Fix read-only pool hang on unmount

During mount a filesystem dataset would have the MS_RDONLY bit
incorrectly cleared even if the entire pool was read-only.
There is existing to code to handle this case but it was being run
before the property callbacks were registered.  To resolve the
issue we move this read-only code after the callback registration.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1338

diff --git a/module/zfs/zfs_vfsops.c b/module/zfs/zfs_vfsops.c
index 602c332..9ae7ab5 100644 (file)
--- a/module/zfs/zfs_vfsops.c
+++ b/module/zfs/zfs_vfsops.c
@@ -233,10 +233,11 @@ zfs_register_callbacks(zfs_sb_t *zsb)
 {
        struct dsl_dataset *ds = NULL;
        objset_t *os = zsb->z_os;
+       boolean_t do_readonly = B_FALSE;
        int error = 0;
 
        if (zfs_is_readonly(zsb) || !spa_writeable(dmu_objset_spa(os)))
-               readonly_changed_cb(zsb, B_TRUE);
+               do_readonly = B_TRUE;
 
        /*
         * Register property callbacks.
@@ -271,6 +272,9 @@ zfs_register_callbacks(zfs_sb_t *zsb)
        if (error)
                goto unregister;
 
+       if (do_readonly)
+               readonly_changed_cb(zsb, B_TRUE);
+
        return (0);
 
 unregister: