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Commit 9e094383 authored by Dave Chinner's avatar Dave Chinner Committed by Jens Axboe
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writeback: Add tracing to write_cache_pages 



Add a trace event to the ->writepage loop in write_cache_pages to give
visibility into how the ->writepage call is changing variables within the
writeback control structure. Of most interest is how wbc->nr_to_write changes
from call to call, especially with filesystems that write multiple pages
in ->writepage.

Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 028c2dd1

include/trace/events/writeback.h

+1 −0
Original line number Diff line number Diff line
@@ -148,6 +148,7 @@ DEFINE_WBC_EVENT(wbc_writeback_wait); 
DEFINE_WBC_EVENT(wbc_balance_dirty_start);

DEFINE_WBC_EVENT(wbc_balance_dirty_written);

DEFINE_WBC_EVENT(wbc_balance_dirty_wait);

DEFINE_WBC_EVENT(wbc_writepage);



#endif /* _TRACE_WRITEBACK_H */

mm/page-writeback.c

+1 −0
Original line number Diff line number Diff line
@@ -933,6 +933,7 @@ int write_cache_pages(struct address_space *mapping, 
			if (!clear_page_dirty_for_io(page))

				goto continue_unlock;



			trace_wbc_writepage(wbc, mapping->backing_dev_info);

			ret = (*writepage)(page, wbc, data);

			if (unlikely(ret)) {

				if (ret == AOP_WRITEPAGE_ACTIVATE) {