Commit c877ce47 authored by Paulo Alcantara's avatar Paulo Alcantara Committed by Steve French
Browse files

cifs: reduce roundtrips on create/qinfo requests 



To work around some Window servers that return
STATUS_OBJECT_NAME_INVALID on query infos under DFS namespaces that
contain non-ASCII characters, we started checking for -ENOENT on every
file open, and if so, then send additional requests to figure out
whether it is a DFS link or not.  It means that all those requests
will be sent to every non-existing file.

So, in order to reduce the number of roundtrips, check earlier whether
status code is STATUS_OBJECT_NAME_INVALID and tcon supports dfs, and
if so, then map -ENOENT to -EREMOTE so mount or automount will take
care of chasing the DFS link -- if it isn't an DFS link, then -ENOENT
will be returned appropriately.

Before patch

  SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
  SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...
  SMB2 228 Ioctl Request FSCTL_DFS_GET_REFERRALS, File: \ada.test\dfs\foo
  SMB2 143 Ioctl Response, Error: STATUS_OBJECT_PATH_NOT_FOUND
  SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
  SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...
  SMB2 228 Ioctl Request FSCTL_DFS_GET_REFERRALS, File: \ada.test\dfs\foo
  SMB2 143 Ioctl Response, Error: STATUS_OBJECT_PATH_NOT_FOUND

After patch

  SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
  SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...
  SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
  SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...

Signed-off-by: default avatarPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 86fe0fa8

fs/cifs/connect.c

+0 −16
Original line number Diff line number Diff line
@@ -3547,9 +3547,6 @@ static int is_path_remote(struct mount_ctx *mnt_ctx) 
	struct cifs_tcon *tcon = mnt_ctx->tcon;

	struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;

	char *full_path;

#ifdef CONFIG_CIFS_DFS_UPCALL

	bool nodfs = cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS;

#endif



	if (!server->ops->is_path_accessible)

		return -EOPNOTSUPP;
@@ -3566,19 +3563,6 @@ static int is_path_remote(struct mount_ctx *mnt_ctx) 


	rc = server->ops->is_path_accessible(xid, tcon, cifs_sb,

					     full_path);

#ifdef CONFIG_CIFS_DFS_UPCALL

	if (nodfs) {

		if (rc == -EREMOTE)

			rc = -EOPNOTSUPP;

		goto out;

	}



	/* path *might* exist with non-ASCII characters in DFS root

	 * try again with full path (only if nodfs is not set) */

	if (rc == -ENOENT && is_tcon_dfs(tcon))

		rc = cifs_dfs_query_info_nonascii_quirk(xid, tcon, cifs_sb,

							full_path);

#endif

	if (rc != 0 && rc != -EREMOTE)

		goto out;

fs/cifs/inode.c

+0 −6
Original line number Diff line number Diff line
@@ -993,12 +993,6 @@ int cifs_get_inode_info(struct inode **inode, const char *full_path, 
		}

		rc = server->ops->query_path_info(xid, tcon, cifs_sb, full_path, &tmp_data,

						  &adjust_tz, &is_reparse_point);

#ifdef CONFIG_CIFS_DFS_UPCALL

		if (rc == -ENOENT && is_tcon_dfs(tcon))

			rc = cifs_dfs_query_info_nonascii_quirk(xid, tcon,

								cifs_sb,

								full_path);

#endif

		data = &tmp_data;

	}

fs/cifs/misc.c

+0 −45
Original line number Diff line number Diff line
@@ -1314,49 +1314,4 @@ int cifs_update_super_prepath(struct cifs_sb_info *cifs_sb, char *prefix) 
	cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;

	return 0;

}



/** cifs_dfs_query_info_nonascii_quirk

 * Handle weird Windows SMB server behaviour. It responds with

 * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request

 * for "\<server>\<dfsname>\<linkpath>" DFS reference,

 * where <dfsname> contains non-ASCII unicode symbols.

 *

 * Check such DFS reference.

 */

int cifs_dfs_query_info_nonascii_quirk(const unsigned int xid,

				       struct cifs_tcon *tcon,

				       struct cifs_sb_info *cifs_sb,

				       const char *linkpath)

{

	char *treename, *dfspath, sep;

	int treenamelen, linkpathlen, rc;



	treename = tcon->tree_name;

	/* MS-DFSC: All paths in REQ_GET_DFS_REFERRAL and RESP_GET_DFS_REFERRAL

	 * messages MUST be encoded with exactly one leading backslash, not two

	 * leading backslashes.

	 */

	sep = CIFS_DIR_SEP(cifs_sb);

	if (treename[0] == sep && treename[1] == sep)

		treename++;

	linkpathlen = strlen(linkpath);

	treenamelen = strnlen(treename, MAX_TREE_SIZE + 1);

	dfspath = kzalloc(treenamelen + linkpathlen + 1, GFP_KERNEL);

	if (!dfspath)

		return -ENOMEM;

	if (treenamelen)

		memcpy(dfspath, treename, treenamelen);

	memcpy(dfspath + treenamelen, linkpath, linkpathlen);

	rc = dfs_cache_find(xid, tcon->ses, cifs_sb->local_nls,

			    cifs_remap(cifs_sb), dfspath, NULL, NULL);

	if (rc == 0) {

		cifs_dbg(FYI, "DFS ref '%s' is found, emulate -EREMOTE\n",

			 dfspath);

		rc = -EREMOTE;

	} else {

		cifs_dbg(FYI, "%s: dfs_cache_find returned %d\n", __func__, rc);

	}

	kfree(dfspath);

	return rc;

}

#endif

fs/cifs/smb2inode.c

+33 −13
Original line number Diff line number Diff line
@@ -556,22 +556,42 @@ int smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon, 
	rc = smb2_compound_op(xid, tcon, cifs_sb, full_path, FILE_READ_ATTRIBUTES, FILE_OPEN,

			      create_options, ACL_NO_MODE, data, SMB2_OP_QUERY_INFO, cfile,

			      NULL, NULL, err_iov, err_buftype);

	if (rc == -EOPNOTSUPP) {

		if (err_iov[0].iov_base && err_buftype[0] != CIFS_NO_BUFFER &&

		    ((struct smb2_hdr *)err_iov[0].iov_base)->Command == SMB2_CREATE &&

		    ((struct smb2_hdr *)err_iov[0].iov_base)->Status == STATUS_STOPPED_ON_SYMLINK) {

			rc = smb2_parse_symlink_response(cifs_sb, err_iov, &data->symlink_target);

	if (rc) {

		struct smb2_hdr *hdr = err_iov[0].iov_base;



		if (unlikely(!hdr || err_buftype[0] == CIFS_NO_BUFFER))

			goto out;

		if (rc == -EOPNOTSUPP && hdr->Command == SMB2_CREATE &&

		    hdr->Status == STATUS_STOPPED_ON_SYMLINK) {

			rc = smb2_parse_symlink_response(cifs_sb, err_iov,

							 &data->symlink_target);

			if (rc)

				goto out;

		}



			*reparse = true;

			create_options |= OPEN_REPARSE_POINT;



			/* Failed on a symbolic link - query a reparse point info */

			cifs_get_readable_path(tcon, full_path, &cfile);

		rc = smb2_compound_op(xid, tcon, cifs_sb, full_path, FILE_READ_ATTRIBUTES,

				      FILE_OPEN, create_options, ACL_NO_MODE, data,

				      SMB2_OP_QUERY_INFO, cfile, NULL, NULL, NULL, NULL);

			rc = smb2_compound_op(xid, tcon, cifs_sb, full_path,

					      FILE_READ_ATTRIBUTES, FILE_OPEN,

					      create_options, ACL_NO_MODE, data,

					      SMB2_OP_QUERY_INFO, cfile, NULL, NULL,

					      NULL, NULL);

			goto out;

		} else if (rc != -EREMOTE && IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) &&

			   hdr->Status == STATUS_OBJECT_NAME_INVALID) {

			/*

			 * Handle weird Windows SMB server behaviour. It responds with

			 * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request

			 * for "\<server>\<dfsname>\<linkpath>" DFS reference,

			 * where <dfsname> contains non-ASCII unicode symbols.

			 */

			rc = -EREMOTE;

		}

		if (rc == -EREMOTE && IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) && cifs_sb &&

		    (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS))

			rc = -EOPNOTSUPP;

	}



out:

fs/cifs/smb2ops.c

+24 −4
Original line number Diff line number Diff line
@@ -796,7 +796,9 @@ smb2_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon, 
	int rc;

	__le16 *utf16_path;

	__u8 oplock = SMB2_OPLOCK_LEVEL_NONE;

	int err_buftype = CIFS_NO_BUFFER;

	struct cifs_open_parms oparms;

	struct kvec err_iov = {};

	struct cifs_fid fid;

	struct cached_fid *cfid;
@@ -820,14 +822,32 @@ smb2_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon, 
	oparms.fid = &fid;

	oparms.reconnect = false;



	rc = SMB2_open(xid, &oparms, utf16_path, &oplock, NULL, NULL, NULL,

		       NULL);

	rc = SMB2_open(xid, &oparms, utf16_path, &oplock, NULL, NULL,

		       &err_iov, &err_buftype);

	if (rc) {

		kfree(utf16_path);

		return rc;

		struct smb2_hdr *hdr = err_iov.iov_base;



		if (unlikely(!hdr || err_buftype == CIFS_NO_BUFFER))

			goto out;

		/*

		 * Handle weird Windows SMB server behaviour. It responds with

		 * STATUS_OBJECT_NAME_INVALID code to SMB2 QUERY_INFO request

		 * for "\<server>\<dfsname>\<linkpath>" DFS reference,

		 * where <dfsname> contains non-ASCII unicode symbols.

		 */

		if (rc != -EREMOTE && IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) &&

		    hdr->Status == STATUS_OBJECT_NAME_INVALID)

			rc = -EREMOTE;

		if (rc == -EREMOTE && IS_ENABLED(CONFIG_CIFS_DFS_UPCALL) && cifs_sb &&

		    (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS))

			rc = -EOPNOTSUPP;

		goto out;

	}



	rc = SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);



out:

	free_rsp_buf(err_buftype, err_iov.iov_base);

	kfree(utf16_path);

	return rc;

}