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Subject[PATCH] trace: Add tracepoints to fs subsystem
Date
From: Jiaying Zhang <jiayingz@google.com>

Many fs tracepoints can now be traced via ftrace, however there are a
few other tracepoints needed. This patch adds entry and exit tracepoints
for a few additional functions, viz.:
wait_on_buffer
block_write_full_page
mpage_readpages
file_read

Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
---
fs/buffer.c | 10 +++
fs/mpage.c | 3 +
include/trace/events/fs.h | 166 +++++++++++++++++++++++++++++++++++++++++++++
mm/filemap.c | 4 +-
4 files changed, 182 insertions(+), 1 deletions(-)
create mode 100644 include/trace/events/fs.h
diff --git a/fs/buffer.c b/fs/buffer.c
index a08bb8e..40a0ce3 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -42,6 +42,9 @@
#include <linux/mpage.h>
#include <linux/bit_spinlock.h>

+#define CREATE_TRACE_POINTS
+#include <trace/events/fs.h>
+
static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);

#define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
@@ -82,7 +85,9 @@ EXPORT_SYMBOL(unlock_buffer);
*/
void __wait_on_buffer(struct buffer_head * bh)
{
+ trace_fs_buffer_wait_start(bh);
wait_on_bit(&bh->b_state, BH_Lock, sleep_on_buffer, TASK_UNINTERRUPTIBLE);
+ trace_fs_buffer_wait_end(bh);
}
EXPORT_SYMBOL(__wait_on_buffer);

@@ -1647,6 +1652,8 @@ static int __block_write_full_page(struct inode *inode, struct page *page,
head = page_buffers(page);
bh = head;

+ trace_block_write_full_page(inode, block, last_block);
+
/*
* Get all the dirty buffers mapped to disk addresses and
* handle any aliases from the underlying blockdev's mapping.
@@ -1736,6 +1743,9 @@ done:
* here on.
*/
}
+
+ trace_block_write_full_page_done(inode, nr_underway, err);
+
return err;

recover:
diff --git a/fs/mpage.c b/fs/mpage.c
index 0afc809..1c3b8e1 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -28,6 +28,7 @@
#include <linux/backing-dev.h>
#include <linux/pagevec.h>

+#include <trace/events/fs.h>
/*
* I/O completion handler for multipage BIOs.
*
@@ -373,6 +374,8 @@ mpage_readpages(struct address_space *mapping, struct list_head *pages,
for (page_idx = 0; page_idx < nr_pages; page_idx++) {
struct page *page = list_entry(pages->prev, struct page, lru);

+ if (page_idx == 0)
+ trace_mpage_readpages(page, mapping, nr_pages);
prefetchw(&page->flags);
list_del(&page->lru);
if (!add_to_page_cache_lru(page, mapping,
diff --git a/include/trace/events/fs.h b/include/trace/events/fs.h
new file mode 100644
index 0000000..40b71db
--- /dev/null
+++ b/include/trace/events/fs.h
@@ -0,0 +1,166 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM fs
+
+#if !defined(_TRACE_FS_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_FS_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(fs_buffer_wait_start,
+
+ TP_PROTO(struct buffer_head *bh),
+
+ TP_ARGS(bh),
+
+ TP_STRUCT__entry(
+ __field( void *, bh )
+ ),
+
+ TP_fast_assign(
+ __entry->bh = bh;
+ ),
+
+ TP_printk("bh %p", __entry->bh)
+);
+
+TRACE_EVENT(fs_buffer_wait_end,
+
+ TP_PROTO(struct buffer_head *bh),
+
+ TP_ARGS(bh),
+
+ TP_STRUCT__entry(
+ __field(void *, bh)
+ ),
+
+ TP_fast_assign(
+ __entry->bh = bh;
+ ),
+
+ TP_printk("bh %p", __entry->bh)
+);
+
+TRACE_EVENT(block_write_full_page,
+
+ TP_PROTO(struct inode *inode, sector_t block, sector_t last_block),
+
+ TP_ARGS(inode, block, last_block),
+
+ TP_STRUCT__entry(
+ __field( dev_t, dev )
+ __field( unsigned long, ino )
+ __field( sector_t, block )
+ __field( sector_t, last_block )
+ ),
+
+ TP_fast_assign(
+ __entry->dev = inode->i_sb->s_dev;
+ __entry->ino = inode->i_ino;
+ __entry->block = block;
+ __entry->last_block = last_block;
+ ),
+
+ TP_printk("dev %d,%d ino %lu block %lu last block %lu",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ __entry->ino,
+ (unsigned long)__entry->block,
+ (unsigned long)__entry->last_block)
+);
+
+TRACE_EVENT(block_write_full_page_done,
+
+ TP_PROTO(struct inode *inode, int nr_underway, int err),
+
+ TP_ARGS(inode, nr_underway, err),
+
+ TP_STRUCT__entry(
+ __field( dev_t, dev )
+ __field( unsigned long, ino )
+ __field( int, nr_underway )
+ __field( int, err )
+ ),
+
+ TP_fast_assign(
+ __entry->dev = inode->i_sb->s_dev;
+ __entry->ino = inode->i_ino;
+ __entry->nr_underway = nr_underway;
+ __entry->err = err;
+ ),
+
+ TP_printk("dev %d,%d ino %lu nr_underway %d err %d",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ __entry->ino, __entry->nr_underway, __entry->err)
+);
+
+DECLARE_EVENT_CLASS(file_read,
+ TP_PROTO(struct inode *inode, loff_t pos, size_t len),
+
+ TP_ARGS(inode, pos, len),
+
+ TP_STRUCT__entry(
+ __field( ino_t, ino )
+ __field( dev_t, dev )
+ __field( loff_t, pos )
+ __field( size_t, len )
+ ),
+
+ TP_fast_assign(
+ __entry->ino = inode->i_ino;
+ __entry->dev = inode->i_sb->s_dev;
+ __entry->pos = pos;
+ __entry->len = len;
+ ),
+
+ TP_printk("dev %d,%d ino %lu pos %llu len %lu",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ (unsigned long) __entry->ino,
+ (unsigned long long) __entry->pos,
+ (unsigned long) __entry->len)
+);
+
+DEFINE_EVENT(file_read, file_read_enter,
+
+ TP_PROTO(struct inode *inode, loff_t pos, size_t len),
+
+ TP_ARGS(inode, pos, len)
+);
+
+DEFINE_EVENT(file_read, file_read_exit,
+
+ TP_PROTO(struct inode *inode, loff_t pos, size_t len),
+
+ TP_ARGS(inode, pos, len)
+);
+
+TRACE_EVENT(mpage_readpages,
+ TP_PROTO(struct page *page, struct address_space *mapping,
+ unsigned nr_pages),
+
+ TP_ARGS(page, mapping, nr_pages),
+
+ TP_STRUCT__entry(
+ __field( pgoff_t, index )
+ __field( ino_t, ino )
+ __field( dev_t, dev )
+ __field( unsigned, nr_pages )
+
+ ),
+
+ TP_fast_assign(
+ __entry->index = page->index;
+ __entry->ino = mapping->host->i_ino;
+ __entry->dev = mapping->host->i_sb->s_dev;
+ __entry->nr_pages = nr_pages;
+ ),
+
+ TP_printk("dev %d,%d ino %lu page_index %lu nr_pages %u",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ (unsigned long) __entry->ino,
+ __entry->index, __entry->nr_pages)
+);
+
+#endif /* _TRACE_FS_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
+
diff --git a/mm/filemap.c b/mm/filemap.c
index c641edf..94e549c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -42,7 +42,7 @@
#include <linux/buffer_head.h> /* for try_to_free_buffers */

#include <asm/mman.h>
-
+#include <trace/events/fs.h>
/*
* Shared mappings implemented 30.11.1994. It's not fully working yet,
* though.
@@ -1054,6 +1054,7 @@ static void do_generic_file_read(struct file *filp, loff_t *ppos,
unsigned int prev_offset;
int error;

+ trace_file_read_enter(inode, *ppos, desc->count);
index = *ppos >> PAGE_CACHE_SHIFT;
prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
@@ -1254,6 +1255,7 @@ out:
ra->prev_pos <<= PAGE_CACHE_SHIFT;
ra->prev_pos |= prev_offset;

+ trace_file_read_exit(inode, *ppos, desc->written);
*ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
file_accessed(filp);
}
--
1.7.3.1


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