b4d909d415
This patch separates the character and block driver communication protocols. The old character protocol remains the same, but a new block protocol is introduced. The libdriver library is replaced by two new libraries: libchardriver and libblockdriver. Their exposed API, and drivers that use them, have been updated accordingly. Together, libbdev and libblockdriver now completely abstract away the message format used by the block protocol. As the memory driver is both a character and a block device driver, it now implements its own message loop. The most important semantic change made to the block protocol is that it is no longer possible to return both partial results and an error for a single transfer. This simplifies the interaction between the caller and the driver, as the I/O vector no longer needs to be copied back. Also, drivers are now no longer supposed to decide based on the layout of the I/O vector when a transfer should be cut short. Put simply, transfers are now supposed to either succeed completely, or result in an error. After this patch, the state of the various pieces is as follows: - block protocol: stable - libbdev API: stable for synchronous communication - libblockdriver API: needs slight revision (the drvlib/partition API in particular; the threading API will also change shortly) - character protocol: needs cleanup - libchardriver API: needs cleanup accordingly - driver restarts: largely unsupported until endpoint changes are reintroduced As a side effect, this patch eliminates several bugs, hacks, and gcc -Wall and -W warnings all over the place. It probably introduces a few new ones, too. Update warning: this patch changes the protocol between MFS and disk drivers, so in order to use old/new images, the MFS from the ramdisk must be used to mount all file systems.
86 lines
1.8 KiB
C
86 lines
1.8 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 (endpoint %d) crashed\n",
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major(dev), bdev_driver_get(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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}
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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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static long id = 0;
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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.BDEV_ID = ++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 != BDEV_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.BDEV_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.BDEV_ID != id) {
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printf("bdev: driver (%d) sent invalid response (%ld)\n",
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endpt, m.BDEV_ID);
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return EIO;
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}
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/* Return the result of our request. */
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return m.BDEV_STATUS;
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}
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