diff options
| author | kib <kib@FreeBSD.org> | 2006-10-03 10:47:04 +0000 |
|---|---|---|
| committer | kib <kib@FreeBSD.org> | 2006-10-03 10:47:04 +0000 |
| commit | 38b2c3b26ff71791f1be25e408220f04e61ea61f (patch) | |
| tree | f208ea8fc9e93064439efb11864fcf850ffb9750 | |
| parent | b2a6f9f628bc2678bab67e0a00ff7be2dcce38da (diff) | |
| download | FreeBSD-src-38b2c3b26ff71791f1be25e408220f04e61ea61f.zip FreeBSD-src-38b2c3b26ff71791f1be25e408220f04e61ea61f.tar.gz | |
Fix the remaining race in the revs. 1.232, 1,233 that could occur during
unmount when mp structure is reused while waiting for coveredvp lock.
Introduce struct mount generation count, increment it on each reuse and
compare the generations before and after obtaining the coveredvp lock.
Reviewed by: tegge, pjd
Approved by: pjd (mentor)
MFC after: 2 weeks
| -rw-r--r-- | sys/kern/vfs_mount.c | 6 | ||||
| -rw-r--r-- | sys/sys/mount.h | 1 |
2 files changed, 6 insertions, 1 deletions
diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c index c89a5fa..0598905 100644 --- a/sys/kern/vfs_mount.c +++ b/sys/kern/vfs_mount.c @@ -475,6 +475,7 @@ vfs_mount_alloc(struct vnode *vp, struct vfsconf *vfsp, MNT_ILOCK(mp); mp->mnt_flag |= vfsp->vfc_flags & MNT_VISFLAGMASK; MNT_IUNLOCK(mp); + mp->mnt_gen++; strlcpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN); mp->mnt_vnodecovered = vp; mp->mnt_cred = crdup(td->td_ucred); @@ -1148,10 +1149,12 @@ dounmount(mp, flags, td) struct vnode *coveredvp, *fsrootvp; int error; int async_flag; + int mnt_gen_r; mtx_assert(&Giant, MA_OWNED); if ((coveredvp = mp->mnt_vnodecovered) != NULL) { + mnt_gen_r = mp->mnt_gen; VI_LOCK(coveredvp); vholdl(coveredvp); error = vn_lock(coveredvp, LK_EXCLUSIVE | LK_INTERLOCK, td); @@ -1162,7 +1165,8 @@ dounmount(mp, flags, td) */ if (error) return (error); - if (coveredvp->v_mountedhere != mp) { + if (coveredvp->v_mountedhere != mp || + coveredvp->v_mountedhere->mnt_gen != mnt_gen_r) { VOP_UNLOCK(coveredvp, 0, td); return (EBUSY); } diff --git a/sys/sys/mount.h b/sys/sys/mount.h index 16ea687..e67de9c 100644 --- a/sys/sys/mount.h +++ b/sys/sys/mount.h @@ -145,6 +145,7 @@ struct vfsopt; struct mount { struct lock mnt_lock; /* mount structure lock */ struct mtx mnt_mtx; /* mount structure interlock */ + int mnt_gen; /* struct mount generation */ #define mnt_startzero mnt_list TAILQ_ENTRY(mount) mnt_list; /* (m) mount list */ struct vfsops *mnt_op; /* operations on fs */ |
