include/trace/events/writeback.h: fix -Wstringop-truncation warnings

There are many of those warnings.

In file included from ./arch/powerpc/include/asm/paca.h:15,
                 from ./arch/powerpc/include/asm/current.h:13,
                 from ./include/linux/thread_info.h:21,
                 from ./include/asm-generic/preempt.h:5,
                 from ./arch/powerpc/include/generated/asm/preempt.h:1,
                 from ./include/linux/preempt.h:78,
                 from ./include/linux/spinlock.h:51,
                 from fs/fs-writeback.c:19:
In function 'strncpy',
    inlined from 'perf_trace_writeback_page_template' at
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified
bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);

Fix it by using the new strscpy_pad() which was introduced in "lib/string:
Add strscpy_pad() function" and will always be NUL-terminated instead of
strncpy().  Also, change strlcpy() to use strscpy_pad() in this file for

Fixes: 455b2864686d ("writeback: Initial tracing support")
Fixes: 028c2dd184c0 ("writeback: Add tracing to balance_dirty_pages")
Fixes: e84d0a4f8e39 ("writeback: trace event writeback_queue_io")
Fixes: b48c104d2211 ("writeback: trace event bdi_dirty_ratelimit")
Fixes: cc1676d917f3 ("writeback: Move requeueing when I_SYNC set to writeback_sb_inodes()")
Fixes: 9fb0a7da0c52 ("writeback: add more tracepoints")
Signed-off-by: Qian Cai <>
Reviewed-by: Jan Kara <>
Cc: Tobin C. Harding <>
Cc: Steven Rostedt (VMware) <>
Cc: Ingo Molnar <>
Cc: Tejun Heo <>
Cc: Dave Chinner <>
Cc: Fengguang Wu <>
Cc: Jens Axboe <>
Cc: Joe Perches <>
Cc: Kees Cook <>
Cc: Jann Horn <>
Cc: Jonathan Corbet <>
Cc: Nitin Gote <>
Cc: Rasmus Villemoes <>
Cc: Stephen Kitt <>
Signed-off-by: Andrew Morton <>
1 file changed