fs: dlm: Fix the size of a buffer in dlm_create_debug_file()

[ Upstream commit b859e01054354033f480d9df41b0ebc2c7537379 ]

8 is not the maximum size of the suffix used when creating debugfs files.

Let the compiler compute the correct size, and only give a hint about the
longest possible string that is used.

When building with W=1, this fixes the following warnings:

  fs/dlm/debug_fs.c: In function ‘dlm_create_debug_file’:
  fs/dlm/debug_fs.c:1020:58: error: ‘snprintf’ output may be truncated before the last format character [-Werror=format-truncation=]
   1020 |         snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_waiters", ls->ls_name);
        |                                                          ^
  fs/dlm/debug_fs.c:1020:9: note: ‘snprintf’ output between 9 and 73 bytes into a destination of size 72
   1020 |         snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_waiters", ls->ls_name);
        |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  fs/dlm/debug_fs.c:1031:50: error: ‘_queued_asts’ directive output may be truncated writing 12 bytes into a region of size between 8 and 72 [-Werror=format-truncation=]
   1031 |         snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_queued_asts", ls->ls_name);
        |                                                  ^~~~~~~~~~~~
  fs/dlm/debug_fs.c:1031:9: note: ‘snprintf’ output between 13 and 77 bytes into a destination of size 72
   1031 |         snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_queued_asts", ls->ls_name);
        |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fixes: 541adb0d4d10b ("fs: dlm: debugfs for queued callbacks")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/dlm/debug_fs.c b/fs/dlm/debug_fs.c
index 5aabcb6..fc44ab6 100644 (file)
--- a/fs/dlm/debug_fs.c
+++ b/fs/dlm/debug_fs.c
@@ -973,7 +973,8 @@ void dlm_delete_debug_comms_file(void *ctx)
 
 void dlm_create_debug_file(struct dlm_ls *ls)
 {
-       char name[DLM_LOCKSPACE_LEN + 8];
+       /* Reserve enough space for the longest file name */
+       char name[DLM_LOCKSPACE_LEN + sizeof("_queued_asts")];
 
        /* format 1 */