xnu-6153.61.1.tar.gz

[apple/xnu.git] / bsd / miscfs / nullfs / null_subr.c

diff --git a/bsd/miscfs/nullfs/null_subr.c b/bsd/miscfs/nullfs/null_subr.c
index cd7f6618e68abdc59419ddbc7350aba1ced4e8c8..3743d52b2c43471a415a8d66895bc583710962a4 100644 (file)
--- a/bsd/miscfs/nullfs/null_subr.c
+++ b/bsd/miscfs/nullfs/null_subr.c
@@ -1,28 +1,29 @@
 /*
 /*

- * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2016 Apple Inc. All rights reserved.

  *
  * @APPLE_LICENSE_HEADER_START@
  *
  * @APPLE_LICENSE_HEADER_START@

- * 
- * The contents of this file constitute Original Code as defined in and
- * are subject to the Apple Public Source License Version 1.1 (the
- * "License").  You may not use this file except in compliance with the
- * License.  Please obtain a copy of the License at
- * http://www.apple.com/publicsource and read it before using this file.
- * 
- * This Original Code and all software distributed under the License are
- * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER

  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,

- * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
- * License for the specific language governing rights and limitations
- * under the License.
- * 
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *

  * @APPLE_LICENSE_HEADER_END@
  */
  * @APPLE_LICENSE_HEADER_END@
  */

-/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
-/*
- * Copyright (c) 1992, 1993
- *     The Regents of the University of California.  All rights reserved.
+
+/*-
+ * Portions Copyright (c) 1992, 1993
+ *  The Regents of the University of California.  All rights reserved.

  *
  * This code is derived from software donated to Berkeley by
  * Jan-Simon Pendry.
  *
  * This code is derived from software donated to Berkeley by
  * Jan-Simon Pendry.


@@ -35,10 +36,6 @@
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.

- * 3. All advertising materials mentioning features or use of this software
- *    must display the following acknowledgement:
- *     This product includes software developed by the University of
- *     California, Berkeley and its contributors.

  * 4. Neither the name of the University nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
  * 4. Neither the name of the University nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.


@@ -55,244 +52,353 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *

- *     @(#)null_subr.c 8.7 (Berkeley) 5/14/95
+ *  @(#)null_subr.c 8.7 (Berkeley) 5/14/95

  *
  *

- *     null_subr.c     8.4 (Berkeley) 1/21/94
+ * $FreeBSD$

  */
  */

-

 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/param.h>
 #include <sys/systm.h>

+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mount.h>

 #include <sys/proc.h>
 #include <sys/proc.h>

-#include <sys/time.h>
-#include <sys/types.h>

 #include <sys/vnode.h>
 #include <sys/vnode.h>

-#include <sys/mount_internal.h>
-#include <sys/namei.h>
-#include <sys/malloc.h>
-#include <sys/ubc.h>
-#include <miscfs/nullfs/null.h>

 
 

-#define LOG2_SIZEVNODE 7               /* log2(sizeof struct vnode) */
-#define        NNULLNODECACHE 16
+#include "nullfs.h"

 
 /*
  * Null layer cache:
  * Each cache entry holds a reference to the lower vnode
  * along with a pointer to the alias vnode.  When an
 
 /*
  * Null layer cache:
  * Each cache entry holds a reference to the lower vnode
  * along with a pointer to the alias vnode.  When an

- * entry is added the lower vnode is vnode_get'd.  When the
- * alias is removed the lower vnode is vnode_put'd.
+ * entry is added the lower vnode is VREF'd.  When the
+ * alias is removed the lower vnode is vrele'd.

  */
 
  */
 

-#define        NULL_NHASH(vp) \
-       (&null_node_hashtbl[(((u_long)vp)>>LOG2_SIZEVNODE) & null_node_hash])
-LIST_HEAD(null_node_hashhead, null_node) *null_node_hashtbl;
-u_long null_node_hash;
+#define NULL_HASH_SIZE (desiredvnodes / 10)
+
+/* osx doesn't really have the functionality freebsd uses here..gonna try this
+ * hacked hash...*/
+#define NULL_NHASH(vp) (&null_node_hashtbl[((((uintptr_t)vp) >> vnsz2log) + (uintptr_t)vnode_mount(vp)) & null_hash_mask])
+
+static LIST_HEAD(null_node_hashhead, null_node) * null_node_hashtbl;
+static lck_mtx_t null_hashmtx;
+static lck_attr_t * null_hashlck_attr;
+static lck_grp_t * null_hashlck_grp;
+static lck_grp_attr_t * null_hashlck_grp_attr;
+static u_long null_hash_mask;
+
+/* os x doesn't have hashes built into vnode. gonna try doing what freebsd does
+ *  anyway
+ *  Don't want to create a dependency on vnode_internal.h and the real struct
+ *  vnode.
+ *  9 is an eyeball of the log 2 size of vnode */
+static int vnsz2log = 9;
+
+static int null_hashins(struct mount *, struct null_node *, struct vnode **);
+
+int
+nullfs_init_lck(lck_mtx_t * lck)
+{
+       int error = 1;
+       if (lck && null_hashlck_grp && null_hashlck_attr) {
+               lck_mtx_init(lck, null_hashlck_grp, null_hashlck_attr);
+               error = 0;
+       }
+       return error;
+}
+
+int
+nullfs_destroy_lck(lck_mtx_t * lck)
+{
+       int error = 1;
+       if (lck && null_hashlck_grp) {
+               lck_mtx_destroy(lck, null_hashlck_grp);
+               error = 0;
+       }
+       return error;
+}

 
 /*
  * Initialise cache headers
  */
 
 /*
  * Initialise cache headers
  */

-nullfs_init()
+int
+nullfs_init(__unused struct vfsconf * vfsp)

 {
 {

+       NULLFSDEBUG("%s\n", __FUNCTION__);
+
+       /* assuming for now that this happens immediately and by default after fs
+        * installation */
+       null_hashlck_grp_attr = lck_grp_attr_alloc_init();
+       if (null_hashlck_grp_attr == NULL) {
+               goto error;
+       }
+       null_hashlck_grp = lck_grp_alloc_init("com.apple.filesystems.nullfs", null_hashlck_grp_attr);
+       if (null_hashlck_grp == NULL) {
+               goto error;
+       }
+       null_hashlck_attr = lck_attr_alloc_init();
+       if (null_hashlck_attr == NULL) {
+               goto error;
+       }
+
+       lck_mtx_init(&null_hashmtx, null_hashlck_grp, null_hashlck_attr);
+       null_node_hashtbl = hashinit(NULL_HASH_SIZE, M_TEMP, &null_hash_mask);
+       NULLFSDEBUG("%s finished\n", __FUNCTION__);
+       return 0;
+error:
+       printf("NULLFS: failed to get lock element\n");
+       if (null_hashlck_grp_attr) {
+               lck_grp_attr_free(null_hashlck_grp_attr);
+               null_hashlck_grp_attr = NULL;
+       }
+       if (null_hashlck_grp) {
+               lck_grp_free(null_hashlck_grp);
+               null_hashlck_grp = NULL;
+       }
+       if (null_hashlck_attr) {
+               lck_attr_free(null_hashlck_attr);
+               null_hashlck_attr = NULL;
+       }
+       return KERN_FAILURE;
+}

 
 

-#ifdef NULLFS_DIAGNOSTIC
-       printf("nullfs_init\n");                /* printed during system boot */
-#endif
-       null_node_hashtbl = hashinit(NNULLNODECACHE, M_CACHE, &null_node_hash);
+int
+nullfs_uninit()
+{
+       /* This gets called when the fs is uninstalled, there wasn't an exact
+        * equivalent in vfsops */
+       lck_mtx_destroy(&null_hashmtx, null_hashlck_grp);
+       FREE(null_node_hashtbl, M_TEMP);
+       if (null_hashlck_grp_attr) {
+               lck_grp_attr_free(null_hashlck_grp_attr);
+               null_hashlck_grp_attr = NULL;
+       }
+       if (null_hashlck_grp) {
+               lck_grp_free(null_hashlck_grp);
+               null_hashlck_grp = NULL;
+       }
+       if (null_hashlck_attr) {
+               lck_attr_free(null_hashlck_attr);
+               null_hashlck_attr = NULL;
+       }
+       return 0;

 }
 
 /*
 }
 
 /*

- * Return a vnode_get'ed alias for lower vnode if already exists, else 0.
+ * Find the nullfs vnode mapped to lowervp. Return it in *vpp with an iocount if found.
+ * Return 0 on success. On failure *vpp will be null and a non-zero error code will be returned.

  */
  */

-static struct vnode *
-null_node_find(mp, lowervp)
-       struct mount *mp;
-       struct vnode *lowervp;
+int
+null_hashget(struct mount * mp, struct vnode * lowervp, struct vnode ** vpp)

 {
 {

-       struct proc *p = curproc;       /* XXX */
-       struct null_node_hashhead *hd;
-       struct null_node *a;
-       struct vnode *vp;
+       struct null_node_hashhead * hd;
+       struct null_node * a;
+       struct vnode * vp;
+       int error = ENOENT;

 
        /*
         * Find hash base, and then search the (two-way) linked
         * list looking for a null_node structure which is referencing
 
        /*
         * Find hash base, and then search the (two-way) linked
         * list looking for a null_node structure which is referencing

-        * the lower vnode.  If found, the increment the null_node
-        * reference count (but NOT the lower vnode's vnode_get counter).
+        * the lower vnode. We only give up our reference at reclaim so
+        * just check whether the lowervp has gotten pulled from under us

         */
        hd = NULL_NHASH(lowervp);
         */
        hd = NULL_NHASH(lowervp);

-loop:
-       for (a = hd->lh_first; a != 0; a = a->null_hash.le_next) {
-               if (a->null_lowervp == lowervp && NULLTOV(a)->v_mount == mp) {
+       lck_mtx_lock(&null_hashmtx);
+       LIST_FOREACH(a, hd, null_hash)
+       {
+               if (a->null_lowervp == lowervp && vnode_mount(NULLTOV(a)) == mp) {

                        vp = NULLTOV(a);
                        vp = NULLTOV(a);

-
-                       if (vnode_get(vp)) {
-                               printf ("null_node_find: vget failed.\n");
-                               goto loop;
-                       };
-                       return (vp);
+                       if (a->null_lowervid != vnode_vid(lowervp)) {
+                               /*lowervp has reved */
+                               error = EIO;
+                       } else {
+                               /* if we found something then get an iocount on it */
+                               error = vnode_getwithvid(vp, a->null_myvid);
+                               if (error == 0) {
+                                       *vpp = vp;
+                               }
+                       }
+                       break;

                }
        }
                }
        }

-
-       return NULL;
+       lck_mtx_unlock(&null_hashmtx);
+       return error;

 }
 
 }
 

-

 /*
 /*

- * Make a new null_node node.
- * Vp is the alias vnode, lofsvp is the lower vnode.
- * Maintain a reference to (lowervp).
+ * Act like null_hashget, but add passed null_node to hash if no existing
+ * node found.

  */
 static int
  */
 static int

-null_node_alloc(mp, lowervp, vpp)
-       struct mount *mp;
-       struct vnode *lowervp;
-       struct vnode **vpp;
+null_hashins(struct mount * mp, struct null_node * xp, struct vnode ** vpp)

 {
 {

-       struct null_node_hashhead *hd;
-       struct null_node *xp;
-       struct vnode *othervp, *vp;
-       int error;
+       struct null_node_hashhead * hd;
+       struct null_node * oxp;
+       struct vnode * ovp;
+       int error = 0;

 
 

-       MALLOC(xp, struct null_node *, sizeof(struct null_node), M_TEMP, M_WAITOK);
-       if (error = getnewvnode(VT_NULL, mp, null_vnodeop_p, vpp)) {
-               FREE(xp, M_TEMP);
-               return (error);
+       hd = NULL_NHASH(xp->null_lowervp);
+       lck_mtx_lock(&null_hashmtx);
+       LIST_FOREACH(oxp, hd, null_hash)
+       {
+               if (oxp->null_lowervp == xp->null_lowervp && vnode_mount(NULLTOV(oxp)) == mp) {
+                       /*
+                        * See null_hashget for a description of this
+                        * operation.
+                        */
+                       ovp = NULLTOV(oxp);
+                       if (oxp->null_lowervid != vnode_vid(oxp->null_lowervp)) {
+                               /*vp doesn't exist so return null (not sure we are actually gonna catch
+                                *  recycle right now
+                                *  This is an exceptional case right now, it suggests the vnode we are
+                                *  trying to add has been recycled
+                                *  don't add it.*/
+                               error = EIO;
+                               goto end;
+                       }
+                       /* if we found something in the hash map then grab an iocount */
+                       error = vnode_getwithvid(ovp, oxp->null_myvid);
+                       if (error == 0) {
+                               *vpp = ovp;
+                       }
+                       goto end;
+               }

        }
        }

-       vp = *vpp;
-
-       vp->v_type = lowervp->v_type;
-       xp->null_vnode = vp;
-       vp->v_data = xp;
-       xp->null_lowervp = lowervp;
-       /*
-        * Before we insert our new node onto the hash chains,
-        * check to see if someone else has beaten us to it.
-        */
-       if (othervp = null_node_find(lowervp)) {
-               FREE(xp, M_TEMP);
-               vp->v_type = VBAD;      /* node is discarded */
-               vp->v_usecount = 0;     /* XXX */
-               vp->v_data = 0; /* prevent access to freed data */
-               *vpp = othervp;
-               return 0;
-       };
-       if (vp->v_type == VREG)
-               ubc_info_init(vp);
-       vnode_get(lowervp);   /* Extra vnode_get will be vnode_put'd in null_node_create */
-       hd = NULL_NHASH(lowervp);
+       /* if it wasn't in the hash map then the vnode pointed to by xp already has a
+        * iocount so don't bother */

        LIST_INSERT_HEAD(hd, xp, null_hash);
        LIST_INSERT_HEAD(hd, xp, null_hash);

-       return 0;
+       xp->null_flags |= NULL_FLAG_HASHED;
+end:
+       lck_mtx_unlock(&null_hashmtx);
+       return error;

 }
 
 }
 

-

 /*
 /*

- * Try to find an existing null_node vnode refering
- * to it, otherwise make a new null_node vnode which
- * contains a reference to the lower vnode.
+ * Remove node from hash.

  */
  */

-int
-null_node_create(mp, lowervp, newvpp)
-       struct mount *mp;
-       struct vnode *lowervp;
-       struct vnode **newvpp;
+void
+null_hashrem(struct null_node * xp)

 {
 {

-       struct vnode *aliasvp;
-
-       if (aliasvp = null_node_find(mp, lowervp)) {
-               /*
-                * null_node_find has taken another reference
-                * to the alias vnode.
-                */
-#ifdef NULLFS_DIAGNOSTIC
-               vprint("null_node_create: exists", NULLTOV(ap));
-#endif
-               /* vnode_get(aliasvp); --- done in null_node_find */
-       } else {
-               int error;
-
-               /*
-                * Get new vnode.
-                */
-#ifdef NULLFS_DIAGNOSTIC
-               printf("null_node_create: create new alias vnode\n");
-#endif
-
-               /*
-                * Make new vnode reference the null_node.
-                */
-               if (error = null_node_alloc(mp, lowervp, &aliasvp))
-                       return error;
-
-               /*
-                * aliasvp is already vnode_get'd by getnewvnode()
-                */
+       lck_mtx_lock(&null_hashmtx);
+       LIST_REMOVE(xp, null_hash);
+       lck_mtx_unlock(&null_hashmtx);
+}
+
+static struct null_node *
+null_nodecreate(struct vnode * lowervp)
+{
+       struct null_node * xp;
+
+       MALLOC(xp, struct null_node *, sizeof(struct null_node), M_TEMP, M_WAITOK | M_ZERO);
+       if (xp != NULL) {
+               if (lowervp) {
+                       xp->null_lowervp  = lowervp;
+                       xp->null_lowervid = vnode_vid(lowervp);
+               }

        }
        }

+       return xp;
+}

 
 

-       vnode_put(lowervp);
+/* assumption is that vnode has iocount on it after vnode create */
+int
+null_getnewvnode(
+       struct mount * mp, struct vnode * lowervp, struct vnode * dvp, struct vnode ** vpp, struct componentname * cnp, int root)
+{
+       struct vnode_fsparam vnfs_param;
+       int error             = 0;
+       enum vtype type       = VDIR;
+       struct null_node * xp = null_nodecreate(lowervp);

 
 

-#if DIAGNOSTIC
-       if (lowervp->v_usecount < 1) {
-               /* Should never happen... */
-               vprint ("null_node_create: alias ", aliasvp);
-               vprint ("null_node_create: lower ", lowervp);
-               panic ("null_node_create: lower has 0 usecount.");
-       };
-#endif
+       if (xp == NULL) {
+               return ENOMEM;
+       }
+
+       if (lowervp) {
+               type = vnode_vtype(lowervp);
+       }

 
 

-#ifdef NULLFS_DIAGNOSTIC
-       vprint("null_node_create: alias", aliasvp);
-       vprint("null_node_create: lower", lowervp);
-#endif
+       vnfs_param.vnfs_mp         = mp;
+       vnfs_param.vnfs_vtype      = type;
+       vnfs_param.vnfs_str        = "nullfs";
+       vnfs_param.vnfs_dvp        = dvp;
+       vnfs_param.vnfs_fsnode     = (void *)xp;
+       vnfs_param.vnfs_vops       = nullfs_vnodeop_p;
+       vnfs_param.vnfs_markroot   = root;
+       vnfs_param.vnfs_marksystem = 0;
+       vnfs_param.vnfs_rdev       = 0;
+       vnfs_param.vnfs_filesize   = 0; // set this to 0 since we should only be shadowing non-regular files
+       vnfs_param.vnfs_cnp        = cnp;
+       vnfs_param.vnfs_flags      = VNFS_ADDFSREF;

 
 

-       *newvpp = aliasvp;
-       return (0);
+       error = vnode_create(VNCREATE_FLAVOR, VCREATESIZE, &vnfs_param, vpp);
+       if (error == 0) {
+               xp->null_vnode = *vpp;
+               xp->null_myvid = vnode_vid(*vpp);
+               vnode_settag(*vpp, VT_NULL);
+       } else {
+               FREE(xp, M_TEMP);
+       }
+       return error;

 }
 }

-#ifdef NULLFS_DIAGNOSTIC
-struct vnode *
-null_checkvp(vp, fil, lno)
-       struct vnode *vp;
-       char *fil;
-       int lno;
+
+/*
+ * Make a new or get existing nullfs node.
+ * Vp is the alias vnode, lowervp is the lower vnode.
+ *
+ * lowervp is assumed to have an iocount on it from the caller
+ */
+int
+null_nodeget(
+       struct mount * mp, struct vnode * lowervp, struct vnode * dvp, struct vnode ** vpp, struct componentname * cnp, int root)

 {
 {

-       struct null_node *a = VTONULL(vp);
-#ifdef notyet
+       struct vnode * vp;
+       int error;
+
+       /* Lookup the hash firstly. */
+       error = null_hashget(mp, lowervp, vpp);
+       /* ENOENT means it wasn't found, EIO is a failure we should bail from, 0 is it
+        * was found */
+       if (error != ENOENT) {
+               /* null_hashget checked the vid, so if we got something here its legit to
+                * the best of our knowledge*/
+               /* if we found something then there is an iocount on vpp,
+                *  if we didn't find something then vpp shouldn't be used by the caller */
+               return error;
+       }
+

        /*
        /*

-        * Can't do this check because vnop_reclaim runs
-        * with a funny vop vector.
+        * We do not serialize vnode creation, instead we will check for
+        * duplicates later, when adding new vnode to hash.

         */
         */

-       if (vp->v_op != null_vnodeop_p) {
-               printf ("null_checkvp: on non-null-node\n");
-               while (null_checkvp_barrier) /*WAIT*/ ;
-               panic("null_checkvp");
-       };
-#endif
-       if (a->null_lowervp == NULL) {
-               /* Should never happen */
-               int i; u_long *p;
-               printf("vp = %x, ZERO ptr\n", vp);
-               for (p = (u_long *) a, i = 0; i < 8; i++)
-                       printf(" %x", p[i]);
-               printf("\n");
-               /* wait for debugger */
-               while (null_checkvp_barrier) /*WAIT*/ ;
-               panic("null_checkvp");
+       error = vnode_ref(lowervp); // take a ref on lowervp so we let the system know we care about it
+       if (error) {
+               // Failed to get a reference on the lower vp so bail. Lowervp may be gone already.
+               return error;
+       }
+
+       error = null_getnewvnode(mp, lowervp, dvp, &vp, cnp, root);
+
+       if (error) {
+               vnode_rele(lowervp);
+               return error;

        }
        }

-       if (a->null_lowervp->v_usecount < 1) {
-               int i; u_long *p;
-               printf("vp = %x, unref'ed lowervp\n", vp);
-               for (p = (u_long *) a, i = 0; i < 8; i++)
-                       printf(" %x", p[i]);
-               printf("\n");
-               /* wait for debugger */
-               while (null_checkvp_barrier) /*WAIT*/ ;
-               panic ("null with unref'ed lowervp");
-       };
-#ifdef notyet
-       printf("null %x/%d -> %x/%d [%s, %d]\n",
-               NULLTOV(a), NULLTOV(a)->v_usecount,
-               a->null_lowervp, a->null_lowervp->v_usecount,
-               fil, lno);
-#endif
-       return a->null_lowervp;
+
+       /*
+        * Atomically insert our new node into the hash or vget existing
+        * if someone else has beaten us to it.
+        */
+       error = null_hashins(mp, VTONULL(vp), vpp);
+       if (error || *vpp != NULL) {
+               /* recycle will call reclaim which will get rid of the internals */
+               vnode_recycle(vp);
+               vnode_put(vp);
+               /* if we found vpp, then null_hashins put an iocount on it */
+               return error;
+       }
+
+       /* vp has an iocount from null_getnewvnode */
+       *vpp = vp;
+
+       return 0;

 }
 }

-#endif