Hi Matthias,
On Wed, Jun 25, 2008 at 12:59:32PM +0200, Matthias Koenig wrote:
> 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.
ah, good catch. Thanks!
> We probably should ignore this error here.
I think we could be smarter. We can try to detect autoclear
loop devices. See the patch below.
[I'm going to create a stable/v2.14 branch.]
Karel
>From e84feaecfdf44a33ef9eccc5a56c8a6999466140 Mon Sep 17 00:00:00 2001
From: Karel Zak <kzak@xxxxxxxxxx>
Date: Wed, 2 Jul 2008 14:26:51 +0200
Subject: [PATCH] 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@xxxxxxx>
Signed-off-by: Karel Zak <kzak@xxxxxxxxxx>
---
mount/lomount.c | 23 +++++++++++++++++++++++
mount/lomount.h | 1 +
mount/umount.c | 12 ++++++++++--
3 files changed, 34 insertions(+), 2 deletions(-)
diff --git a/mount/lomount.c b/mount/lomount.c
index c3ac68a..7937052 100644
--- 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 f332a70..59108d4 100644
--- 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 65c8622..b2bbdae 100644
--- 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:
--
1.5.4.1
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