tree 6476fb6c8423ee65bc8b73182436ccfc7361ed05
parent eafd2b6ddd8604998bdfbf7550b23795c07f03bb
author Stefan Weinhuber <wein@de.ibm.com> 1281370379 +0200
committer Martin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com> 1281370374 +0200

[S390] dasd: allocate fallback cqr for reserve/release

The DASD reserve and release ioctls use the preallocated memory pool
of the respective device to build their CCW requests. However, when
the device is busy, the pool may already be empty and the ioctl fails.
Usually this can be recovered by calling the ioctl again, but in
a situation in which we need to issue an unconditional reserve to
make a device operational again, this would be not recoverable.
To avoid a failure due to lack of memory, DASD device driver will
preallocate enough memory for a single reserve/release request, which
can be used if normal allocation fails.

Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>