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tracing: Document tracefs gid mount option

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Commit ee7f366699 ("tracefs: Have new files inherit the ownership of
their parent") and commit 48b27b6b51 ("tracefs: Set all files to the
same group ownership as the mount option") introduced a new gid mount
option that allows specifying a group to apply to all entries in tracefs.

Document this in the tracing readme.

Cc: Eric Sandeen <sandeen@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Ali Zahraee <ahzahraee@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/20241030171928.4168869-3-kaleshsingh@google.com
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Kalesh Singh 2024-10-30 10:17:49 -07:00 committed by Steven Rostedt (Google)
parent e4d32142d1
commit fa17cb4b3b
1 changed files with 4 additions and 0 deletions
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4
kernel/trace/trace.c
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@ -5501,6 +5501,10 @@ static const struct file_operations tracing_iter_fops = {
static const char readme_msg[] = static const char readme_msg[] =
"tracing mini-HOWTO:\n\n" "tracing mini-HOWTO:\n\n"
"By default tracefs removes all OTH file permission bits.\n"
"When mounting tracefs an optional group id can be specified\n"
"which adds the group to every directory and file in tracefs:\n\n"
"\t e.g. mount -t tracefs [-o [gid=<gid>]] nodev /sys/kernel/tracing\n\n"
"# echo 0 > tracing_on : quick way to disable tracing\n" "# echo 0 > tracing_on : quick way to disable tracing\n"
"# echo 1 > tracing_on : quick way to re-enable tracing\n\n" "# echo 1 > tracing_on : quick way to re-enable tracing\n\n"
" Important files:\n" " Important files:\n"