basic FSH

*** 82,91 ****
--- 82,93 ----
  #include <sys/attr.h>
  #include <sys/zio.h>
  #include <sys/spa.h>
  #include <sys/lofi.h>
  #include <sys/bootprops.h>
+ #include <sys/fsh.h>
+ #include <sys/fsh_impl.h>
  
  #include <vm/page.h>
  
  #include <fs/fs_subr.h>
  /* Private interfaces to create vopstats-related data structures */
*** 214,237 ****
   */
  
  int
  fsop_mount(vfs_t *vfsp, vnode_t *mvp, struct mounta *uap, cred_t *cr)
  {
!         return (*(vfsp)->vfs_op->vfs_mount)(vfsp, mvp, uap, cr);
  }
  
  int
  fsop_unmount(vfs_t *vfsp, int flag, cred_t *cr)
  {
!         return (*(vfsp)->vfs_op->vfs_unmount)(vfsp, flag, cr);
  }
  
  int
  fsop_root(vfs_t *vfsp, vnode_t **vpp)
  {
          refstr_t *mntpt;
!         int ret = (*(vfsp)->vfs_op->vfs_root)(vfsp, vpp);
          /*
           * Make sure this root has a path.  With lofs, it is possible to have
           * a NULL mountpoint.
           */
          if (ret == 0 && vfsp->vfs_mntpt != NULL && (*vpp)->v_path == NULL) {
--- 216,239 ----
   */
  
  int
  fsop_mount(vfs_t *vfsp, vnode_t *mvp, struct mounta *uap, cred_t *cr)
  {
!         return (fsh_mount(vfsp, mvp, uap, cr));
  }
  
  int
  fsop_unmount(vfs_t *vfsp, int flag, cred_t *cr)
  {
!         return (fsh_unmount(vfsp, flag, cr));
  }
  
  int
  fsop_root(vfs_t *vfsp, vnode_t **vpp)
  {
          refstr_t *mntpt;
!         int ret = fsh_root(vfsp, vpp);
          /*
           * Make sure this root has a path.  With lofs, it is possible to have
           * a NULL mountpoint.
           */
          if (ret == 0 && vfsp->vfs_mntpt != NULL && (*vpp)->v_path == NULL) {
*** 245,255 ****
  }
  
  int
  fsop_statfs(vfs_t *vfsp, statvfs64_t *sp)
  {
!         return (*(vfsp)->vfs_op->vfs_statvfs)(vfsp, sp);
  }
  
  int
  fsop_sync(vfs_t *vfsp, short flag, cred_t *cr)
  {
--- 247,257 ----
  }
  
  int
  fsop_statfs(vfs_t *vfsp, statvfs64_t *sp)
  {
!         return (fsh_statfs(vfsp, sp));
  }
  
  int
  fsop_sync(vfs_t *vfsp, short flag, cred_t *cr)
  {
*** 272,282 ****
           */
          if (vfs_has_feature(vfsp, VFSFT_SYSATTR_VIEWS) &&
              fidp->fid_len == XATTR_FIDSZ)
                  return (xattr_dir_vget(vfsp, vpp, fidp));
  
!         return (*(vfsp)->vfs_op->vfs_vget)(vfsp, vpp, fidp);
  }
  
  int
  fsop_mountroot(vfs_t *vfsp, enum whymountroot reason)
  {
--- 274,284 ----
           */
          if (vfs_has_feature(vfsp, VFSFT_SYSATTR_VIEWS) &&
              fidp->fid_len == XATTR_FIDSZ)
                  return (xattr_dir_vget(vfsp, vpp, fidp));
  
!         return (fsh_vget(vfsp, vpp, fidp));
  }
  
  int
  fsop_mountroot(vfs_t *vfsp, enum whymountroot reason)
  {
*** 1783,1792 ****
--- 1785,1795 ----
                                  vfs_unlock(vfsp);
                          }
                  }
                  /* Return vfsp to caller. */
                  *vfspp = vfsp;
+                 fsh_exec_mount_callbacks(vfsp);
          }
  errout:
          vfs_freeopttbl(&mnt_mntopts);
          if (resource != NULL)
                  kmem_free(resource, strlen(resource) + 1);
*** 4233,4242 ****
--- 4236,4248 ----
          vn_create_cache();
  
          /* Setup event monitor framework */
          fem_init();
  
+         /* Setup filesystem hook framework */
+         fsh_init();
+ 
          /* Initialize the dummy stray file system type. */
          error = vfs_setfsops(0, stray_vfsops_template, NULL);
  
          /* Initialize the dummy EIO file system. */
          error = vfs_makefsops(EIO_vfsops_template, &EIO_vfsops);
*** 4317,4326 ****
--- 4323,4339 ----
                  mutex_destroy(&vfsp->vfs_femhead->femh_lock);
                  kmem_free(vfsp->vfs_femhead, sizeof (*(vfsp->vfs_femhead)));
                  vfsp->vfs_femhead = NULL;
          }
  
+         /*
+          * FSH cleanup
+          * There's no need here to use atomic operations on vfs_fshrecord.
+          */
+         fsh_fsrec_destroy(vfsp->vfs_fshrecord);
+         vfsp->vfs_fshrecord = NULL;
+ 
          if (vfsp->vfs_implp)
                  vfsimpl_teardown(vfsp);
          sema_destroy(&vfsp->vfs_reflock);
          kmem_cache_free(vfs_cache, vfsp);
  }
*** 4343,4352 ****
--- 4356,4366 ----
  void
  vfs_rele(vfs_t *vfsp)
  {
          ASSERT(vfsp->vfs_count != 0);
          if (atomic_add_32_nv(&vfsp->vfs_count, -1) == 0) {
+                 fsh_exec_free_callbacks(vfsp);
                  VFS_FREEVFS(vfsp);
                  lofi_remove(vfsp);
                  if (vfsp->vfs_zone)
                          zone_rele_ref(&vfsp->vfs_implp->vi_zone_ref,
                              ZONE_REF_VFS);