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[v2,2/3] tracing: Document tracefs gid mount option

Message ID 20241030171928.4168869-3-kaleshsingh@google.com
State New
Headers show
Series Tracefs mount option fixes | expand

Commit Message

Kalesh Singh Oct. 30, 2024, 5:17 p.m. UTC 
Commit ee7f3666995d ("tracefs: Have new files inherit the ownership
of their parent") and commit 48b27b6b5191 ("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: David Howells <dhowells@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---

Changes in v2:
  - Reference commits instead of lore links, per Steve

 kernel/trace/trace.c | 4 ++++
 1 file changed, 4 insertions(+)

--
2.47.0.163.g1226f6d8fa-goog
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Patch

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a8f52b6527ca..2b64b3ec67d9 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5501,6 +5501,10 @@  static const struct file_operations tracing_iter_fops = {

 static const char readme_msg[] =
 	"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 1 > tracing_on : quick way to re-enable tracing\n\n"
 	" Important files:\n"