From: Zhi Yong Wu Subject: Re: [RFC v4+ hot_track 12/19] vfs: add one ioctl interface Date: Wed, 7 Nov 2012 15:36:56 +0800 Message-ID: References: <1351485061-12297-1-git-send-email-zwu.kernel@gmail.com> <1351485061-12297-13-git-send-email-zwu.kernel@gmail.com> <20121106233058.GW3102@twin.jikos.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 To: dave@jikos.cz, zwu.kernel@gmail.com, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linuxram@linux.vnet.ibm.com, viro@zeniv.linux.org.uk, david@fromorbit.com, tytso@mit.edu, cmm@us.ibm.com, wuzhy@linux.vnet.ibm.com, wenqing.lz@taobao.com Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:43594 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751053Ab2KGHg6 (ORCPT ); Wed, 7 Nov 2012 02:36:58 -0500 In-Reply-To: <20121106233058.GW3102@twin.jikos.cz> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Nov 7, 2012 at 7:30 AM, David Sterba wrote: > On Mon, Oct 29, 2012 at 12:30:54PM +0800, zwu.kernel@gmail.com wrote: >> +static int ioctl_heat_info(struct file *file, void __user *argp) >> +{ >> + struct inode *inode = file->f_dentry->d_inode; >> + struct hot_heat_info *heat_info; >> + struct hot_inode_item *he; >> + int ret = 0; >> + >> + heat_info = kmalloc(sizeof(struct hot_heat_info), >> + GFP_KERNEL | GFP_NOFS); > > heat_info is small enough to fit onto the stack, so you can avoid the > kmalloc, I don't think there are deep callstacks to be expected. ok, done. > Nevertheless, if you want to use kmalloc here, then please check the > return value and use GFP_KERNEL. thanks for your pointing out. > >> + >> + if (copy_from_user((void *) heat_info, >> + argp, >> + sizeof(struct hot_heat_info)) != 0) { >> + ret = -EFAULT; >> + goto err; >> + } >> + >> + he = hot_inode_item_find(inode->i_sb->s_hot_root, inode->i_ino); >> + if (!he) { >> + /* we don't have any info on this file yet */ >> + ret = -ENODATA; >> + goto err; >> + } >> + >> + spin_lock(&he->hot_inode.lock); >> + heat_info->avg_delta_reads = >> + (__u64) he->hot_inode.hot_freq_data.avg_delta_reads; >> + heat_info->avg_delta_writes = >> + (__u64) he->hot_inode.hot_freq_data.avg_delta_writes; >> + heat_info->last_read_time = >> + (__u64) timespec_to_ns(&he->hot_inode.hot_freq_data.last_read_time); >> + heat_info->last_write_time = >> + (__u64) timespec_to_ns(&he->hot_inode.hot_freq_data.last_write_time); >> + heat_info->num_reads = >> + (__u32) he->hot_inode.hot_freq_data.nr_reads; >> + heat_info->num_writes = >> + (__u32) he->hot_inode.hot_freq_data.nr_writes; >> + >> + if (heat_info->live > 0) { >> + /* >> + * got a request for live temperature, >> + * call hot_hash_calc_temperature to recalculate >> + */ >> + heat_info->temp = >> + inode->i_sb->s_hot_root->hot_func_type->ops.hot_temp_calc_fn( >> + &he->hot_inode.hot_freq_data); >> + } else { >> + /* not live temperature, get it from the hashlist */ >> + heat_info->temp = he->hot_inode.hot_freq_data.last_temp; >> + } >> + spin_unlock(&he->hot_inode.lock); >> + >> + hot_inode_item_put(he); >> + >> + if (copy_to_user(argp, (void *) heat_info, >> + sizeof(struct hot_heat_info))) { >> + ret = -EFAULT; >> + goto err; >> + } >> + >> +err: >> + kfree(heat_info); >> + return ret; >> +} > > david -- Regards, Zhi Yong Wu