Re: [PATCH 01/11] iomap: add tracing for the readpage / readpages

[Brian Foster <bfoster@redhat.com>]

On Sun, Oct 06, 2019 at 05:45:58PM +0200, Christoph Hellwig wrote:
> Lift the xfs code for tracing address space operations to the iomap
> layer.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

For the v7 version:

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/iomap/Makefile      | 16 ++++++++------
>  fs/iomap/buffered-io.c |  5 +++++
>  fs/iomap/trace.h       | 49 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 63 insertions(+), 7 deletions(-)
>  create mode 100644 fs/iomap/trace.h
> 
> diff --git a/fs/iomap/Makefile b/fs/iomap/Makefile
> index 93cd11938bf5..eef2722d93a1 100644
> --- a/fs/iomap/Makefile
> +++ b/fs/iomap/Makefile
> @@ -3,13 +3,15 @@
>  # Copyright (c) 2019 Oracle.
>  # All Rights Reserved.
>  #
> -obj-$(CONFIG_FS_IOMAP)		+= iomap.o
>  
> -iomap-y				+= \
> -					apply.o \
> -					buffered-io.o \
> -					direct-io.o \
> -					fiemap.o \
> -					seek.o
> +ccflags-y += -I $(srctree)/$(src)		# needed for trace events
> +
> +obj-$(CONFIG_FS_IOMAP)		+= iomap.o
>  
> +iomap-y				+= trace.o \
> +				   apply.o \
> +				   buffered-io.o \
> +				   direct-io.o \
> +				   fiemap.o \
> +				   seek.o
>  iomap-$(CONFIG_SWAP)		+= swapfile.o
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index e25901ae3ff4..fb209272765c 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -16,6 +16,7 @@
>  #include <linux/bio.h>
>  #include <linux/sched/signal.h>
>  #include <linux/migrate.h>
> +#include "trace.h"
>  
>  #include "../internal.h"
>  
> @@ -293,6 +294,8 @@ iomap_readpage(struct page *page, const struct iomap_ops *ops)
>  	unsigned poff;
>  	loff_t ret;
>  
> +	trace_iomap_readpage(page->mapping->host, 1);
> +
>  	for (poff = 0; poff < PAGE_SIZE; poff += ret) {
>  		ret = iomap_apply(inode, page_offset(page) + poff,
>  				PAGE_SIZE - poff, 0, ops, &ctx,
> @@ -389,6 +392,8 @@ iomap_readpages(struct address_space *mapping, struct list_head *pages,
>  	loff_t last = page_offset(list_entry(pages->next, struct page, lru));
>  	loff_t length = last - pos + PAGE_SIZE, ret = 0;
>  
> +	trace_iomap_readpages(mapping->host, nr_pages);
> +
>  	while (length > 0) {
>  		ret = iomap_apply(mapping->host, pos, length, 0, ops,
>  				&ctx, iomap_readpages_actor);
> diff --git a/fs/iomap/trace.h b/fs/iomap/trace.h
> new file mode 100644
> index 000000000000..7798aeda7fb9
> --- /dev/null
> +++ b/fs/iomap/trace.h
> @@ -0,0 +1,49 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2009-2019, Christoph Hellwig
> + *
> + * NOTE: none of these tracepoints shall be consider a stable kernel ABI
> + * as they can change at any time.
> + */
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM iomap
> +
> +#if !defined(_IOMAP_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _IOMAP_TRACE_H
> +
> +#include <linux/tracepoint.h>
> +
> +struct inode;
> +
> +DECLARE_EVENT_CLASS(iomap_readpage_class,
> +	TP_PROTO(struct inode *inode, int nr_pages),
> +	TP_ARGS(inode, nr_pages),
> +	TP_STRUCT__entry(
> +		__field(dev_t, dev)
> +		__field(u64, ino)
> +		__field(int, nr_pages)
> +	),
> +	TP_fast_assign(
> +		__entry->dev = inode->i_sb->s_dev;
> +		__entry->ino = inode->i_ino;
> +		__entry->nr_pages = nr_pages;
> +	),
> +	TP_printk("dev %d:%d ino 0x%llx nr_pages %d",
> +		  MAJOR(__entry->dev), MINOR(__entry->dev),
> +		  __entry->ino,
> +		  __entry->nr_pages)
> +)
> +
> +#define DEFINE_READPAGE_EVENT(name)		\
> +DEFINE_EVENT(iomap_readpage_class, name,	\
> +	TP_PROTO(struct inode *inode, int nr_pages), \
> +	TP_ARGS(inode, nr_pages))
> +DEFINE_READPAGE_EVENT(iomap_readpage);
> +DEFINE_READPAGE_EVENT(iomap_readpages);
> +
> +#endif /* _IOMAP_TRACE_H */
> +
> +#undef TRACE_INCLUDE_PATH
> +#define TRACE_INCLUDE_PATH .
> +#define TRACE_INCLUDE_FILE trace
> +#include <trace/define_trace.h>
> -- 
> 2.20.1
>