559,7 +3559,7 @@ 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]; @@ -3580,9 +3580,10 @@ 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; } @@ -3611,7 +3612,7 @@ 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