Date: Sun, 27 Jul 2025 22:44:20 +0000 From: bugzilla-noreply@freebsd.org To: virtualization@FreeBSD.org Subject: [Bug 288444] p9fs chokes on mountpoints in the exported filesystem Message-ID: <bug-288444-27103-hqmtFjW9we@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-288444-27103@https.bugs.freebsd.org/bugzilla/> References: <bug-288444-27103@https.bugs.freebsd.org/bugzilla/>
index | next in thread | previous in thread | raw e-mail
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=288444 Mark Johnston <markj@FreeBSD.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|New |Open --- Comment #1 from Mark Johnston <markj@FreeBSD.org> --- This is basically a limitation of the 9p protocol as implemented by bhyve (and QEMU). Each file in a 9p share has a unique 64-bit identifier, the QID, and our lib9p just sets qid = st_ino. Of course, inode numbers are not unique across datasets, so aliases arise, and this violates some invariants of p9fs. It looks like QEMU has an option which lets one work around this problem by dynamically remapping host inode numbers to provide unique QIDs, at the cost of some overhead and the lack of a guarantee that it always work. (This is "multidevs=remap".) For 15.0 it seems best to simply disallow exporting anything under a mountpoint. That is, if a walk or readdir encounters a file belonging to a different host mountpoint, the 9p server should either hide it or generate an error. That's a bit inconvenient, but it's a bit easier to implement and it's the safest option. -- You are receiving this mail because: You are the assignee for the bug.help
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?bug-288444-27103-hqmtFjW9we>