[PATCH 07/54] tune2fs: Add inode checksum support

["Darrick J. Wong" <djwong@us.ibm.com>]

This patch adds to tune2fs the ability to toggle the metadata checksum rocompat
feature flag, which will rewrite the inode table with checksums.  Disallow
changing the UUID while the fs is mounted, because rewriting the metadata
objects is racy.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
---
 misc/tune2fs.c |  108 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 106 insertions(+), 2 deletions(-)


diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index 74a0489..cb1aff3 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -91,6 +91,7 @@ static char *extended_cmd;
 static unsigned long new_inode_size;
 static char *ext_mount_opts;
 static int usrquota, grpquota;
+static int rewrite_checksums;
 
 int journal_size, journal_flags;
 char *journal_device;
@@ -142,7 +143,8 @@ static __u32 ok_features[3] = {
 		EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE|
 		EXT4_FEATURE_RO_COMPAT_GDT_CSUM |
 		EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER |
-		EXT4_FEATURE_RO_COMPAT_QUOTA
+		EXT4_FEATURE_RO_COMPAT_QUOTA |
+		EXT4_FEATURE_RO_COMPAT_METADATA_CSUM
 };
 
 static __u32 clear_ok_features[3] = {
@@ -160,7 +162,8 @@ static __u32 clear_ok_features[3] = {
 		EXT4_FEATURE_RO_COMPAT_DIR_NLINK|
 		EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE|
 		EXT4_FEATURE_RO_COMPAT_GDT_CSUM |
-		EXT4_FEATURE_RO_COMPAT_QUOTA
+		EXT4_FEATURE_RO_COMPAT_QUOTA |
+		EXT4_FEATURE_RO_COMPAT_METADATA_CSUM
 };
 
 /*
@@ -351,6 +354,16 @@ static int update_mntopts(ext2_filsys fs, char *mntopts)
 	return 0;
 }
 
+static int check_fsck_needed(ext2_filsys fs)
+{
+	if (fs->super->s_state & EXT2_VALID_FS)
+		return 0;
+	printf("\n%s\n", _(please_fsck));
+	if (mount_flags & EXT2_MF_READONLY)
+		printf(_("(and reboot afterwards!)\n"));
+	return 1;
+}
+
 static void request_fsck_afterwards(ext2_filsys fs)
 {
 	static int requested = 0;
@@ -364,6 +377,60 @@ static void request_fsck_afterwards(ext2_filsys fs)
 }
 
 /*
+ * Forcibly set checksums in all inodes.
+ */
+static void rewrite_inodes(ext2_filsys fs)
+{
+	int length = EXT2_INODE_SIZE(fs->super);
+	struct ext2_inode *inode;
+	ext2_inode_scan	scan;
+	errcode_t	retval;
+	ext2_ino_t	ino;
+
+	if (fs->super->s_creator_os != EXT2_OS_LINUX)
+		return;
+
+	retval = ext2fs_open_inode_scan(fs, 0, &scan);
+	if (retval) {
+		com_err("set_csum", retval, "while opening inode scan");
+		exit(1);
+	}
+
+	retval = ext2fs_get_mem(length, &inode);
+	if (retval) {
+		com_err("set_csum", retval, "while allocating memory");
+		exit(1);
+	}
+
+	do {
+		retval = ext2fs_get_next_inode_full(scan, &ino, inode, length);
+		if (retval) {
+			com_err("set_csum", retval, "while getting next inode");
+			exit(1);
+		}
+		if (!ino)
+			break;
+
+		retval = ext2fs_write_inode_full(fs, ino, inode, length);
+		if (retval) {
+			com_err("set_csum", retval, "while writing inode");
+			exit(1);
+		}
+	} while (ino);
+
+	ext2fs_free_mem(&inode);
+	ext2fs_close_inode_scan(scan);
+}
+
+static void rewrite_metadata_checksums(ext2_filsys fs)
+{
+	fs->flags |= EXT2_FLAG_IGNORE_CSUM_ERRORS;
+	ext2fs_init_csum_seed(fs);
+	rewrite_inodes(fs);
+	fs->flags &= ~EXT2_FLAG_IGNORE_CSUM_ERRORS;
+}
+
+/*
  * Update the feature set as provided by the user.
  */
 static int update_feature_set(ext2_filsys fs, char *features)
@@ -536,6 +603,20 @@ mmp_error:
 	}
 
 	if (FEATURE_ON(E2P_FEATURE_RO_INCOMPAT,
+		       EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) {
+		if (check_fsck_needed(fs))
+			exit(1);
+		rewrite_checksums = 1;
+	}
+
+	if (FEATURE_OFF(E2P_FEATURE_RO_INCOMPAT,
+			EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) {
+		if (check_fsck_needed(fs))
+			exit(1);
+		rewrite_checksums = 1;
+	}
+
+	if (FEATURE_ON(E2P_FEATURE_RO_INCOMPAT,
 		       EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
 		for (i = 0; i < fs->group_desc_count; i++) {
 			gd = ext2fs_group_desc(fs, fs->group_desc, i);
@@ -2128,6 +2209,23 @@ retry_open:
 		int set_csum = 0;
 		dgrp_t i;
 
+		if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+				EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) {
+			/*
+			 * Changing the UUID requires rewriting all metadata,
+			 * which can race with a mounted fs.  Don't allow that.
+			 */
+			if (mount_flags & EXT2_MF_MOUNTED) {
+				fputs(_("The UUID may only be "
+					"changed when the filesystem is "
+					"unmounted.\n"), stderr);
+				exit(1);
+			}
+
+			if (check_fsck_needed(fs))
+				exit(1);
+		}
+
 		if (sb->s_feature_ro_compat &
 		    EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
 			/*
@@ -2153,13 +2251,19 @@ retry_open:
 			rc = 1;
 			goto closefs;
 		}
+		ext2fs_init_csum_seed(fs);
 		if (set_csum) {
 			for (i = 0; i < fs->group_desc_count; i++)
 				ext2fs_group_desc_csum_set(fs, i);
 			fs->flags &= ~EXT2_FLAG_SUPER_ONLY;
 		}
 		ext2fs_mark_super_dirty(fs);
+		if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+				EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+			rewrite_checksums = 1;
 	}
+	if (rewrite_checksums)
+		rewrite_metadata_checksums(fs);
 	if (I_flag) {
 		if (mount_flags & EXT2_MF_MOUNTED) {
 			fputs(_("The inode size may only be "