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b32d45824a
Add an optional flag that ensures dm_bufio_client does not sleep (primary focus is to service dm_bufio_get without sleeping). This allows the dm-bufio cache to be queried from interrupt context. To ensure that dm-bufio does not sleep, dm-bufio must use a spinlock instead of a mutex. Additionally, to avoid deadlocks, special care must be taken so that dm-bufio does not sleep while holding the spinlock. But again: the scope of this no_sleep is initially confined to dm_bufio_get, so __alloc_buffer_wait_no_callback is _not_ changed to avoid sleeping because __bufio_new avoids allocation for NF_GET. Signed-off-by: Nathan Huckleberry <nhuck@google.com> Signed-off-by: Mike Snitzer <snitzer@kernel.org>