f2fs: add a tracepoint for f2fs_issue_discard

This patch adds a tracepoint for f2fs_issue_discard.

Signed-off-by: Jaegeuk Kim <[email protected]>
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index c51fa4b..cfc0eb4f 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -272,6 +272,7 @@
 	sector_t start = ((sector_t)blkstart) << sbi->log_sectors_per_block;
 	sector_t len = ((sector_t)blklen) << sbi->log_sectors_per_block;
 	blkdev_issue_discard(sbi->sb->s_bdev, start, len, GFP_NOFS, 0);
+	trace_f2fs_issue_discard(sbi->sb, blkstart, blklen);
 }
 
 static void add_discard_addrs(struct f2fs_sb_info *sbi,