Split block/character protocols and libdriver
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.
This commit is contained in:
David van Moolenbroek
@@ -32,9 +32,10 @@ static int bdev_opcl(int req, dev_t dev, int access)
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*/
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message m;
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memset(&m, 0, sizeof(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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m.BDEV_MINOR = minor(dev);
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m.BDEV_ACCESS = access;
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return bdev_sendrec(dev, &m);
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}
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@@ -45,7 +46,7 @@ int bdev_open(dev_t dev, int access)
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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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return bdev_opcl(BDEV_OPEN, dev, access);
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}
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int bdev_close(dev_t dev)
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@@ -54,11 +55,11 @@ int bdev_close(dev_t dev)
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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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return bdev_opcl(BDEV_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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static int bdev_rdwt_setup(int req, dev_t dev, u64_t pos, char *buf,
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size_t count, int 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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@@ -66,10 +67,12 @@ static int bdev_rdwt_setup(int req, dev_t dev, u64_t pos, char *buf, int count,
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cp_grant_id_t grant;
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int access;
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assert((ssize_t) count >= 0);
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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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access = (req == BDEV_READ) ? CPF_WRITE : CPF_READ;
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grant = cpf_grant_direct(endpt, (vir_bytes) buf, count, access);
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@@ -78,12 +81,14 @@ static int bdev_rdwt_setup(int req, dev_t dev, u64_t pos, char *buf, int count,
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return EINVAL;
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}
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memset(m, 0, sizeof(*m));
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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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m->BDEV_MINOR = minor(dev);
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m->BDEV_POS_LO = ex64lo(pos);
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m->BDEV_POS_HI = ex64hi(pos);
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m->BDEV_COUNT = count;
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m->BDEV_GRANT = grant;
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m->BDEV_FLAGS = flags;
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return OK;
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}
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@@ -92,15 +97,12 @@ 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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cpf_revoke(m->BDEV_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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static ssize_t bdev_rdwt(int req, dev_t dev, u64_t pos, char *buf,
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size_t count, 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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@@ -118,11 +120,11 @@ static int bdev_rdwt(int req, dev_t dev, u64_t pos, char *buf, int count,
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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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int count, int flags, message *m, iovec_s_t *gvec)
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{
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/* Set up a vectored read/write request.
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*/
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ssize_t size;
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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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@@ -132,154 +134,118 @@ static int bdev_vrdwt_setup(int req, dev_t dev, u64_t pos, iovec_t *vec,
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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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access = (req == BDEV_GATHER) ? 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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grant = 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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if (!GRANT_VALID(grant)) {
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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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cpf_revoke(gvec[i].iov_grant);
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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_grant = grant;
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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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assert((ssize_t) (size + vec[i].iov_size) > size);
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*size += vec[i].iov_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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CPF_READ);
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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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cpf_revoke(gvec[i].iov_grant);
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return EINVAL;
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}
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memset(m, 0, sizeof(*m));
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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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m->BDEV_MINOR = minor(dev);
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m->BDEV_POS_LO = ex64lo(pos);
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m->BDEV_POS_HI = ex64hi(pos);
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m->BDEV_COUNT = count;
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m->BDEV_GRANT = grant;
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m->BDEV_FLAGS = flags;
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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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static void bdev_vrdwt_cleanup(message *m, iovec_s_t *gvec)
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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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grant = m->BDEV_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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for (i = m->BDEV_COUNT - 1; i >= 0; i--)
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cpf_revoke(gvec[i].iov_grant);
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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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static ssize_t bdev_vrdwt(int req, dev_t dev, u64_t pos, iovec_t *vec,
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int count, int flags)
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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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/* Perform a read or write call using a vector of buffers.
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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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if ((r = bdev_vrdwt_setup(req, dev, pos, vec, count, flags, &m, gvec)) != OK)
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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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bdev_vrdwt_cleanup(&m, gvec);
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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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ssize_t bdev_read(dev_t dev, u64_t pos, char *buf, size_t 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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return bdev_rdwt(BDEV_READ, 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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ssize_t bdev_write(dev_t dev, u64_t pos, char *buf, size_t 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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return bdev_rdwt(BDEV_WRITE, 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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ssize_t bdev_gather(dev_t dev, u64_t pos, iovec_t *vec, int count, int flags)
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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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return bdev_vrdwt(BDEV_GATHER, dev, pos, vec, count, flags);
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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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ssize_t bdev_scatter(dev_t dev, u64_t pos, iovec_t *vec, int count, int flags)
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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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return bdev_vrdwt(BDEV_SCATTER, dev, pos, vec, count, flags);
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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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@@ -311,10 +277,11 @@ static int bdev_ioctl_setup(dev_t dev, int request, void *buf, message *m)
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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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memset(m, 0, sizeof(*m));
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m->m_type = BDEV_IOCTL;
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m->BDEV_MINOR = minor(dev);
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m->BDEV_REQUEST = request;
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m->BDEV_GRANT = grant;
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return OK;
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}
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@@ -323,11 +290,8 @@ 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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cpf_revoke(m->BDEV_GRANT);
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}
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int bdev_ioctl(dev_t dev, int request, void *buf)
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