AFS Fixes

Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
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Merge tag 'afs-fixes-20190814' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull afs fixes from David Howells:

 - Fix the CB.ProbeUuid handler to generate its reply correctly.

 - Fix a mix up in indices when parsing a Volume Location entry record.

 - Fix a potential NULL-pointer deref when cleaning up a read request.

 - Fix the expected data version of the destination directory in
   afs_rename().

 - Fix afs_d_revalidate() to only update d_fsdata if it's not the same
   as the directory data version to reduce the likelihood of overwriting
   the result of a competing operation. (d_fsdata carries the directory
   DV or the least-significant word thereof).

 - Fix the tracking of the data-version on a directory and make sure
   that dentry objects get properly initialised, updated and
   revalidated.

   Also fix rename to update d_fsdata to match the new directory's DV if
   the dentry gets moved over and unhash the dentry to stop
   afs_d_revalidate() from interfering.

* tag 'afs-fixes-20190814' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  afs: Fix missing dentry data version updating
  afs: Only update d_fsdata if different in afs_d_revalidate()
  afs: Fix off-by-one in afs_rename() expected data version calculation
  fs: afs: Fix a possible null-pointer dereference in afs_put_read()
  afs: Fix loop index mixup in afs_deliver_vl_get_entry_by_name_u()
  afs: Fix the CB.ProbeUuid service handler to reply correctly

fs/afs/cmservice.c

@@ -505,18 +505,14 @@ static void SRXAFSCB_ProbeUuid(struct work_struct *work)
 	struct afs_call *call = container_of(work, struct afs_call, work);
 	struct afs_uuid *r = call->request;
 
-	struct {
-		__be32	match;
-	} reply;
-
 	_enter("");
 
 	if (memcmp(r, &call->net->uuid, sizeof(call->net->uuid)) == 0)
-		reply.match = htonl(0);
+		afs_send_empty_reply(call);
 	else
-		reply.match = htonl(1);
+		rxrpc_kernel_abort_call(call->net->socket, call->rxcall,
+					1, 1, "K-1");
 
-	afs_send_simple_reply(call, &reply, sizeof(reply));
 	afs_put_call(call);
 	_leave("");
 }

fs/afs/dir.c

@@ -440,7 +440,7 @@ static int afs_dir_iterate_block(struct afs_vnode *dvnode,
  * iterate through the data blob that lists the contents of an AFS directory
  */
 static int afs_dir_iterate(struct inode *dir, struct dir_context *ctx,
-			   struct key *key)
+			   struct key *key, afs_dataversion_t *_dir_version)
 {
 	struct afs_vnode *dvnode = AFS_FS_I(dir);
 	struct afs_xdr_dir_page *dbuf;
@@ -460,6 +460,7 @@ static int afs_dir_iterate(struct inode *dir, struct dir_context *ctx,
 	req = afs_read_dir(dvnode, key);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
+	*_dir_version = req->data_version;
 
 	/* round the file position up to the next entry boundary */
 	ctx->pos += sizeof(union afs_xdr_dirent) - 1;
@@ -514,7 +515,10 @@ out:
  */
 static int afs_readdir(struct file *file, struct dir_context *ctx)
 {
-	return afs_dir_iterate(file_inode(file), ctx, afs_file_key(file));
+	afs_dataversion_t dir_version;
+
+	return afs_dir_iterate(file_inode(file), ctx, afs_file_key(file),
+			       &dir_version);
 }
 
 /*
@@ -555,7 +559,8 @@ static int afs_lookup_one_filldir(struct dir_context *ctx, const char *name,
  * - just returns the FID the dentry name maps to if found
  */
 static int afs_do_lookup_one(struct inode *dir, struct dentry *dentry,
-			     struct afs_fid *fid, struct key *key)
+			     struct afs_fid *fid, struct key *key,
+			     afs_dataversion_t *_dir_version)
 {
 	struct afs_super_info *as = dir->i_sb->s_fs_info;
 	struct afs_lookup_one_cookie cookie = {
@@ -568,7 +573,7 @@ static int afs_do_lookup_one(struct inode *dir, struct dentry *dentry,
 	_enter("{%lu},%p{%pd},", dir->i_ino, dentry, dentry);
 
 	/* search the directory */
-	ret = afs_dir_iterate(dir, &cookie.ctx, key);
+	ret = afs_dir_iterate(dir, &cookie.ctx, key, _dir_version);
 	if (ret < 0) {
 		_leave(" = %d [iter]", ret);
 		return ret;
@@ -642,6 +647,7 @@ static struct inode *afs_do_lookup(struct inode *dir, struct dentry *dentry,
 	struct afs_server *server;
 	struct afs_vnode *dvnode = AFS_FS_I(dir), *vnode;
 	struct inode *inode = NULL, *ti;
+	afs_dataversion_t data_version = READ_ONCE(dvnode->status.data_version);
 	int ret, i;
 
 	_enter("{%lu},%p{%pd},", dir->i_ino, dentry, dentry);
@@ -669,12 +675,14 @@ static struct inode *afs_do_lookup(struct inode *dir, struct dentry *dentry,
 		cookie->fids[i].vid = as->volume->vid;
 
 	/* search the directory */
-	ret = afs_dir_iterate(dir, &cookie->ctx, key);
+	ret = afs_dir_iterate(dir, &cookie->ctx, key, &data_version);
 	if (ret < 0) {
 		inode = ERR_PTR(ret);
 		goto out;
 	}
 
+	dentry->d_fsdata = (void *)(unsigned long)data_version;
+
 	inode = ERR_PTR(-ENOENT);
 	if (!cookie->found)
 		goto out;
@@ -968,7 +976,8 @@ static int afs_d_revalidate(struct dentry *dentry, unsigned int flags)
 	struct dentry *parent;
 	struct inode *inode;
 	struct key *key;
-	long dir_version, de_version;
+	afs_dataversion_t dir_version;
+	long de_version;
 	int ret;
 
 	if (flags & LOOKUP_RCU)
@@ -1014,20 +1023,20 @@ static int afs_d_revalidate(struct dentry *dentry, unsigned int flags)
 	 * on a 32-bit system, we only have 32 bits in the dentry to store the
 	 * version.
 	 */
-	dir_version = (long)dir->status.data_version;
+	dir_version = dir->status.data_version;
 	de_version = (long)dentry->d_fsdata;
-	if (de_version == dir_version)
+	if (de_version == (long)dir_version)
-		goto out_valid;
+		goto out_valid_noupdate;
 
-	dir_version = (long)dir->invalid_before;
+	dir_version = dir->invalid_before;
-	if (de_version - dir_version >= 0)
+	if (de_version - (long)dir_version >= 0)
 		goto out_valid;
 
 	_debug("dir modified");
 	afs_stat_v(dir, n_reval);
 
 	/* search the directory for this vnode */
-	ret = afs_do_lookup_one(&dir->vfs_inode, dentry, &fid, key);
+	ret = afs_do_lookup_one(&dir->vfs_inode, dentry, &fid, key, &dir_version);
 	switch (ret) {
 	case 0:
 		/* the filename maps to something */
@@ -1080,7 +1089,8 @@ static int afs_d_revalidate(struct dentry *dentry, unsigned int flags)
 	}
 
 out_valid:
-	dentry->d_fsdata = (void *)dir_version;
+	dentry->d_fsdata = (void *)(unsigned long)dir_version;
+out_valid_noupdate:
 	dput(parent);
 	key_put(key);
 	_leave(" = 1 [valid]");
@@ -1185,6 +1195,20 @@ static void afs_prep_for_new_inode(struct afs_fs_cursor *fc,
 	iget_data->cb_s_break = fc->cbi->server->cb_s_break;
 }
 
+/*
+ * Note that a dentry got changed.  We need to set d_fsdata to the data version
+ * number derived from the result of the operation.  It doesn't matter if
+ * d_fsdata goes backwards as we'll just revalidate.
+ */
+static void afs_update_dentry_version(struct afs_fs_cursor *fc,
+				      struct dentry *dentry,
+				      struct afs_status_cb *scb)
+{
+	if (fc->ac.error == 0)
+		dentry->d_fsdata =
+			(void *)(unsigned long)scb->status.data_version;
+}
+
 /*
  * create a directory on an AFS filesystem
  */
@@ -1227,6 +1251,7 @@ static int afs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 		afs_check_for_remote_deletion(&fc, dvnode);
 		afs_vnode_commit_status(&fc, dvnode, fc.cb_break,
 					&data_version, &scb[0]);
+		afs_update_dentry_version(&fc, dentry, &scb[0]);
 		afs_vnode_new_inode(&fc, dentry, &iget_data, &scb[1]);
 		ret = afs_end_vnode_operation(&fc);
 		if (ret < 0)
@@ -1319,6 +1344,7 @@ static int afs_rmdir(struct inode *dir, struct dentry *dentry)
 
 		afs_vnode_commit_status(&fc, dvnode, fc.cb_break,
 					&data_version, scb);
+		afs_update_dentry_version(&fc, dentry, scb);
 		ret = afs_end_vnode_operation(&fc);
 		if (ret == 0) {
 			afs_dir_remove_subdir(dentry);
@@ -1458,6 +1484,7 @@ static int afs_unlink(struct inode *dir, struct dentry *dentry)
 					&data_version, &scb[0]);
 		afs_vnode_commit_status(&fc, vnode, fc.cb_break_2,
 					&data_version_2, &scb[1]);
+		afs_update_dentry_version(&fc, dentry, &scb[0]);
 		ret = afs_end_vnode_operation(&fc);
 		if (ret == 0 && !(scb[1].have_status || scb[1].have_error))
 			ret = afs_dir_remove_link(dvnode, dentry, key);
@@ -1526,6 +1553,7 @@ static int afs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 		afs_check_for_remote_deletion(&fc, dvnode);
 		afs_vnode_commit_status(&fc, dvnode, fc.cb_break,
 					&data_version, &scb[0]);
+		afs_update_dentry_version(&fc, dentry, &scb[0]);
 		afs_vnode_new_inode(&fc, dentry, &iget_data, &scb[1]);
 		ret = afs_end_vnode_operation(&fc);
 		if (ret < 0)
@@ -1607,6 +1635,7 @@ static int afs_link(struct dentry *from, struct inode *dir,
 		afs_vnode_commit_status(&fc, vnode, fc.cb_break_2,
 					NULL, &scb[1]);
 		ihold(&vnode->vfs_inode);
+		afs_update_dentry_version(&fc, dentry, &scb[0]);
 		d_instantiate(dentry, &vnode->vfs_inode);
 
 		mutex_unlock(&vnode->io_lock);
@@ -1686,6 +1715,7 @@ static int afs_symlink(struct inode *dir, struct dentry *dentry,
 		afs_check_for_remote_deletion(&fc, dvnode);
 		afs_vnode_commit_status(&fc, dvnode, fc.cb_break,
 					&data_version, &scb[0]);
+		afs_update_dentry_version(&fc, dentry, &scb[0]);
 		afs_vnode_new_inode(&fc, dentry, &iget_data, &scb[1]);
 		ret = afs_end_vnode_operation(&fc);
 		if (ret < 0)
@@ -1791,6 +1821,17 @@ static int afs_rename(struct inode *old_dir, struct dentry *old_dentry,
 		}
 	}
 
+	/* This bit is potentially nasty as there's a potential race with
+	 * afs_d_revalidate{,_rcu}().  We have to change d_fsdata on the dentry
+	 * to reflect it's new parent's new data_version after the op, but
+	 * d_revalidate may see old_dentry between the op having taken place
+	 * and the version being updated.
+	 *
+	 * So drop the old_dentry for now to make other threads go through
+	 * lookup instead - which we hold a lock against.
+	 */
+	d_drop(old_dentry);
+
 	ret = -ERESTARTSYS;
 	if (afs_begin_vnode_operation(&fc, orig_dvnode, key, true)) {
 		afs_dataversion_t orig_data_version;
@@ -1802,9 +1843,9 @@ static int afs_rename(struct inode *old_dir, struct dentry *old_dentry,
 		if (orig_dvnode != new_dvnode) {
 			if (mutex_lock_interruptible_nested(&new_dvnode->io_lock, 1) < 0) {
 				afs_end_vnode_operation(&fc);
-				goto error_rehash;
+				goto error_rehash_old;
 			}
-			new_data_version = new_dvnode->status.data_version;
+			new_data_version = new_dvnode->status.data_version + 1;
 		} else {
 			new_data_version = orig_data_version;
 			new_scb = &scb[0];
@@ -1827,7 +1868,7 @@ static int afs_rename(struct inode *old_dir, struct dentry *old_dentry,
 		}
 		ret = afs_end_vnode_operation(&fc);
 		if (ret < 0)
-			goto error_rehash;
+			goto error_rehash_old;
 	}
 
 	if (ret == 0) {
@@ -1853,10 +1894,26 @@ static int afs_rename(struct inode *old_dir, struct dentry *old_dentry,
 				drop_nlink(new_inode);
 			spin_unlock(&new_inode->i_lock);
 		}
+
+		/* Now we can update d_fsdata on the dentries to reflect their
+		 * new parent's data_version.
+		 *
+		 * Note that if we ever implement RENAME_EXCHANGE, we'll have
+		 * to update both dentries with opposing dir versions.
+		 */
+		if (new_dvnode != orig_dvnode) {
+			afs_update_dentry_version(&fc, old_dentry, &scb[1]);
+			afs_update_dentry_version(&fc, new_dentry, &scb[1]);
+		} else {
+			afs_update_dentry_version(&fc, old_dentry, &scb[0]);
+			afs_update_dentry_version(&fc, new_dentry, &scb[0]);
+		}
 		d_move(old_dentry, new_dentry);
 		goto error_tmp;
 	}
 
+error_rehash_old:
+	d_rehash(new_dentry);
 error_rehash:
 	if (rehash)
 		d_rehash(rehash);

fs/afs/file.c

@@ -191,11 +191,13 @@ void afs_put_read(struct afs_read *req)
 	int i;
 
 	if (refcount_dec_and_test(&req->usage)) {
-		for (i = 0; i < req->nr_pages; i++)
+		if (req->pages) {
-			if (req->pages[i])
+			for (i = 0; i < req->nr_pages; i++)
-				put_page(req->pages[i]);
+				if (req->pages[i])
-		if (req->pages != req->array)
+					put_page(req->pages[i]);
-			kfree(req->pages);
+			if (req->pages != req->array)
+				kfree(req->pages);
+		}
 		kfree(req);
 	}
 }

fs/afs/vlclient.c

@@ -56,23 +56,24 @@ static int afs_deliver_vl_get_entry_by_name_u(struct afs_call *call)
 		struct afs_uuid__xdr *xdr;
 		struct afs_uuid *uuid;
 		int j;
+		int n = entry->nr_servers;
 
 		tmp = ntohl(uvldb->serverFlags[i]);
 		if (tmp & AFS_VLSF_DONTUSE ||
 		    (new_only && !(tmp & AFS_VLSF_NEWREPSITE)))
 			continue;
 		if (tmp & AFS_VLSF_RWVOL) {
-			entry->fs_mask[i] |= AFS_VOL_VTM_RW;
+			entry->fs_mask[n] |= AFS_VOL_VTM_RW;
 			if (vlflags & AFS_VLF_BACKEXISTS)
-				entry->fs_mask[i] |= AFS_VOL_VTM_BAK;
+				entry->fs_mask[n] |= AFS_VOL_VTM_BAK;
 		}
 		if (tmp & AFS_VLSF_ROVOL)
-			entry->fs_mask[i] |= AFS_VOL_VTM_RO;
+			entry->fs_mask[n] |= AFS_VOL_VTM_RO;
-		if (!entry->fs_mask[i])
+		if (!entry->fs_mask[n])
 			continue;
 
 		xdr = &uvldb->serverNumber[i];
-		uuid = (struct afs_uuid *)&entry->fs_server[i];
+		uuid = (struct afs_uuid *)&entry->fs_server[n];
 		uuid->time_low			= xdr->time_low;
 		uuid->time_mid			= htons(ntohl(xdr->time_mid));
 		uuid->time_hi_and_version	= htons(ntohl(xdr->time_hi_and_version));