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, 102 insertions, 68 deletions

diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index ad10c61ab5c9..be6dafcb25e3 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -210,6 +210,17 @@ cifs_fattr_to_inode(struct inode *inode, struct cifs_fattr *fattr)
 		 */
 		inode->i_blocks = (512 - 1 + fattr->cf_bytes) >> 9;
 	}
+
+	if (S_ISLNK(fattr->cf_mode)) {
+		kfree(cifs_i->symlink_target);
+		cifs_i->symlink_target = fattr->cf_symlink_target;
+		fattr->cf_symlink_target = NULL;
+
+		if (unlikely(!cifs_i->symlink_target))
+			inode->i_link = ERR_PTR(-EOPNOTSUPP);
+		else
+			inode->i_link = cifs_i->symlink_target;
+	}
 	spin_unlock(&inode->i_lock);
 
 	if (fattr->cf_flags & CIFS_FATTR_DFS_REFERRAL)
@@ -347,13 +358,20 @@ cifs_get_file_info_unix(struct file *filp)
 	int rc;
 	unsigned int xid;
 	FILE_UNIX_BASIC_INFO find_data;
-	struct cifs_fattr fattr;
+	struct cifs_fattr fattr = {};
 	struct inode *inode = file_inode(filp);
 	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 	struct cifsFileInfo *cfile = filp->private_data;
 	struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
 
 	xid = get_xid();
+
+	if (cfile->symlink_target) {
+		fattr.cf_symlink_target = kstrdup(cfile->symlink_target, GFP_KERNEL);
+		if (!fattr.cf_symlink_target)
+			return -ENOMEM;
+	}
+
 	rc = CIFSSMBUnixQFileInfo(xid, tcon, cfile->fid.netfid, &find_data);
 	if (!rc) {
 		cifs_unix_basic_to_fattr(&fattr, &find_data, cifs_sb);
@@ -378,6 +396,7 @@ int cifs_get_inode_info_unix(struct inode **pinode,
 	FILE_UNIX_BASIC_INFO find_data;
 	struct cifs_fattr fattr;
 	struct cifs_tcon *tcon;
+	struct TCP_Server_Info *server;
 	struct tcon_link *tlink;
 	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
 
@@ -387,10 +406,12 @@ int cifs_get_inode_info_unix(struct inode **pinode,
 	if (IS_ERR(tlink))
 		return PTR_ERR(tlink);
 	tcon = tlink_tcon(tlink);
+	server = tcon->ses->server;
 
 	/* could have done a find first instead but this returns more info */
 	rc = CIFSSMBUnixQPathInfo(xid, tcon, full_path, &find_data,
 				  cifs_sb->local_nls, cifs_remap(cifs_sb));
+	cifs_dbg(FYI, "%s: query path info: rc = %d\n", __func__, rc);
 	cifs_put_tlink(tlink);
 
 	if (!rc) {
@@ -410,6 +431,17 @@ int cifs_get_inode_info_unix(struct inode **pinode,
 			cifs_dbg(FYI, "check_mf_symlink: %d\n", tmprc);
 	}
 
+	if (S_ISLNK(fattr.cf_mode) && !fattr.cf_symlink_target) {
+		if (!server->ops->query_symlink)
+			return -EOPNOTSUPP;
+		rc = server->ops->query_symlink(xid, tcon, cifs_sb, full_path,
+						&fattr.cf_symlink_target, false);
+		if (rc) {
+			cifs_dbg(FYI, "%s: query_symlink: %d\n", __func__, rc);
+			goto cgiiu_exit;
+		}
+	}
+
 	if (*pinode == NULL) {
 		/* get new inode */
 		cifs_fill_uniqueid(sb, &fattr);
@@ -432,6 +464,7 @@ int cifs_get_inode_info_unix(struct inode **pinode,
 	}
 
 cgiiu_exit:
+	kfree(fattr.cf_symlink_target);
 	return rc;
 }
 #else
@@ -601,10 +634,10 @@ static int cifs_sfu_mode(struct cifs_fattr *fattr, const unsigned char *path,
 }
 
 /* Fill a cifs_fattr struct with info from POSIX info struct */
-static void
-smb311_posix_info_to_fattr(struct cifs_fattr *fattr, struct smb311_posix_qinfo *info,
-			   struct super_block *sb, bool adjust_tz, bool symlink)
+static void smb311_posix_info_to_fattr(struct cifs_fattr *fattr, struct cifs_open_info_data *data,
+				       struct super_block *sb, bool adjust_tz, bool symlink)
 {
+	struct smb311_posix_qinfo *info = &data->posix_fi;
 	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
 	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
 
@@ -639,6 +672,8 @@ smb311_posix_info_to_fattr(struct cifs_fattr *fattr, struct smb311_posix_qinfo *
 	if (symlink) {
 		fattr->cf_mode |= S_IFLNK;
 		fattr->cf_dtype = DT_LNK;
+		fattr->cf_symlink_target = data->symlink_target;
+		data->symlink_target = NULL;
 	} else if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
 		fattr->cf_mode |= S_IFDIR;
 		fattr->cf_dtype = DT_DIR;
@@ -655,13 +690,11 @@ smb311_posix_info_to_fattr(struct cifs_fattr *fattr, struct smb311_posix_qinfo *
 		fattr->cf_mode, fattr->cf_uniqueid, fattr->cf_nlink);
 }
 
-
-/* Fill a cifs_fattr struct with info from FILE_ALL_INFO */
-static void
-cifs_all_info_to_fattr(struct cifs_fattr *fattr, FILE_ALL_INFO *info,
-		       struct super_block *sb, bool adjust_tz,
-		       bool symlink, u32 reparse_tag)
+static void cifs_open_info_to_fattr(struct cifs_fattr *fattr, struct cifs_open_info_data *data,
+				    struct super_block *sb, bool adjust_tz, bool symlink,
+				    u32 reparse_tag)
 {
+	struct smb2_file_all_info *info = &data->fi;
 	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
 	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
 
@@ -703,7 +736,8 @@ cifs_all_info_to_fattr(struct cifs_fattr *fattr, FILE_ALL_INFO *info,
 	} else if (reparse_tag == IO_REPARSE_TAG_LX_BLK) {
 		fattr->cf_mode |= S_IFBLK | cifs_sb->ctx->file_mode;
 		fattr->cf_dtype = DT_BLK;
-	} else if (symlink) { /* TODO add more reparse tag checks */
+	} else if (symlink || reparse_tag == IO_REPARSE_TAG_SYMLINK ||
+		   reparse_tag == IO_REPARSE_TAG_NFS) {
 		fattr->cf_mode = S_IFLNK;
 		fattr->cf_dtype = DT_LNK;
 	} else if (fattr->cf_cifsattrs & ATTR_DIRECTORY) {
@@ -735,6 +769,11 @@ cifs_all_info_to_fattr(struct cifs_fattr *fattr, FILE_ALL_INFO *info,
 		}
 	}
 
+	if (S_ISLNK(fattr->cf_mode)) {
+		fattr->cf_symlink_target = data->symlink_target;
+		data->symlink_target = NULL;
+	}
+
 	fattr->cf_uid = cifs_sb->ctx->linux_uid;
 	fattr->cf_gid = cifs_sb->ctx->linux_gid;
 }
@@ -744,23 +783,28 @@ cifs_get_file_info(struct file *filp)
 {
 	int rc;
 	unsigned int xid;
-	FILE_ALL_INFO find_data;
+	struct cifs_open_info_data data = {};
 	struct cifs_fattr fattr;
 	struct inode *inode = file_inode(filp);
 	struct cifsFileInfo *cfile = filp->private_data;
 	struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
 	struct TCP_Server_Info *server = tcon->ses->server;
+	bool symlink = false;
+	u32 tag = 0;
 
 	if (!server->ops->query_file_info)
 		return -ENOSYS;
 
 	xid = get_xid();
-	rc = server->ops->query_file_info(xid, tcon, &cfile->fid, &find_data);
+	rc = server->ops->query_file_info(xid, tcon, cfile, &data);
 	switch (rc) {
 	case 0:
 		/* TODO: add support to query reparse tag */
-		cifs_all_info_to_fattr(&fattr, &find_data, inode->i_sb, false,
-				       false, 0 /* no reparse tag */);
+		if (data.symlink_target) {
+			symlink = true;
+			tag = IO_REPARSE_TAG_SYMLINK;
+		}
+		cifs_open_info_to_fattr(&fattr, &data, inode->i_sb, false, symlink, tag);
 		break;
 	case -EREMOTE:
 		cifs_create_dfs_fattr(&fattr, inode->i_sb);
@@ -789,6 +833,7 @@ cifs_get_file_info(struct file *filp)
 	/* if filetype is different, return error */
 	rc = cifs_fattr_to_inode(inode, &fattr);
 cgfi_exit:
+	cifs_free_open_info(&data);
 	free_xid(xid);
 	return rc;
 }
@@ -860,14 +905,9 @@ cifs_backup_query_path_info(int xid,
 }
 #endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
 
-static void
-cifs_set_fattr_ino(int xid,
-		   struct cifs_tcon *tcon,
-		   struct super_block *sb,
-		   struct inode **inode,
-		   const char *full_path,
-		   FILE_ALL_INFO *data,
-		   struct cifs_fattr *fattr)
+static void cifs_set_fattr_ino(int xid, struct cifs_tcon *tcon, struct super_block *sb,
+			       struct inode **inode, const char *full_path,
+			       struct cifs_open_info_data *data, struct cifs_fattr *fattr)
 {
 	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
 	struct TCP_Server_Info *server = tcon->ses->server;
@@ -885,11 +925,8 @@ cifs_set_fattr_ino(int xid,
 	 * If we have an inode pass a NULL tcon to ensure we don't
 	 * make a round trip to the server. This only works for SMB2+.
 	 */
-	rc = server->ops->get_srv_inum(xid,
-				       *inode ? NULL : tcon,
-				       cifs_sb, full_path,
-				       &fattr->cf_uniqueid,
-				       data);
+	rc = server->ops->get_srv_inum(xid, *inode ? NULL : tcon, cifs_sb, full_path,
+				       &fattr->cf_uniqueid, data);
 	if (rc) {
 		/*
 		 * If that fails reuse existing ino or generate one
@@ -923,14 +960,10 @@ static inline bool is_inode_cache_good(struct inode *ino)
 	return ino && CIFS_CACHE_READ(CIFS_I(ino)) && CIFS_I(ino)->time != 0;
 }
 
-int
-cifs_get_inode_info(struct inode **inode,
-		    const char *full_path,
-		    FILE_ALL_INFO *in_data,
-		    struct super_block *sb, int xid,
-		    const struct cifs_fid *fid)
+int cifs_get_inode_info(struct inode **inode, const char *full_path,
+			struct cifs_open_info_data *data, struct super_block *sb, int xid,
+			const struct cifs_fid *fid)
 {
-
 	struct cifs_tcon *tcon;
 	struct TCP_Server_Info *server;
 	struct tcon_link *tlink;
@@ -938,8 +971,7 @@ cifs_get_inode_info(struct inode **inode,
 	bool adjust_tz = false;
 	struct cifs_fattr fattr = {0};
 	bool is_reparse_point = false;
-	FILE_ALL_INFO *data = in_data;
-	FILE_ALL_INFO *tmp_data = NULL;
+	struct cifs_open_info_data tmp_data = {};
 	void *smb1_backup_rsp_buf = NULL;
 	int rc = 0;
 	int tmprc = 0;
@@ -960,21 +992,15 @@ cifs_get_inode_info(struct inode **inode,
 			cifs_dbg(FYI, "No need to revalidate cached inode sizes\n");
 			goto out;
 		}
-		tmp_data = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL);
-		if (!tmp_data) {
-			rc = -ENOMEM;
-			goto out;
-		}
-		rc = server->ops->query_path_info(xid, tcon, cifs_sb,
-						 full_path, tmp_data,
-						 &adjust_tz, &is_reparse_point);
+		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;
+		data = &tmp_data;
 	}
 
 	/*
@@ -988,14 +1014,24 @@ cifs_get_inode_info(struct inode **inode,
 		 * since we have to check if its reparse tag matches a known
 		 * special file type e.g. symlink or fifo or char etc.
 		 */
-		if ((le32_to_cpu(data->Attributes) & ATTR_REPARSE) &&
-		    server->ops->query_reparse_tag) {
-			rc = server->ops->query_reparse_tag(xid, tcon, cifs_sb,
-						full_path, &reparse_tag);
-			cifs_dbg(FYI, "reparse tag 0x%x\n", reparse_tag);
+		if (is_reparse_point && data->symlink_target) {
+			reparse_tag = IO_REPARSE_TAG_SYMLINK;
+		} else if ((le32_to_cpu(data->fi.Attributes) & ATTR_REPARSE) &&
+			   server->ops->query_reparse_tag) {
+			tmprc = server->ops->query_reparse_tag(xid, tcon, cifs_sb, full_path,
+							    &reparse_tag);
+			if (tmprc)
+				cifs_dbg(FYI, "%s: query_reparse_tag: rc = %d\n", __func__, tmprc);
+			if (server->ops->query_symlink) {
+				tmprc = server->ops->query_symlink(xid, tcon, cifs_sb, full_path,
+								   &data->symlink_target,
+								   is_reparse_point);
+				if (tmprc)
+					cifs_dbg(FYI, "%s: query_symlink: rc = %d\n", __func__,
+						 tmprc);
+			}
 		}
-		cifs_all_info_to_fattr(&fattr, data, sb, adjust_tz,
-				       is_reparse_point, reparse_tag);
+		cifs_open_info_to_fattr(&fattr, data, sb, adjust_tz, is_reparse_point, reparse_tag);
 		break;
 	case -EREMOTE:
 		/* DFS link, no metadata available on this server */
@@ -1014,18 +1050,20 @@ cifs_get_inode_info(struct inode **inode,
 		 */
 		if (backup_cred(cifs_sb) && is_smb1_server(server)) {
 			/* for easier reading */
+			FILE_ALL_INFO *fi;
 			FILE_DIRECTORY_INFO *fdi;
 			SEARCH_ID_FULL_DIR_INFO *si;
 
 			rc = cifs_backup_query_path_info(xid, tcon, sb,
 							 full_path,
 							 &smb1_backup_rsp_buf,
-							 &data);
+							 &fi);
 			if (rc)
 				goto out;
 
-			fdi = (FILE_DIRECTORY_INFO *)data;
-			si = (SEARCH_ID_FULL_DIR_INFO *)data;
+			move_cifs_info_to_smb2(&data->fi, fi);
+			fdi = (FILE_DIRECTORY_INFO *)fi;
+			si = (SEARCH_ID_FULL_DIR_INFO *)fi;
 
 			cifs_dir_info_to_fattr(&fattr, fdi, cifs_sb);
 			fattr.cf_uniqueid = le64_to_cpu(si->UniqueId);
@@ -1123,7 +1161,8 @@ handle_mnt_opt:
 out:
 	cifs_buf_release(smb1_backup_rsp_buf);
 	cifs_put_tlink(tlink);
-	kfree(tmp_data);
+	cifs_free_open_info(&tmp_data);
+	kfree(fattr.cf_symlink_target);
 	return rc;
 }
 
@@ -1138,7 +1177,7 @@ smb311_posix_get_inode_info(struct inode **inode,
 	bool adjust_tz = false;
 	struct cifs_fattr fattr = {0};
 	bool symlink = false;
-	struct smb311_posix_qinfo *data = NULL;
+	struct cifs_open_info_data data = {};
 	int rc = 0;
 	int tmprc = 0;
 
@@ -1155,15 +1194,9 @@ smb311_posix_get_inode_info(struct inode **inode,
 		cifs_dbg(FYI, "No need to revalidate cached inode sizes\n");
 		goto out;
 	}
-	data = kmalloc(sizeof(struct smb311_posix_qinfo), GFP_KERNEL);
-	if (!data) {
-		rc = -ENOMEM;
-		goto out;
-	}
 
-	rc = smb311_posix_query_path_info(xid, tcon, cifs_sb,
-						  full_path, data,
-						  &adjust_tz, &symlink);
+	rc = smb311_posix_query_path_info(xid, tcon, cifs_sb, full_path, &data, &adjust_tz,
+					  &symlink);
 
 	/*
 	 * 2. Convert it to internal cifs metadata (fattr)
@@ -1171,7 +1204,7 @@ smb311_posix_get_inode_info(struct inode **inode,
 
 	switch (rc) {
 	case 0:
-		smb311_posix_info_to_fattr(&fattr, data, sb, adjust_tz, symlink);
+		smb311_posix_info_to_fattr(&fattr, &data, sb, adjust_tz, symlink);
 		break;
 	case -EREMOTE:
 		/* DFS link, no metadata available on this server */
@@ -1228,7 +1261,8 @@ smb311_posix_get_inode_info(struct inode **inode,
 	}
 out:
 	cifs_put_tlink(tlink);
-	kfree(data);
+	cifs_free_open_info(&data);
+	kfree(fattr.cf_symlink_target);
 	return rc;
 }