On Wed, May 11, 2011 at 07:56:13PM +0100, Ben Hutchings wrote: > On Wed, May 11, 2011 at 05:40:52PM +0100, rleigh wrote: > [...] > > The fix for this is straightforward: by making initramfs-tools use the > > same options as initscripts and any additional user entries in > > /etc/fstab (which will naturally use the same options as the scripts > > in order to be functional), mount failures are prevented and existing > > user configuration is preserved and functional. > > How is that supposed to work when initramfs-tools mounts directories > before /etc/fstab is accessible? Well, the mnt_fsname for each is hard-coded in the initscripts scripts' domount() calls. If the user adds an fstab entry, they'll use the same fsname (or else the scripts won't use it and you'll also get mount errors). As a result, there's no choice in the naming here--they have been hardcoded in initscripts for many years. The only reason we haven't had much reported breakage is that until now very few users have made /proc/mounts a symlink, and those that have probably manually fixed things up rather than go to the effort of getting the initramfs fixed. The order is like this: init (initramfs) mounts /proc /dev /dev/pts /sys /run etc. --- mountkernfs.sh mounts /run, proc, /sys (if not already mounted by the initramfs). Defaults are taken from /lib/init and /etc/fstab. mountdevsubfs.sh does the same for /dev/pts /dev/shm. [root is made r/w] mtab.sh generates the initial mtab; this uses the defaults from /lib/init and /etc/fstab as for the earlier scripts. mtab then remounts the filesystems with the options from /lib/init and /etc/fstab to ensure that user-configured filesystem options are applied to the initramfs mounts [note: this does not affect mnt_fsname] mountall.sh calls "mount -a" to mount filesystems This is the problematic step. When we use the generated mtab, it exactly matches what we did, and runs without error. When we use a symlink to /proc/mounts, there's a mismatch with the options initramfs init used, and what the initscripts and fstab used, and this is what causes the error. The cause is simple to test for yourself. Just take the proc /proc proc defaults 0 0 line from /etc/fstab, and change the first "proc" to "none" (or anything else) and run "mount -a", and you'll see it fail. Change it back, and it works just fine. This is why updating initramfs init to use the same mnt_fsname for its mounts as the system/admin would use corrects the problem. It's purely the "none" mnt_fsname from initramfs that's breaking mount here because it doesn't match what every system has in their fstab (by default). Regards, Roger -- .''`. Roger Leigh : :' : Debian GNU/Linux http://people.debian.org/~rleigh/ `. `' Printing on GNU/Linux? http://gutenprint.sourceforge.net/ `- GPG Public Key: 0x25BFB848 Please GPG sign your mail.
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