af01bda509
The "bdev" library provides basic primitives for file systems to talk to block device drivers, hiding the details of the underlying protocol and interaction model. This version of libbdev is rather basic. It is planned to support the following features in the long run: - asynchronous requests and replies; - recovery support for underlying block drivers; - retrying of failed I/O requests. The commit also changes our block-based file systems (mfs, ext2, isofs) to make use of libbdev.
90 lines
2 KiB
C
90 lines
2 KiB
C
/* libbdev - IPC and recovery functions */
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#include <minix/drivers.h>
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#include <minix/bdev.h>
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#include <assert.h>
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#include "proto.h"
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static void bdev_cancel(dev_t dev)
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{
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/* Recovering the driver for the given device has failed repeatedly. Mark it as
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* permanently unusable, and clean up any associated calls and resources.
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*/
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printf("bdev: driver for major %d crashed\n", major(dev));
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/* Mark the driver as unusable. */
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bdev_driver_clear(dev);
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}
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void bdev_update(dev_t dev, endpoint_t endpt)
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{
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/* Set the endpoint for a driver. Perform recovery if necessary.
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*/
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endpoint_t old_endpt;
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old_endpt = bdev_driver_get(dev);
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bdev_driver_set(dev, endpt);
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/* If updating the driver causes an endpoint change, the driver has
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* restarted.
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*/
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if (old_endpt != NONE && old_endpt != endpt)
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bdev_cancel(dev);
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}
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int bdev_sendrec(dev_t dev, const message *m_orig)
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{
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/* Send a request to the given device, and wait for the reply.
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*/
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endpoint_t endpt;
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message m;
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int r;
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/* If we have no usable driver endpoint, fail instantly. */
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if ((endpt = bdev_driver_get(dev)) == NONE)
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return EDEADSRCDST;
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/* Send the request and block until we receive a reply. */
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m = *m_orig;
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m.USER_ENDPT = (endpoint_t) -1; /* synchronous request; no ID */
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r = sendrec(endpt, &m);
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/* This version of libbdev does not support recovery. Forget the driver. */
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if (r == EDEADSRCDST) {
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bdev_cancel(dev);
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return EDEADSRCDST;
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}
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if (r != OK) {
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printf("bdev: IPC to driver (%d) failed (%d)\n", endpt, r);
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return r;
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}
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if (m.m_type != TASK_REPLY) {
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printf("bdev: driver (%d) sent weird response (%d)\n",
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endpt, m.m_type);
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return EIO;
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}
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/* ERESTART signifies a driver restart. Again, we do not support this yet. */
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if (m.REP_STATUS == ERESTART) {
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bdev_cancel(dev);
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return EDEADSRCDST;
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}
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if (m.REP_ENDPT != (endpoint_t) -1) {
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printf("bdev: driver (%d) sent invalid response (%d)\n",
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endpt, m.REP_ENDPT);
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return EIO;
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}
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/* We got a reply to our request. */
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return m.REP_STATUS;
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}
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