cifs: improve symlink handling for smb2+

When creating inode for symlink, the client used to send below
requests to fill it in:

    * create+query_info+close (STATUS_STOPPED_ON_SYMLINK)
    * create(+reparse_flag)+query_info+close (set file attrs)
    * create+ioctl(get_reparse)+close (query reparse tag)

and then for every access to the symlink dentry, the ->link() method
would send another:

    * create+ioctl(get_reparse)+close (parse symlink)

So, in order to improve:

    (i) Get rid of unnecessary roundtrips and then resolve symlinks as
	follows:

        * create+query_info+close (STATUS_STOPPED_ON_SYMLINK +
	                           parse symlink + get reparse tag)
        * create(+reparse_flag)+query_info+close (set file attrs)

    (ii) Set the resolved symlink target directly in inode->i_link and
         use simple_get_link() for ->link() to simply return it.

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 23 insertions, 86 deletions

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 32d5387a9dde..73e951e9858c 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -831,33 +831,25 @@ smb2_is_path_accessible(const unsigned int xid, struct cifs_tcon *tcon,
 	return rc;
 }
 
-static int
-smb2_get_srv_inum(const unsigned int xid, struct cifs_tcon *tcon,
-		  struct cifs_sb_info *cifs_sb, const char *full_path,
-		  u64 *uniqueid, FILE_ALL_INFO *data)
+static int smb2_get_srv_inum(const unsigned int xid, struct cifs_tcon *tcon,
+			     struct cifs_sb_info *cifs_sb, const char *full_path,
+			     u64 *uniqueid, struct cifs_open_info_data *data)
 {
-	*uniqueid = le64_to_cpu(data->IndexNumber);
+	*uniqueid = le64_to_cpu(data->fi.IndexNumber);
 	return 0;
 }
 
-static int
-smb2_query_file_info(const unsigned int xid, struct cifs_tcon *tcon,
-		     struct cifs_fid *fid, FILE_ALL_INFO *data)
+static int smb2_query_file_info(const unsigned int xid, struct cifs_tcon *tcon,
+				struct cifsFileInfo *cfile, struct cifs_open_info_data *data)
 {
-	int rc;
-	struct smb2_file_all_info *smb2_data;
+	struct cifs_fid *fid = &cfile->fid;
 
-	smb2_data = kzalloc(sizeof(struct smb2_file_all_info) + PATH_MAX * 2,
-			    GFP_KERNEL);
-	if (smb2_data == NULL)
-		return -ENOMEM;
-
-	rc = SMB2_query_info(xid, tcon, fid->persistent_fid, fid->volatile_fid,
-			     smb2_data);
-	if (!rc)
-		move_smb2_info_to_cifs(data, smb2_data);
-	kfree(smb2_data);
-	return rc;
+	if (cfile->symlink_target) {
+		data->symlink_target = kstrdup(cfile->symlink_target, GFP_KERNEL);
+		if (!data->symlink_target)
+			return -ENOMEM;
+	}
+	return SMB2_query_info(xid, tcon, fid->persistent_fid, fid->volatile_fid, &data->fi);
 }
 
 #ifdef CONFIG_CIFS_XATTR
@@ -2828,9 +2820,6 @@ parse_reparse_point(struct reparse_data_buffer *buf,
 	}
 }
 
-#define SMB2_SYMLINK_STRUCT_SIZE \
-	(sizeof(struct smb2_err_rsp) - 1 + sizeof(struct smb2_symlink_err_rsp))
-
 static int
 smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 		   struct cifs_sb_info *cifs_sb, const char *full_path,
@@ -2842,13 +2831,7 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 	struct cifs_open_parms oparms;
 	struct cifs_fid fid;
 	struct kvec err_iov = {NULL, 0};
-	struct smb2_err_rsp *err_buf = NULL;
-	struct smb2_symlink_err_rsp *symlink;
 	struct TCP_Server_Info *server = cifs_pick_channel(tcon->ses);
-	unsigned int sub_len;
-	unsigned int sub_offset;
-	unsigned int print_len;
-	unsigned int print_offset;
 	int flags = CIFS_CP_CREATE_CLOSE_OP;
 	struct smb_rqst rqst[3];
 	int resp_buftype[3];
@@ -2965,47 +2948,7 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 		goto querty_exit;
 	}
 
-	err_buf = err_iov.iov_base;
-	if (le32_to_cpu(err_buf->ByteCount) < sizeof(struct smb2_symlink_err_rsp) ||
-	    err_iov.iov_len < SMB2_SYMLINK_STRUCT_SIZE) {
-		rc = -EINVAL;
-		goto querty_exit;
-	}
-
-	symlink = (struct smb2_symlink_err_rsp *)err_buf->ErrorData;
-	if (le32_to_cpu(symlink->SymLinkErrorTag) != SYMLINK_ERROR_TAG ||
-	    le32_to_cpu(symlink->ReparseTag) != IO_REPARSE_TAG_SYMLINK) {
-		rc = -EINVAL;
-		goto querty_exit;
-	}
-
-	/* open must fail on symlink - reset rc */
-	rc = 0;
-	sub_len = le16_to_cpu(symlink->SubstituteNameLength);
-	sub_offset = le16_to_cpu(symlink->SubstituteNameOffset);
-	print_len = le16_to_cpu(symlink->PrintNameLength);
-	print_offset = le16_to_cpu(symlink->PrintNameOffset);
-
-	if (err_iov.iov_len < SMB2_SYMLINK_STRUCT_SIZE + sub_offset + sub_len) {
-		rc = -EINVAL;
-		goto querty_exit;
-	}
-
-	if (err_iov.iov_len <
-	    SMB2_SYMLINK_STRUCT_SIZE + print_offset + print_len) {
-		rc = -EINVAL;
-		goto querty_exit;
-	}
-
-	*target_path = cifs_strndup_from_utf16(
-				(char *)symlink->PathBuffer + sub_offset,
-				sub_len, true, cifs_sb->local_nls);
-	if (!(*target_path)) {
-		rc = -ENOMEM;
-		goto querty_exit;
-	}
-	convert_delimiter(*target_path, '/');
-	cifs_dbg(FYI, "%s: target path: %s\n", __func__, *target_path);
+	rc = smb2_parse_symlink_response(cifs_sb, &err_iov, target_path);
 
  querty_exit:
 	cifs_dbg(FYI, "query symlink rc %d\n", rc);
@@ -5115,7 +5058,7 @@ smb2_make_node(unsigned int xid, struct inode *inode,
 {
 	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 	int rc = -EPERM;
-	FILE_ALL_INFO *buf = NULL;
+	struct cifs_open_info_data buf = {};
 	struct cifs_io_parms io_parms = {0};
 	__u32 oplock = 0;
 	struct cifs_fid fid;
@@ -5131,7 +5074,7 @@ smb2_make_node(unsigned int xid, struct inode *inode,
 	 * and was used by default in earlier versions of Windows
 	 */
 	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL))
-		goto out;
+		return rc;
 
 	/*
 	 * TODO: Add ability to create instead via reparse point. Windows (e.g.
@@ -5140,16 +5083,10 @@ smb2_make_node(unsigned int xid, struct inode *inode,
 	 */
 
 	if (!S_ISCHR(mode) && !S_ISBLK(mode))
-		goto out;
+		return rc;
 
 	cifs_dbg(FYI, "sfu compat create special file\n");
 
-	buf = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL);
-	if (buf == NULL) {
-		rc = -ENOMEM;
-		goto out;
-	}
-
 	oparms.tcon = tcon;
 	oparms.cifs_sb = cifs_sb;
 	oparms.desired_access = GENERIC_WRITE;
@@ -5164,21 +5101,21 @@ smb2_make_node(unsigned int xid, struct inode *inode,
 		oplock = REQ_OPLOCK;
 	else
 		oplock = 0;
-	rc = tcon->ses->server->ops->open(xid, &oparms, &oplock, buf);
+	rc = tcon->ses->server->ops->open(xid, &oparms, &oplock, &buf);
 	if (rc)
-		goto out;
+		return rc;
 
 	/*
 	 * BB Do not bother to decode buf since no local inode yet to put
 	 * timestamps in, but we can reuse it safely.
 	 */
 
-	pdev = (struct win_dev *)buf;
+	pdev = (struct win_dev *)&buf.fi;
 	io_parms.pid = current->tgid;
 	io_parms.tcon = tcon;
 	io_parms.offset = 0;
 	io_parms.length = sizeof(struct win_dev);
-	iov[1].iov_base = buf;
+	iov[1].iov_base = &buf.fi;
 	iov[1].iov_len = sizeof(struct win_dev);
 	if (S_ISCHR(mode)) {
 		memcpy(pdev->type, "IntxCHR", 8);
@@ -5197,8 +5134,8 @@ smb2_make_node(unsigned int xid, struct inode *inode,
 	d_drop(dentry);
 
 	/* FIXME: add code here to set EAs */
-out:
-	kfree(buf);
+
+	cifs_free_open_info(&buf);
 	return rc;
 }