CIFS: refactor cifs_get_inode_info()

Make logic of cifs_get_inode() much clearer by moving code to sub
functions and adding comments.

Document the steps this function does.

cifs_get_inode_info() gets and updates a file inode metadata from its
file path.

* If caller already has raw info data from server they can pass it.
* If inode already exists (just need to update) caller can pass it.

Step 1: get raw data from server if none was passed
Step 2: parse raw data into intermediate internal cifs_fattr struct
Step 3: set fattr uniqueid which is later used for inode number. This
can sometime be done from raw data
Step 4: tweak fattr according to mount options (file_mode, acl to mode
bits, uid, gid, etc)
Step 5: update or create inode from final fattr struct

* add is_smb1_server() helper
* add is_inode_cache_good() helper
* move SMB1-backupcreds-getinfo-retry to separate func
cifs_backup_query_path_info().
* move set-uniqueid code to separate func cifs_set_fattr_ino()
* don't clobber uniqueid from backup cred retry
* fix some probable corner cases memleaks

Signed-off-by: Aurelien Aptel <[e-mail]>
Signed-off-by: Steve French <[e-mail]>

fs/cifs/cifsglob.h

···
 #define ALT_SMB311_VERSION_STRING "3.11"
 extern struct smb_version_operations smb311_operations;
 extern struct smb_version_values smb311_values;
+
+static inline bool is_smb1_server(struct TCP_Server_Info *server)
+{
+	return strcmp(server->vals->version_string, SMB1_VERSION_STRING) == 0;
+}
+
 #endif	/* _CIFS_GLOB_H */

fs/cifs/inode.c

···
 	return hash;
 }
 
+/**
+ * cifs_backup_query_path_info - SMB1 fallback code to get ino
+ *
+ * Fallback code to get file metadata when we don't have access to
+ * @full_path (EACCESS) and have backup creds.
+ *
+ * @data will be set to search info result buffer
+ * @resp_buf will be set to cifs resp buf and needs to be freed with
+ * cifs_buf_release() when done with @data.
+ */
+static int
+cifs_backup_query_path_info(int xid,
+			    struct cifs_tcon *tcon,
+			    struct super_block *sb,
+			    const char *full_path,
+			    void **resp_buf,
+			    FILE_ALL_INFO **data)
+{
+	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
+	struct cifs_search_info info = {0};
+	u16 flags;
+	int rc;
+
+	*resp_buf = NULL;
+	info.endOfSearch = false;
+	if (tcon->unix_ext)
+		info.info_level = SMB_FIND_FILE_UNIX;
+	else if ((tcon->ses->capabilities &
+		  tcon->ses->server->vals->cap_nt_find) == 0)
+		info.info_level = SMB_FIND_FILE_INFO_STANDARD;
+	else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)
+		info.info_level = SMB_FIND_FILE_ID_FULL_DIR_INFO;
+	else /* no srvino useful for fallback to some netapp */
+		info.info_level = SMB_FIND_FILE_DIRECTORY_INFO;
+
+	flags = CIFS_SEARCH_CLOSE_ALWAYS |
+		CIFS_SEARCH_CLOSE_AT_END |
+		CIFS_SEARCH_BACKUP_SEARCH;
+
+	rc = CIFSFindFirst(xid, tcon, full_path,
+			   cifs_sb, NULL, flags, &info, false);
+	if (rc)
+		return rc;
+
+	*resp_buf = (void *)info.ntwrk_buf_start;
+	*data = (FILE_ALL_INFO *)info.srch_entries_start;
+	return 0;
+}
+
+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)
+{
+	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
+	struct TCP_Server_Info *server = tcon->ses->server;
+	int rc;
+
+	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)) {
+		if (*inode)
+			fattr->cf_uniqueid = CIFS_I(*inode)->uniqueid;
+		else
+			fattr->cf_uniqueid = iunique(sb, ROOT_I);
+		return;
+	}
+
+	/*
+	 * 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);
+	if (rc) {
+		/*
+		 * If that fails reuse existing ino or generate one
+		 * and disable server ones
+		 */
+		if (*inode)
+			fattr->cf_uniqueid = CIFS_I(*inode)->uniqueid;
+		else {
+			fattr->cf_uniqueid = iunique(sb, ROOT_I);
+			cifs_autodisable_serverino(cifs_sb);
+		}
+		return;
+	}
+
+	/* If no errors, check for zero root inode (invalid) */
+	if (fattr->cf_uniqueid == 0 && strlen(full_path) == 0) {
+		cifs_dbg(FYI, "Invalid (0) inodenum\n");
+		if (*inode) {
+			/* reuse */
+			fattr->cf_uniqueid = CIFS_I(*inode)->uniqueid;
+		} else {
+			/* make an ino by hashing the UNC */
+			fattr->cf_flags |= CIFS_FATTR_FAKE_ROOT_INO;
+			fattr->cf_uniqueid = simple_hashstr(tcon->treeName);
+		}
+	}
+}
+
+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 *data, struct super_block *sb, int xid,
+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)
 {
-	__u16 srchflgs;
-	int rc = 0, tmprc = ENOSYS;
+
 	struct cifs_tcon *tcon;
 	struct TCP_Server_Info *server;
 	struct tcon_link *tlink;
 	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
-	char *buf = NULL;
 	bool adjust_tz = false;
-	struct cifs_fattr fattr;
-	struct cifs_search_info *srchinf = NULL;
+	struct cifs_fattr fattr = {0};
 	bool symlink = false;
+	FILE_ALL_INFO *data = in_data;
+	FILE_ALL_INFO *tmp_data = NULL;
+	void *smb1_backup_rsp_buf = NULL;
+	int rc = 0;
+	int tmprc = 0;
 
 	tlink = cifs_sb_tlink(cifs_sb);
 	if (IS_ERR(tlink))
···
 	tcon = tlink_tcon(tlink);
 	server = tcon->ses->server;
 
-	cifs_dbg(FYI, "Getting info on %s\n", full_path);
+	/*
+	 * 1. Fetch file metadata if not provided (data)
+	 */
 
-	if ((data == NULL) && (*inode != NULL)) {
-		if (CIFS_CACHE_READ(CIFS_I(*inode)) &&
-		    CIFS_I(*inode)->time != 0) {
+	if (!data) {
+		if (is_inode_cache_good(*inode)) {
 			cifs_dbg(FYI, "No need to revalidate cached inode sizes\n");
-			goto cgii_exit;
+			goto out;
 		}
-	}
-
-	/* if inode info is not passed, get it from server */
-	if (data == NULL) {
-		if (!server->ops->query_path_info) {
-			rc = -ENOSYS;
-			goto cgii_exit;
-		}
-		buf = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL);
-		if (buf == NULL) {
+		tmp_data = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL);
+		if (!tmp_data) {
 			rc = -ENOMEM;
-			goto cgii_exit;
+			goto out;
 		}
-		data = (FILE_ALL_INFO *)buf;
-		rc = server->ops->query_path_info(xid, tcon, cifs_sb, full_path,
-						  data, &adjust_tz, &symlink);
+		rc = server->ops->query_path_info(xid, tcon, cifs_sb,
+						  full_path, tmp_data,
+						  &adjust_tz, &symlink);
+		data = tmp_data;
 	}
-
-	if (!rc) {
-		cifs_all_info_to_fattr(&fattr, data, sb, adjust_tz,
-				       symlink);
-	} else if (rc == -EREMOTE) {
-		cifs_create_dfs_fattr(&fattr, sb);
-		rc = 0;
-	} else if ((rc == -EACCES) && backup_cred(cifs_sb) &&
-		   (strcmp(server->vals->version_string, SMB1_VERSION_STRING)
-		      == 0)) {
-		/*
-		 * For SMB2 and later the backup intent flag is already
-		 * sent if needed on open and there is no path based
-		 * FindFirst operation to use to retry with
-		 */
-
-		srchinf = kzalloc(sizeof(struct cifs_search_info),
-					GFP_KERNEL);
-		if (srchinf == NULL) {
-			rc = -ENOMEM;
-			goto cgii_exit;
-		}
-
-		srchinf->endOfSearch = false;
-		if (tcon->unix_ext)
-			srchinf->info_level = SMB_FIND_FILE_UNIX;
-		else if ((tcon->ses->capabilities &
-			 tcon->ses->server->vals->cap_nt_find) == 0)
-			srchinf->info_level = SMB_FIND_FILE_INFO_STANDARD;
-		else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)
-			srchinf->info_level = SMB_FIND_FILE_ID_FULL_DIR_INFO;
-		else /* no srvino useful for fallback to some netapp */
-			srchinf->info_level = SMB_FIND_FILE_DIRECTORY_INFO;
-
-		srchflgs = CIFS_SEARCH_CLOSE_ALWAYS |
-				CIFS_SEARCH_CLOSE_AT_END |
-				CIFS_SEARCH_BACKUP_SEARCH;
-
-		rc = CIFSFindFirst(xid, tcon, full_path,
-			cifs_sb, NULL, srchflgs, srchinf, false);
-		if (!rc) {
-			data = (FILE_ALL_INFO *)srchinf->srch_entries_start;
-
-			cifs_dir_info_to_fattr(&fattr,
-			(FILE_DIRECTORY_INFO *)data, cifs_sb);
-			fattr.cf_uniqueid = le64_to_cpu(
-			((SEARCH_ID_FULL_DIR_INFO *)data)->UniqueId);
-
-			cifs_buf_release(srchinf->ntwrk_buf_start);
-		}
-		kfree(srchinf);
-		if (rc)
-			goto cgii_exit;
-	} else
-		goto cgii_exit;
 
 	/*
-	 * If an inode wasn't passed in, then get the inode number
-	 *
-	 * Is an i_ino of zero legal? Can we use that to check if the server
-	 * supports returning inode numbers?  Are there other sanity checks we
-	 * can use to ensure that the server is really filling in that field?
+	 * 2. Convert it to internal cifs metadata (fattr)
 	 */
-	if (*inode == NULL) {
-		if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
-			if (server->ops->get_srv_inum)
-				tmprc = server->ops->get_srv_inum(xid,
-								  tcon, cifs_sb, full_path,
-								  &fattr.cf_uniqueid, data);
-			if (tmprc) {
-				cifs_dbg(FYI, "GetSrvInodeNum rc %d\n",
-					 tmprc);
-				fattr.cf_uniqueid = iunique(sb, ROOT_I);
-				cifs_autodisable_serverino(cifs_sb);
-			} else if ((fattr.cf_uniqueid == 0) &&
-				   strlen(full_path) == 0) {
-				/* some servers ret bad root ino ie 0 */
-				cifs_dbg(FYI, "Invalid (0) inodenum\n");
-				fattr.cf_flags |=
-					CIFS_FATTR_FAKE_ROOT_INO;
-				fattr.cf_uniqueid =
-					simple_hashstr(tcon->treeName);
-			}
-		} else
-			fattr.cf_uniqueid = iunique(sb, ROOT_I);
-	} else {
-		if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)
-		    && server->ops->get_srv_inum) {
-			/*
-			 * Pass a NULL tcon to ensure we don't make a round
-			 * trip to the server. This only works for SMB2+.
-			 */
-			tmprc = server->ops->get_srv_inum(xid,
-				NULL, cifs_sb, full_path,
-				&fattr.cf_uniqueid, data);
-			if (tmprc)
-				fattr.cf_uniqueid = CIFS_I(*inode)->uniqueid;
-			else if ((fattr.cf_uniqueid == 0) &&
-					strlen(full_path) == 0) {
-				/*
-				 * Reuse existing root inode num since
-				 * inum zero for root causes ls of . and .. to
-				 * not be returned
-				 */
-				cifs_dbg(FYI, "Srv ret 0 inode num for root\n");
-				fattr.cf_uniqueid = CIFS_I(*inode)->uniqueid;
-			}
-		} else
-			fattr.cf_uniqueid = CIFS_I(*inode)->uniqueid;
+
+	switch (rc) {
+	case 0:
+		cifs_all_info_to_fattr(&fattr, data, sb, adjust_tz, symlink);
+		break;
+	case -EREMOTE:
+		/* DFS link, no metadata available on this server */
+		cifs_create_dfs_fattr(&fattr, sb);
+		rc = 0;
+		break;
+	case -EACCES:
+		/*
+		 * perm errors, try again with backup flags if possible
+		 *
+		 * For SMB2 and later the backup intent flag
+		 * is already sent if needed on open and there
+		 * is no path based FindFirst operation to use
+		 * to retry with
+		 */
+		if (backup_cred(cifs_sb) && is_smb1_server(server)) {
+			/* for easier reading */
+			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);
+			if (rc)
+				goto out;
+
+			fdi = (FILE_DIRECTORY_INFO *)data;
+			si = (SEARCH_ID_FULL_DIR_INFO *)data;
+
+			cifs_dir_info_to_fattr(&fattr, fdi, cifs_sb);
+			fattr.cf_uniqueid = le64_to_cpu(si->UniqueId);
+			/* uniqueid set, skip get inum step */
+			goto handle_mnt_opt;
+		} else {
+			/* nothing we can do, bail out */
+			goto out;
+		}
+		break;
+	default:
+		cifs_dbg(FYI, "%s: unhandled err rc %d\n", __func__, rc);
+		goto out;
 	}
 
+	/*
+	 * 3. Get or update inode number (fattr.cf_uniqueid)
+	 */
+
+	cifs_set_fattr_ino(xid, tcon, sb, inode, full_path, data, &fattr);
+
+	/*
+	 * 4. Tweak fattr based on mount options
+	 */
+
+handle_mnt_opt:
 	/* query for SFU type info if supported and needed */
 	if (fattr.cf_cifsattrs & ATTR_SYSTEM &&
 	    cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
···
 				       full_path, fid);
 		if (rc) {
 			cifs_dbg(FYI, "%s: Get mode from SID failed. rc=%d\n",
-				__func__, rc);
-			goto cgii_exit;
+				 __func__, rc);
+			goto out;
 		}
 	} else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL) {
 		rc = cifs_acl_to_fattr(cifs_sb, &fattr, *inode, false,
-				       full_path, fid);
-		if (rc) {
+				       full_path, fid);		if (rc) {
 			cifs_dbg(FYI, "%s: Getting ACL failed with error: %d\n",
 				 __func__, rc);
-			goto cgii_exit;
+			goto out;
 		}
 	}
 
···
 			cifs_dbg(FYI, "check_mf_symlink: %d\n", tmprc);
 	}
 
+	/*
+	 * 5. Update inode with final fattr data
+	 */
+
 	if (!*inode) {
 		*inode = cifs_iget(sb, &fattr);
 		if (!*inode)
···
 		    CIFS_I(*inode)->uniqueid != fattr.cf_uniqueid)) {
 			CIFS_I(*inode)->time = 0; /* force reval */
 			rc = -ESTALE;
-			goto cgii_exit;
+			goto out;
 		}
 
 		/* if filetype is different, return error */
···
 		    (fattr.cf_mode & S_IFMT))) {
 			CIFS_I(*inode)->time = 0; /* force reval */
 			rc = -ESTALE;
-			goto cgii_exit;
+			goto out;
 		}
 
 		cifs_fattr_to_inode(*inode, &fattr);
 	}
-
-cgii_exit:
-	if ((*inode) && ((*inode)->i_ino == 0))
-		cifs_dbg(FYI, "inode number of zero returned\n");
-
-	kfree(buf);
+out:
+	cifs_buf_release(smb1_backup_rsp_buf);
 	cifs_put_tlink(tlink);
+	kfree(tmp_data);
 	return rc;
 }