Require libblkid

Historically libblkid support was detected as part of configure
and optionally enabled.  This was done because at the time support
for detecting ZFS pool vdevs had just be added to libblkid and
those updated packages were not yet part of many distributions.
This is no longer the case and any reasonably current distribution
will ship a version of libblkid which can detect ZFS pool vdevs.

This patch makes libblkid mandatory at build time and libblkid
the preferred method of scanning for ZFS pools.  For distributions
which include a modern version of libblkid there is no change in
behavior.  Explicitly scanning the default search paths is still
supported and can be enabled with the '-s' command line option.

Additionally making libblkid mandatory means that the 'zpool create'
command can reliably detect if a specified device has an existing
non-ZFS filesystem (ext4, xfs) and print a warning.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2448

cmd/zpool/zpool_main.c

@@ -2080,6 +2080,9 @@ do_import(nvlist_t *config, const char *newname, const char *mntopts,
  *
  *       -o	Set property=value and/or temporary mount options (without '=').
  *
+ *	 -s	Scan using the default search path, the libblkid cache will
+ *	        not be consulted.
+ *
  * The import command scans for pools to import, and import pools based on pool
  * name and GUID.  The pool can also be renamed as part of the import process.
  */
@@ -2109,13 +2112,14 @@ zpool_do_import(int argc, char **argv)
 	boolean_t dryrun = B_FALSE;
 	boolean_t do_rewind = B_FALSE;
 	boolean_t xtreme_rewind = B_FALSE;
+	boolean_t do_scan = B_FALSE;
 	uint64_t pool_state, txg = -1ULL;
 	char *cachefile = NULL;
 	importargs_t idata = { 0 };
 	char *endptr;
 
 	/* check options */
-	while ((c = getopt(argc, argv, ":aCc:d:DEfFmnNo:R:tT:VX")) != -1) {
+	while ((c = getopt(argc, argv, ":aCc:d:DEfFmnNo:R:stT:VX")) != -1) {
 		switch (c) {
 		case 'a':
 			do_all = B_TRUE;
@@ -2173,6 +2177,9 @@ zpool_do_import(int argc, char **argv)
 			    ZPOOL_PROP_CACHEFILE), "none", &props, B_TRUE))
 				goto error;
 			break;
+		case 's':
+			do_scan = B_TRUE;
+			break;
 		case 't':
 			flags |= ZFS_IMPORT_TEMP_NAME;
 			if (add_prop_list_default(zpool_prop_to_name(
@@ -2322,6 +2329,7 @@ zpool_do_import(int argc, char **argv)
 	idata.poolname = searchname;
 	idata.guid = searchguid;
 	idata.cachefile = cachefile;
+	idata.scan = do_scan;
 
 	pools = zpool_search_import(g_zfs, &idata);
 

cmd/zpool/zpool_vdev.c

@@ -78,12 +78,7 @@
 #include <sys/vtoc.h>
 #include <sys/mntent.h>
 #include <uuid/uuid.h>
-#ifdef HAVE_LIBBLKID
 #include <blkid/blkid.h>
-#else
-#define	blkid_cache void *
-#endif /* HAVE_LIBBLKID */
-
 #include "zpool_util.h"
 #include <sys/zfs_context.h>
 
@@ -374,7 +369,6 @@ static int
 check_slice(const char *path, blkid_cache cache, int force, boolean_t isspare)
 {
 	int err;
-#ifdef HAVE_LIBBLKID
 	char *value;
 
 	/* No valid type detected device is safe to use */
@@ -400,9 +394,6 @@ check_slice(const char *path, blkid_cache cache, int force, boolean_t isspare)
 	}
 
 	free(value);
-#else
-	err = check_file(path, force, isspare);
-#endif /* HAVE_LIBBLKID */
 
 	return (err);
 }
@@ -500,7 +491,6 @@ check_device(const char *path, boolean_t force,
 {
 	static blkid_cache cache = NULL;
 
-#ifdef HAVE_LIBBLKID
 	/*
 	 * There is no easy way to add a correct blkid_put_cache() call,
 	 * memory will be reclaimed when the command exits.
@@ -519,7 +509,6 @@ check_device(const char *path, boolean_t force,
 			return (-1);
 		}
 	}
-#endif /* HAVE_LIBBLKID */
 
 	return (check_disk(path, cache, force, isspare, iswholedisk));
 }

config/user-libblkid.m4

@@ -1,113 +1,13 @@
 dnl #
-dnl # Check for ZFS support in libblkid.  This test needs to check
+dnl # Check for libblkid.  Basic support for detecting ZFS pools
-dnl # more than if the library exists because we expect there are
+dnl # has existing in blkid since 2008.
-dnl # at least 3 flavors of the library out in the wild:
-dnl #
-dnl #   1) blkid which has no ZFS support
-dnl #   2) blkid with ZFS support and a flawed method of probing
-dnl #   3) blkid with ZFS support and a working method of probing
-dnl #
-dnl # To handle this the check first validates that there is a version
-dnl # of the library installed.  If there is it creates a simulated
-dnl # ZFS filesystem and then links a small test app which attempts
-dnl # to detect the simualated filesystem type.  If it correctly
-dnl # identifies the filesystem as ZFS we can safely assume case 3).
-dnl # Otherwise we disable blkid support and resort to manual probing.
 dnl #
 AC_DEFUN([ZFS_AC_CONFIG_USER_LIBBLKID], [
-	AC_ARG_WITH([blkid],
-		[AS_HELP_STRING([--with-blkid],
-		[support blkid caching @<:@default=check@:>@])],
-		[],
-		[with_blkid=check])
-
 	LIBBLKID=
-	AS_IF([test "x$with_blkid" = xyes],
-	[
-		AC_SUBST([LIBBLKID], ["-lblkid"])
-		AC_DEFINE([HAVE_LIBBLKID], 1,
-			[Define if you have libblkid])
-	])
 
-	AS_IF([test "x$with_blkid" = xcheck],
+	AC_CHECK_HEADER([blkid/blkid.h], [], [AC_MSG_FAILURE([
-	[
+        *** blkid.h missing, libblkid-devel package required])])
-		AC_CHECK_LIB([blkid], [blkid_get_cache],
-		[
-			AC_MSG_CHECKING([for blkid zfs support])
 
-			ZFS_DEV=`mktemp`
+	AC_SUBST([LIBBLKID], ["-lblkid"])
-			truncate -s 64M $ZFS_DEV
+	AC_DEFINE([HAVE_LIBBLKID], 1, [Define if you have libblkid])
-			echo -en "\x0c\xb1\xba\0\0\0\0\0" | \
-				dd of=$ZFS_DEV bs=1k count=8 \
-				seek=128 conv=notrunc &>/dev/null \
-				>/dev/null 2>/dev/null
-			echo -en "\x0c\xb1\xba\0\0\0\0\0" | \
-				dd of=$ZFS_DEV bs=1k count=8 \
-				seek=132 conv=notrunc &>/dev/null \
-				>/dev/null 2>/dev/null
-			echo -en "\x0c\xb1\xba\0\0\0\0\0" | \
-				dd of=$ZFS_DEV bs=1k count=8 \
-				seek=136 conv=notrunc &>/dev/null \
-				>/dev/null 2>/dev/null
-			echo -en "\x0c\xb1\xba\0\0\0\0\0" | \
-				dd of=$ZFS_DEV bs=1k count=8 \
-				seek=140 conv=notrunc &>/dev/null \
-				>/dev/null 2>/dev/null
-
-			saved_LIBS="$LIBS"
-			LIBS="-lblkid"
-
-			AC_RUN_IFELSE([AC_LANG_PROGRAM(
-			[
-				#include <stdio.h>
-				#include <stdlib.h>
-				#include <blkid/blkid.h>
-			],
-			[
-				blkid_cache cache;
-				char *value;
-
-			        if (blkid_get_cache(&cache, NULL) < 0)
-					return 1;
-
-				value = blkid_get_tag_value(cache, "TYPE",
-				                            "$ZFS_DEV");
-				if (!value) {
-					blkid_put_cache(cache);
-					return 2;
-				}
-
-				if (strcmp(value, "zfs_member")) {
-					free(value);
-					blkid_put_cache(cache);
-					return 0;
-				}
-
-				free(value);
-				blkid_put_cache(cache);
-			])],
-			[
-				rm -f $ZFS_DEV
-				AC_MSG_RESULT([yes])
-				AC_SUBST([LIBBLKID], ["-lblkid"])
-				AC_DEFINE([HAVE_LIBBLKID], 1,
-					[Define if you have libblkid])
-			],
-			[
-				rm -f $ZFS_DEV
-				AC_MSG_RESULT([no])
-				AS_IF([test "x$with_blkid" != xcheck],
-					[AC_MSG_FAILURE(
-					[--with-blkid given but unavailable])])
-			])
-
-			LIBS="$saved_LIBS"
-		],
-		[
-			AS_IF([test "x$with_blkid" != xcheck],
-				[AC_MSG_FAILURE(
-				[--with-blkid given but unavailable])])
-		]
-		[])
-	])
 ])

include/libzfs.h

@@ -391,6 +391,7 @@ typedef struct importargs {
 	int can_be_active : 1;	/* can the pool be active?		*/
 	int unique : 1;		/* does 'poolname' already exist?	*/
 	int exists : 1;		/* set on return if pool already exists	*/
+	int scan : 1;		/* prefer scanning to libblkid cache    */
 } importargs_t;
 
 extern nvlist_t *zpool_search_import(libzfs_handle_t *, importargs_t *);

lib/libzfs/libzfs_import.c

@@ -55,12 +55,8 @@
 #include <sys/vtoc.h>
 #include <sys/dktp/fdisk.h>
 #include <sys/efi_partition.h>
-
 #include <sys/vdev_impl.h>
-#ifdef HAVE_LIBBLKID
 #include <blkid/blkid.h>
-#endif
-
 #include "libzfs.h"
 #include "libzfs_impl.h"
 
@@ -1203,7 +1199,6 @@ zpool_clear_label(int fd)
 	return (0);
 }
 
-#ifdef HAVE_LIBBLKID
 /*
  * Use libblkid to quickly search for zfs devices
  */
@@ -1273,7 +1268,6 @@ err_blkid2:
 err_blkid1:
 	return (err);
 }
-#endif /* HAVE_LIBBLKID */
 
 char *
 zpool_default_import_path[DEFAULT_IMPORT_PATH_SIZE] = {
@@ -1313,17 +1307,15 @@ zpool_find_import_impl(libzfs_handle_t *hdl, importargs_t *iarg)
 
 	verify(iarg->poolname == NULL || iarg->guid == 0);
 
+	/*
+	 * Prefer to locate pool member vdevs using libblkid.  Only fall
+	 * back to legacy directory scanning when explicitly requested or
+	 * if an error is encountered when consulted the libblkid cache.
+	 */
 	if (dirs == 0) {
-#ifdef HAVE_LIBBLKID
+		if (!iarg->scan && (zpool_find_import_blkid(hdl, &pools) == 0))
-		/* Use libblkid to scan all device for their type */
-		if (zpool_find_import_blkid(hdl, &pools) == 0)
 			goto skip_scanning;
 
-		(void) zfs_error_fmt(hdl, EZFS_BADCACHE,
-		    dgettext(TEXT_DOMAIN, "blkid failure falling back "
-		    "to manual probing"));
-#endif /* HAVE_LIBBLKID */
-
 		dir = zpool_default_import_path;
 		dirs = DEFAULT_IMPORT_PATH_SIZE;
 	}
@@ -1465,9 +1457,7 @@ zpool_find_import_impl(libzfs_handle_t *hdl, importargs_t *iarg)
 			goto error;
 	}
 
-#ifdef HAVE_LIBBLKID
 skip_scanning:
-#endif
 	ret = get_configs(hdl, &pools, iarg->can_be_active);
 
 error:

man/man8/zpool.8

@@ -83,13 +83,14 @@ zpool \- configures ZFS storage pools
 .LP
 .nf
 \fBzpool import\fR [\fB-o \fImntopts\fR\fR] [\fB-o\fR \fIproperty=value\fR] ... [\fB-d\fR \fIdir\fR | \fB-c\fR \fIcachefile\fR]
-     [\fB-D\fR] [\fB-f\fR] [\fB-m\fR] [\fB-N\fR] [\fB-R\fR \fIroot\fR] [\fB-F\fR [\fB-n\fR] [\fB-X\fR\] [\fB-T\fR\]] \fB-a\fR
+     [\fB-D\fR] [\fB-f\fR] [\fB-m\fR] [\fB-N\fR] [\fB-R\fR \fIroot\fR] [\fB-F\fR [\fB-n\fR] [\fB-X\fR\] [\fB-T\fR\]] [\fB-s\fR] \fB-a\fR
 .fi
 
 .LP
 .nf
 \fBzpool import\fR [\fB-o \fImntopts\fR\fR] [\fB-o\fR \fIproperty=value\fR] ... [\fB-d\fR \fIdir\fR | \fB-c\fR \fIcachefile\fR]
-     [\fB-D\fR] [\fB-f\fR] [\fB-m\fR] [\fB-R\fR \fIroot\fR] [\fB-F\fR [\fB-n\fR] [\fB-X\fR] [\fB-T\fR\]] [\fB-t\fR]] \fIpool\fR |\fIid\fR [\fInewpool\fR]
+     [\fB-D\fR] [\fB-f\fR] [\fB-m\fR] [\fB-R\fR \fIroot\fR] [\fB-F\fR [\fB-n\fR] [\fB-X\fR] [\fB-T\fR\]] [\fB-t\fR]] [\fB-s\fR]
+     \fIpool\fR | \fIid\fR [\fInewpool\fR]
 .fi
 
 .LP
@@ -1322,7 +1323,7 @@ Lists destroyed pools only.
 .ne 2
 .mk
 .na
-\fB\fBzpool import\fR [\fB-o\fR \fImntopts\fR] [ \fB-o\fR \fIproperty\fR=\fIvalue\fR] ... [\fB-d\fR \fIdir\fR | \fB-c\fR \fIcachefile\fR] [\fB-D\fR] [\fB-f\fR] [\fB-m\fR] [\fB-N\fR] [\fB-R\fR \fIroot\fR] [\fB-F\fR [\fB-n\fR]] \fB-a\fR\fR
+\fB\fBzpool import\fR [\fB-o\fR \fImntopts\fR] [ \fB-o\fR \fIproperty\fR=\fIvalue\fR] ... [\fB-d\fR \fIdir\fR | \fB-c\fR \fIcachefile\fR] [\fB-D\fR] [\fB-f\fR] [\fB-m\fR] [\fB-N\fR] [\fB-R\fR \fIroot\fR] [\fB-F\fR [\fB-n\fR]] [\fB-s\fR] \fB-a\fR\fR
 .ad
 .sp .6
 .RS 4n
@@ -1477,13 +1478,24 @@ Specify the txg to use for rollback.  Implies \fB-FX\fR. For more details about
 \fBWARNING\fR: This option can be extremely hazardous to the health of your pool and should only be used as a last resort.
 .RE
 
+.sp
+.ne 2
+.mk
+.na
+\fB\fB-s\fR
+.ad
+.RS 21n
+.rt
+Scan using the default search path, the libblkid cache will not be consulted.  A custom search path may be specified by setting the \fBZPOOL_IMPORT_PATH\fR environment variable.
+.RE
+
 .RE
 
 .sp
 .ne 2
 .mk
 .na
-\fB\fBzpool import\fR [\fB-o\fR \fImntopts\fR] [ \fB-o\fR \fIproperty\fR=\fIvalue\fR] ... [\fB-d\fR \fIdir\fR | \fB-c\fR \fIcachefile\fR] [\fB-D\fR] [\fB-f\fR] [\fB-m\fR] [\fB-R\fR \fIroot\fR] [\fB-F\fR [\fB-n\fR]] [\fB-t\fR]] \fIpool\fR | \fIid\fR [\fInewpool\fR]\fR
+\fB\fBzpool import\fR [\fB-o\fR \fImntopts\fR] [ \fB-o\fR \fIproperty\fR=\fIvalue\fR] ... [\fB-d\fR \fIdir\fR | \fB-c\fR \fIcachefile\fR] [\fB-D\fR] [\fB-f\fR] [\fB-m\fR] [\fB-R\fR \fIroot\fR] [\fB-F\fR [\fB-n\fR]] [\fB-t\fR]] [\fB-s\fR] \fIpool\fR | \fIid\fR [\fInewpool\fR]\fR
 .ad
 .sp .6
 .RS 4n
@@ -1635,6 +1647,17 @@ Used with "\fBnewpool\fR". Specifies that "\fBnewpool\fR" is temporary. Temporar
 Allows a pool to import when there is a missing log device.
 .RE
 
+.sp
+.ne 2
+.mk
+.na
+\fB\fB-s\fR
+.ad
+.sp .6
+.RS 4n
+Scan using the default search path, the libblkid cache will not be consulted.  A custom search path may be specified by setting the \fBZPOOL_IMPORT_PATH\fR environment variable.
+.RE
+
 .RE
 
 .sp

rpm/generic/zfs.spec.in

@@ -34,7 +34,6 @@
 %endif
 
 %bcond_with    debug
-%bcond_with    blkid
 %bcond_with    systemd
 
 # Generic enable switch for systemd
@@ -89,10 +88,8 @@ Conflicts:      zfs-fuse
 %if 0%{?rhel}%{?fedora}%{?suse_version}
 BuildRequires:  zlib-devel
 BuildRequires:  libuuid-devel
-%if %{with blkid}
 BuildRequires:  libblkid-devel
 %endif
-%endif
 %if 0%{?_systemd}
 Requires(post): systemd
 Requires(preun): systemd
@@ -213,11 +210,6 @@ image which is ZFS aware.
 %else
     %define debug --disable-debug
 %endif
-%if %{with blkid}
-    %define blkid --with-blkid
-%else
-    %define blkid --without-blkid
-%endif
 %if 0%{?_systemd}
     %define systemd --enable-systemd --with-systemdunitdir=%{_unitdir} --with-systemdpresetdir=%{_presetdir} --disable-sysvinit
 %else
@@ -234,7 +226,6 @@ image which is ZFS aware.
     --with-dracutdir=%{_dracutdir} \
     --disable-static \
     %{debug} \
-    %{blkid} \
     %{systemd}
 make %{?_smp_mflags}