Rework v_object lifecycle for vnodes.

Current implementation of vnode_create_vobject() and
vnode_destroy_vobject() is written so that it prepared to handle the
vm object destruction for live vnode.  Practically, no filesystems use
this, except for some remnants that were present in UFS till today.
One of the consequences of that model is that each filesystem must
call vnode_destroy_vobject() in VOP_RECLAIM() or earlier, as result
all of them get rid of the v_object in reclaim.

Move the call to vnode_destroy_vobject() to vgonel() before
VOP_RECLAIM().  This makes v_object stable: either the object is NULL,
or it is valid vm object till the vnode reclamation.  Remove code from
vnode_create_vobject() to handle races with the parallel destruction.

Reviewed by:	markj
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D21412

diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
index fa3085d2def9759bc1a0b09ccdb45897dda42b87..30e312104bbbe07f9fa5e3dd54e5783d8e090d4d 100644 (file)
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
@@ -5375,9 +5375,6 @@ zfs_freebsd_reclaim(ap)
 
        ASSERT(zp != NULL);
 
-       /* Destroy the vm object and flush associated pages. */
-       vnode_destroy_vobject(vp);
-
        /*
         * z_teardown_inactive_lock protects from a race with
         * zfs_znode_dmu_fini in zfsvfs_teardown during

diff --git a/sys/fs/cd9660/cd9660_node.c b/sys/fs/cd9660/cd9660_node.c
index 17d70d869b79396810759396ff310c8ba3a49228..c74bf4a3005c96a9894142b3552826f6b36fb193 100644 (file)
--- a/sys/fs/cd9660/cd9660_node.c
+++ b/sys/fs/cd9660/cd9660_node.c
@@ -91,10 +91,6 @@ cd9660_reclaim(ap)
 {
        struct vnode *vp = ap->a_vp;
 
-       /*
-        * Destroy the vm object and flush associated pages.
-        */
-       vnode_destroy_vobject(vp);
        /*
         * Remove the inode from its hash chain.
         */

diff --git a/sys/fs/devfs/devfs_vnops.c b/sys/fs/devfs/devfs_vnops.c
index 590334f1615b7ecdf1b623156ad753f0db253442..ab6e7e13b8baec2bd475221d8922362ae1b7d42f 100644 (file)
--- a/sys/fs/devfs/devfs_vnops.c
+++ b/sys/fs/devfs/devfs_vnops.c
@@ -1428,7 +1428,6 @@ devfs_reclaim(struct vop_reclaim_args *ap)
                vp->v_data = NULL;
        }
        mtx_unlock(&devfs_de_interlock);
-       vnode_destroy_vobject(vp);
        return (0);
 }
 

diff --git a/sys/fs/ext2fs/ext2_inode.c b/sys/fs/ext2fs/ext2_inode.c
index 4f0de4b6f5c99ba669fbe3c2422ff620ab4ad71c..d5e05cbe4747f6c56db34b3e0204cf4104be0372 100644 (file)
--- a/sys/fs/ext2fs/ext2_inode.c
+++ b/sys/fs/ext2fs/ext2_inode.c
@@ -639,6 +639,5 @@ ext2_reclaim(struct vop_reclaim_args *ap)
        vfs_hash_remove(vp);
        free(vp->v_data, M_EXT2NODE);
        vp->v_data = 0;
-       vnode_destroy_vobject(vp);
        return (0);
 }

diff --git a/sys/fs/fuse/fuse_vnops.c b/sys/fs/fuse/fuse_vnops.c
index 537f1b734c29381e752eea62fa5f16f21bddebc9..c886527b480a9467c754f60d165156dfb1f8b7c3 100644 (file)
--- a/sys/fs/fuse/fuse_vnops.c
+++ b/sys/fs/fuse/fuse_vnops.c
@@ -1537,7 +1537,6 @@ fuse_vnop_reclaim(struct vop_reclaim_args *ap)
        fuse_vnode_setparent(vp, NULL);
        cache_purge(vp);
        vfs_hash_remove(vp);
-       vnode_destroy_vobject(vp);
        fuse_vnode_destroy(vp);
 
        return 0;

diff --git a/sys/fs/msdosfs/msdosfs_denode.c b/sys/fs/msdosfs/msdosfs_denode.c
index 19ba40fed97f2062fce612aa45db874f87a613e9..858cf1b58908a3537f21d34b30e6201f59450ae7 100644 (file)
--- a/sys/fs/msdosfs/msdosfs_denode.c
+++ b/sys/fs/msdosfs/msdosfs_denode.c
@@ -551,10 +551,6 @@ msdosfs_reclaim(struct vop_reclaim_args *ap)
            dep, dep->de_Name, dep->de_refcnt);
 #endif
 
-       /*
-        * Destroy the vm object and flush associated pages.
-        */
-       vnode_destroy_vobject(vp);
        /*
         * Remove the denode from its hash chain.
         */

diff --git a/sys/fs/nfsclient/nfs_clnode.c b/sys/fs/nfsclient/nfs_clnode.c
index 9e54f6e9f238299a7551d948ce68143a73b3f098..0baf710d9cfaea189066057d128d86d32a4eeb0d 100644 (file)
--- a/sys/fs/nfsclient/nfs_clnode.c
+++ b/sys/fs/nfsclient/nfs_clnode.c
@@ -296,11 +296,6 @@ ncl_reclaim(struct vop_reclaim_args *ap)
        ncl_releasesillyrename(vp, ap->a_td);
        mtx_unlock(&np->n_mtx);
 
-       /*
-        * Destroy the vm object and flush associated pages.
-        */
-       vnode_destroy_vobject(vp);
-
        if (NFS_ISV4(vp) && vp->v_type == VREG)
                /*
                 * We can now safely close any remaining NFSv4 Opens for

diff --git a/sys/fs/smbfs/smbfs_node.c b/sys/fs/smbfs/smbfs_node.c
index 299d07a0b4af44ad6eefa702daaeaa0d16be651e..16b5de938464761f40f0276e45bcfa6459f0389f 100644 (file)
--- a/sys/fs/smbfs/smbfs_node.c
+++ b/sys/fs/smbfs/smbfs_node.c
@@ -272,10 +272,6 @@ smbfs_reclaim(ap)
 
        KASSERT((np->n_flag & NOPEN) == 0, ("file not closed before reclaim"));
 
-       /*
-        * Destroy the vm object and flush associated pages.
-        */
-       vnode_destroy_vobject(vp);
        dvp = (np->n_parent && (np->n_flag & NREFPARENT)) ?
            np->n_parent : NULL;
        

diff --git a/sys/fs/tmpfs/tmpfs_vnops.c b/sys/fs/tmpfs/tmpfs_vnops.c
index 1b3aa6d2db92dfc7c609db0ae79b5457d199e54f..1c181bc3a59d4bc44ee903e4ee20a35ee39aa624 100644 (file)
--- a/sys/fs/tmpfs/tmpfs_vnops.c
+++ b/sys/fs/tmpfs/tmpfs_vnops.c
@@ -1317,8 +1317,6 @@ tmpfs_reclaim(struct vop_reclaim_args *v)
 
        if (vp->v_type == VREG)
                tmpfs_destroy_vobject(vp, node->tn_reg.tn_aobj);
-       else
-               vnode_destroy_vobject(vp);
        vp->v_object = NULL;
        if (tmpfs_use_nc(vp))
                cache_purge(vp);

diff --git a/sys/fs/udf/udf_vnops.c b/sys/fs/udf/udf_vnops.c
index b1b004f95166c28eb84cd621e4a1fd276ac703ee..3f0666054f955a97b39ff7a0219cbb14b5dd0e84 100644 (file)
--- a/sys/fs/udf/udf_vnops.c
+++ b/sys/fs/udf/udf_vnops.c
@@ -1266,11 +1266,6 @@ udf_reclaim(struct vop_reclaim_args *a)
        vp = a->a_vp;
        unode = VTON(vp);
 
-       /*
-        * Destroy the vm object and flush associated pages.
-        */
-       vnode_destroy_vobject(vp);
-
        if (unode != NULL) {
                vfs_hash_remove(vp);
 

diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 1af4aa02883354c6998d54640c4f08b0f76a2ca7..b6ec815fca071b61018ab6e2ab12829fe6745835 100644 (file)
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -3481,9 +3481,9 @@ static void
 vgonel(struct vnode *vp)
 {
        struct thread *td;
-       int oweinact;
-       int active;
        struct mount *mp;
+       vm_object_t object;
+       bool active, oweinact;
 
        ASSERT_VOP_ELOCKED(vp, "vgonel");
        ASSERT_VI_LOCKED(vp, "vgonel");
@@ -3503,8 +3503,8 @@ vgonel(struct vnode *vp)
         * Check to see if the vnode is in use.  If so, we have to call
         * VOP_CLOSE() and VOP_INACTIVE().
         */
-       active = vp->v_usecount;
-       oweinact = (vp->v_iflag & VI_OWEINACT);
+       active = vp->v_usecount > 0;
+       oweinact = (vp->v_iflag & VI_OWEINACT) != 0;
        VI_UNLOCK(vp);
        vfs_notify_upper(vp, VFS_NOTIFY_UPPER_RECLAIM);
 
@@ -3543,13 +3543,25 @@ vgonel(struct vnode *vp)
            ("vp %p bufobj not invalidated", vp));
 
        /*
-        * For VMIO bufobj, BO_DEAD is set in vm_object_terminate()
-        * after the object's page queue is flushed.
+        * For VMIO bufobj, BO_DEAD is set later, or in
+        * vm_object_terminate() after the object's page queue is
+        * flushed.
         */
-       if (vp->v_bufobj.bo_object == NULL)
+       object = vp->v_bufobj.bo_object;
+       if (object == NULL)
                vp->v_bufobj.bo_flag |= BO_DEAD;
        BO_UNLOCK(&vp->v_bufobj);
 
+       /*
+        * Handle the VM part.  Tmpfs handles v_object on its own (the
+        * OBJT_VNODE check).  Nullfs or other bypassing filesystems
+        * should not touch the object borrowed from the lower vnode
+        * (the handle check).
+        */
+       if (object != NULL && object->type == OBJT_VNODE &&
+           object->handle == vp)
+               vnode_destroy_vobject(vp);
+
        /*
         * Reclaim the vnode.
         */

diff --git a/sys/ufs/ufs/ufs_extern.h b/sys/ufs/ufs/ufs_extern.h
index db75d3a2f66accd41cfc0c0cbb3e7c2378dcff3a..9a326a92eb3372c4047cd6a1ebdad1d5d8ff6513 100644 (file)
--- a/sys/ufs/ufs/ufs_extern.h
+++ b/sys/ufs/ufs/ufs_extern.h
@@ -79,7 +79,6 @@ int    ufs_inactive(struct vop_inactive_args *);
 int     ufs_init(struct vfsconf *);
 void    ufs_itimes(struct vnode *vp);
 int     ufs_lookup(struct vop_cachedlookup_args *);
-void    ufs_prepare_reclaim(struct vnode *vp);
 int     ufs_readdir(struct vop_readdir_args *);
 int     ufs_reclaim(struct vop_reclaim_args *);
 void    ffs_snapgone(struct inode *);

diff --git a/sys/ufs/ufs/ufs_inode.c b/sys/ufs/ufs/ufs_inode.c
index 7ef5e6fb8ad82a2e11448dd38c0fd7b13d4927df..8fd54b384d3b9dee3090ed2d45ca4ab0d1898230 100644 (file)
--- a/sys/ufs/ufs/ufs_inode.c
+++ b/sys/ufs/ufs/ufs_inode.c
@@ -179,18 +179,21 @@ out:
        return (error);
 }
 
-void
-ufs_prepare_reclaim(struct vnode *vp)
+/*
+ * Reclaim an inode so that it can be used for other purposes.
+ */
+int
+ufs_reclaim(ap)
+       struct vop_reclaim_args /* {
+               struct vnode *a_vp;
+               struct thread *a_td;
+       } */ *ap;
 {
-       struct inode *ip;
+       struct vnode *vp = ap->a_vp;
+       struct inode *ip = VTOI(vp);
 #ifdef QUOTA
        int i;
-#endif
 
-       ip = VTOI(vp);
-
-       vnode_destroy_vobject(vp);
-#ifdef QUOTA
        for (i = 0; i < MAXQUOTAS; i++) {
                if (ip->i_dquot[i] != NODQUOT) {
                        dqrele(vp, ip->i_dquot[i]);
@@ -202,22 +205,6 @@ ufs_prepare_reclaim(struct vnode *vp)
        if (ip->i_dirhash != NULL)
                ufsdirhash_free(ip);
 #endif
-}
-
-/*
- * Reclaim an inode so that it can be used for other purposes.
- */
-int
-ufs_reclaim(ap)
-       struct vop_reclaim_args /* {
-               struct vnode *a_vp;
-               struct thread *a_td;
-       } */ *ap;
-{
-       struct vnode *vp = ap->a_vp;
-       struct inode *ip = VTOI(vp);
-
-       ufs_prepare_reclaim(vp);
 
        if (ip->i_flag & IN_LAZYMOD)
                ip->i_flag |= IN_MODIFIED;

diff --git a/sys/vm/vm_object.h b/sys/vm/vm_object.h
index 8625e1022ca491563372b46808439e9139822e62..3910e3d19528748cb20084e6d5f704a8f16e03d5 100644 (file)
--- a/sys/vm/vm_object.h
+++ b/sys/vm/vm_object.h
@@ -189,7 +189,6 @@ struct vm_object {
 #define        OBJ_TMPFS_DIRTY 0x0400          /* dirty tmpfs obj */
 #define        OBJ_COLORED     0x1000          /* pg_color is defined */
 #define        OBJ_ONEMAPPING  0x2000          /* One USE (a single, non-forked) mapping flag */
-#define        OBJ_DISCONNECTWNT 0x4000        /* disconnect from vnode wanted */
 #define        OBJ_TMPFS       0x8000          /* has tmpfs vnode allocated */
 
 /*

diff --git a/sys/vm/vnode_pager.c b/sys/vm/vnode_pager.c
index ed286e0024cde14c99b08a99ed2621eb0a184175..a12a4b80defdd4a03edab0cf9c889c9b2aa9447b 100644 (file)
--- a/sys/vm/vnode_pager.c
+++ b/sys/vm/vnode_pager.c
@@ -147,17 +147,9 @@ vnode_create_vobject(struct vnode *vp, off_t isize, struct thread *td)
        if (!vn_isdisk(vp, NULL) && vn_canvmio(vp) == FALSE)
                return (0);
 
-       while ((object = vp->v_object) != NULL) {
-               VM_OBJECT_WLOCK(object);
-               if (!(object->flags & OBJ_DEAD)) {
-                       VM_OBJECT_WUNLOCK(object);
-                       return (0);
-               }
-               VOP_UNLOCK(vp, 0);
-               vm_object_set_flag(object, OBJ_DISCONNECTWNT);
-               VM_OBJECT_SLEEP(object, object, PDROP | PVM, "vodead", 0);
-               vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
-       }
+       object = vp->v_object;
+       if (object != NULL)
+               return (0);
 
        if (size == 0) {
                if (vn_isdisk(vp, NULL)) {
@@ -190,10 +182,11 @@ vnode_destroy_vobject(struct vnode *vp)
        struct vm_object *obj;
 
        obj = vp->v_object;
-       if (obj == NULL)
+       if (obj == NULL || obj->handle != vp)
                return;
        ASSERT_VOP_ELOCKED(vp, "vnode_destroy_vobject");
        VM_OBJECT_WLOCK(obj);
+       MPASS(obj->type == OBJT_VNODE);
        umtx_shm_object_terminated(obj);
        if (obj->ref_count == 0) {
                /*
@@ -223,9 +216,6 @@ vnode_destroy_vobject(struct vnode *vp)
                         * prevented new waiters from referencing the dying
                         * object.
                         */
-                       KASSERT((obj->flags & OBJ_DISCONNECTWNT) == 0,
-                           ("OBJ_DISCONNECTWNT set obj %p flags %x",
-                           obj, obj->flags));
                        vp->v_object = NULL;
                        VM_OBJECT_WUNLOCK(obj);
                }
@@ -243,8 +233,6 @@ vnode_destroy_vobject(struct vnode *vp)
 /*
  * Allocate (or lookup) pager for a vnode.
  * Handle is a vnode pointer.
- *
- * MPSAFE
  */
 vm_object_t
 vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
@@ -259,28 +247,18 @@ vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
        if (handle == NULL)
                return (NULL);
 
-       vp = (struct vnode *) handle;
-
-       /*
-        * If the object is being terminated, wait for it to
-        * go away.
-        */
-retry:
-       while ((object = vp->v_object) != NULL) {
-               VM_OBJECT_WLOCK(object);
-               if ((object->flags & OBJ_DEAD) == 0)
-                       break;
-               vm_object_set_flag(object, OBJ_DISCONNECTWNT);
-               VM_OBJECT_SLEEP(object, object, PDROP | PVM, "vadead", 0);
-       }
-
+       vp = (struct vnode *)handle;
+       ASSERT_VOP_LOCKED(vp, "vnode_pager_alloc");
        KASSERT(vp->v_usecount != 0, ("vnode_pager_alloc: no vnode reference"));
+retry:
+       object = vp->v_object;
 
        if (object == NULL) {
                /*
                 * Add an object of the appropriate size
                 */
-               object = vm_object_allocate(OBJT_VNODE, OFF_TO_IDX(round_page(size)));
+               object = vm_object_allocate(OBJT_VNODE,
+                   OFF_TO_IDX(round_page(size)));
 
                object->un_pager.vnp.vnp_size = size;
                object->un_pager.vnp.writemappings = 0;
@@ -290,7 +268,7 @@ retry:
                VI_LOCK(vp);
                if (vp->v_object != NULL) {
                        /*
-                        * Object has been created while we were sleeping
+                        * Object has been created while we were allocating.
                         */
                        VI_UNLOCK(vp);
                        VM_OBJECT_WLOCK(object);
@@ -305,6 +283,7 @@ retry:
                vp->v_object = object;
                VI_UNLOCK(vp);
        } else {
+               VM_OBJECT_WLOCK(object);
                object->ref_count++;
 #if VM_NRESERVLEVEL > 0
                vm_object_color(object, 0);
@@ -334,10 +313,6 @@ vnode_pager_dealloc(vm_object_t object)
 
        object->handle = NULL;
        object->type = OBJT_DEAD;
-       if (object->flags & OBJ_DISCONNECTWNT) {
-               vm_object_clear_flag(object, OBJ_DISCONNECTWNT);
-               wakeup(object);
-       }
        ASSERT_VOP_ELOCKED(vp, "vnode_pager_dealloc");
        if (object->un_pager.vnp.writemappings > 0) {
                object->un_pager.vnp.writemappings = 0;