[PATCH 2/3] e2info: create a tool to display ext4 fs geometry online

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

Create e2info, which reports the fs geometry of an online ext4 filesystem.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 configure            |    4 +
 configure.ac         |    3 +
 lib/ext2fs/ext2_fs.h |   34 ++++++++
 misc/Makefile.in     |   30 ++++++-
 misc/e2info.8.in     |   64 ++++++++++++++++
 misc/e2info.c        |  205 ++++++++++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 336 insertions(+), 4 deletions(-)
 create mode 100644 misc/e2info.8.in
 create mode 100644 misc/e2info.c


diff --git a/configure b/configure
index 5f7b429..b553da1 100755
--- a/configure
+++ b/configure
@@ -642,6 +642,7 @@ root_prefix
 UNIX_CMT
 CYGWIN_CMT
 LINUX_CMT
+E2INFO_CMT
 UNI_DIFF_OPTS
 SEM_INIT_LIB
 FUSE_CMT
@@ -13663,13 +13664,16 @@ fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $UNI_DIFF_OPTS" >&5
 $as_echo "$UNI_DIFF_OPTS" >&6; }
 
+E2INFO_CMT="#"
 case "$host_os" in
 linux*)
 
 $as_echo "#define HAVE_EXT2_IOCTLS 1" >>confdefs.h
 
+	E2INFO_CMT=
 	;;
 esac
+
 LINUX_CMT="#"
 CYGWIN_CMT="#"
 UNIX_CMT=
diff --git a/configure.ac b/configure.ac
index 9da7b86..bf613fd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1260,11 +1260,14 @@ AC_SUBST(UNI_DIFF_OPTS)
 dnl
 dnl We use the EXT2 ioctls only under Linux
 dnl
+E2INFO_CMT="#"
 case "$host_os" in
 linux*)
 	AC_DEFINE(HAVE_EXT2_IOCTLS, 1, [Define to 1 if Ext2 ioctls present])
+	E2INFO_CMT=
 	;;
 esac
+AC_SUBST(E2INFO_CMT)
 dnl
 dnl OS-specific uncomment control
 dnl
diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
index 27a7d3a..bad7648 100644
--- a/lib/ext2fs/ext2_fs.h
+++ b/lib/ext2fs/ext2_fs.h
@@ -372,6 +372,40 @@ struct ext4_new_group_input {
 #define EXT4_IOC_GROUP_ADD		_IOW('f', 8,struct ext4_new_group_input)
 #define EXT4_IOC_RESIZE_FS		_IOW('f', 16, __u64)
 
+/* ext4 fs geometry. */
+struct ext4_fsop_geom {
+	__u32		efg_blocksize;	/* filesystem (data) block size */
+	__u32		efg_bgblocks;	/* fsblocks in an AG		*/
+	__u32		efg_bgcount;	/* number of allocation groups	*/
+	__u32		efg_logblocks;	/* fsblocks in the log		*/
+	__u32		efg_resvblocks;	/* number of reserved blocks	*/
+	__u32		efg_inodesize;	/* inode size in bytes		*/
+	__u32		efg_bg_iblocks;	/* inode blocks per AG		*/
+	__u32		efg_flags;	/* superblock version flags	*/
+	__u64		efg_inodecount;	/* inode count			*/
+	__u64		efg_blockcount;	/* fsblocks in filesystem	*/
+	unsigned char	efg_uuid[16];	/* unique id of the filesystem	*/
+	__u32		efg_sunit;	/* stripe unit, fsblocks	*/
+	__u32		efg_swidth;	/* stripe width, fsblocks	*/
+	__u32		efg_clustersize;/* fs cluster size		*/
+	__u32		efg_flexbgsize;	/* number of bg's in a flexbg	*/
+	__u64		efg_resv[6];
+};
+
+#define EXT4_FSOP_GEOM_FLAGS_ATTR	0x00001	/* extended attr in use	 */
+#define EXT4_FSOP_GEOM_FLAGS_NLINK	0x00002	/* 32-bit nlink values	 */
+#define EXT4_FSOP_GEOM_FLAGS_QUOTA	0x00004	/* quotas enabled	 */
+#define EXT4_FSOP_GEOM_FLAGS_PROJQ	0x00008	/* project quotas	 */
+#define EXT4_FSOP_GEOM_FLAGS_META_CSUM	0x00010	/* metadata checksums	 */
+#define EXT4_FSOP_GEOM_FLAGS_FTYPE	0x00020	/* inode directory types */
+#define EXT4_FSOP_GEOM_FLAGS_64BIT	0x00040	/* 64-bit support	 */
+#define EXT4_FSOP_GEOM_FLAGS_INLINEDATA	0x00080	/* inline data		 */
+#define EXT4_FSOP_GEOM_FLAGS_ENCRYPT	0x00100	/* encrypted files	 */
+#define EXT4_FSOP_GEOM_FLAGS_LARGEDIR	0x00200	/* large directories	 */
+#define EXT4_FSOP_GEOM_FLAGS_EXTENTS	0x00400	/* extents		 */
+
+#define EXT4_IOC_FSGEOMETRY		_IOR ('f', 19, struct ext4_fsop_geom)
+
 /*
  * Structure of an inode on the disk
  */
diff --git a/misc/Makefile.in b/misc/Makefile.in
index 467c15d..311aa57 100644
--- a/misc/Makefile.in
+++ b/misc/Makefile.in
@@ -32,14 +32,19 @@ INSTALL = @INSTALL@
 
 @FUSE_CMT@FUSE_PROG= fuse2fs
 
+@E2INFO_CMT@E2INFO_PROG= e2info
+@E2INFO_CMT@E2INFO_MAN= e2info.8
+
 SPROGS=		mke2fs badblocks tune2fs dumpe2fs $(BLKID_PROG) logsave \
 			$(E2IMAGE_PROG) @FSCK_PROG@ e2undo
 USPROGS=	mklost+found filefrag e2freefrag $(UUIDD_PROG) \
-			$(E4DEFRAG_PROG) $(E4CRYPT_PROG) $(FUSE_PROG)
+			$(E4DEFRAG_PROG) $(E4CRYPT_PROG) $(FUSE_PROG) \
+			$(E2INFO_PROG)
 SMANPAGES=	tune2fs.8 mklost+found.8 mke2fs.8 dumpe2fs.8 badblocks.8 \
 			e2label.8 $(FINDFS_MAN) $(BLKID_MAN) $(E2IMAGE_MAN) \
 			logsave.8 filefrag.8 e2freefrag.8 e2undo.8 \
-			$(UUIDD_MAN) $(E4DEFRAG_MAN) $(E4CRYPT_MAN) @FSCK_MAN@
+			$(UUIDD_MAN) $(E4DEFRAG_MAN) $(E4CRYPT_MAN) @FSCK_MAN@ \
+			$(E2INFO_MAN)
 FMANPAGES=	mke2fs.conf.5 ext4.5
 
 UPROGS=		chattr lsattr @UUID_CMT@ uuidgen
@@ -68,6 +73,7 @@ E4CRYPT_OBJS=   e4crypt.o
 E2FREEFRAG_OBJS= e2freefrag.o
 E2FUZZ_OBJS=	e2fuzz.o
 FUSE2FS_OBJS=	fuse2fs.o journal.o recovery.o revoke.o
+E2INFO_OBJS=	e2info.o
 
 PROFILED_TUNE2FS_OBJS=	profiled/tune2fs.o profiled/util.o
 PROFILED_MKLPF_OBJS=	profiled/mklost+found.o
@@ -90,8 +96,9 @@ PROFILED_E2FREEFRAG_OBJS= profiled/e2freefrag.o
 PROFILED_E2UNDO_OBJS=	profiled/e2undo.o
 PROFILED_E4DEFRAG_OBJS=	profiled/e4defrag.o
 PROFILED_E4CRYPT_OBJS=	profiled/e4crypt.o
-PROFILED_FUSE2FS_OJBS=	profiled/fuse2fs.o profiled/journal.o \
+PROFILED_FUSE2FS_OBJS=	profiled/fuse2fs.o profiled/journal.o \
 			profiled/recovery.o profiled/revoke.o
+PROFILED_E2INFO_OBJS=	profiled/e2info.o
 
 SRCS=	$(srcdir)/tune2fs.c $(srcdir)/mklost+found.c $(srcdir)/mke2fs.c $(srcdir)/mk_hugefiles.c \
 		$(srcdir)/chattr.c $(srcdir)/lsattr.c $(srcdir)/dumpe2fs.c \
@@ -102,7 +109,7 @@ SRCS=	$(srcdir)/tune2fs.c $(srcdir)/mklost+found.c $(srcdir)/mke2fs.c $(srcdir)/
 		$(srcdir)/e2freefrag.c $(srcdir)/create_inode.c \
 		$(srcdir)/fuse2fs.c \
 		$(srcdir)/../debugfs/journal.c $(srcdir)/../e2fsck/revoke.c \
-		$(srcdir)/../e2fsck/recovery.c
+		$(srcdir)/../e2fsck/recovery.c $(srcdir)/e2info.c
 
 LIBS= $(LIBEXT2FS) $(LIBCOM_ERR) $(LIBSUPPORT)
 DEPLIBS= $(LIBEXT2FS) $(DEPLIBCOM_ERR) $(DEPLIBSUPPORT)
@@ -391,6 +398,11 @@ fuse2fs: $(FUSE2FS_OBJS) $(DEPLIBS) $(DEPLIBBLKID) $(DEPLIBUUID) \
 		$(LIBFUSE) $(LIBBLKID) $(LIBUUID) $(LIBEXT2FS) $(LIBINTL) \
 		$(CLOCK_GETTIME_LIB) $(SYSLIBS)
 
+e2info: $(E2INFO_OBJS) $(DEPLIBS)
+	$(E) "	LD $@"
+	$(Q) $(CC) $(ALL_LDFLAGS) -o e2info $(E2INFO_OBJS) $(LIBINTL) \
+		$(SYSLIBS)
+
 journal.o: $(srcdir)/../debugfs/journal.c
 	$(E) "	CC $@"
 	$(Q) $(CC) -c $(JOURNAL_CFLAGS) -I$(srcdir) \
@@ -411,6 +423,10 @@ tst_ismounted: $(srcdir)/ismounted.c $(STATIC_LIBEXT2FS) $(DEPLIBCOM_ERR)
 	$(CC) -o tst_ismounted $(srcdir)/ismounted.c -DDEBUG $(ALL_CFLAGS) \
 		$(LIBCOM_ERR) $(SYSLIBS)
 
+e2info.8: $(DEP_SUBSTITUTE) $(srcdir)/e2info.8.in
+	$(E) "	SUBST $@"
+	$(Q) $(SUBSTITUTE_UPTIME) $(srcdir)/e2info.8.in e2info.8
+
 tune2fs.8: $(DEP_SUBSTITUTE) $(srcdir)/tune2fs.8.in
 	$(E) "	SUBST $@"
 	$(Q) $(SUBSTITUTE_UPTIME) $(srcdir)/tune2fs.8.in tune2fs.8
@@ -844,3 +860,9 @@ recovery.o: $(srcdir)/../e2fsck/recovery.c $(srcdir)/../e2fsck/jfs_user.h \
  $(top_srcdir)/lib/support/quotaio_tree.h \
  $(top_srcdir)/lib/ext2fs/kernel-jbd.h $(top_srcdir)/lib/ext2fs/jfs_compat.h \
  $(top_srcdir)/lib/ext2fs/kernel-list.h
+e2info.o: $(srcdir)/e2info.c $(top_builddir)/lib/config.h \
+ $(top_builddir)/lib/dirpaths.h $(top_srcdir)/lib/ext2fs/ext2fs.h \
+ $(top_builddir)/lib/ext2fs/ext2_types.h $(top_srcdir)/lib/ext2fs/ext2_fs.h \
+ $(top_srcdir)/lib/ext2fs/ext3_extents.h $(top_srcdir)/lib/et/com_err.h \
+ $(top_srcdir)/lib/ext2fs/ext2_io.h $(top_builddir)/lib/ext2fs/ext2_err.h \
+ $(top_srcdir)/lib/ext2fs/ext2_ext_attr.h $(top_srcdir)/lib/ext2fs/bitops.h
diff --git a/misc/e2info.8.in b/misc/e2info.8.in
new file mode 100644
index 0000000..c7f580f
--- /dev/null
+++ b/misc/e2info.8.in
@@ -0,0 +1,64 @@
+.\" -*- nroff -*-
+.\" Copyright 2017 Oracle Inc.  All Rights Reserved.
+.\" This file may be copied under the terms of the GNU Public License.
+.\" 
+.\" Verbatim blocks taken from openssl req manpage content
+.de Vb \" Begin verbatim text
+.ft CW
+.nf
+.ne \\$1
+..
+.de Ve \" End verbatim text
+.ft R
+.fi
+..
+
+.TH E2INFO 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
+.SH NAME
+e2info \- Display information about a mounted ext4 filesystem
+.SH SYNOPSIS
+.B e2info
+.I mount-point
+.br
+.B e2info \-V
+.SH DESCRIPTION
+Prints the filesystem geometry of an ext4 filesystem.  If the mounted
+filesystem is an ext2 or ext3 filesystem mounted with the ext4 driver,
+the geometry will be displayed.
+.SH "EXAMPLES"
+
+Understanding e2info output.
+.PP
+Suppose one has the following "e2info /dev/sda" output:
+.PP
+.RS 2
+.Vb
+\&meta-data=/dev/loop0             isize=256    bgcount=14808 bgsize=32768 blks
+\&         =                       attr=1       quota=0 pquota=0
+\&         =                       crc=0        64bit=0 inlinedata=0 extents=1
+\&         =                       flexbg=16
+\&data     =                       bsize=4096   blocks=485198848 bg_iblocks=512
+\&         =                       sunit=32     swidth=128 blks clustersize=0
+\&         =                       encrypt=0
+\&naming   =                       bsize=4096   largedir=0 ftype=1 nlink=1
+\&log      =                       bsize=4096   blocks=32768
+.Ve
+.RE
+.PP
+
+Here, the data section of the output indicates "bsize=4096",
+meaning the data block size for this filesystem is 4096 bytes.
+This section also shows "sunit=32 swidth=128 blks", which means
+the stripe unit is 32*4096 bytes = 128 kibibytes and the stripe
+width is 128*4096 bytes = 512 kibibytes.
+A single stripe of this filesystem therefore consists
+of four stripe units (128 blocks / 32 blocks per unit).
+Note also that "flexbg=16", which means that this filesystem has
+512MB flex block groups.
+That is the upper limit of how much physical disk space can be mapped
+into a file.
+.SH SEE ALSO
+.BR mkfs.ext4 (8),
+.BR md (4),
+.BR lvm (8),
+.BR mount (8).
diff --git a/misc/e2info.c b/misc/e2info.c
new file mode 100644
index 0000000..675f005
--- /dev/null
+++ b/misc/e2info.c
@@ -0,0 +1,205 @@
+/*
+ * Copyright (c) 2017 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 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#include "config.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libgen.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <mntent.h>
+#include <limits.h>
+
+#include "ext2fs/ext2_fs.h"
+
+#include "../version.h"
+#include "support/nls-enable.h"
+
+static const char *progname = "e2info";
+
+static void
+usage(void)
+{
+	fprintf(stderr, _(
+"Usage: %s [options] mountpoint\n\n\
+	-V          print version information\n"),
+		progname);
+	exit(2);
+}
+
+#define PROC_MOUNTS	"/proc/mounts"
+int
+find_datadev(
+	const char	*arg,
+	char		*datadev,
+	char		*mntpoint)
+{
+	struct mntent	*mnt;
+	FILE		*mtp;
+	char		*mtab_file;
+	char		rmnt_fsname[PATH_MAX], rmnt_dir[PATH_MAX];
+	struct stat	sbuf;
+	dev_t		fd_dev;
+
+	if (stat(arg, &sbuf) < 0)
+		return errno;
+	/*
+	 * We want to match st_rdev if the path provided is a device
+	 * special file.  Otherwise we are looking for the the
+	 * device id for the containing filesystem, in st_dev.
+	 */
+	if (S_ISBLK(sbuf.st_mode) || S_ISCHR(sbuf.st_mode))
+		fd_dev = sbuf.st_rdev;
+	else
+		fd_dev = sbuf.st_dev;
+
+	mtab_file = PROC_MOUNTS;
+	if (access(mtab_file, R_OK) != 0)
+		mtab_file = MOUNTED;
+
+	if ((mtp = setmntent(mtab_file, "r")) == NULL)
+		return ENOENT;
+
+	while ((mnt = getmntent(mtp)) != NULL) {
+		if (!realpath(mnt->mnt_dir, rmnt_dir))
+			continue;
+		if (!realpath(mnt->mnt_fsname, rmnt_fsname))
+			continue;
+
+		if (stat(rmnt_fsname, &sbuf) < 0)
+			continue;
+		if (sbuf.st_rdev == fd_dev) {
+			strncpy(datadev, rmnt_fsname, PATH_MAX);
+			strncpy(mntpoint, rmnt_dir, PATH_MAX);
+			break;
+		}
+	}
+	endmntent(mtp);
+	return 0;
+}
+
+int
+main(int argc, char **argv)
+{
+	struct ext4_fsop_geom	geo;
+	char			*progname;
+	int			fd;
+	int			c;
+	int			attr_enabled;
+	int			nlink_enabled;
+	int			quota_enabled;
+	int			projquota_enabled;
+	int			metacrc_enabled;
+	int			ftype_enabled;
+	int			is_64bit;
+	int			inlinedata_enabled;
+	int			encrypt_enabled;
+	int			largedir_enabled;
+	int			extents_enabled;
+	char			datadev[PATH_MAX];
+	char			mntpoint[PATH_MAX];
+
+	progname = basename(argv[0]);
+#ifdef ENABLE_NLS
+	setlocale(LC_ALL, "");
+	bindtextdomain(PACKAGE, LOCALEDIR);
+	textdomain(PACKAGE);
+#endif
+
+	while ((c = getopt(argc, argv, "V")) != EOF) {
+		switch (c) {
+		case 'V':
+			printf(_("%s version %s\n"), progname, VERSION);
+			exit(0);
+		case '?':
+		default:
+			usage();
+		}
+	}
+	if (argc - optind != 1)
+		usage();
+
+	fd = open(argv[optind], O_RDONLY);
+	if (fd < 0) {
+		perror(argv[optind]);
+		return 1;
+	}
+
+	if (find_datadev(argv[optind], datadev, mntpoint)) {
+		perror("find_datadev");
+		strncpy(datadev, argv[optind], PATH_MAX);
+		strncpy(mntpoint, argv[optind], PATH_MAX);
+	}
+
+	close(fd);
+	fd = open(mntpoint, O_RDONLY);
+	if (fd < 0) {
+		perror(mntpoint);
+		return 1;
+	}
+
+	/* get the current filesystem size & geometry */
+	if (ioctl(fd, EXT4_IOC_FSGEOMETRY, &geo) < 0) {
+		fprintf(stderr, _(
+			"%s: cannot determine geometry of filesystem"
+			" mounted at %s: %s\n"),
+			progname, argv[optind], strerror(errno));
+		exit(1);
+	}
+
+	attr_enabled = geo.efg_flags & EXT4_FSOP_GEOM_FLAGS_ATTR ? 1 : 0;
+	nlink_enabled = geo.efg_flags & EXT4_FSOP_GEOM_FLAGS_NLINK ? 1 : 0;
+	quota_enabled = geo.efg_flags & EXT4_FSOP_GEOM_FLAGS_QUOTA ? 1 : 0;
+	projquota_enabled = geo.efg_flags & EXT4_FSOP_GEOM_FLAGS_PROJQ ? 1 : 0;
+	metacrc_enabled = geo.efg_flags & EXT4_FSOP_GEOM_FLAGS_META_CSUM ? 1 : 0;
+	ftype_enabled = geo.efg_flags & EXT4_FSOP_GEOM_FLAGS_FTYPE ? 1 : 0;
+	is_64bit = geo.efg_flags & EXT4_FSOP_GEOM_FLAGS_64BIT ? 1 : 0;
+	inlinedata_enabled = geo.efg_flags & EXT4_FSOP_GEOM_FLAGS_INLINEDATA ? 1 : 0;
+	encrypt_enabled = geo.efg_flags & EXT4_FSOP_GEOM_FLAGS_ENCRYPT ? 1 : 0;
+	largedir_enabled = geo.efg_flags & EXT4_FSOP_GEOM_FLAGS_LARGEDIR ? 1 : 0;
+	extents_enabled = geo.efg_flags & EXT4_FSOP_GEOM_FLAGS_EXTENTS ? 1 : 0;
+
+	printf(_(
+	    "meta-data=%-22s isize=%-6u bgcount=%u bgsize=%u blks\n"
+	    "         =%-22s attr=%-7u quota=%u pquota=%u\n"
+	    "         =%-22s crc=%-8u 64bit=%u inlinedata=%u extents=%u\n"
+	    "         =%-22s flexbg=%u\n"
+	    "data     =%-22s bsize=%-6u blocks=%llu bg_iblocks=%u\n"
+	    "         =%-22s sunit=%-6u swidth=%u blks clustersize=%u\n"
+	    "         =%-22s encrypt=%u\n"
+	    "naming   =%-22s bsize=%-6u largedir=%d ftype=%d nlink=%u\n"
+	    "log      =%-22s bsize=%-6u blocks=%u\n"),
+		datadev, geo.efg_inodesize, geo.efg_bgcount, geo.efg_bgblocks,
+		"", attr_enabled, quota_enabled, projquota_enabled,
+		"", metacrc_enabled, is_64bit, inlinedata_enabled,
+			extents_enabled,
+		"", geo.efg_flexbgsize,
+		"", geo.efg_blocksize, (unsigned long long)geo.efg_blockcount,
+			geo.efg_bg_iblocks,
+		"", geo.efg_sunit, geo.efg_swidth, geo.efg_clustersize,
+		"", encrypt_enabled,
+		"", geo.efg_blocksize, largedir_enabled, ftype_enabled,
+			nlink_enabled,
+		"", geo.efg_blocksize, geo.efg_logblocks);
+
+	exit(0);
+}