From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.fusionio.com ([66.114.96.31]:44923 "EHLO mx2.fusionio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756143Ab2FVRQT (ORCPT ); Fri, 22 Jun 2012 13:16:19 -0400 Message-ID: <4FE4A860.1040606@fusionio.com> Date: Fri, 22 Jun 2012 13:16:16 -0400 From: Josef Bacik MIME-Version: 1.0 To: Stefan Behrens CC: David Sterba , "Chris L. Mason" , "linux-btrfs@vger.kernel.org" Subject: Re: [PATCH] btrfs: join DEV_STATS ioctls to one References: <1340368239-8152-1-git-send-email-dsterba@suse.cz> <4FE49CC4.6030606@giantdisaster.de> In-Reply-To: <4FE49CC4.6030606@giantdisaster.de> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 06/22/2012 12:26 PM, Stefan Behrens wrote: > On Fri, 22 Jun 2012 14:30:39 +0200, David Sterba wrote: >> Hi Chris, >> >> please consider this patch for 3.5-rc before it goes final. Thanks. >> >> From: David Sterba >> >> Commit c11d2c236cc260b36 (Btrfs: add ioctl to get and reset the device >> stats) introduced two ioctls doing almost the same thing distinguished >> by just the ioctl number which encodes "do reset after read". I have >> suggested >> >> http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg16604.html >> >> to implement it via the ioctl args. This hasn't happen, and I think we >> should use a more clean way to pass flags and should not waste ioctl >> numbers. >> >> CC: Stefan Behrens >> Signed-off-by: David Sterba >> --- >> fs/btrfs/ioctl.c | 16 ++++++++-------- >> fs/btrfs/ioctl.h | 6 ++++-- >> fs/btrfs/volumes.c | 5 ++--- >> fs/btrfs/volumes.h | 3 +-- >> 4 files changed, 15 insertions(+), 15 deletions(-) >> >> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c >> index 0e92e57..670c5d2 100644 >> --- a/fs/btrfs/ioctl.c >> +++ b/fs/btrfs/ioctl.c >> @@ -3063,19 +3063,21 @@ static long btrfs_ioctl_scrub_progress(struct btrfs_root *root, >> } >> >> static long btrfs_ioctl_get_dev_stats(struct btrfs_root *root, >> - void __user *arg, int reset_after_read) >> + void __user *arg) >> { >> struct btrfs_ioctl_get_dev_stats *sa; >> int ret; >> >> - if (reset_after_read && !capable(CAP_SYS_ADMIN)) >> - return -EPERM; >> - >> sa = memdup_user(arg, sizeof(*sa)); >> if (IS_ERR(sa)) >> return PTR_ERR(sa); >> >> - ret = btrfs_get_dev_stats(root, sa, reset_after_read); >> + if ((sa->flags & BTRFS_DEV_STATS_RESET) && !capable(CAP_SYS_ADMIN)) { >> + kfree(sa); >> + return -EPERM; >> + } >> + >> + ret = btrfs_get_dev_stats(root, sa); >> >> if (copy_to_user(arg, sa, sizeof(*sa))) >> ret = -EFAULT; >> @@ -3473,9 +3475,7 @@ long btrfs_ioctl(struct file *file, unsigned int >> case BTRFS_IOC_BALANCE_PROGRESS: >> return btrfs_ioctl_balance_progress(root, argp); >> case BTRFS_IOC_GET_DEV_STATS: >> - return btrfs_ioctl_get_dev_stats(root, argp, 0); >> - case BTRFS_IOC_GET_AND_RESET_DEV_STATS: >> - return btrfs_ioctl_get_dev_stats(root, argp, 1); >> + return btrfs_ioctl_get_dev_stats(root, argp); >> } >> >> return -ENOTTY; >> diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h >> index 497c530..c4089c5 100644 >> --- a/fs/btrfs/ioctl.h >> +++ b/fs/btrfs/ioctl.h >> @@ -285,9 +285,13 @@ enum btrfs_dev_stat_values { >> BTRFS_DEV_STAT_VALUES_MAX >> }; >> >> +/* Reset statistics after reading; needs SYS_ADMIN capability */ >> +#define BTRFS_DEV_STATS_RESET (1ULL << 0) >> + >> struct btrfs_ioctl_get_dev_stats { >> __u64 devid; /* in */ >> __u64 nr_items; /* in/out */ >> + __u64 flags; /* in/out */ >> >> /* out values: */ >> __u64 values[BTRFS_DEV_STAT_VALUES_MAX]; >> @@ -361,7 +365,5 @@ struct btrfs_ioctl_get_dev_stats { >> struct btrfs_ioctl_ino_path_args) >> #define BTRFS_IOC_GET_DEV_STATS _IOWR(BTRFS_IOCTL_MAGIC, 52, \ >> struct btrfs_ioctl_get_dev_stats) >> -#define BTRFS_IOC_GET_AND_RESET_DEV_STATS _IOWR(BTRFS_IOCTL_MAGIC, 53, \ >> - struct btrfs_ioctl_get_dev_stats) >> >> #endif >> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c >> index 8a3d259..661e6ca 100644 >> --- a/fs/btrfs/volumes.c >> +++ b/fs/btrfs/volumes.c >> @@ -4871,8 +4871,7 @@ static void btrfs_dev_stat_print_on_load(struct btrfs_device *dev) >> } >> >> int btrfs_get_dev_stats(struct btrfs_root *root, >> - struct btrfs_ioctl_get_dev_stats *stats, >> - int reset_after_read) >> + struct btrfs_ioctl_get_dev_stats *stats) >> { >> struct btrfs_device *dev; >> struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices; >> @@ -4890,7 +4889,7 @@ int btrfs_get_dev_stats(struct btrfs_root *root, >> printk(KERN_WARNING >> "btrfs: get dev_stats failed, not yet valid\n"); >> return -ENODEV; >> - } else if (reset_after_read) { >> + } else if (stats->flags & BTRFS_DEV_STATS_RESET) { >> for (i = 0; i < BTRFS_DEV_STAT_VALUES_MAX; i++) { >> if (stats->nr_items > i) >> stats->values[i] = >> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h >> index 74366f2..e673589 100644 >> --- a/fs/btrfs/volumes.h >> +++ b/fs/btrfs/volumes.h >> @@ -292,8 +292,7 @@ struct btrfs_device *btrfs_find_device_for_logical(struct btrfs_root *root, >> void btrfs_dev_stat_print_on_error(struct btrfs_device *device); >> void btrfs_dev_stat_inc_and_print(struct btrfs_device *dev, int index); >> int btrfs_get_dev_stats(struct btrfs_root *root, >> - struct btrfs_ioctl_get_dev_stats *stats, >> - int reset_after_read); >> + struct btrfs_ioctl_get_dev_stats *stats); >> int btrfs_init_dev_stats(struct btrfs_fs_info *fs_info); >> int btrfs_run_dev_stats(struct btrfs_trans_handle *trans, >> struct btrfs_fs_info *fs_info); >> > > I still do not understand your reason and the benefit of your change. > The reset command and the read command are two completely different > operations. Therefore I assigned two different ioctl commands. Then you > can use strace to see which command is sent, and you can also grep the > sources without additional effort. If the difference in behaviour between two different ioctls is indicated by a single flag to the same function then there is no reason it cannot be implemented in one ioctl with a flag in the ioctl arguments. I'd rather not waste ioctl numbers. Thanks, Josef