[PATCH] swapoff: make LABEL= and UUID= work when turning off swap files

[Sami Kerola <kerolasa@xxxxxx>]

Before this commit the swapoff was unable to find swap files by UUID or
LABEL.  For example if one had:

$ swapon --show=name,uuid,label
NAME      UUID                                 LABEL
/swapfile bf6237f4-db89-4761-a1a3-275cfc68b114 xyzzy

then turning off the swap had issues:

$ swapoff -U bf6237f4-db89-4761-a1a3-275cfc68b114
swapoff: cannot find the device for bf6237f4-db89-4761-a1a3-275cfc68b114
$ swapoff -L xyzzy
swapoff: cannot find the device for xyzzy

Signed-off-by: Sami Kerola <kerolasa@xxxxxx>
---
 sys-utils/Makemodule.am | 13 ++++++++++---
 sys-utils/swapoff.c     | 35 ++++++++++++++++++++++++-----------
 2 files changed, 34 insertions(+), 14 deletions(-)

diff --git a/sys-utils/Makemodule.am b/sys-utils/Makemodule.am
index f540d38..b256fda 100644
--- a/sys-utils/Makemodule.am
+++ b/sys-utils/Makemodule.am
@@ -279,9 +279,16 @@ swapon_LDADD = $(LDADD) \
 swapoff_SOURCES = \
 	sys-utils/swapoff.c \
 	sys-utils/swapon-common.c \
-	sys-utils/swapon-common.h
-swapoff_CFLAGS = $(AM_CFLAGS) -I$(ul_libmount_incdir)
-swapoff_LDADD = $(LDADD) libmount.la
+	sys-utils/swapon-common.h \
+	lib/swapprober.c \
+	include/swapprober.h
+swapoff_CFLAGS = $(AM_CFLAGS) \
+	-I$(ul_libblkid_incdir) \
+	-I$(ul_libmount_incdir)
+swapoff_LDADD = $(LDADD) \
+	libblkid.la \
+	libcommon.la \
+	libmount.la
 endif
 
 if BUILD_LSCPU
diff --git a/sys-utils/swapoff.c b/sys-utils/swapoff.c
index 182ce95..83d84ca 100644
--- a/sys-utils/swapoff.c
+++ b/sys-utils/swapoff.c
@@ -9,6 +9,7 @@
 #include "nls.h"
 #include "c.h"
 #include "closestream.h"
+#include "swapprober.h"
 
 #include "swapon-common.h"
 
@@ -49,16 +50,28 @@ static int do_swapoff(const char *orig_special, int quiet, int canonic)
 	return -1;
 }
 
-static int swapoff_by_label(const char *label, int quiet)
+static int swapoff_by(const char *type, const char *request, int quiet)
 {
-	const char *special = mnt_resolve_tag("LABEL", label, mntcache);
-	return special ? do_swapoff(special, quiet, CANONIC) : cannot_find(label);
-}
-
-static int swapoff_by_uuid(const char *uuid, int quiet)
-{
-	const char *special = mnt_resolve_tag("UUID", uuid, mntcache);
-	return special ? do_swapoff(special, quiet, CANONIC) : cannot_find(uuid);
+	const char *special = mnt_resolve_tag(type, request, mntcache);
+
+	/* if not a block device, try to find swap file */
+	if (!special) {
+		struct libmnt_table *tb = get_swaps();
+		struct libmnt_iter *itr = mnt_new_iter(MNT_ITER_BACKWARD);
+		struct libmnt_fs *fs;
+
+		while (tb && mnt_table_find_next_fs(tb, itr, match_swap, NULL, &fs) == 0) {
+			const char *dev = mnt_fs_get_source(fs);
+			blkid_probe pr;
+			const char *data;
+
+			pr = get_swap_prober(dev);
+			blkid_probe_lookup_value(pr, type, &data, NULL);
+			if (!strcmp(request, data))
+				special = dev;
+		}
+	}
+	return special ? do_swapoff(special, quiet, CANONIC) : cannot_find(request);
 }
 
 static void __attribute__ ((__noreturn__)) usage(FILE * out)
@@ -178,10 +191,10 @@ int main(int argc, char *argv[])
 	mntcache = mnt_new_cache();
 
 	for (i = 0; i < numof_labels(); i++)
-		status |= swapoff_by_label(get_label(i), !QUIET);
+		status |= swapoff_by("LABEL", get_label(i), !QUIET);
 
 	for (i = 0; i < numof_uuids(); i++)
-		status |= swapoff_by_uuid(get_uuid(i), !QUIET);
+		status |= swapoff_by("UUID", get_uuid(i), !QUIET);
 
 	while (*argv != NULL)
 		status |= do_swapoff(*argv++, !QUIET, !CANONIC);
-- 
2.1.3

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