On Mon, Feb 15, 2021 at 10:46:23PM +0000, David Howells wrote:

The in_softirq() in netfs_rreq_terminated() works fine for the cache being
on a normal disk, as the completion handlers may get called in softirq
context, but for an NVMe drive, the completion handler may get called in
IRQ context.

Fix to use in_interrupt() instead of in_softirq() throughout the read
helpers, particularly when deciding whether to punt code that might sleep
off to a worker thread.

We must not use either check, as they all are unreliable especially
for PREEMPT-RT.