[5/5] fs: enable filesystem freeze/thaw events

Commit Message

Frank Sorenson March 2, 2016, 7:01 p.m. UTC

Add tracepoints to enable filesystem freeze/thaw
trace events.

Signed-off-by: Frank Sorenson <[e-mail]>
---
 fs/block_dev.c | 13 +++++++++++++
 fs/super.c     | 10 ++++++++++
 2 files changed, 23 insertions(+)

Comments

Al Viro March 2, 2016, 8:15 p.m. UTC | #1

On Wed, Mar 02, 2016 at 01:01:59PM -0600, Frank Sorenson wrote:
> Add tracepoints to enable filesystem freeze/thaw
> trace events.

... and they are defined in highly meaningful terms of entering and leaving
a specific function.  Which implementation detail, again, is turned into
a userland ABI, with usual stability warranties.

Again, NAK.
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Patch

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 1207f40..095ef3e 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -32,6 +32,9 @@ 
 #include <asm/uaccess.h>
 #include "internal.h"
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/fs_bdev.h>
+
 struct bdev_inode {
 	struct block_device bdev;
 	struct inode vfs_inode;
@@ -228,6 +231,8 @@  struct super_block *freeze_bdev(struct block_device *bdev)
 	struct super_block *sb;
 	int error = 0;
 
+	trace_freeze_bdev_enter(bdev);
+
 	mutex_lock(&bdev->bd_fsfreeze_mutex);
 	if (++bdev->bd_fsfreeze_count > 1) {
 		/*
@@ -258,6 +263,9 @@  out:
 	sync_blockdev(bdev);
 out_unlock:
 	mutex_unlock(&bdev->bd_fsfreeze_mutex);
+
+	trace_freeze_bdev_exit(bdev, sb);
+
 	return sb;	/* thaw_bdev releases s->s_umount */
 }
 EXPORT_SYMBOL(freeze_bdev);
@@ -273,6 +281,8 @@  int thaw_bdev(struct block_device *bdev, struct super_block *sb)
 {
 	int error = -EINVAL;
 
+	trace_thaw_bdev_enter(bdev, sb);
+
 	mutex_lock(&bdev->bd_fsfreeze_mutex);
 	if (!bdev->bd_fsfreeze_count)
 		goto out;
@@ -292,6 +302,9 @@  int thaw_bdev(struct block_device *bdev, struct super_block *sb)
 		bdev->bd_fsfreeze_count++;
 out:
 	mutex_unlock(&bdev->bd_fsfreeze_mutex);
+
+	trace_thaw_bdev_exit(bdev, sb, error);
+
 	return error;
 }
 EXPORT_SYMBOL(thaw_bdev);
diff --git a/fs/super.c b/fs/super.c
index 5e9a974..70218ed 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -35,6 +35,8 @@ 
 #include <linux/lockdep.h>
 #include "internal.h"
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/fs.h>
 
 static LIST_HEAD(super_blocks);
 static DEFINE_SPINLOCK(sb_lock);
@@ -1274,6 +1276,8 @@  int freeze_super(struct super_block *sb)
 {
 	int ret = 0;
 
+	trace_freeze_super_enter(sb);
+
 	atomic_inc(&sb->s_active);
 	down_write(&sb->s_umount);
 	if (sb->s_writers.frozen != SB_UNFROZEN) {
@@ -1326,6 +1330,8 @@  out_complete:
 out_unlock:
 	up_write(&sb->s_umount);
 out:
+	trace_freeze_super_exit(sb, ret);
+
 	return ret;
 }
 EXPORT_SYMBOL(freeze_super);
@@ -1340,6 +1346,8 @@  int thaw_super(struct super_block *sb)
 {
 	int ret = 0;
 
+	trace_thaw_super_enter(sb);
+
 	down_write(&sb->s_umount);
 	if (sb->s_writers.frozen == SB_UNFROZEN) {
 		up_write(&sb->s_umount);
@@ -1368,6 +1376,8 @@  out_wake:
 	wake_up(&sb->s_writers.wait_unfrozen);
 	deactivate_locked_super(sb);
 out:
+	trace_thaw_super_exit(sb, ret);
+
 	return ret;
 }
 EXPORT_SYMBOL(thaw_super);