[Bug 1647485] [NEW] NVMe symlinks broken by devices with spaces in model or serial strings

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[Impact]

After including the patch from bug 1642903, NVMe devices that include spaces in their model or serial strings result in incorrect symlinks, e.g. if the model string is "XYZ Corp NVMe drive" then instead of creating:
/dev/disk/by-id/nvme-XYZ Corp NVMe drive_SERIAL -> ../../nvme0n1
it creates:
/dev/disk/by-id/nvme-XYZ -> ../../nvme0n1
/dev/Corp -> nvme0n1
/dev/NVMe -> nvme0n1
/dev/drive_SERIAL -> nvme0n1

This is because of the way udev handles the SYMLINK value strings; by
default, it does not do any whitespace replacement.  To enable
whitespace replacement of a symlink value, the rule must also include
OPTIONS+="string_escape=replace".  This is done for 'md' and 'dm'
devices in their rules.  However, there are no rules that actually want
to specify multiple symlinks, and defaulting to not replacing whitespace
makes no sense; instead, the default should be to replace all whitespace
in each symlink value, unless the rule explicitly specifies
OPTIONS+="string_escape=none".

[Test Case]

This assumes using udev with the patch from bug 1642903.

Without this patch, when using a NVMe drive that contains spaces in its
model and/or serial strings, check the /dev/disk/by-id/ directory.  It
should contain a partially-correct symlink to the NVMe drive, with the
name up to the first space.  All following space-separated parts of the
mode/serial string should have symlinks in the /dev/ directory.  This is
the incorrect behavior.

With this patch, check the /dev/disk/by-id/ directory.  It should
contain a fully-correct symlink to the NVMe drive, and no part of the
drive's model/serial number string should be a link in the /dev
directory.

An example of the correct/incorrect naming is in the Impact section.

There should be no other changes to any of the symlinks under /dev
before and after this patch.  Typical locations for symlinks are /dev/,
/dev/disk/by-name/, /dev/disk/by-id/, /dev/disk/by-uuid/, /dev/disk/by-
label/

[Regression Potential]

Errors in udev rules can lead to an unbootable or otherwise completely
broken system if they unintentionally break or clobber existing
/dev/disks/ symlinks.

[Other Info]

This is also tracked with upstream systemd (udev) bug 4833:
https://github.com/systemd/systemd/issues/4833

Also note, this can be worked around in individual rules ONLY (i.e. not
fixed for all rules) by appending OPTIONS+="string_escape=replace" to
each of the NVMe rules with SYMLINK+="..." assignment, e.g.:

KERNEL=="nvme*[0-9]n*[0-9]", ENV{DEVTYPE}=="disk", ATTRS{model}=="?*",
ENV{ID_SERIAL_SHORT}=="?*",
ENV{ID_SERIAL}="$attr{model}_$env{ID_SERIAL_SHORT}", SYMLINK+="disk/by-
id/nvme-$env{ID_SERIAL}", OPTIONS+="string_escape=replace"

** Affects: systemd (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: patch sts sts-sponsor sts-sru
-- 
NVMe symlinks broken by devices with spaces in model or serial strings
https://bugs.launchpad.net/bugs/1647485
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