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diff --git a/sys/kern/vfs_mount.c.setexp b/sys/kern/vfs_mount.c
--- a/sys/kern/vfs_mount.c.setexp
+++ b/sys/kern/vfs_mount.c
@@ -74,7 +74,7 @@
#define VFS_MOUNTARG_SIZE_MAX (1024 * 64)
static int vfs_domount(struct thread *td, const char *fstype, char *fspath,
- uint64_t fsflags, bool jail_export,
+ uint64_t fsflags, bool only_export, bool jail_export,
struct vfsoptlist **optlist);
static void free_mntarg(struct mntarg *ma);
@@ -806,7 +806,7 @@
struct vfsopt *opt, *tmp_opt;
char *fstype, *fspath, *errmsg;
int error, fstypelen, fspathlen, errmsg_len, errmsg_pos;
- bool autoro, has_nonexport, jail_export;
+ bool autoro, has_nonexport, only_export, jail_export;
errmsg = fspath = NULL;
errmsg_len = fspathlen = 0;
@@ -861,12 +861,11 @@
* when we want to update the root filesystem.
*/
has_nonexport = false;
- jail_export = false;
+ only_export = false;
TAILQ_FOREACH_SAFE(opt, optlist, link, tmp_opt) {
int do_freeopt = 0;
- if (jailed(td->td_ucred) &&
- strcmp(opt->name, "export") != 0 &&
+ if (strcmp(opt->name, "export") != 0 &&
strcmp(opt->name, "update") != 0 &&
strcmp(opt->name, "fstype") != 0 &&
strcmp(opt->name, "fspath") != 0 &&
@@ -957,7 +956,7 @@
fsflags |= MNT_UNION;
else if (strcmp(opt->name, "export") == 0) {
fsflags |= MNT_EXPORTED;
- jail_export = true;
+ only_export = true;
} else if (strcmp(opt->name, "automounted") == 0) {
fsflags |= MNT_AUTOMOUNTED;
do_freeopt = 1;
@@ -989,14 +988,22 @@
}
/*
- * If has_nonexport is true or the caller is not running within a
- * vnet prison that can run mountd(8), set jail_export false.
+ * only_export is set to true only if exports are being
+ * updated and nothing else is being updated.
*/
- if (has_nonexport || !jailed(td->td_ucred) ||
- !prison_check_nfsd(td->td_ucred))
- jail_export = false;
+ if (has_nonexport)
+ only_export = false;
+ /*
+ * If only_export is true and the caller is running within a
+ * vnet prison that can run mountd(8), set jail_export true.
+ */
+ jail_export = false;
+ if (only_export && jailed(td->td_ucred) &&
+ prison_check_nfsd(td->td_ucred))
+ jail_export = true;
- error = vfs_domount(td, fstype, fspath, fsflags, jail_export, &optlist);
+ error = vfs_domount(td, fstype, fspath, fsflags, only_export,
+ jail_export, &optlist);
if (error == ENODEV) {
error = EINVAL;
if (errmsg != NULL)
@@ -1014,8 +1021,8 @@
printf("%s: R/W mount failed, possibly R/O media,"
" trying R/O mount\n", __func__);
fsflags |= MNT_RDONLY;
- error = vfs_domount(td, fstype, fspath, fsflags, jail_export,
- &optlist);
+ error = vfs_domount(td, fstype, fspath, fsflags, only_export,
+ jail_export, &optlist);
}
bail:
/* copyout the errmsg */
@@ -1307,6 +1314,7 @@
struct thread *td, /* Calling thread. */
struct vnode *vp, /* Mount point vnode. */
uint64_t fsflags, /* Flags common to all filesystems. */
+ bool only_export, /* Got export option. */
bool jail_export, /* Got export option in vnet prison. */
struct vfsoptlist **optlist /* Options local to the filesystem. */
)
@@ -1442,15 +1450,16 @@
* get. No freeing of cn_pnbuf.
*/
/*
+ * When only updating mount exports, VFS_MOUNT() does not need to
+ * be called, as indicated by only_export being set true.
* For the case of mountd(8) doing exports from within a vnet jail,
* "from" is typically not set correctly such that VFS_MOUNT() will
- * return ENOENT. It is not obvious that VFS_MOUNT() ever needs to be
- * called when mountd is doing exports, but this check only applies to
- * the specific case where it is running inside a vnet jail, to
- * avoid any POLA violation.
+ * return ENOENT. For ZFS, there is a locking bug which can result in
+ * deadlock if VFS_MOUNT() is called when extended attributes are
+ * being updated.
*/
error = 0;
- if (!jail_export)
+ if (!only_export)
error = VFS_MOUNT(mp);
export_error = 0;
@@ -1590,6 +1599,7 @@
const char *fstype, /* Filesystem type. */
char *fspath, /* Mount path. */
uint64_t fsflags, /* Flags common to all filesystems. */
+ bool only_export, /* Got export option. */
bool jail_export, /* Got export option in vnet prison. */
struct vfsoptlist **optlist /* Options local to the filesystem. */
)
@@ -1693,8 +1703,8 @@
}
free(pathbuf, M_TEMP);
} else
- error = vfs_domount_update(td, vp, fsflags, jail_export,
- optlist);
+ error = vfs_domount_update(td, vp, fsflags, only_export,
+ jail_export, optlist);
out:
NDFREE_PNBUF(&nd);

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