Messages in this thread | | | Date | Thu, 28 Mar 2024 13:07:12 +0800 | Subject | Re: FAILED: Patch "btrfs: do not skip re-registration for the mounted device" failed to apply to 6.8-stable tree | From | Anand Jain <> |
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On 3/28/24 05:37, David Sterba wrote: > On Wed, Mar 27, 2024 at 08:06:40AM -0400, Sasha Levin wrote: >> The patch below does not apply to the 6.8-stable tree. >> If someone wants it applied there, or to any other stable or longterm >> tree, then please email the backport, including the original git commit >> id to <stable@vger.kernel.org>. > > Please use the version below, applies cleanly on 6.7.x and 6.8.x. >
Thank You! Anand
> --- > > From: Anand Jain <anand.jain@oracle.com> > Subject: [PATCH] btrfs: do not skip re-registration for the mounted device > > [ Upstream commit d565fffa68560ac540bf3d62cc79719da50d5e7a ] > > There are reports that since version 6.7 update-grub fails to find the > device of the root on systems without initrd and on a single device. > > This looks like the device name changed in the output of > /proc/self/mountinfo: > > 6.5-rc5 working > > 18 1 0:16 / / rw,noatime - btrfs /dev/sda8 ... > > 6.7 not working: > > 17 1 0:15 / / rw,noatime - btrfs /dev/root ... > > and "update-grub" shows this error: > > /usr/sbin/grub-probe: error: cannot find a device for / (is /dev mounted?) > > This looks like it's related to the device name, but grub-probe > recognizes the "/dev/root" path and tries to find the underlying device. > However there's a special case for some filesystems, for btrfs in > particular. > > The generic root device detection heuristic is not done and it all > relies on reading the device infos by a btrfs specific ioctl. This ioctl > returns the device name as it was saved at the time of device scan (in > this case it's /dev/root). > > The change in 6.7 for temp_fsid to allow several single device > filesystem to exist with the same fsid (and transparently generate a new > UUID at mount time) was to skip caching/registering such devices. > > This also skipped mounted device. One step of scanning is to check if > the device name hasn't changed, and if yes then update the cached value. > > This broke the grub-probe as it always read the device /dev/root and > couldn't find it in the system. A temporary workaround is to create a > symlink but this does not survive reboot. > > The right fix is to allow updating the device path of a mounted > filesystem even if this is a single device one. > > In the fix, check if the device's major:minor number matches with the > cached device. If they do, then we can allow the scan to happen so that > device_list_add() can take care of updating the device path. The file > descriptor remains unchanged. > > This does not affect the temp_fsid feature, the UUID of the mounted > filesystem remains the same and the matching is based on device major:minor > which is unique per mounted filesystem. > > This covers the path when the device (that exists for all mounted > devices) name changes, updating /dev/root to /dev/sdx. Any other single > device with filesystem and is not mounted is still skipped. > > Note that if a system is booted and initial mount is done on the > /dev/root device, this will be the cached name of the device. Only after > the command "btrfs device scan" it will change as it triggers the > rename. > > The fix was verified by users whose systems were affected. > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=218353 > Link: https://lore.kernel.org/lkml/CAKLYgeJ1tUuqLcsquwuFqjDXPSJpEiokrWK2gisPKDZLs8Y2TQ@mail.gmail.com/ > Fixes: bc27d6f0aa0e ("btrfs: scan but don't register device on single device filesystem") > CC: stable@vger.kernel.org # 6.7+ > Tested-by: Alex Romosan <aromosan@gmail.com> > Tested-by: CHECK_1234543212345@protonmail.com > Signed-off-by: Anand Jain <anand.jain@oracle.com> > Reviewed-by: David Sterba <dsterba@suse.com> > Signed-off-by: David Sterba <dsterba@suse.com> > --- > fs/btrfs/volumes.c | 57 ++++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 47 insertions(+), 10 deletions(-) > > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index f627674b37db..6f4dd3ebbf7a 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -1290,6 +1290,47 @@ int btrfs_forget_devices(dev_t devt) > return ret; > } > > +static bool btrfs_skip_registration(struct btrfs_super_block *disk_super, > + const char *path, dev_t devt, > + bool mount_arg_dev) > +{ > + struct btrfs_fs_devices *fs_devices; > + > + /* > + * Do not skip device registration for mounted devices with matching > + * maj:min but different paths. Booting without initrd relies on > + * /dev/root initially, later replaced with the actual root device. > + * A successful scan ensures grub2-probe selects the correct device. > + */ > + list_for_each_entry(fs_devices, &fs_uuids, fs_list) { > + struct btrfs_device *device; > + > + mutex_lock(&fs_devices->device_list_mutex); > + > + if (!fs_devices->opened) { > + mutex_unlock(&fs_devices->device_list_mutex); > + continue; > + } > + > + list_for_each_entry(device, &fs_devices->devices, dev_list) { > + if (device->bdev && (device->bdev->bd_dev == devt) && > + strcmp(device->name->str, path) != 0) { > + mutex_unlock(&fs_devices->device_list_mutex); > + > + /* Do not skip registration. */ > + return false; > + } > + } > + mutex_unlock(&fs_devices->device_list_mutex); > + } > + > + if (!mount_arg_dev && btrfs_super_num_devices(disk_super) == 1 && > + !(btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_SEEDING)) > + return true; > + > + return false; > +} > + > /* > * Look for a btrfs signature on a device. This may be called out of the mount path > * and we are not allowed to call set_blocksize during the scan. The superblock > @@ -1346,18 +1387,14 @@ struct btrfs_device *btrfs_scan_one_device(const char *path, blk_mode_t flags, > goto error_bdev_put; > } > > - if (!mount_arg_dev && btrfs_super_num_devices(disk_super) == 1 && > - !(btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_SEEDING)) { > - dev_t devt; > + if (btrfs_skip_registration(disk_super, path, bdev_handle->bdev->bd_dev, > + mount_arg_dev)) { > + pr_debug("BTRFS: skip registering single non-seed device %s (%d:%d)\n", > + path, MAJOR(bdev_handle->bdev->bd_dev), > + MINOR(bdev_handle->bdev->bd_dev)); > > - ret = lookup_bdev(path, &devt); > - if (ret) > - btrfs_warn(NULL, "lookup bdev failed for path %s: %d", > - path, ret); > - else > - btrfs_free_stale_devices(devt, NULL); > + btrfs_free_stale_devices(bdev_handle->bdev->bd_dev, NULL); > > - pr_debug("BTRFS: skip registering single non-seed device %s\n", path); > device = NULL; > goto free_disk_super; > }
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