BACKPORT: f2fs: fix up f2fs_lookup tracepoints

[ Upstream commit 70a9ac36 ]

Fix up a misuse that the filename pointer isn't always valid in
the ring buffer, and we should copy the content instead.

Fixes: 0c5e36db ("f2fs: trace f2fs_lookup")
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Bug: 218970249
Link: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/include/trace/events?h=v5.10.99&id=e8bd5e33057c02d377a76a42987c083afcb43579


Change-Id: Ida688a8551a7361cd32f928f805a88b88f735884
Signed-off-by: Chun-Hung Wu <chun-hung.wu@mediatek.com>