From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753276Ab0IVL0W (ORCPT ); Wed, 22 Sep 2010 07:26:22 -0400 Received: from mail-fx0-f46.google.com ([209.85.161.46]:56023 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751401Ab0IVL0U (ORCPT ); Wed, 22 Sep 2010 07:26:20 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=g7y1FRvf4Tk1b4kzo2aM4DjiSRDp1fOMl2Ffx69IvsKgS5a1JgvYJWDalArPH8rT0I 1IrPLOBhRIYsd+rmZ7WZTm1majOlp331KmcaYhwrmJO1faXZy1WulHrOGPL2D+isVSZg oPgAOQtFZMz+4bnqiaoT5xsLMAeRS99RWnxzQ= Message-ID: <4C99E7D6.1040004@gmail.com> Date: Wed, 22 Sep 2010 13:26:14 +0200 From: Boaz Harrosh User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.11) Gecko/20100720 Fedora/3.0.6-1.fc12 Thunderbird/3.0.6 MIME-Version: 1.0 To: "Nicholas A. Bellinger" CC: linux-kernel , linux-scsi , Christoph Hellwig , FUJITA Tomonori , Mike Christie , Fubo Chen Subject: Re: [PATCH] tcm/fileio: Convert to iov allocations for fd_do_readv() and fd_do_writev() References: <1285142558-13219-1-git-send-email-nab@linux-iscsi.org> In-Reply-To: <1285142558-13219-1-git-send-email-nab@linux-iscsi.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/22/2010 10:02 AM, Nicholas A. Bellinger wrote: > From: Nicholas Bellinger > > Greetings all, > > This patch converts target_core_file.c fd_do_readv() and fd_do_writev() code to > use dynamic allocation for *iov[] instead of local scope static memory to > properly handle cases with TCM_Loop that can potentially exceed the 8K stack > on 64-bit kernels with per 1:1 struct scatterlist <-> 512-byte block_size SGL length > mapping up to the current FD_MAX_SECTORS=1024. For more information please see: > > http://lkml.org/lkml/2010/9/22/42 > > Many thanks to Fubo Chen for spotting this one! > > Signed-off-by: Nicholas A. Bellinger > --- > drivers/target/target_core_file.c | 20 ++++++++++++++++---- > 1 files changed, 16 insertions(+), 4 deletions(-) > > diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c > index 221b41e..93d3f63 100644 > --- a/drivers/target/target_core_file.c > +++ b/drivers/target/target_core_file.c > @@ -476,12 +476,16 @@ static int fd_do_readv(struct fd_request *req, struct se_task *task) > { > struct file *fd = req->fd_dev->fd_file; > struct scatterlist *sg = task->task_sg; > - struct iovec iov[req->fd_sg_count]; > + struct iovec *iov; > mm_segment_t old_fs; > loff_t pos = (req->fd_lba * DEV_ATTRIB(task->se_dev)->block_size); > int ret = 0, i; > > - memset(iov, 0, sizeof(struct iovec) * req->fd_sg_count); > + iov = kzalloc(sizeof(struct iovec) * req->fd_sg_count, GFP_KERNEL); A kzalloc allocation bigger then PAG_SIZE is very unstable, more so when the system is up for a long time. Better prepare to loop here, up to PAG_SIZE iov at a time. Boaz > + if (!(iov)) { > + printk(KERN_ERR "Unable to allocate fd_do_readv iov[]\n"); > + return -1; > + } > > for (i = 0; i < req->fd_sg_count; i++) { > iov[i].iov_len = sg[i].length; > @@ -492,6 +496,8 @@ static int fd_do_readv(struct fd_request *req, struct se_task *task) > set_fs(get_ds()); > ret = vfs_readv(fd, &iov[0], req->fd_sg_count, &pos); > set_fs(old_fs); > + > + kfree(iov); > /* > * Return zeros and GOOD status even if the READ did not return > * the expected virt_size for struct file w/o a backing struct > @@ -583,12 +589,16 @@ static int fd_do_writev(struct fd_request *req, struct se_task *task) > { > struct file *fd = req->fd_dev->fd_file; > struct scatterlist *sg = task->task_sg; > - struct iovec iov[req->fd_sg_count]; > + struct iovec *iov; > mm_segment_t old_fs; > loff_t pos = (req->fd_lba * DEV_ATTRIB(task->se_dev)->block_size); > int ret, i = 0; > > - memset(iov, 0, sizeof(struct iovec) * req->fd_sg_count); > + iov = kzalloc(sizeof(struct iovec) * req->fd_sg_count, GFP_KERNEL); > + if (!(iov)) { > + printk(KERN_ERR "Unable to allocate fd_do_writev iov[]\n"); > + return -1; > + } > > for (i = 0; i < req->fd_sg_count; i++) { > iov[i].iov_len = sg[i].length; > @@ -600,6 +610,8 @@ static int fd_do_writev(struct fd_request *req, struct se_task *task) > ret = vfs_writev(fd, &iov[0], req->fd_sg_count, &pos); > set_fs(old_fs); > > + kfree(iov); > + > if (ret < 0 || ret != req->fd_size) { > printk(KERN_ERR "vfs_writev() returned %d\n", ret); > return -1;