Reimplement traverse() helper function:
1. Pass locking flags to VFS_ROOT(). 2. Check v_mountedhere while the vnode is locked. 3. Always return locked vnode on success. Change 1 fixes problem reported by Stephen M. Rumble - after zfs_vfsops.c,1.9 change, zfs_root() no longer locks the vnode unconditionally and traverse() didn't pass right lock type to VFS_ROOT(). The result was that kernel paniced when .zfs/ directory was accessed via NFS.
This commit is contained in:
Pawel Jakub Dawidek
parent
7344a290dc
commit
b166b92692
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=170281
@ -110,7 +110,7 @@ vfs_optionisset(const vfs_t *vfsp, const char *opt, char **argp)
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}
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int
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traverse(vnode_t **cvpp)
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traverse(vnode_t **cvpp, int lktype)
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{
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kthread_t *td = curthread;
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vnode_t *cvp;
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@ -119,7 +119,7 @@ traverse(vnode_t **cvpp)
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int error;
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cvp = *cvpp;
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error = 0;
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tvp = NULL;
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/*
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* If this vnode is mounted on, then we transparently indirect
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@ -135,22 +135,26 @@ traverse(vnode_t **cvpp)
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vfsp = vn_mountedvfs(cvp);
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if (vfsp == NULL)
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break;
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VN_RELE(cvp);
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/*
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* tvp is NULL for *cvpp vnode, which we can't unlock.
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*/
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if (tvp != NULL)
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vput(cvp);
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else
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vrele(cvp);
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/*
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* The read lock must be held across the call to VFS_ROOT() to
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* prevent a concurrent unmount from destroying the vfs.
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*/
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error = VFS_ROOT(vfsp, 0, &tvp, td);
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if (error)
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break;
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VOP_UNLOCK(tvp, 0, td);
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error = VFS_ROOT(vfsp, lktype, &tvp, td);
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if (error != 0)
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return (error);
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cvp = tvp;
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}
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*cvpp = cvp;
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return (error);
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return (0);
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}
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int
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@ -107,7 +107,7 @@ void vfs_setmntopt(vfs_t *vfsp, const char *name, const char *arg,
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int flags __unused);
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void vfs_clearmntopt(vfs_t *vfsp, const char *name);
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int vfs_optionisset(const vfs_t *vfsp, const char *opt, char **argp);
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int traverse(vnode_t **cvpp);
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int traverse(vnode_t **cvpp, int lktype);
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int domount(kthread_t *td, vnode_t *vp, const char *fstype, char *fspath,
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char *fspec, int fsflags);
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@ -924,18 +924,14 @@ zfsctl_snapshot_inactive(ap)
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}
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static int
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zfsctl_traverse_begin(vnode_t **vpp, kthread_t *td)
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zfsctl_traverse_begin(vnode_t **vpp, int lktype, kthread_t *td)
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{
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int err;
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VN_HOLD(*vpp);
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/* Snapshot should be already mounted, but just in case. */
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if (vn_mountedvfs(*vpp) == NULL)
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return (ENOENT);
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err = traverse(vpp);
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if (err == 0)
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vn_lock(*vpp, LK_SHARED | LK_RETRY, td);
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return (err);
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return (traverse(vpp, lktype));
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}
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static void
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@ -960,7 +956,7 @@ zfsctl_snapshot_getattr(ap)
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vnode_t *vp = ap->a_vp;
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int err;
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err = zfsctl_traverse_begin(&vp, ap->a_td);
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err = zfsctl_traverse_begin(&vp, LK_SHARED | LK_RETRY, ap->a_td);
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if (err == 0)
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err = VOP_GETATTR(vp, ap->a_vap, ap->a_cred, ap->a_td);
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zfsctl_traverse_end(vp, err);
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@ -977,7 +973,7 @@ zfsctl_snapshot_fid(ap)
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vnode_t *vp = ap->a_vp;
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int err;
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err = zfsctl_traverse_begin(&vp, curthread);
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err = zfsctl_traverse_begin(&vp, LK_SHARED | LK_RETRY, curthread);
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if (err == 0)
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err = VOP_VPTOFH(vp, (void *)ap->a_fid);
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zfsctl_traverse_end(vp, err);
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@ -1026,7 +1022,7 @@ zfsctl_lookup_objset(vfs_t *vfsp, uint64_t objsetid, zfsvfs_t **zfsvfsp)
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if (sep != NULL) {
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VN_HOLD(vp);
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error = traverse(&vp);
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error = traverse(&vp, LK_SHARED | LK_RETRY);
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if (error == 0) {
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if (vp == sep->se_root)
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error = EINVAL;
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@ -1034,7 +1030,10 @@ zfsctl_lookup_objset(vfs_t *vfsp, uint64_t objsetid, zfsvfs_t **zfsvfsp)
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*zfsvfsp = VTOZ(vp)->z_zfsvfs;
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}
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mutex_exit(&sdp->sd_lock);
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VN_RELE(vp);
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if (error == 0)
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VN_URELE(vp);
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else
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VN_RELE(vp);
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} else {
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error = EINVAL;
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mutex_exit(&sdp->sd_lock);
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@ -110,7 +110,7 @@ vfs_optionisset(const vfs_t *vfsp, const char *opt, char **argp)
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}
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int
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traverse(vnode_t **cvpp)
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traverse(vnode_t **cvpp, int lktype)
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{
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kthread_t *td = curthread;
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vnode_t *cvp;
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@ -119,7 +119,7 @@ traverse(vnode_t **cvpp)
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int error;
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cvp = *cvpp;
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error = 0;
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tvp = NULL;
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/*
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* If this vnode is mounted on, then we transparently indirect
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@ -135,22 +135,26 @@ traverse(vnode_t **cvpp)
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vfsp = vn_mountedvfs(cvp);
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if (vfsp == NULL)
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break;
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VN_RELE(cvp);
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/*
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* tvp is NULL for *cvpp vnode, which we can't unlock.
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*/
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if (tvp != NULL)
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vput(cvp);
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else
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vrele(cvp);
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/*
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* The read lock must be held across the call to VFS_ROOT() to
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* prevent a concurrent unmount from destroying the vfs.
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*/
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error = VFS_ROOT(vfsp, 0, &tvp, td);
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if (error)
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break;
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VOP_UNLOCK(tvp, 0, td);
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error = VFS_ROOT(vfsp, lktype, &tvp, td);
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if (error != 0)
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return (error);
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cvp = tvp;
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}
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*cvpp = cvp;
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return (error);
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return (0);
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}
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int
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@ -107,7 +107,7 @@ void vfs_setmntopt(vfs_t *vfsp, const char *name, const char *arg,
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int flags __unused);
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void vfs_clearmntopt(vfs_t *vfsp, const char *name);
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int vfs_optionisset(const vfs_t *vfsp, const char *opt, char **argp);
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int traverse(vnode_t **cvpp);
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int traverse(vnode_t **cvpp, int lktype);
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int domount(kthread_t *td, vnode_t *vp, const char *fstype, char *fspath,
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char *fspec, int fsflags);
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@ -924,18 +924,14 @@ zfsctl_snapshot_inactive(ap)
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}
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static int
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zfsctl_traverse_begin(vnode_t **vpp, kthread_t *td)
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zfsctl_traverse_begin(vnode_t **vpp, int lktype, kthread_t *td)
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{
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int err;
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VN_HOLD(*vpp);
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/* Snapshot should be already mounted, but just in case. */
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if (vn_mountedvfs(*vpp) == NULL)
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return (ENOENT);
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err = traverse(vpp);
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if (err == 0)
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vn_lock(*vpp, LK_SHARED | LK_RETRY, td);
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return (err);
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return (traverse(vpp, lktype));
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}
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static void
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@ -960,7 +956,7 @@ zfsctl_snapshot_getattr(ap)
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vnode_t *vp = ap->a_vp;
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int err;
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err = zfsctl_traverse_begin(&vp, ap->a_td);
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err = zfsctl_traverse_begin(&vp, LK_SHARED | LK_RETRY, ap->a_td);
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if (err == 0)
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err = VOP_GETATTR(vp, ap->a_vap, ap->a_cred, ap->a_td);
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zfsctl_traverse_end(vp, err);
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@ -977,7 +973,7 @@ zfsctl_snapshot_fid(ap)
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vnode_t *vp = ap->a_vp;
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int err;
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err = zfsctl_traverse_begin(&vp, curthread);
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err = zfsctl_traverse_begin(&vp, LK_SHARED | LK_RETRY, curthread);
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if (err == 0)
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err = VOP_VPTOFH(vp, (void *)ap->a_fid);
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zfsctl_traverse_end(vp, err);
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@ -1026,7 +1022,7 @@ zfsctl_lookup_objset(vfs_t *vfsp, uint64_t objsetid, zfsvfs_t **zfsvfsp)
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if (sep != NULL) {
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VN_HOLD(vp);
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error = traverse(&vp);
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error = traverse(&vp, LK_SHARED | LK_RETRY);
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if (error == 0) {
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if (vp == sep->se_root)
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error = EINVAL;
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@ -1034,7 +1030,10 @@ zfsctl_lookup_objset(vfs_t *vfsp, uint64_t objsetid, zfsvfs_t **zfsvfsp)
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*zfsvfsp = VTOZ(vp)->z_zfsvfs;
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}
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mutex_exit(&sdp->sd_lock);
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VN_RELE(vp);
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if (error == 0)
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VN_URELE(vp);
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else
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VN_RELE(vp);
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} else {
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error = EINVAL;
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mutex_exit(&sdp->sd_lock);
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