On Tue, May 22, 2012 at 12:53:48PM +0200, Stefan Behrens wrote:
> An ioctl interface is added to get the device statistic counters.
> A second ioctl is added to atomically get and reset these counters.
>
> Signed-off-by: Stefan Behrens <sbehr...@giantdisaster.de>
> ---
> fs/btrfs/ioctl.c | 26 ++++++++++++++++++++
> fs/btrfs/ioctl.h | 28 +++++++++++++++++++++
> fs/btrfs/volumes.c | 69
> ++++++++++++++++++++++++++++++++++++++++++++++++++++
> fs/btrfs/volumes.h | 13 ++++++++++
> 4 files changed, 136 insertions(+)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 14f8e1f..19d2244 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -3424,6 +3446,10 @@ long btrfs_ioctl(struct file *file, unsigned int
> return btrfs_ioctl_balance_ctl(root, arg);
> case BTRFS_IOC_BALANCE_PROGRESS:
> return btrfs_ioctl_balance_progress(root, argp);
> + case BTRFS_IOC_GET_DEVICE_STATS:
> + return btrfs_ioctl_get_device_stats(root, argp, 0);
> + case BTRFS_IOC_GET_AND_RESET_DEVICE_STATS:
> + return btrfs_ioctl_get_device_stats(root, argp, 1);
> }
>
> return -ENOTTY;
> diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
> index 086e6bd..f1c1196 100644
> --- a/fs/btrfs/ioctl.h
> +++ b/fs/btrfs/ioctl.h
> @@ -266,6 +266,30 @@ struct btrfs_ioctl_logical_ino_args {
> __u64 inodes;
> };
>
> +#define BTRFS_IOCTL_GET_DEVICE_STATS_MAX_NR_ITEMS 5
The check at the end of btrfs_get_device_stats() should use this number:
> + if (stats->nr_items > 5)
> + stats->nr_items = 5;
> + return 0;
> +}
> +struct btrfs_ioctl_get_device_stats {
> + __u64 devid; /* in */
> + __u64 nr_items; /* in/out */
> +
> + /* out values: */
> +
> + /* disk I/O failure stats */
> + __u64 cnt_write_io_errs; /* EIO or EREMOTEIO from lower layers */
> + __u64 cnt_read_io_errs; /* EIO or EREMOTEIO from lower layers */
> + __u64 cnt_flush_io_errs; /* EIO or EREMOTEIO from lower layers */
> +
> + /* stats for indirect indications for I/O failures */
> + __u64 cnt_corruption_errs; /* checksum error, bytenr error or
> + * contents is illegal: this is an
> + * indication that the block was damaged
> + * during read or write, or written to
> + * wrong location or read from wrong
> + * location */
> + __u64 cnt_generation_errs; /* an indication that blocks have not
> + * been written */
> + __u64 unused[121]; /* pad to 1k */
> +};
Padding has landed, and thanks for the explanation in the V3, I see how
the compatibility works.
> +
> #define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \
> struct btrfs_ioctl_vol_args)
> #define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, \
> @@ -330,5 +354,9 @@ struct btrfs_ioctl_logical_ino_args {
> struct btrfs_ioctl_ino_path_args)
> #define BTRFS_IOC_LOGICAL_INO _IOWR(BTRFS_IOCTL_MAGIC, 36, \
> struct btrfs_ioctl_ino_path_args)
> +#define BTRFS_IOC_GET_DEVICE_STATS _IOWR(BTRFS_IOCTL_MAGIC, 52, \
> + struct btrfs_ioctl_get_device_stats)
> +#define BTRFS_IOC_GET_AND_RESET_DEVICE_STATS _IOWR(BTRFS_IOCTL_MAGIC, 53, \
> + struct btrfs_ioctl_get_device_stats)
I think that 'reset device' should go into the structure, besides the
ioctl number there is no difference.
Then the permission check will look like:
> @@ -3042,6 +3042,28 @@ static long btrfs_ioctl_scrub_progress(struct
> btrfs_root *root,
> return ret;
> }
>
> +static long btrfs_ioctl_get_device_stats(struct btrfs_root *root,
> + void __user *arg, int reset_after_read)
void __user *arg)
> +{
> + struct btrfs_ioctl_get_device_stats *sa;
> + int ret;
> +
> + sa = memdup_user(arg, sizeof(*sa));
> + if (IS_ERR(sa))
> + return PTR_ERR(sa);
> +
> + if (reset_after_read && !capable(CAP_SYS_ADMIN))
if (sa->reset_after_read && !capable(CAP_SYS_ADMIN)) {
kfree(sa);
> + return -EPERM;
}
> +
> + ret = btrfs_get_device_stats(root, sa, reset_after_read);
> +
> + if (copy_to_user(arg, sa, sizeof(*sa)))
> + ret = -EFAULT;
> +
> + kfree(sa);
> + return ret;
> +}
So the EINVAL could come earlier than EPERM, but I don't think it's a
problem.
david
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