Package: mount Version: 2.13-8 Debian Version: testing In cooperation with the kernels loopback device driver, losetup doesn't handle then timestamps of image files correctly. If an image file, which is mounted via a loopback device is changed, the modification timestamp of the related image file stays constant:
Example: Create an image file with a file system, mount it and make some content: mkdir mnt dd if=/dev/zero of=test.img count=1440 bs=1024 losetup --help losetup --help /dev/loop0 test.img losetup /dev/loop0 test.img mkfs.vfat /dev/loop0 mount /dev/loop0 mnt touch mnt/test1 umount mnt losetup -d /dev/loop0 See timestamps: stat test.img File: »test.img« Size: 1474560 Blocks: 2888 IO Block: 4096 reguläre Datei Device: 302h/770d Inode: 5473079 Links: 1 Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root) Access: 2008-01-08 07:44:05.000000000 +0100 Modify: 2008-01-08 07:42:58.000000000 +0100 Change: 2008-01-08 07:42:58.000000000 +0100 Mount it again and change the content: losetup /dev/loop0 test.img mount /dev/loop0 mnt touch mnt/test2 umount mnt losetup -d /dev/loop0 ls mnt See timestamps: stat test.img File: »test.img« Size: 1474560 Blocks: 2888 IO Block: 4096 reguläre Datei Device: 302h/770d Inode: 5473079 Links: 1 Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root) Access: 2008-01-08 07:45:17.000000000 +0100 Modify: 2008-01-08 07:42:58.000000000 +0100 Change: 2008-01-08 07:42:58.000000000 +0100 **** As you can see, the modification time of the image file stays constant! **************************** The result of this behavior is, that every backup program, which compares the modification times of files to decide which file has to be stored again and which not will NOT backup the image file although it has been changed! **************************** Suggestions: a) The loopback device driver should update the modification time of the image file on every write access. b) If this is too difficult, the modification time should be updated each time an image file is been mounted with rw access rights. Kind Regards Matthias Faulstich
