When CONFIG_FS_BACKTRACE is enabled, collecting a stack trace for every
new file descriptor adds overhead to fast path operations like open(),
dup(), and socket().
This patch adds a new configuration option CONFIG_FS_BACKTRACE_DEFAULT.
When enabled (default behavior), the GROUP_FLAG_FD_BACKTRACE flag is
automatically set during group allocation, causing backtrace to be
captured for all tasks globally, preserving the original diagnostic
capability.
When disabled, backtrace capture is zero-cost by default and must be
explicitly enabled per task group using GROUP_FLAG_FD_BACKTRACE.
Signed-off-by: zhanxiaoqi <zhanxiaoqi@bytedance.com>
786b315947