Re: [RFC][PATCH 10/10 v1][RESEND] ext4: add two tracepoints in punching hole

Lukáš Czerner
2012-07-27T13:43:56Z

On Sun, 22 Jul 2012, Zheng Liu wrote:

> Date: Sun, 22 Jul 2012 15:59:46 +0800
> From: Zheng Liu <gnehzuil.liu@gmail.com>
> To: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org
> Cc: xiaoqiangnk@gmail.com, achender@linux.vnet.ibm.com, wenqing.lz@taobao.com
> Subject: [RFC][PATCH 10/10 v1][RESEND] ext4: add two tracepoints in punching
> hole
>
> From: Zheng Liu <wenqing.lz@taobao.com>
>
> This patch adds two tracepoints in ext4_ext_punch_hole.

Hi,

the trace_ext4_ext_punch_hole_enter() looks good, but I am not so
sure about the trace_ext4_ext_punch_hole_exit() trace point. What is
the point of having this tracepoint ? The only thing it adds to the
information we already have is return value of the function and
that's something we'll know anyway, right ?

Is there any special reason for having this ? If not, I think it can
be removed and trace_ext4_ext_punch_hole_enter() can be renamed to
trace_ext4_ext_punch_hole() to match the naming conventions of other
ext4 tracepoints.

Thanks!
-Lukas

>
> Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
> ---
> fs/ext4/extents.c | 3 ++
> include/trace/events/ext4.h | 53 +++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 56 insertions(+), 0 deletions(-)
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 2a526b4..0fb4ff5 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4529,6 +4529,8 @@ int ext4_ext_punch_hole(struct file *file, loff_t offset, loff_t length)
> loff_t first_page_offset, last_page_offset;
> int credits, err = 0;
>
> + trace_ext4_ext_punch_hole_enter(inode, offset, length);
> +
> mutex_lock(&inode->i_mutex);
>
> /* No need to punch hole beyond i_size */
> @@ -4663,6 +4665,7 @@ out:
> ext4_journal_stop(handle);
> error:
> mutex_unlock(&inode->i_mutex);
> + trace_ext4_ext_punch_hole_exit(inode, offset, length, err);
> return err;
> }
> int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
> diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
> index 5c17592..583f066 100644
> --- a/include/trace/events/ext4.h
> +++ b/include/trace/events/ext4.h
> @@ -1312,6 +1312,59 @@ TRACE_EVENT(ext4_fallocate_exit,
> __entry->ret)
> );
>
> +TRACE_EVENT(ext4_ext_punch_hole_enter,
> + TP_PROTO(struct inode *inode, loff_t offset, loff_t len),
> +
> + TP_ARGS(inode, offset, len),
> +
> + TP_STRUCT__entry(
> + __field( dev_t, dev )
> + __field( ino_t, ino )
> + __field( loff_t, offset )
> + __field( loff_t, len )
> + ),
> +
> + TP_fast_assign(
> + __entry->dev = inode->i_sb->s_dev;
> + __entry->ino = inode->i_ino;
> + __entry->offset = offset;
> + __entry->len = len;
> + ),
> +
> + TP_printk("dev %d,%d ino %lu offset %lld len %lld",
> + MAJOR(__entry->dev), MINOR(__entry->dev),
> + (unsigned long) __entry->ino,
> + __entry->offset, __entry->len)
> +);
> +
> +TRACE_EVENT(ext4_ext_punch_hole_exit,
> + TP_PROTO(struct inode *inode, loff_t offset,
> + loff_t len, int err),
> +
> + TP_ARGS(inode, offset, len, err),
> +
> + TP_STRUCT__entry(
> + __field( dev_t, dev )
> + __field( ino_t, ino )
> + __field( loff_t, offset )
> + __field( loff_t, len )
> + __field( int, err )
> + ),
> +
> + TP_fast_assign(
> + __entry->dev = inode->i_sb->s_dev;
> + __entry->ino = inode->i_ino;
> + __entry->offset = offset;
> + __entry->len = len;
> + __entry->err = err;
> + ),
> +
> + TP_printk("dev %d,%d ino %lu offset %lld len %lld err %d",
> + MAJOR(__entry->dev), MINOR(__entry->dev),
> + (unsigned long) __entry->ino,
> + __entry->offset, __entry->len, __entry->err)
> +);
> +
> TRACE_EVENT(ext4_unlink_enter,
> TP_PROTO(struct inode *parent, struct dentry *dentry),
>
>