On Tue, 2 Sept 2025 at 10:48, David Howells <dhowells@xxxxxxxxxx> wrote:
>
> The problem with that is that it appears that people are making use of this.
Ok. So disallowing it isn't in the cards, but let's try to minimize the impact.
> The standard format of AFS volume names is [%#][<cell>:]<volume-name-or-id>
> but I could make it an option to stick something on the front and use that
> internally and display that in /proc/mounts, e.g.:
>
> mount afs:#openafs.org:afs.root /mnt
Yeah, let's aim for trying to avoid the '#' at the beginning when all
possible, by trying to make at least the default formats not start
with a hash.
And then make the escaping logic only escape the hashmark if it's the
first character.
> I don't think there should be a problem with still accepting lines beginning
> with '#' in mount() if I display them with an appropriate prefix. That would
> at least permit backward compatibility.
Well, right now we obviously escape it everywhere, but how about we
make it the rule that 'show_devname()' at least doesn't use it as the
first character, and then if somebody uses '#' for the mount name from
user space, we would just do the octal-escape then.
Something ENTIRELY UNTESTED like this, in other words?
Linus
fs/afs/super.c | 2 +-
fs/proc_namespace.c | 9 +++++++--
2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/fs/afs/super.c b/fs/afs/super.c
index da407f2d6f0d..31f9cc30ae23 100644
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -180,7 +180,7 @@ static int afs_show_devname(struct seq_file *m, struct dentry *root)
break;
}
- seq_printf(m, "%c%s:%s%s", pref, cell->name, volume->name, suf);
+ seq_printf(m, "afs-%c%s:%s%s", pref, cell->name, volume->name, suf);
return 0;
}
diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
index 5c555db68aa2..ca5773bfb98e 100644
--- a/fs/proc_namespace.c
+++ b/fs/proc_namespace.c
@@ -86,7 +86,7 @@ static void show_vfsmnt_opts(struct seq_file *m, struct vfsmount *mnt)
static inline void mangle(struct seq_file *m, const char *s)
{
- seq_escape(m, s, " \t\n\\#");
+ seq_escape(m, s, " \t\n\\");
}
static void show_type(struct seq_file *m, struct super_block *sb)
@@ -111,7 +111,12 @@ static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
if (err)
goto out;
} else {
- mangle(m, r->mnt_devname);
+ const char *mnt_devname = r->mnt_devname;
+ if (*mnt_devname == '#') {
+ seq_printf(m, "\\%o", '#');
+ mnt_devname++;
+ }
+ mangle(m, mnt_devname);
}
seq_putc(m, ' ');
/* mountpoints outside of chroot jail will give SEQ_SKIP on this */
