Date: Sat, 4 Nov 2023 17:15:50 GMT From: "Jason A. Harmening" <jah@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 586fed0b0356 - main - vfs_lookup_cross_mount(): restore previous do...while loop Message-ID: <202311041715.3A4HFoZW004108@gitrepo.freebsd.org>
next in thread | raw e-mail | index | archive | help
The branch main has been updated by jah: URL: https://cgit.FreeBSD.org/src/commit/?id=586fed0b03561558644eccc37f824c7110500182 commit 586fed0b03561558644eccc37f824c7110500182 Author: Jason A. Harmening <jah@FreeBSD.org> AuthorDate: 2023-11-04 16:56:45 +0000 Commit: Jason A. Harmening <jah@FreeBSD.org> CommitDate: 2023-11-04 17:15:20 +0000 vfs_lookup_cross_mount(): restore previous do...while loop When the cross-mount walking logic in vfs_lookup() was factored into a separate function, the main cross-mount traversal loop was changed from a do...while loop conditional on the current vnode having VIRF_MOUNTPOINT set to an unconditional for(;;) loop. For the unionfs 'crosslock' case in which the vnode may be re-locked, this meant that continuing the loop upon finding inconsistent v_mountedhere state would no longer branch to a check that the vnode is in fact still a mountpoint. This would in turn lead to over- iteration and, for INVARIANTS builds, a failed assert on the next iteration. Fix this by restoring the previous loop behavior. Reported by: pho Tested by: pho Fixes: 80bd5ef0702562c546fa1717e8fe221058974eac MFC after: 1 week --- sys/kern/vfs_lookup.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c index d75351c34314..922adda33b94 100644 --- a/sys/kern/vfs_lookup.c +++ b/sys/kern/vfs_lookup.c @@ -882,7 +882,7 @@ vfs_lookup_cross_mount(struct nameidata *ndp) * The vnode has been mounted on, find the root of the mounted * filesystem. */ - for (;;) { + do { mp = dp->v_mountedhere; ASSERT_VOP_LOCKED(dp, __func__); VNPASS((vn_irflag_read(dp) & VIRF_MOUNTPOINT) != 0 && mp != NULL, dp); @@ -915,6 +915,12 @@ vfs_lookup_cross_mount(struct nameidata *ndp) break; } if (dp->v_mountedhere != mp) { + /* + * Note that we rely on the + * VIRF_MOUNTPOINT loop condition to + * ensure we stop iterating if dp is + * no longer a mountpoint at all. + */ continue; } } else @@ -939,9 +945,7 @@ vfs_lookup_cross_mount(struct nameidata *ndp) if (error != 0) break; ndp->ni_vp = dp = tdp; - if ((vn_irflag_read(dp) & VIRF_MOUNTPOINT) == 0) - break; - } + } while ((vn_irflag_read(dp) & VIRF_MOUNTPOINT) != 0); return (error); }
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?202311041715.3A4HFoZW004108>