umount: improve "-d" option for autoclear loops

The new loop auto-destruct feature detaches automatically loop devices
when no longer used. This means they are detached with the umount()
call. But when we call umount with -d, del_loop() is called and fails
because the ioctl() returns ENXIO. We have to check for autoclear
loop devices rather than blindly call del_loop().

Reported-by: Matthias Koenig <mkoenig@suse.de>
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/mount/lomount.c b/mount/lomount.c
index c3ac68a704f89765eb257a5af8526a3d587becde..793705249f0f707456e84f09ba97c30922ea4d6c 100644 (file)
--- a/mount/lomount.c
+++ b/mount/lomount.c
@@ -102,6 +102,29 @@ is_loop_used(int fd)
        return ioctl (fd, LOOP_GET_STATUS, &li) == 0;
 }
 
+int
+is_loop_autoclear(const char *device)
+{
+       struct loop_info lo;
+       struct loop_info64 lo64;
+       int fd, rc = 0;
+
+       if ((fd = open(device, O_RDONLY)) < 0)
+               return 0;
+
+       if (ioctl(fd, LOOP_GET_STATUS64, &lo64) == 0) {
+               if (lo64.lo_flags & LO_FLAGS_AUTOCLEAR)
+                       rc = 1;
+
+       } else if (ioctl(fd, LOOP_GET_STATUS, &lo) == 0) {
+               if (lo.lo_flags & LO_FLAGS_AUTOCLEAR)
+                       rc = 1;
+       }
+
+       close(fd);
+       return rc;
+}
+
 static char *
 looplist_mk_devname(struct looplist *ll, int num)
 {

diff --git a/mount/lomount.h b/mount/lomount.h
index f332a70d14fb20bb3cbfac975f793cf6d45ff7a9..59108d4085683ee1c0de6d487669fc5bfbfa9ca8 100644 (file)
--- a/mount/lomount.h
+++ b/mount/lomount.h
@@ -2,6 +2,7 @@ extern int set_loop(const char *, const char *, unsigned long long, unsigned lon
                    const char *, int, int *);
 extern int del_loop(const char *);
 extern int is_loop_device(const char *);
+extern int is_loop_autoclear(const char *device);
 extern char * find_unused_loop_device(void);
 
 extern int loopfile_used_with(char *devname, const char *filename, unsigned long long offset);

diff --git a/mount/umount.c b/mount/umount.c
index 65c8622b57de857c2125489429c52351e69618ce..b2bbdae3c6be93f5e2a224d7bfaf48e9feeda4c7 100644 (file)
--- a/mount/umount.c
+++ b/mount/umount.c
@@ -190,6 +190,7 @@ umount_one (const char *spec, const char *node, const char *type,
        int res;
        int status;
        const char *loopdev;
+       int myloop = 0;
 
        /* Special case for root.  As of 0.99pl10 we can (almost) unmount root;
           the kernel will remount it readonly so that we can carry on running
@@ -201,7 +202,7 @@ umount_one (const char *spec, const char *node, const char *type,
                  || streq (node, "rootfs"));
        if (isroot)
                nomtab++;
-       
+
        /*
         * Call umount.TYPE for types that require a separate umount program.
         * All such special things must occur isolated in the types string.
@@ -209,6 +210,13 @@ umount_one (const char *spec, const char *node, const char *type,
        if (check_special_umountprog(spec, node, type, &status))
                return status;
 
+       /*
+        * Ignore the option "-d" for non-loop devices and loop devices with
+        * LO_FLAGS_AUTOCLEAR flag.
+        */
+       if (delloop && is_loop_device(spec) && !is_loop_autoclear(spec))
+               myloop = 1;
+
        umnt_err = umnt_err2 = 0;
        if (lazy) {
                res = umount2 (node, MNT_DETACH);
@@ -310,7 +318,7 @@ umount_one (const char *spec, const char *node, const char *type,
                }
 
                /* Also free loop devices when -d flag is given */
-               if (delloop && is_loop_device(spec))
+               if (myloop)
                        loopdev = spec;
        }
  gotloop: