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author | Valerie Aurora | 2010-08-04 02:09:19 +0200 |
---|---|---|
committer | Karel Zak | 2010-08-04 11:46:25 +0200 |
commit | 5d79666f8f7563ed9904a7ce2087f430ee2702b6 (patch) | |
tree | d08764576220783c6fdccc633b6ab314e8a24877 /mount/fstab.c | |
parent | libblkid: remove dead code section (diff) | |
download | kernel-qcow2-util-linux-5d79666f8f7563ed9904a7ce2087f430ee2702b6.tar.gz kernel-qcow2-util-linux-5d79666f8f7563ed9904a7ce2087f430ee2702b6.tar.xz kernel-qcow2-util-linux-5d79666f8f7563ed9904a7ce2087f430ee2702b6.zip |
mount: get most recently mounted fs from /etc/mtab.
I spent most of the day tracking down this subtle remount bug. I
think this is the correct solution but I'd appreciate some
double-checking. I suspect this bug will munge the mount options
whenever you remount a file system mounted on the same mountpoint as
another file system, using the mountpoint as the handle.
-VAL
commit c010b3a0783430e2b94f3b3dc0929ae299e383eb
Author: Valerie Aurora <vaurora@redhat.com>
Date: Tue Aug 3 16:32:52 2010 -0700
mount: get most recently mounted fs from /etc/mtab.
In mount, when using /etc/mtab to lookup a mount entry, get the most
recently mounted entry instead of the first mounted entry. You want
to manipulate the most recent mount, not a covered mount. See comment
to umount_one_bw().
This bug has been util-linux-ng since the first git checkin. It
finally showed up on my system with the change to stop using
SETLOOP_AUTOCLEAR if /etc/mtab is writable (commit af092544). If you
do a remount of a file system mounted on the same dir as another file
system, it will take the options from the first mount and write them
out to /etc/mtab as the options to the second mount - including, in
the case of a loop device, loop=/dev/loop0. Then when you umount the
second mount, it grabs the line from /etc/mtab and tries to tear down
the loop device, which complains because it is still in use by the
first mount.
Reproducible test case (on a system with writable /etc/mtab):
mount -o loop,ro /tmp/ro /mnt
mount -t tmpfs tmpfs /mnt
mount -o remount,ro /mnt
cat /etc/mtab | tail -2
Signed-off-by: Valerie Aurora <vaurora@redhat.com>
Diffstat (limited to 'mount/fstab.c')
-rw-r--r-- | mount/fstab.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/mount/fstab.c b/mount/fstab.c index 97d64a2c8..bfb2e5d35 100644 --- a/mount/fstab.c +++ b/mount/fstab.c @@ -216,6 +216,24 @@ getmntfile (const char *name) { } /* + * Given the name NAME, and the place MCPREV we found it last time, + * try to find it in mtab. + */ +struct mntentchn * +getmntfilebackward (const char *name, struct mntentchn *mcprev) { + struct mntentchn *mc, *mc0; + + mc0 = mtab_head(); + if (!mcprev) + mcprev = mc0; + for (mc = mcprev->prev; mc && mc != mc0; mc = mc->prev) + if (streq(mc->m.mnt_dir, name) || + streq(mc->m.mnt_fsname, name)) + return mc; + return NULL; +} + +/* * Given the directory name NAME, and the place MCPREV we found it last time, * try to find more occurrences. */ |