iomap: trace iomap_zero_iter zeroing activities

Trace which bytes actually get zeroed.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/175803480303.966383.2380024013746734540.stgit@frogsfrogsfrogs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: Darrick J. Wong

fs/iomap/buffered-io.c

@@ -1396,6 +1396,9 @@ static int iomap_zero_iter(struct iomap_iter *iter, bool *did_zero,
 		/* warn about zeroing folios beyond eof that won't write back */
 		WARN_ON_ONCE(folio_pos(folio) > iter->inode->i_size);
 
+		trace_iomap_zero_iter(iter->inode, folio_pos(folio) + offset,
+				bytes);
+
 		folio_zero_range(folio, offset, bytes);
 		folio_mark_accessed(folio);
 

fs/iomap/trace.h

@@ -84,6 +84,7 @@ DEFINE_RANGE_EVENT(iomap_release_folio);
 DEFINE_RANGE_EVENT(iomap_invalidate_folio);
 DEFINE_RANGE_EVENT(iomap_dio_invalidate_fail);
 DEFINE_RANGE_EVENT(iomap_dio_rw_queued);
+DEFINE_RANGE_EVENT(iomap_zero_iter);
 
 #define IOMAP_TYPE_STRINGS \
 	{ IOMAP_HOLE,		"HOLE" }, \