md/bitmap: add blktrace event for writes to the bitmap

We trace wheneven bitmap_unplug() finds that it needs to write
to the bitmap, or when bitmap_daemon_work() find there is work
to do.

This makes it easier to correlate bitmap updates with data writes.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
This commit is contained in:
NeilBrown 2016-11-14 16:30:21 +11:00 committed by Shaohua Li
parent 109e376530
commit 581dbd94da

View File

@ -27,6 +27,7 @@
#include <linux/mount.h>
#include <linux/buffer_head.h>
#include <linux/seq_file.h>
#include <trace/events/block.h>
#include "md.h"
#include "bitmap.h"
@ -1008,8 +1009,12 @@ void bitmap_unplug(struct bitmap *bitmap)
need_write = test_and_clear_page_attr(bitmap, i,
BITMAP_PAGE_NEEDWRITE);
if (dirty || need_write) {
if (!writing)
if (!writing) {
bitmap_wait_writes(bitmap);
if (bitmap->mddev->queue)
blk_add_trace_msg(bitmap->mddev->queue,
"md bitmap_unplug");
}
clear_page_attr(bitmap, i, BITMAP_PAGE_PENDING);
write_page(bitmap, bitmap->storage.filemap[i], 0);
writing = 1;
@ -1234,6 +1239,10 @@ void bitmap_daemon_work(struct mddev *mddev)
}
bitmap->allclean = 1;
if (bitmap->mddev->queue)
blk_add_trace_msg(bitmap->mddev->queue,
"md bitmap_daemon_work");
/* Any file-page which is PENDING now needs to be written.
* So set NEEDWRITE now, then after we make any last-minute changes
* we will write it.