Exemplo n.º 1
0
/*
 * Lookup gets a vnode for a pathname.
 */
static
int
sfs_lookup(struct vnode *v, char *path, struct vnode **ret)
{
	struct sfs_vnode *sv = v->vn_data;
	struct sfs_vnode *parent, *child;
        char name[SFS_NAMELEN];
        int i, err;

        if (sv->sv_i.sfi_type != SFS_TYPE_DIR) {
                return ENOTDIR;
        }

        parent = sv; 
        VOP_INCREF(&parent->sv_v);
        child = NULL; //just to be safe

        while(1){
                i = 0;  
                while(path[i] != '/' && path[i] != '\0' && i < SFS_NAMELEN) i++;
                if(i >= SFS_NAMELEN){
                        VOP_DECREF(&parent->sv_v);
                        return ENAMETOOLONG;
                }
                else if(path[i] == '/'){
                        path[i] = 0;
                        strcpy(name, path);
                        path = &path[i + 1];
         
                        err = sfs_lookonce(parent, name, &child, NULL);
                        if(err){
                                VOP_DECREF(&parent->sv_v);
                                return err;
                        }

                        VOP_DECREF(&parent->sv_v);
                        parent = child;
                        if(parent->sv_i.sfi_type != SFS_TYPE_DIR) return ENOTDIR;
                } else{ /* Hit NULL, so this is our last time through */
                        assert(path[i] == '\0');
                        
			err = sfs_lookonce(parent, path, &child, NULL);
                        if(err){
                                VOP_DECREF(&parent->sv_v);
                                return err;
                        }       
         
                        VOP_DECREF(&parent->sv_v);

			break;
                }
        }

	*ret = &child->sv_v;

	return 0;
}
Exemplo n.º 2
0
/*
 * Delete a file.
 */
static
int
sfs_remove(struct vnode *dir, const char *name)
{
	struct sfs_vnode *sv = dir->vn_data;
	struct sfs_vnode *victim;
	int slot;
	int result;

	/* Look for the file and fetch a vnode for it. */
	result = sfs_lookonce(sv, name, &victim, &slot);
	if (result) {
		return result;
	}

	/* Erase its directory entry. */
	result = sfs_dir_unlink(sv, slot);
	if (result==0) {
		/* If we succeeded, decrement the link count. */
		assert(victim->sv_i.sfi_linkcount > 0);
		victim->sv_i.sfi_linkcount--;
		victim->sv_dirty = 1;
	}

	/* Discard the reference that sfs_lookonce got us */
	VOP_DECREF(&victim->sv_v);

	return result;
}
Exemplo n.º 3
0
static
int
sfs_lookparent_internal(struct vnode *v, char *path, struct vnode **ret,
		  char *buf, size_t buflen)
{
	struct sfs_vnode *sv = v->vn_data;
	struct sfs_vnode *next;
	char *s;
	int result;

	VOP_INCREF(&sv->sv_absvn);

	while (1) {
		/* Don't need lock to check vnode type; it's constant */
		if (sv->sv_type != SFS_TYPE_DIR) {
			VOP_DECREF(&sv->sv_absvn);
			return ENOTDIR;
		}

		s = strchr(path, '/');
		if (!s) {
			/* Last component. */
			break;
		}
		*s = 0;
		s++;

		lock_acquire(sv->sv_lock);
		result = sfs_lookonce(sv, path, &next, NULL);
		lock_release(sv->sv_lock);

		if (result) {
			VOP_DECREF(&sv->sv_absvn);
			return result;
		}

		VOP_DECREF(&sv->sv_absvn);
		sv = next;
		path = s;
	}

	if (strlen(path)+1 > buflen) {
		VOP_DECREF(&sv->sv_absvn);
		return ENAMETOOLONG;
	}
	strcpy(buf, path);

	*ret = &sv->sv_absvn;

	return 0;
}
Exemplo n.º 4
0
/*
 * Helper function for rename. Make sure COMPARE is not a direct
 * ancestor of (or the same as) CHILD.
 *
 * Note: acquires locks as it goes up.
 */
static
int
check_parent(struct sfs_vnode *lookfor, struct sfs_vnode *failon,
	     struct sfs_vnode *child, int *found)
{
	struct sfs_vnode *up;
	int result;

	*found = 0;

	VOP_INCREF(&child->sv_absvn);
	while (1) {
		if (failon == child) {
			/* Bad */
			VOP_DECREF(&child->sv_absvn);
			return EINVAL;
		}

		if (lookfor == child) {
			*found = 1;
		}

		lock_acquire(child->sv_lock);
		result = sfs_lookonce(child, "..", &up, NULL);
		lock_release(child->sv_lock);

		if (result) {
			VOP_DECREF(&child->sv_absvn);
			return result;
		}
		if (child == up) {
			/* Hit root, done */
			VOP_DECREF(&up->sv_absvn);
			break;
		}
		VOP_DECREF(&child->sv_absvn);
		child = up;
	}

	VOP_DECREF(&child->sv_absvn);
	return 0;
}
Exemplo n.º 5
0
static
int
sfs_rmdir(struct vnode *vv, const char *name){
	struct sfs_vnode *sv = vv->vn_data;
        struct sfs_vnode *victim;
	struct sfs_dir tsd;
        int slot, slot2, nentries;
        int result;

        /* Look for the directory and fetch a vnode for it. */
        result = sfs_lookonce(sv, name, &victim, &slot);
        if (result) {
                return result;
        }

	/* Make sure it's a directory and that only . and .. are left */
	if(victim->sv_i.sfi_type != SFS_TYPE_DIR){
		VOP_DECREF(&victim->sv_v);
		return ENOTDIR;
	}

	nentries = sfs_dir_nentries(victim);
	if(nentries != 2){
		slot2 = 2; 
		while(slot2 < nentries){
			/* Ensure all other entries are blank */
			result = sfs_readdir(victim, &tsd, slot2);
                	if(result){
				VOP_DECREF(&victim->sv_v);
				return result;
			}

                	if(tsd.sfd_ino != SFS_NOINO){
				VOP_DECREF(&victim->sv_v);
                                return ENOTEMPTY;
			}
                	slot2++;
		}	
	}

	/* Get rid of . and .. (should always be in slot 0 and 1) */
	result = sfs_dir_unlink(victim, 0);
	if(result){
		VOP_DECREF(&victim->sv_v);
		return result;
	}
	assert(victim->sv_i.sfi_linkcount > 0);
        victim->sv_i.sfi_linkcount--;
        victim->sv_dirty = 1;

	result = sfs_dir_unlink(victim, 1);
        if(result){
                VOP_DECREF(&victim->sv_v);
                return result;
        }       
	assert(sv->sv_i.sfi_linkcount > 0);
        sv->sv_i.sfi_linkcount--;
        sv->sv_dirty = 1;

        /* Erase its directory entry. */
        result = sfs_dir_unlink(sv, slot);
        if (result==0) {
                /* If we succeeded, decrement the link count. */
                assert(victim->sv_i.sfi_linkcount > 0);
                victim->sv_i.sfi_linkcount--;
                victim->sv_dirty = 1;
        }

        /* Discard the reference that sfs_lookonce got us */
        VOP_DECREF(&victim->sv_v);

	return result;
}
Exemplo n.º 6
0
/*
 * Rename a file.
 */
static
int
sfs_rename(struct vnode *d1, const char *n1, 
	   struct vnode *d2, const char *n2)
{
	struct sfs_vnode *sv1 = d1->vn_data;
	struct sfs_vnode *sv2 = d2->vn_data;
	struct sfs_vnode *g1;
	int slot1, slot2;
	int result, result2;

	/* Look up the old name of the file and get its inode and slot number*/
	result = sfs_lookonce(sv1, n1, &g1, &slot1);
	if (result) {
		return result;
	}

	/*
	 * Link it to the 'new' directory under the new name.
	 *
	 * We could theoretically just overwrite the original
	 * directory entry, except that we need to check to make sure
	 * the new name doesn't already exist; might as well use the
	 * existing link routine.
	 */
	result = sfs_dir_link(sv2, n2, g1->sv_ino, &slot2);
	if (result) {
		goto puke;
	}
	
	/* Increment the link count, and mark inode dirty */
	g1->sv_i.sfi_linkcount++;
	g1->sv_dirty = 1;

	/* Unlink the old slot */
	result = sfs_dir_unlink(sv1, slot1);
	if (result) {
		goto puke_harder;
	}

	/*
	 * Decrement the link count again, and mark the inode dirty again,
	 * in case it's been synced behind our back.
	 */
	assert(g1->sv_i.sfi_linkcount>0);
	g1->sv_i.sfi_linkcount--;
	g1->sv_dirty = 1;

	/* Let go of the reference to g1 */
	VOP_DECREF(&g1->sv_v);

	return 0;

 puke_harder:
	/*
	 * Error recovery: try to undo what we already did
	 */
	result2 = sfs_dir_unlink(sv2, slot2);
	if (result2) {
		kprintf("sfs: rename: %s\n", strerror(result));
		kprintf("sfs: rename: while cleaning up: %s\n", 
			strerror(result2));
		panic("sfs: rename: Cannot recover\n");
	}
	g1->sv_i.sfi_linkcount--;
 puke:
	/* Let go of the reference to g1 */
	VOP_DECREF(&g1->sv_v);
	return result;
}
Exemplo n.º 7
0
/*
 * Delete a file.
 *
 * Locking: locks the directory, then the file. Unlocks both.
 *   This follows the hierarchical locking order imposed by the directory tree.
 *
 * Requires up to 4 buffers.
 */
static
int
sfs_remove(struct vnode *dir, const char *name)
{
	struct sfs_vnode *sv = dir->vn_data;
	struct sfs_vnode *victim;
	struct sfs_dinode *victim_inodeptr;
	struct sfs_dinode *dir_inodeptr;
	int slot;
	int result;

	/* need to check this to avoid deadlock even in error condition */
	if (!strcmp(name, ".") || !strcmp(name, "..")) {
		return EISDIR;
	}

	lock_acquire(sv->sv_lock);
	reserve_buffers(SFS_BLOCKSIZE);

	result = sfs_dinode_load(sv);
	if (result) {
		goto out_buffers;
	}
	dir_inodeptr = sfs_dinode_map(sv);

	if (dir_inodeptr->sfi_linkcount == 0) {
		result = ENOENT;
		goto out_loadsv;
	}

	/* Look for the file and fetch a vnode for it. */
	result = sfs_lookonce(sv, name, &victim, &slot);
	if (result) {
		goto out_loadsv;
	}

	lock_acquire(victim->sv_lock);
	result = sfs_dinode_load(victim);
	if (result) {
		lock_release(victim->sv_lock);
		VOP_DECREF(&victim->sv_absvn);
		goto out_loadsv;
	}
	victim_inodeptr = sfs_dinode_map(victim);
	KASSERT(victim_inodeptr->sfi_linkcount > 0);

	/* Not allowed on directories */
	if (victim_inodeptr->sfi_type == SFS_TYPE_DIR) {
		result = EISDIR;
		goto out_reference;
	}

	/* Erase its directory entry. */
	result = sfs_dir_unlink(sv, slot);
	if (result) {
		goto out_reference;
	}

	/* Decrement the link count. */
	KASSERT(victim_inodeptr->sfi_linkcount > 0);
	victim_inodeptr->sfi_linkcount--;
	sfs_dinode_mark_dirty(victim);

out_reference:
	/* Discard the reference that sfs_lookonce got us */
	sfs_dinode_unload(victim);
	lock_release(victim->sv_lock);
	VOP_DECREF(&victim->sv_absvn);

out_loadsv:
	sfs_dinode_unload(sv);

out_buffers:
	lock_release(sv->sv_lock);
	unreserve_buffers(SFS_BLOCKSIZE);
	return result;
}
Exemplo n.º 8
0
/*
 * Delete a directory.
 *
 * Locking: Acquires vnode lock for parent dir and then vnode lock for
 * victim dir. Releases both.
 *
 * Requires 4 buffers.
 */
static
int
sfs_rmdir(struct vnode *v, const char *name)
{
	struct sfs_vnode *sv = v->vn_data;
	struct sfs_fs *sfs = sv->sv_absvn.vn_fs->fs_data;
	struct sfs_vnode *victim;
	struct sfs_dinode *dir_inodeptr;
	struct sfs_dinode *victim_inodeptr;
	int result, result2;
	int slot;

	/* Cannot remove the . or .. entries from a directory! */
	if (!strcmp(name, ".") || !strcmp(name, "..")) {
		return EINVAL;
	}

	lock_acquire(sv->sv_lock);
	reserve_buffers(SFS_BLOCKSIZE);

	result = sfs_dinode_load(sv);
	if (result) {
		goto die_loadsv;
	}
	dir_inodeptr = sfs_dinode_map(sv);

	if (dir_inodeptr->sfi_linkcount == 0) {
		result = ENOENT;
		goto die_linkcount;
	}

	result = sfs_lookonce(sv, name, &victim, &slot);
	if (result) {
		goto die_linkcount;
	}

	lock_acquire(victim->sv_lock);
	result = sfs_dinode_load(victim);
	if (result) {
		goto die_loadvictim;
	}
	victim_inodeptr = sfs_dinode_map(victim);

	if (victim->sv_ino == SFS_ROOTDIR_INO) {
		result = EPERM;
		goto die_total;
	}

	/* Only allowed on directories */
	if (victim_inodeptr->sfi_type != SFS_TYPE_DIR) {
		result = ENOTDIR;
		goto die_total;
	}

	result = sfs_dir_checkempty(victim);
	if (result) {
		goto die_total;
	}

	result = sfs_dir_unlink(sv, slot);
	if (result) {
		goto die_total;
	}

	KASSERT(dir_inodeptr->sfi_linkcount > 1);
	KASSERT(victim_inodeptr->sfi_linkcount==2);

	dir_inodeptr->sfi_linkcount--;
	sfs_dinode_mark_dirty(sv);

	victim_inodeptr->sfi_linkcount -= 2;
	sfs_dinode_mark_dirty(victim);

	result = sfs_itrunc(victim, 0);
	if (result) {
		victim_inodeptr->sfi_linkcount += 2;
		dir_inodeptr->sfi_linkcount++;
		result2 = sfs_dir_link(sv, name, victim->sv_ino, NULL);
		if (result2) {
			/* XXX: would be better if this case didn't exist */
			panic("sfs: %s: rmdir: %s; while recovering: %s\n",
			      sfs->sfs_sb.sb_volname, 
			      strerror(result), strerror(result2));
		}
		goto die_total;
	}

die_total:
	sfs_dinode_unload(victim);
die_loadvictim:
	lock_release(victim->sv_lock);
 	VOP_DECREF(&victim->sv_absvn);
die_linkcount:
	sfs_dinode_unload(sv);
die_loadsv:
 	unreserve_buffers(SFS_BLOCKSIZE);
 	lock_release(sv->sv_lock);

	return result;
}
Exemplo n.º 9
0
/*
 * Get the full pathname for a file. This only needs to work on directories.
 *
 * Locking: Gets/releases vnode locks, but only one at a time.
 *
 * Requires up to 3 buffers.
 */
static
int
sfs_namefile(struct vnode *vv, struct uio *uio)
{
	struct sfs_vnode *sv = vv->vn_data;
	struct sfs_vnode *parent = NULL;
	int result;
	char *buf;
	size_t bufpos, bufmax, len;

	KASSERT(uio->uio_rw == UIO_READ);

	bufmax = uio->uio_resid+1;
	if (bufmax > PATH_MAX) {
		bufmax = PATH_MAX;
	}

	buf = kmalloc(bufmax);
	if (buf == NULL) {
		return ENOMEM;
	}

	reserve_buffers(SFS_BLOCKSIZE);

	bufpos = bufmax;

	VOP_INCREF(&sv->sv_absvn);

	while (1) {
		lock_acquire(sv->sv_lock);
		/* not allowed to lock child since we're going up the tree */
		result = sfs_lookonce(sv, "..", &parent, NULL);
		lock_release(sv->sv_lock);

		if (result) {
			VOP_DECREF(&sv->sv_absvn);
			kfree(buf);
			unreserve_buffers(SFS_BLOCKSIZE);
			return result;
		}

		if (parent == sv) {
			/* .. was equal to . - must be root, so we're done */
			VOP_DECREF(&parent->sv_absvn);
			VOP_DECREF(&sv->sv_absvn);
			break;
		}

		lock_acquire(parent->sv_lock);
		result = sfs_getonename(parent, sv->sv_ino, buf, &bufpos);
		lock_release(parent->sv_lock);

		if (result) {
			VOP_DECREF(&parent->sv_absvn);
			VOP_DECREF(&sv->sv_absvn);
			kfree(buf);
			unreserve_buffers(SFS_BLOCKSIZE);
			return result;
		}

		VOP_DECREF(&sv->sv_absvn);
		sv = parent;
		parent = NULL;
	}

	/* Done looking, now send back the string */

	if (bufmax == bufpos) {
		/* root directory; do nothing (send back empty string) */
		result = 0;
	}
	else {
		len = bufmax - bufpos;
		len--;  /* skip the trailing slash */
		KASSERT(len <= uio->uio_resid);
		result = uiomove(buf+bufpos, len, uio);
	}

	kfree(buf);
	unreserve_buffers(SFS_BLOCKSIZE);
	return result;
}
Exemplo n.º 10
0
/*
 * Rename a file.
 *
 * Locking:
 *    Locks sfs_renamelock.
 *    Calls check_parent, which locks various directories one at a
 *       time.
 *    Locks the target vnodes and their parents in a complex fashion
 *       (described in detail below) which is carefully arranged so
 *       it won't deadlock with rmdir. Or at least I hope so.
 *    Then unlocks everything.
 *
 *    The rationale for all this is complex. See the comments below.
 *
 * Requires up to 7 buffers.
 */
static
int
sfs_rename(struct vnode *absdir1, const char *name1,
	   struct vnode *absdir2, const char *name2)
{
	struct sfs_fs *sfs = absdir1->vn_fs->fs_data;
	struct sfs_vnode *dir1 = absdir1->vn_data;
	struct sfs_vnode *dir2 = absdir2->vn_data;
	struct sfs_vnode *obj1=NULL, *obj2=NULL;
	struct sfs_dinode *dir1_inodeptr, *dir2_inodeptr;
	struct sfs_dinode *obj1_inodeptr, *obj2_inodeptr;
	int slot1=-1, slot2=-1;
	int result, result2;
	struct sfs_direntry sd;
	int found_dir1;

	/* make gcc happy */
	obj2_inodeptr = NULL;

	/* The VFS layer is supposed to enforce this */
	KASSERT(absdir1->vn_fs == absdir2->vn_fs);

	if (!strcmp(name1, ".") || !strcmp(name2, ".") ||
	    !strcmp(name1, "..") || !strcmp(name2, "..")) {
		return EINVAL;
	}

	if (strlen(name2)+1 > sizeof(sd.sfd_name)) {
		return ENAMETOOLONG;
	}

	/*
	 * We only allow one rename to occur at a time. This appears
	 * to be necessary to preserve the consistency of the
	 * filesystem: once you do the parent check (that n1 is not an
	 * ancestor of d2/n2) nothing may be allowed to happen that
	 * might invalidate that result until all of the
	 * rearrangements are complete. If other renames are allowed
	 * to proceed, we'd need to lock every descendent of n1 to
	 * make sure that some ancestor of d2/n2 doesn't get inserted
	 * at some point deep down. This is impractical, so we use one
	 * global lock.
	 *
	 * To prevent certain deadlocks while locking the vnodes we
	 * need, the rename lock goes outside all the vnode locks.
	 */

	reserve_buffers(SFS_BLOCKSIZE);

	lock_acquire(sfs->sfs_renamelock);

	/*
	 * Get the objects we're moving.
	 *
	 * Lock each directory temporarily. We'll check again later to
	 * make sure they haven't disappeared and to find slots.
	 */
	lock_acquire(dir1->sv_lock);
	result = sfs_lookonce(dir1, name1, &obj1, NULL);
	lock_release(dir1->sv_lock);

	if (result) {
		goto out0;
	}

	lock_acquire(dir2->sv_lock);
	result = sfs_lookonce(dir2, name2, &obj2, NULL);
	lock_release(dir2->sv_lock);

	if (result && result != ENOENT) {
		goto out0;
	}

	if (result==ENOENT) {
		/*
		 * sfs_lookonce returns a null vnode with ENOENT in
		 * order to make our life easier.
		 */
		KASSERT(obj2==NULL);
	}

	/*
	 * Prohibit the case where obj1 is a directory and it's a direct
	 * ancestor in the tree of dir2 (or is the same as dir2). If
	 * that were to be permitted, it'd create a detached chunk of
	 * the directory tree, and we don't like that.
	 *
	 * If we see dir1 while checking up the tree, found_dir1 is
	 * set to true. We use this info to choose the correct ordering
	 * for locking dir1 and dir2.
	 *
	 * To prevent deadlocks, the parent check must be done without
	 * holding locks on any other directories.
	 */
	result = check_parent(dir1, obj1, dir2, &found_dir1);
	if (result) {
		goto out0;
	}

	/*
	 * Now check for cases where some of the four vnodes we have
	 * are the same.
	 *
	 * These cases are, in the order they are handled below:
	 *
	 *    dir1 == obj1		Already checked.
	 *    dir2 == obj2		Already checked.
	 *    dir2 == obj1		Already checked.
	 *    dir1 == obj2		Checked below.
	 *    dir1 == dir2		Legal.
	 *    obj1 == obj2		Legal, special handling.
	 */

	/*
	 * A directory should have no entries for itself other than '.'.
	 * Thus, since we explicitly reject '.' above, the names
	 * within the directories should not refer to the directories
	 * themselves.
	 */
	KASSERT(dir1 != obj1);
	KASSERT(dir2 != obj2);

	/*
	 * The parent check should have caught this case.
	 */
	KASSERT(dir2 != obj1);

	/*
	 * Check for dir1 == obj2.
	 *
	 * This is not necessarily wrong if obj1 is the last entry in
	 * dir1 (this is essentially "mv ./foo/bar ./foo") but our
	 * implementation doesn't tolerate it. Because we need to
	 * unlink g2 before linking g1 in the new place, it will
	 * always fail complaining that g2 (sv1) isn't empty. We could
	 * just charge ahead and let this happen, but we'll get into
	 * trouble with our locks if we do, so detect this as a
	 * special case and return ENOTEMPTY.
	 */

	if (obj2==dir1) {
		result = ENOTEMPTY;
		goto out0;
	}


	/*
	 * Now we can begin acquiring locks for real.
	 *
	 * If we saw dir1 while doing the parent check, it means
	 * dir1 is higher in the tree than dir2. Thus, we should
	 * lock dir1 before dir2.
	 *
	 * If on the other hand we didn't see dir1, either dir2 is
	 * higher in the tree than dir1, in which case we should lock
	 * dir2 first, or dir1 and dir2 are on disjoint branches of
	 * the tree, in which case (because there's a single rename
	 * lock for the whole fs) it doesn't matter what order we lock
	 * in.
	 *
	 * If we lock dir1 first, we don't need to lock obj1 before
	 * dir2, since (due to the parent check) obj1 cannot be an
	 * ancestor of dir2.
	 *
	 * However, if we lock dir2 first, obj2 must be locked before
	 * dir1, in case obj2 is an ancestor of dir1. (In this case we
	 * will find that obj2 is not empty and cannot be removed, but
	 * we must lock it before we can check that.)
	 *
	 * Thus we lock in this order:
	 *
	 * dir1   (if found_dir1)
	 * dir2
	 * obj2   (if non-NULL)
	 * dir1   (if !found_dir1)
	 * obj1
	 *
	 * Also, look out for the case where both dirs are the same.
	 * (If this is true, found_dir1 will be set.)
	 */

	if (dir1==dir2) {
		/* This locks "both" dirs */
		lock_acquire(dir1->sv_lock);
		KASSERT(found_dir1);
	}
	else {
		if (found_dir1) {
			lock_acquire(dir1->sv_lock);
		}
		lock_acquire(dir2->sv_lock);
	}

	/*
	 * Now lock obj2.
	 *
	 * Note that we must redo the lookup and get a new obj2, as it
	 * may have changed under us. Since we hold the rename lock
	 * for the whole fs, the fs structure cannot have changed, so
	 * we don't need to redo the parent check or any of the checks
	 * for vnode aliasing with dir1 or dir2 above. Note however
	 * that obj1 and obj2 may now be the same even if they weren't
	 * before.
	 */
	KASSERT(lock_do_i_hold(dir2->sv_lock));
	if (obj2) {
		VOP_DECREF(&obj2->sv_absvn);
		obj2 = NULL;
	}
	result = sfs_lookonce(dir2, name2, &obj2, &slot2);
	if (result==0) {
		KASSERT(obj2 != NULL);
		lock_acquire(obj2->sv_lock);
		result = sfs_dinode_load(obj2);
		if (result) {
			/* ENOENT would confuse us below; but it can't be */
			KASSERT(result != ENOENT);
			lock_release(obj2->sv_lock);
			VOP_DECREF(&obj2->sv_absvn);
			/* continue to check below */
		}
		else {
			obj2_inodeptr = sfs_dinode_map(obj2);
		}
	}
	else if (result==ENOENT) {
		/*
		 * sfs_lookonce returns a null vnode and an empty slot
		 * with ENOENT in order to make our life easier.
		 */
		KASSERT(obj2==NULL);
		KASSERT(slot2>=0);
	}

	if (!found_dir1) {
		lock_acquire(dir1->sv_lock);
	}

	/* Postpone this check to simplify the error cleanup. */
	if (result != 0 && result != ENOENT) {
		goto out1;
	}

	/*
	 * Now reload obj1.
	 */
	KASSERT(lock_do_i_hold(dir1->sv_lock));
	VOP_DECREF(&obj1->sv_absvn);
	obj1 = NULL;
	result = sfs_lookonce(dir1, name1, &obj1, &slot1);
	if (result) {
		goto out1;
	}
	/*
	 * POSIX mandates that if obj1==obj2, we succeed and nothing
	 * happens.  This is somewhat stupid if obj1==obj2 and dir1 != dir2,
	 * but we'll go with POSIX anyway.
	 */
	if (obj1==obj2) {
		result = 0;
		VOP_DECREF(&obj1->sv_absvn);
		obj1 = NULL;
		goto out1;
	}
	lock_acquire(obj1->sv_lock);
	result = sfs_dinode_load(obj1);
	if (result) {
		lock_release(obj1->sv_lock);
		VOP_DECREF(&obj1->sv_absvn);
		obj1 = NULL;
		goto out1;
	}
	obj1_inodeptr = sfs_dinode_map(obj1);

	result = sfs_dinode_load(dir2);
	if (result) {
		goto out2;
	}
	dir2_inodeptr = sfs_dinode_map(dir2);

	result = sfs_dinode_load(dir1);
	if (result) {
		goto out3;
	}
	dir1_inodeptr = sfs_dinode_map(dir1);

	/*
	 * One final piece of paranoia: make sure dir2 hasn't been rmdir'd.
	 * (If dir1 was, the obj1 lookup above would have failed.)
	 */
	if (dir2_inodeptr->sfi_linkcount==0) {
		result = ENOENT;
		goto out4;
	}

	/*
	 * Now we have all the locks we need and we can proceed with
	 * the operation.
	 */

	/* At this point we should have valid slots in both dirs. */
	KASSERT(slot1>=0);
	KASSERT(slot2>=0);

	if (obj2 != NULL) {
		/*
		 * Target already exists.
		 * Must be the same type (file or directory) as the source,
		 * and if a directory, must be empty. Then unlink it.
		 */

		if (obj1_inodeptr->sfi_type == SFS_TYPE_DIR) {
			if (obj2_inodeptr->sfi_type != SFS_TYPE_DIR) {
				result = ENOTDIR;
				goto out4;
			}
			result = sfs_dir_checkempty(obj2);
			if (result) {
				goto out4;
			}

			/* Remove the name */
			result = sfs_dir_unlink(dir2, slot2);
			if (result) {
				goto out4;
			}

			/* Dispose of the directory */
			KASSERT(dir2_inodeptr->sfi_linkcount > 1);
			KASSERT(obj2_inodeptr->sfi_linkcount == 2);
			dir2_inodeptr->sfi_linkcount--;
			obj2_inodeptr->sfi_linkcount -= 2;
			sfs_dinode_mark_dirty(dir2);
			sfs_dinode_mark_dirty(obj2);

			/* ignore errors on this */
			sfs_itrunc(obj2, 0);
		}
		else {
			KASSERT(obj1->sv_type == SFS_TYPE_FILE);
			if (obj2->sv_type != SFS_TYPE_FILE) {
				result = EISDIR;
				goto out4;
			}

			/* Remove the name */
			result = sfs_dir_unlink(dir2, slot2);
			if (result) {
				goto out4;
			}

			/* Dispose of the file */
			KASSERT(obj2_inodeptr->sfi_linkcount > 0);
			obj2_inodeptr->sfi_linkcount--;
			sfs_dinode_mark_dirty(obj2);
		}

		sfs_dinode_unload(obj2);

		lock_release(obj2->sv_lock);
		VOP_DECREF(&obj2->sv_absvn);
		obj2 = NULL;
	}

	/*
	 * At this point the target should be nonexistent and we have
	 * a slot in the target directory we can use. Create a link
	 * there. Do it by hand instead of using sfs_dir_link to avoid
	 * duplication of effort.
	 */
	KASSERT(obj2==NULL);

	bzero(&sd, sizeof(sd));
	sd.sfd_ino = obj1->sv_ino;
	strcpy(sd.sfd_name, name2);
	result = sfs_writedir(dir2, slot2, &sd);
	if (result) {
		goto out4;
	}

	obj1_inodeptr->sfi_linkcount++;
	sfs_dinode_mark_dirty(obj1);

	if (obj1->sv_type == SFS_TYPE_DIR && dir1 != dir2) {
		/* Directory: reparent it */
		result = sfs_readdir(obj1, DOTDOTSLOT, &sd);
		if (result) {
			goto recover1;
		}
		if (strcmp(sd.sfd_name, "..")) {
			panic("sfs: %s: rename: moving dir: .. is not "
			      "in slot %d\n", sfs->sfs_sb.sb_volname,
			      DOTDOTSLOT);
		}
		if (sd.sfd_ino != dir1->sv_ino) {
			panic("sfs: %s: rename: moving dir: .. is i%u "
			      "and not i%u\n", sfs->sfs_sb.sb_volname,
			      sd.sfd_ino, dir1->sv_ino);
		}
		sd.sfd_ino = dir2->sv_ino;
		result = sfs_writedir(obj1, DOTDOTSLOT, &sd);
		if (result) {
			goto recover1;
		}
		dir1_inodeptr->sfi_linkcount--;
		sfs_dinode_mark_dirty(dir1);
		dir2_inodeptr->sfi_linkcount++;
		sfs_dinode_mark_dirty(dir2);
	}

	result = sfs_dir_unlink(dir1, slot1);
	if (result) {
		goto recover2;
	}
	obj1_inodeptr->sfi_linkcount--;
	sfs_dinode_mark_dirty(obj1);

	KASSERT(result==0);

	if (0) {
		/* Only reached on error */
    recover2:
		if (obj1->sv_type == SFS_TYPE_DIR) {
			sd.sfd_ino = dir1->sv_ino;
			result2 = sfs_writedir(obj1, DOTDOTSLOT, &sd);
			if (result2) {
				recovermsg(sfs->sfs_sb.sb_volname,
					   result, result2);
			}
			dir1_inodeptr->sfi_linkcount++;
			sfs_dinode_mark_dirty(dir1);
			dir2_inodeptr->sfi_linkcount--;
			sfs_dinode_mark_dirty(dir2);
		}
    recover1:
		result2 = sfs_dir_unlink(dir2, slot2);
		if (result2) {
			recovermsg(sfs->sfs_sb.sb_volname,
				   result, result2);
		}
		obj1_inodeptr->sfi_linkcount--;
		sfs_dinode_mark_dirty(obj1);
	}

 out4:
 	sfs_dinode_unload(dir1);
 out3:
 	sfs_dinode_unload(dir2);
 out2:
 	sfs_dinode_unload(obj1);
	lock_release(obj1->sv_lock);
 out1:
	if (obj2) {
		sfs_dinode_unload(obj2);
		lock_release(obj2->sv_lock);
	}
	lock_release(dir1->sv_lock);
	if (dir1 != dir2) {
		lock_release(dir2->sv_lock);
	}
 out0:
	if (obj2 != NULL) {
		VOP_DECREF(&obj2->sv_absvn);
	}
	if (obj1 != NULL) {
		VOP_DECREF(&obj1->sv_absvn);
	}

	unreserve_buffers(SFS_BLOCKSIZE);

	lock_release(sfs->sfs_renamelock);

	return result;
}