From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-170.mta0.migadu.com (out-170.mta0.migadu.com [91.218.175.170]) (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 62DDA3F7A84 for ; Fri, 26 Jun 2026 13:48:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782481684; cv=none; b=Nvs0CAGjgLV10eqB782WXTdhKbJavcKjunELD2AKFIAfBO+MkGmjY4nyCBCG5XG+C3GfFn1pGEiDJihIkJvloqZzghfG0YrmOq+LoD7JCa3vs/JqEWbpzlwZiL+HgS4N82R1wbeBUOni30m6VYvmB36ajqocwu62TXEKhX364hY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782481684; c=relaxed/simple; bh=AKxFgbdvk0wht9pcL5rPU9WWR91PRU2ihqJRXHiGw8k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=epMpdONHK26f8CJkQNiRaodR+/HvhzxVKeOQyRXs6ifa1g7svbCyqawaQ+FuAoDVdbQy6W6aOA+GrXIysDytO4pL3uTVaeA3x0j3pxYpth8Hs5TdWSHQ1kDHqfc9PXEMiQJp/Lek2Zz3qohEjI/mOoC5Bd9HET7X/Ex0pSYHWaA= 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=X98Nisl2; arc=none smtp.client-ip=91.218.175.170 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="X98Nisl2" 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=1782481681; 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=jheHAPeAhzK+e9HSmJmEbjL7BMXtv2nU1RmPS93cnio=; b=X98Nisl21QavQ0xilqjwidrG42sIuQgMbZVMg6t+sw+Ysc54IWl3uteJhy7ZCpQapkOMmQ hMUWrDDXZUwJR5u3tlyVh19W1qtoLJLp/QlGj5uhUhcdb2y5Y71yoR8CHI+eKwzljXJs0T ZM5sbAPaRM8tfJCctkaU46YCDU2qsYE= 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 v4 5/7] smb/client: reduce fallocate zero buffer allocation Date: Fri, 26 Jun 2026 21:47:17 +0800 Message-ID: <20260626134719.158270-6-huiwen.he@linux.dev> In-Reply-To: <20260626134719.158270-1-huiwen.he@linux.dev> References: <20260626134719.158270-1-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 4cd0e578e3ce..311709d73798 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; } @@ -3612,7 +3613,7 @@ 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