On Tue, 2024-07-23 at 20:38 +0800, Yuwei Guan wrote:
> The current lock_get_status() function shows ino, but it’s not
> intuitive enough for debugging. This patch will add the file’s
> path information, making it easier to debug which specific file
> is holding the lock.
>
> Signed-off-by: Yuwei Guan <Yuwei.Guan@xxxxxxxxxxxxx>
> ---
> fs/locks.c | 25 ++++++++++++++++++++++++-
> 1 file changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/fs/locks.c b/fs/locks.c
> index bdd94c32256f..feb0a4427a5b 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -2764,6 +2764,8 @@ static void lock_get_status(struct seq_file *f,
> struct file_lock_core *flc,
> struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f-
> >file)->i_sb);
> int type = flc->flc_type;
> struct file_lock *fl = file_lock(flc);
> + struct dentry *dentry = NULL;
> + char *path, *pathbuf;
>
> pid = locks_translate_pid(flc, proc_pidns);
>
> @@ -2819,8 +2821,29 @@ static void lock_get_status(struct seq_file
> *f, struct file_lock_core *flc,
> seq_printf(f, "%d %02x:%02x:%lu ", pid,
> MAJOR(inode->i_sb->s_dev),
> MINOR(inode->i_sb->s_dev), inode-
> >i_ino);
> +
> + pathbuf = __getname();
This won't work. locks_show is called under the blocked_lock_lock
spinlock, and __getname does a GFP_KERNEL allocation.
The second problem is that the procfiles that this alters (/proc/locks
and /proc/<pid>/fdinfo/*) are considered part of the kernel's ABI, so
we can't just go change the format of them.
If you're interested in getting pathnames, I suggest using the lslocks
program which resolves these pathnames in userland.
> + if (!pathbuf)
> + seq_printf(f, "%s ", "UNKNOWN");
> + else {
> + ihold(inode);
> + dentry = d_obtain_alias(inode);
> + if (!IS_ERR(dentry)) {
> + path = dentry_path_raw(dentry,
> pathbuf, PATH_MAX);
> + if (IS_ERR(path)) {
> + strscpy(pathbuf, "UNKNOWN",
> PATH_MAX);
> + path = pathbuf;
> + }
> + dput(dentry);
> + } else {
> + strscpy(pathbuf, "UNKNOWN",
> PATH_MAX);
> + path = pathbuf;
> + }
> + seq_printf(f, "%s ", path);
> + __putname(pathbuf);
> + }
> } else {
> - seq_printf(f, "%d <none>:0 ", pid);
> + seq_printf(f, "%d <none>:0:<none> UNKNOWN ", pid);
> }
> if (flc->flc_flags & FL_POSIX) {
> if (fl->fl_end == OFFSET_MAX)
--
Jeff Layton <jlayton@xxxxxxxxxx>
