[PATCH 0/1] [SRU][O/gcp] Fix switching IO scheduler to "none"

[Paolo Pisati]

BugLink: https://bugs.launchpad.net/bugs/2083845

[Impact]
With Oracular linux-gcp kernel version 6.11.0-1002.2, running the google-guest-agent causes an error. The guest-agent sets the I/O scheduler to 'none', causing errors such as below:

```
2024-10-07T09:24:03.262548+00:00 oracular-old-gga-test google_guest_agent[1125]: panic: invalid return from write: got 256 from a write of 4
```

With strace, we can also see that the return value of write is unexpected:

[pid 3127] write(7, "none", 4) = 256

[Fix]

Fix commit is e3accac1a976e65491a9b9fba82ce8ddbd3d2389 ("block: Fix elv_iosched_local_module handling of "none" scheduler").

[How to test]

Apply the fix, rebuild the kernel and try to change scheduler in sysfs, e.g.:

# echo "none" > /sys/devices/virtual/block/loop1/queue/scheduler
# echo $?
0

[Regression potential]

Upstream clean cherry-pick, already part of v6.11.2.

Damien Le Moal (1):
  block: Fix elv_iosched_local_module handling of "none" scheduler

 block/elevator.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

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2.34.1