[Ocfs2-tools-devel] [PATCH 17/24] tunefs rework: Add feature_backup_super.c

[Joel Becker]

Enable and disable the backup superblock feature.

This is the 'backup-super' key to the tunefs option '--fs-features', as
well as the tunefs option '--backup-super'.

Signed-off-by: Joel Becker <joel.becker at oracle.com>
Signed-off-by: Mark Fasheh <mfasheh at suse.com>
---
 tunefs.ocfs2/feature_backup_super.c |  229 +++++++++++++++++++++++++++++++++++
 1 files changed, 229 insertions(+), 0 deletions(-)
 create mode 100644 tunefs.ocfs2/feature_backup_super.c

diff --git a/tunefs.ocfs2/feature_backup_super.c b/tunefs.ocfs2/feature_backup_super.c
new file mode 100644
index 0000000..a8af858
--- /dev/null
+++ b/tunefs.ocfs2/feature_backup_super.c
@@ -0,0 +1,229 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * feature_backup_super.c
+ *
+ * ocfs2 tune utility to enable and disable the backup superblock feature.
+ *
+ * Copyright (C) 2004, 2008 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <inttypes.h>
+
+#include "ocfs2/ocfs2.h"
+
+#include "libocfs2ne.h"
+
+
+static errcode_t empty_backup_supers(ocfs2_filesys *fs)
+{
+	errcode_t ret;
+	int num;
+	uint64_t blocks[OCFS2_MAX_BACKUP_SUPERBLOCKS];
+
+	num = ocfs2_get_backup_super_offsets(fs, blocks,
+					     ARRAY_SIZE(blocks));
+	if (!num)
+		return 0;
+
+	ret = ocfs2_clear_backup_super_list(fs, blocks, num);
+	if (ret)
+		tcom_err(ret, "while freeing backup  superblock locations");
+
+	return ret;
+}
+
+static errcode_t fill_backup_supers(ocfs2_filesys *fs)
+{
+	errcode_t ret;
+	int num;
+	uint64_t blocks[OCFS2_MAX_BACKUP_SUPERBLOCKS];
+
+	num = ocfs2_get_backup_super_offsets(fs, blocks,
+					     ARRAY_SIZE(blocks));
+	ret = ocfs2_set_backup_super_list(fs, blocks, num);
+	if (ret)
+		tcom_err(ret, "while backing up the superblock");
+
+	return ret;
+}
+
+static int disable_backup_super(ocfs2_filesys *fs, int flags)
+{
+	errcode_t err = 0;
+	struct ocfs2_super_block *super = OCFS2_RAW_SB(fs->fs_super);
+
+	if (!OCFS2_HAS_COMPAT_FEATURE(super,
+				      OCFS2_FEATURE_COMPAT_BACKUP_SB)) {
+		verbosef(VL_APP,
+			 "Backup superblock feature is not enabled; "
+			 "nothing to disable\n");
+		goto out;
+	}
+
+	if (!tunefs_interact("Disable the backup superblock feature on "
+			     "device \"%s\"? ",
+			     fs->fs_devname))
+		goto out;
+
+	tunefs_block_signals();
+	err = empty_backup_supers(fs);
+	if (!err) {
+		super->s_feature_compat &= ~OCFS2_FEATURE_COMPAT_BACKUP_SB;
+		err = ocfs2_write_super(fs);
+		if (err)
+			tcom_err(err,
+				 "while writing out the superblock\n"
+				 "Unable to disable the backup superblock "
+				 "feature on device \"%s\"",
+				 fs->fs_devname);
+	}
+	tunefs_unblock_signals();
+
+out:
+	return err;
+}
+
+static errcode_t load_global_bitmap(ocfs2_filesys *fs,
+				    ocfs2_cached_inode** inode)
+{
+	errcode_t ret;
+	uint64_t blkno;
+
+	ret = ocfs2_lookup_system_inode(fs, GLOBAL_BITMAP_SYSTEM_INODE,
+					0, &blkno);
+	if (ret)
+		goto bail;
+
+	ret = ocfs2_read_cached_inode(fs, blkno, inode);
+	if (ret)
+		goto bail;
+
+	ret = ocfs2_load_chain_allocator(fs, *inode);
+
+bail:
+	return ret;
+}
+
+static errcode_t check_backup_offsets(ocfs2_filesys *fs)
+{
+
+	errcode_t ret;
+	int i, num, val, failed = 0;
+	ocfs2_cached_inode *chain_alloc = NULL;
+	uint64_t blocks[OCFS2_MAX_BACKUP_SUPERBLOCKS];
+
+	num = ocfs2_get_backup_super_offsets(fs, blocks,
+					     ARRAY_SIZE(blocks));
+	if (!num) {
+		ret = 1;
+		errorf("Volume on device \"%s\" is too small to contain "
+		       "backup superblocks\n",
+		       fs->fs_devname);
+		goto bail;
+	}
+
+	ret = load_global_bitmap(fs, &chain_alloc);
+	if (ret) {
+		tcom_err(ret, "while loading the global bitmap");
+		goto bail;
+	}
+
+	for (i = 0; i < num; i++) {
+		ret = ocfs2_bitmap_test(chain_alloc->ci_chains,
+					ocfs2_blocks_to_clusters(fs, blocks[i]),
+					&val);
+		if (ret) {
+			tcom_err(ret,
+				 "looking up backup superblock locations "
+				 "in the global bitmap");
+			goto bail;
+		}
+
+		if (val) {
+			verbosef(VL_APP,
+				 "Backup superblock location %d at block "
+				 "%"PRIu64" is in use\n", i, blocks[i]);
+			/* in order to verify all the block in the 'blocks',
+			 * we don't stop the loop here.
+			 */
+			failed = 1;
+		}
+	}
+
+	if (failed) {
+		ret = 1;
+		errorf("One or more backup superblock locations are "
+		       "already in use\n");
+	} else
+		ret = 0;
+
+	if (chain_alloc)
+		ocfs2_free_cached_inode(fs, chain_alloc);
+
+bail:
+	return ret;
+}
+
+static int enable_backup_super(ocfs2_filesys *fs, int flags)
+{
+	errcode_t err = 0;
+	struct ocfs2_super_block *super = OCFS2_RAW_SB(fs->fs_super);
+
+	if (OCFS2_HAS_COMPAT_FEATURE(super,
+				     OCFS2_FEATURE_COMPAT_BACKUP_SB)) {
+		verbosef(VL_APP,
+			 "Backup superblock feature is already enabled; "
+			 "nothing to enable\n");
+		goto out;
+	}
+
+	if (!tunefs_interact("Enable the backup superblock feature on "
+			     "device \"%s\"? ",
+			     fs->fs_devname))
+		goto out;
+
+	tunefs_block_signals();
+	err = check_backup_offsets(fs);
+	if (!err)
+		err = fill_backup_supers(fs);
+	if (!err) {
+		super->s_feature_compat |= OCFS2_FEATURE_COMPAT_BACKUP_SB;
+		err = ocfs2_write_super(fs);
+		if (err)
+			tcom_err(err, "while writing out the superblock\n");
+	}
+	tunefs_unblock_signals();
+
+	if (err)
+		errorf("Unable to enable the backup superblock feature on "
+		       "device \"%s\"\n",
+		       fs->fs_devname);
+out:
+	return err;
+}
+
+DEFINE_TUNEFS_FEATURE_COMPAT(backup_super,
+			     OCFS2_FEATURE_COMPAT_BACKUP_SB,
+			     TUNEFS_FLAG_RW | TUNEFS_FLAG_ALLOCATION,
+			     enable_backup_super,
+			     disable_backup_super);
+
+#ifdef DEBUG_EXE
+int main(int argc, char *argv[])
+{
+	return tunefs_feature_main(argc, argv, &backup_super_feature);
+}
+#endif
-- 
1.5.6.3