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Subject[PATCH 7/9] vfs: add fcheck tracepoint
Date
All file accesses from userland go through fcheck to map fd to struct
file, making it a very good location for peeking at what files
userland is accessing. Add a tracepoint there.

This is part of tracepoint additions to improve visiblity into
dirtying / writeback operations for io tracer and userland.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
fs/super.c | 2 ++
include/linux/fdtable.h | 3 +++
include/trace/events/vfs.h | 40 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 45 insertions(+), 0 deletions(-)
create mode 100644 include/trace/events/vfs.h
diff --git a/fs/super.c b/fs/super.c
index de41e1e..3055f32 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -34,6 +34,8 @@
#include <linux/cleancache.h>
#include "internal.h"

+#define CREATE_TRACE_POINTS
+#include <trace/events/vfs.h>

LIST_HEAD(super_blocks);
DEFINE_SPINLOCK(sb_lock);
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index 82163c4..72df04b 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -12,6 +12,7 @@
#include <linux/types.h>
#include <linux/init.h>
#include <linux/fs.h>
+#include <trace/events/vfs.h>

#include <linux/atomic.h>

@@ -87,6 +88,8 @@ static inline struct file * fcheck_files(struct files_struct *files, unsigned in

if (fd < fdt->max_fds)
file = rcu_dereference_check_fdtable(files, fdt->fd[fd]);
+
+ trace_vfs_fcheck(files, fd, file);
return file;
}

diff --git a/include/trace/events/vfs.h b/include/trace/events/vfs.h
new file mode 100644
index 0000000..9a9bae4
--- /dev/null
+++ b/include/trace/events/vfs.h
@@ -0,0 +1,40 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM vfs
+
+#if !defined(_TRACE_VFS_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_VFS_H
+
+#include <linux/tracepoint.h>
+#include <linux/fs.h>
+
+TRACE_EVENT(vfs_fcheck,
+
+ TP_PROTO(struct files_struct *files, unsigned int fd,
+ struct file *file),
+
+ TP_ARGS(files, fd, file),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, fd)
+ __field(umode_t, mode)
+ __field(dev_t, dev)
+ __field(ino_t, ino)
+ ),
+
+ TP_fast_assign(
+ __entry->fd = fd;
+ __entry->mode = file ? file->f_path.dentry->d_inode->i_mode : 0;
+ __entry->dev = file ? file->f_path.dentry->d_inode->i_sb->s_dev : 0;
+ __entry->ino = file ? file->f_path.dentry->d_inode->i_ino : 0;
+ ),
+
+ TP_printk("fd %u mode 0x%x dev %d,%d ino %lu",
+ __entry->fd, __entry->mode,
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ (unsigned long)__entry->ino)
+);
+
+#endif /* _TRACE_VFS_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
--
1.7.3.1


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