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.
348 lines
7.1 KiB
C
348 lines
7.1 KiB
C
/* libbdev - block device interfacing library, by D.C. van Moolenbroek */
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/* This is a preliminary, bare-essentials-only version of this library. */
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#include <minix/drivers.h>
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#include <minix/bdev.h>
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#include <minix/ioctl.h>
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#include <assert.h>
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#include "proto.h"
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void bdev_driver(dev_t dev, endpoint_t endpt)
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{
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/* Associate a driver with the given (major) device, using its endpoint.
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* File system usage note: typically called from mount and newdriver.
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*/
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static int first = TRUE;
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if (first) {
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/* Initialize the driver endpoint array. */
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bdev_driver_init();
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first = FALSE;
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}
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bdev_update(dev, endpt);
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}
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static int bdev_opcl(int req, dev_t dev, int access)
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{
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/* Open or close the given minor device.
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*/
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message m;
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m.m_type = req;
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m.DEVICE = minor(dev);
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m.COUNT = access;
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return bdev_sendrec(dev, &m);
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}
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int bdev_open(dev_t dev, int access)
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{
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/* Open the given minor device.
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* File system usage note: typically called from mount, after bdev_driver.
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*/
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return bdev_opcl(DEV_OPEN, dev, access);
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}
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int bdev_close(dev_t dev)
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{
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/* Close the given minor device.
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* File system usage note: typically called from unmount.
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*/
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return bdev_opcl(DEV_CLOSE, dev, 0);
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}
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static int bdev_rdwt_setup(int req, dev_t dev, u64_t pos, char *buf, int count,
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int UNUSED(flags), message *m)
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{
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/* Set up a single-buffer read/write request.
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*/
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endpoint_t endpt;
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cp_grant_id_t grant;
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int access;
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if ((endpt = bdev_driver_get(dev)) == NONE)
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return EDEADSRCDST;
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access = (req == DEV_READ_S) ? CPF_WRITE : CPF_READ;
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grant = cpf_grant_direct(endpt, (vir_bytes) buf, count, access);
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if (!GRANT_VALID(grant)) {
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printf("bdev: unable to allocate grant!\n");
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return EINVAL;
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}
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m->m_type = req;
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m->DEVICE = minor(dev);
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m->POSITION = ex64lo(pos);
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m->HIGHPOS = ex64hi(pos);
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m->COUNT = count;
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m->IO_GRANT = (void *) grant;
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return OK;
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}
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static void bdev_rdwt_cleanup(message *m)
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{
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/* Clean up a single-buffer read/write request.
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*/
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cp_grant_id_t grant;
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grant = (cp_grant_id_t) m->IO_GRANT;
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cpf_revoke(grant);
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}
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static int bdev_rdwt(int req, dev_t dev, u64_t pos, char *buf, int count,
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int flags)
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{
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/* Perform a read or write call using a single buffer.
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*/
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message m;
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int r;
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if ((r = bdev_rdwt_setup(req, dev, pos, buf, count, flags, &m)) != OK)
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return r;
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r = bdev_sendrec(dev, &m);
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bdev_rdwt_cleanup(&m);
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return r;
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}
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static int bdev_vrdwt_setup(int req, dev_t dev, u64_t pos, iovec_t *vec,
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int count, int UNUSED(flags), message *m, iovec_s_t *gvec,
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cp_grant_id_t *grants, vir_bytes *size)
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{
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/* Set up a vectored read/write request.
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*/
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endpoint_t endpt;
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cp_grant_id_t grant;
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int i, access;
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assert(count <= NR_IOREQS);
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if ((endpt = bdev_driver_get(dev)) == NONE)
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return EDEADSRCDST;
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access = (req == DEV_GATHER_S) ? CPF_WRITE : CPF_READ;
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*size = 0;
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for (i = 0; i < count; i++) {
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grants[i] = cpf_grant_direct(endpt, vec[i].iov_addr, vec[i].iov_size,
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access);
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if (!GRANT_VALID(grants[i])) {
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printf("bdev: unable to allocate grant!\n");
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for (i--; i >= 0; i--)
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cpf_revoke(grants[i]);
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return EINVAL;
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}
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/* We keep a separate grants array to prevent local leaks if the driver
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* ends up clobbering the grant vector. Future protocol updates should
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* make the grant for the vector read-only.
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*/
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gvec[i].iov_grant = grants[i];
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gvec[i].iov_size = vec[i].iov_size;
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assert(*size + vec[i].iov_size > *size);
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*size += vec[i].iov_size;
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}
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grant = cpf_grant_direct(endpt, (vir_bytes) gvec, sizeof(gvec[0]) * count,
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CPF_READ | CPF_WRITE);
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if (!GRANT_VALID(grant)) {
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printf("bdev: unable to allocate grant!\n");
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for (i = count - 1; i >= 0; i--)
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cpf_revoke(grants[i]);
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return EINVAL;
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}
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m->m_type = req;
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m->DEVICE = minor(dev);
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m->POSITION = ex64lo(pos);
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m->HIGHPOS = ex64hi(pos);
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m->COUNT = count;
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m->IO_GRANT = (void *) grant;
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return OK;
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}
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static void bdev_vrdwt_cleanup(message *m, cp_grant_id_t *grants)
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{
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/* Clean up a vectored read/write request.
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*/
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cp_grant_id_t grant;
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int i;
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grant = (cp_grant_id_t) m->IO_GRANT;
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cpf_revoke(grant);
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for (i = m->COUNT - 1; i >= 0; i--)
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cpf_revoke(grants[i]);
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}
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static int bdev_vrdwt_adjust(dev_t dev, iovec_s_t *gvec, int count,
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vir_bytes *size)
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{
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/* Adjust the number of bytes transferred, by subtracting from it the number of
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* bytes *not* transferred according to the result vector.
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*/
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int i;
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for (i = 0; i < count; i++) {
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if (*size < gvec[i].iov_size) {
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printf("bdev: driver (%d) returned bad vector\n",
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bdev_driver_get(dev));
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return FALSE;
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}
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*size -= gvec[i].iov_size;
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}
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return TRUE;
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}
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static int bdev_vrdwt(int req, dev_t dev, u64_t pos, iovec_t *vec, int count,
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int flags, vir_bytes *size)
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{
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/* Perform a read or write call using a vector of buffer.
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*/
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iovec_s_t gvec[NR_IOREQS];
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cp_grant_id_t grants[NR_IOREQS];
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message m;
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int r;
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if ((r = bdev_vrdwt_setup(req, dev, pos, vec, count, flags, &m, gvec,
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grants, size)) != OK) {
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*size = 0;
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return r;
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}
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r = bdev_sendrec(dev, &m);
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bdev_vrdwt_cleanup(&m, grants);
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/* Also return the number of bytes transferred. */
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if (!bdev_vrdwt_adjust(dev, gvec, count, size)) {
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*size = 0;
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r = EIO;
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}
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return r;
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}
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int bdev_read(dev_t dev, u64_t pos, char *buf, int count, int flags)
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{
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/* Perform a read call into a single buffer.
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*/
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return bdev_rdwt(DEV_READ_S, dev, pos, buf, count, flags);
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}
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int bdev_write(dev_t dev, u64_t pos, char *buf, int count, int flags)
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{
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/* Perform a write call from a single buffer.
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*/
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return bdev_rdwt(DEV_WRITE_S, dev, pos, buf, count, flags);
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}
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int bdev_gather(dev_t dev, u64_t pos, iovec_t *vec, int count, int flags,
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vir_bytes *size)
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{
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/* Perform a read call into a vector of buffers.
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*/
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return bdev_vrdwt(DEV_GATHER_S, dev, pos, vec, count, flags, size);
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}
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int bdev_scatter(dev_t dev, u64_t pos, iovec_t *vec, int count, int flags,
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vir_bytes *size)
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{
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/* Perform a write call from a vector of buffers.
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*/
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return bdev_vrdwt(DEV_SCATTER_S, dev, pos, vec, count, flags, size);
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}
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static int bdev_ioctl_setup(dev_t dev, int request, void *buf, message *m)
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{
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/* Set up an I/O control request.
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*/
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endpoint_t endpt;
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size_t size;
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cp_grant_id_t grant;
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int access;
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if ((endpt = bdev_driver_get(dev)) == NONE)
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return EDEADSRCDST;
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if (_MINIX_IOCTL_BIG(request))
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size = _MINIX_IOCTL_SIZE_BIG(request);
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else
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size = _MINIX_IOCTL_SIZE(request);
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access = 0;
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if (_MINIX_IOCTL_IOR(access)) access |= CPF_WRITE;
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if (_MINIX_IOCTL_IOW(access)) access |= CPF_READ;
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/* The size may be 0, in which case 'buf' need not be a valid pointer. */
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grant = cpf_grant_direct(endpt, (vir_bytes) buf, size, access);
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if (!GRANT_VALID(grant)) {
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printf("bdev: unable to allocate grant!\n");
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return EINVAL;
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}
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m->m_type = DEV_IOCTL_S;
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m->DEVICE = minor(dev);
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m->REQUEST = request;
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m->IO_GRANT = (void *) grant;
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return OK;
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}
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static void bdev_ioctl_cleanup(message *m)
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{
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/* Clean up an I/O control request.
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*/
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cp_grant_id_t grant;
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grant = (cp_grant_id_t) m->IO_GRANT;
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cpf_revoke(grant);
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}
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int bdev_ioctl(dev_t dev, int request, void *buf)
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{
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/* Perform an I/O control request.
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*/
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message m;
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int r;
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if ((r = bdev_ioctl_setup(dev, request, buf, &m)) != OK)
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return r;
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r = bdev_sendrec(dev, &m);
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bdev_ioctl_cleanup(&m);
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return r;
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}
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