misc: add e2mmpstatus utility via dumpe2fs

e2mmpstatus is a Multi-Mount Protection (MMP) helper utility to read
an MMP block to see if it is being updated.  It can also output the
latest update time, nodename, and device from the MMP block.

This is useful for HA and other maintenance scripts to determine if
the filesystem is in use on another node, and which node it is.

Signed-off-by: Shuichi Ihara <sihara@ddn.com>
Signed-off-by: Li Xi <lixi@ddn.com>
Signed-off-by: Wang Shilong <wshilong@ddn.com>

Moved e2mmpstatus checking/dumping code to be part of dumpe2fs rather
than a standalone program, using the "-m" option to check MMP status,
and "-i" to dump info.  If dumpe2fs is called as "e2mmpstatus" (and
also "mmpstatus" for compatibility reasons), assume "-m" is specified.

Re-use the existing MMP block handing routines (with some changes) to
check and dump the MMP block, rather than adding duplicate versions.

Modify dumpe2fs to exit with a non-zero error code if there is an
error while reading the filesystem metadata or MMP block, or if
"-m" is used with the "mmp" feature and is in use by another node.

Add a configure check for gethostname() rather than depending on
_BSD_SOURCE or _XOPEN_SOURCE to be set.

Update the f_mmp, m_mmp, m_mmp_bad_csum, and m_mmp_bad_magic tests
to use e2mmpstatus to check and dump the MMP state before and after
e2fsck is run to verify that the tool is working correctly.

Signed-off-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 162 insertions, 40 deletions

diff --git a/misc/dumpe2fs.c b/misc/dumpe2fs.c
index 395ea9ee..384ce925 100644
--- a/misc/dumpe2fs.c
+++ b/misc/dumpe2fs.c
@@ -53,7 +53,7 @@ static int blocks64 = 0;
 
 static void usage(void)
 {
-	fprintf(stderr, _("Usage: %s [-bfghixV] [-o superblock=<num>] "
+	fprintf(stderr, _("Usage: %s [-bfghimxV] [-o superblock=<num>] "
 		 "[-o blocksize=<num>] device\n"), program_name);
 	exit(1);
 }
@@ -420,6 +420,79 @@ static void print_journal_information(ext2_filsys fs)
 	e2p_list_journal_super(stdout, buf, fs->blocksize, 0);
 }
 
+static int check_mmp(ext2_filsys fs)
+{
+	int retval;
+
+	/* This won't actually start MMP on the filesystem, since fs is opened
+	 * readonly, but it will do the proper activity checking for us. */
+	retval = ext2fs_mmp_start(fs);
+	if (retval) {
+		com_err(program_name, retval, _("while trying to open %s"),
+			fs->device_name);
+		if (retval == EXT2_ET_MMP_FAILED ||
+		    retval == EXT2_ET_MMP_FSCK_ON ||
+		    retval == EXT2_ET_MMP_CSUM_INVALID ||
+		    retval == EXT2_ET_MMP_UNKNOWN_SEQ) {
+			if (fs->mmp_buf) {
+				struct mmp_struct *mmp = fs->mmp_buf;
+				time_t mmp_time = mmp->mmp_time;
+
+				fprintf(stderr,
+					"%s: MMP last updated by '%s' on %s",
+					program_name, mmp->mmp_nodename,
+					ctime(&mmp_time));
+			}
+			retval = 1;
+		} else {
+			retval = 2;
+		}
+	} else {
+		printf("%s: it is safe to mount '%s', MMP is clean\n",
+		       program_name, fs->device_name);
+	}
+
+	return retval;
+}
+
+static void print_mmp_block(ext2_filsys fs)
+{
+	struct mmp_struct *mmp;
+	time_t mmp_time;
+	errcode_t retval;
+
+	if (fs->mmp_buf == NULL) {
+		retval = ext2fs_get_mem(fs->blocksize, &fs->mmp_buf);
+		if (retval) {
+			com_err(program_name, retval,
+				_("failed to alloc MMP buffer\n"));
+			return;
+		}
+	}
+
+	retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, fs->mmp_buf);
+	/* this is only dumping, not checking status, so OK to skip this */
+	if (retval == EXT2_ET_OP_NOT_SUPPORTED)
+		return;
+	if (retval) {
+		com_err(program_name, retval,
+			_("reading MMP block %llu from '%s'\n"),
+			fs->super->s_mmp_block, fs->device_name);
+		return;
+	}
+
+	mmp = fs->mmp_buf;
+	mmp_time = mmp->mmp_time;
+	printf("MMP_block:\n");
+	printf("    mmp_magic: 0x%x\n", mmp->mmp_magic);
+	printf("    mmp_check_interval: %d\n", mmp->mmp_check_interval);
+	printf("    mmp_sequence: %#08x\n", mmp->mmp_seq);
+	printf("    mmp_update_date: %s", ctime(&mmp_time));
+	printf("    mmp_update_time: %lld\n", mmp->mmp_time);
+	printf("    mmp_node_name: %s\n", mmp->mmp_nodename);
+	printf("    mmp_device_name: %s\n", mmp->mmp_bdevname);
+}
+
 static void parse_extended_opts(const char *opts, blk64_t *superblock,
 				int *blocksize)
 {
@@ -500,11 +573,15 @@ static void parse_extended_opts(const char *opts, blk64_t *superblock,
 int main (int argc, char ** argv)
 {
 	errcode_t	retval;
+	errcode_t	retval_csum = 0;
+	const char	*error_csum = NULL;
 	ext2_filsys	fs;
 	int		print_badblocks = 0;
 	blk64_t		use_superblock = 0;
 	int		use_blocksize = 0;
 	int		image_dump = 0;
+	int		mmp_check = 0;
+	int		mmp_info = 0;
 	int		force = 0;
 	int		flags;
 	int		header_only = 0;
@@ -519,12 +596,23 @@ int main (int argc, char ** argv)
 	set_com_err_gettext(gettext);
 #endif
 	add_error_table(&et_ext2_error_table);
-	fprintf (stderr, "dumpe2fs %s (%s)\n", E2FSPROGS_VERSION,
-		 E2FSPROGS_DATE);
-	if (argc && *argv)
-		program_name = *argv;
+	if (argc && *argv) {
+		if (strrchr(*argv, '/'))
+			program_name = strrchr(*argv, '/') + 1;
+		else
+			program_name = *argv;
+
+		if (strstr(program_name, "mmpstatus") != NULL) {
+			mmp_check = 1;
+			header_only = 1;
+		}
+	}
 
-	while ((c = getopt(argc, argv, "bfghixVo:")) != EOF) {
+	if (!mmp_check)
+		fprintf(stderr, "dumpe2fs %s (%s)\n", E2FSPROGS_VERSION,
+			E2FSPROGS_DATE);
+
+	while ((c = getopt(argc, argv, "bfghimxVo:")) != EOF) {
 		switch (c) {
 		case 'b':
 			print_badblocks++;
@@ -539,7 +627,18 @@ int main (int argc, char ** argv)
 			header_only++;
 			break;
 		case 'i':
-			image_dump++;
+			if (mmp_check)
+				mmp_info++;
+			else
+				image_dump++;
+			break;
+		case 'm':
+			mmp_check++;
+			header_only++;
+			if (image_dump) {
+				mmp_info = image_dump;
+				image_dump = 0;
+			}
 			break;
 		case 'o':
 			parse_extended_opts(optarg, &use_superblock,
@@ -557,12 +656,12 @@ int main (int argc, char ** argv)
 			usage();
 		}
 	}
-	if (optind != argc - 1) {
+	if (optind != argc - 1)
 		usage();
-		exit(1);
-	}
+
 	device_name = argv[optind++];
-	flags = EXT2_FLAG_JOURNAL_DEV_OK | EXT2_FLAG_SOFTSUPP_FEATURES | EXT2_FLAG_64BITS;
+	flags = EXT2_FLAG_JOURNAL_DEV_OK | EXT2_FLAG_SOFTSUPP_FEATURES |
+		EXT2_FLAG_64BITS;
 	if (force)
 		flags |= EXT2_FLAG_FORCE;
 	if (image_dump)
@@ -579,64 +678,87 @@ try_open_again:
 			if (!retval)
 				break;
 		}
-	} else
-		retval = ext2fs_open (device_name, flags, use_superblock,
-				      use_blocksize, unix_io_manager, &fs);
-	if (retval && !(flags & EXT2_FLAG_IGNORE_CSUM_ERRORS)) {
-		flags |= EXT2_FLAG_IGNORE_CSUM_ERRORS;
-		goto try_open_again;
+	} else {
+		retval = ext2fs_open(device_name, flags, use_superblock,
+				     use_blocksize, unix_io_manager, &fs);
 	}
-	if (!retval && (fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS))
-		printf("%s", _("\n*** Checksum errors detected in filesystem!  Run e2fsck now!\n\n"));
 	flags |= EXT2_FLAG_IGNORE_CSUM_ERRORS;
+	if (retval && !retval_csum) {
+		retval_csum = retval;
+		error_csum = _("while trying to open %s");
+		goto try_open_again;
+	}
 	if (retval) {
-		com_err (program_name, retval, _("while trying to open %s"),
-			 device_name);
+		com_err(program_name, retval, _("while trying to open %s"),
+			device_name);
 		printf("%s", _("Couldn't find valid filesystem superblock.\n"));
 		if (retval == EXT2_ET_BAD_MAGIC)
 			check_plausibility(device_name, CHECK_FS_EXIST, NULL);
-		exit (1);
+		goto out;
 	}
 	fs->default_bitmap_type = EXT2FS_BMAP64_RBTREE;
 	if (ext2fs_has_feature_64bit(fs->super))
 		blocks64 = 1;
-	if (print_badblocks) {
+	if (mmp_check) {
+		if (ext2fs_has_feature_mmp(fs->super) &&
+		    fs->super->s_mmp_block != 0) {
+			if (mmp_info) {
+				print_mmp_block(fs);
+				printf("    mmp_block_number: ");
+				print_number(fs->super->s_mmp_block);
+				printf("\n");
+			} else {
+				retval = check_mmp(fs);
+			}
+			if (!retval && retval_csum)
+				retval = 2;
+		} else {
+			fprintf(stderr, _("%s: MMP feature not enabled.\n"),
+				program_name);
+			retval = 2;
+		}
+	} else if (print_badblocks) {
 		list_bad_blocks(fs, 1);
 	} else {
 		if (grp_only)
 			goto just_descriptors;
-		list_super (fs->super);
+		list_super(fs->super);
 		if (ext2fs_has_feature_journal_dev(fs->super)) {
 			print_journal_information(fs);
-			ext2fs_close_free(&fs);
-			exit(0);
+
+			goto out_close;
 		}
 		if (ext2fs_has_feature_journal(fs->super) &&
 		    (fs->super->s_journal_inum != 0))
 			print_inline_journal_information(fs);
+		if (ext2fs_has_feature_mmp(fs->super) &&
+		    fs->super->s_mmp_block != 0)
+			print_mmp_block(fs);
 		list_bad_blocks(fs, 0);
-		if (header_only) {
-			ext2fs_close_free(&fs);
-			exit (0);
-		}
+		if (header_only)
+			goto out_close;
+
 		fs->flags &= ~EXT2_FLAG_IGNORE_CSUM_ERRORS;
 try_bitmaps_again:
-		retval = ext2fs_read_bitmaps (fs);
-		if (retval && !(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS)) {
+		retval = ext2fs_read_bitmaps(fs);
+		if (retval && !retval_csum) {
 			fs->flags |= EXT2_FLAG_IGNORE_CSUM_ERRORS;
+			retval_csum = retval;
+			error_csum = _("while trying to read '%s' bitmaps\n");
 			goto try_bitmaps_again;
 		}
-		if (!retval && (fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS))
-			printf("%s", _("\n*** Checksum errors detected in bitmaps!  Run e2fsck now!\n\n"));
 just_descriptors:
 		list_desc(fs, grp_only);
-		if (retval) {
-			printf(_("\n%s: %s: error reading bitmaps: %s\n"),
-			       program_name, device_name,
-			       error_message(retval));
-		}
+	}
+out_close:
+	if (retval_csum) {
+		com_err(program_name, retval_csum, error_csum, device_name);
+		printf("%s", _("*** Run e2fsck now!\n\n"));
+		if (!retval)
+			retval = retval_csum;
 	}
 	ext2fs_close_free(&fs);
 	remove_error_table(&et_ext2_error_table);
-	exit (0);
+out:
+	return retval;
 }