diff options
Diffstat (limited to 'c_src/linux/blkdev.c')
-rw-r--r-- | c_src/linux/blkdev.c | 428 |
1 files changed, 428 insertions, 0 deletions
diff --git a/c_src/linux/blkdev.c b/c_src/linux/blkdev.c new file mode 100644 index 00000000..61f23362 --- /dev/null +++ b/c_src/linux/blkdev.c @@ -0,0 +1,428 @@ + +#include <alloca.h> +#include <errno.h> +#include <fcntl.h> +#include <sys/ioctl.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <sys/uio.h> +#include <unistd.h> + +#include <libaio.h> + +#ifdef CONFIG_VALGRIND +#include <valgrind/memcheck.h> +#endif + +#include <linux/bio.h> +#include <linux/blkdev.h> +#include <linux/completion.h> +#include <linux/fs.h> +#include <linux/kthread.h> + +#include "tools-util.h" + +struct fops { + void (*init)(void); + void (*cleanup)(void); + void (*read)(struct bio *bio, struct iovec * iov, unsigned i); + void (*write)(struct bio *bio, struct iovec * iov, unsigned i); +}; + +static struct fops *fops; +static io_context_t aio_ctx; +static atomic_t running_requests; + +void generic_make_request(struct bio *bio) +{ + struct iovec *iov; + struct bvec_iter iter; + struct bio_vec bv; + ssize_t ret; + unsigned i; + + if (bio->bi_opf & REQ_PREFLUSH) { + ret = fdatasync(bio->bi_bdev->bd_fd); + if (ret) { + fprintf(stderr, "fsync error: %m\n"); + bio->bi_status = BLK_STS_IOERR; + bio_endio(bio); + return; + } + } + + i = 0; + bio_for_each_segment(bv, bio, iter) + i++; + + iov = alloca(sizeof(*iov) * i); + + i = 0; + bio_for_each_segment(bv, bio, iter) { + void *start = page_address(bv.bv_page) + bv.bv_offset; + size_t len = bv.bv_len; + + iov[i++] = (struct iovec) { + .iov_base = start, + .iov_len = len, + }; + +#ifdef CONFIG_VALGRIND + /* To be pedantic it should only be on IO completion. */ + if (bio_op(bio) == REQ_OP_READ) + VALGRIND_MAKE_MEM_DEFINED(start, len); +#endif + } + + switch (bio_op(bio)) { + case REQ_OP_READ: + fops->read(bio, iov, i); + break; + case REQ_OP_WRITE: + fops->write(bio, iov, i); + break; + case REQ_OP_FLUSH: + ret = fsync(bio->bi_bdev->bd_fd); + if (ret) + die("fsync error: %m"); + bio_endio(bio); + break; + default: + BUG(); + } +} + +static void submit_bio_wait_endio(struct bio *bio) +{ + complete(bio->bi_private); +} + +int submit_bio_wait(struct bio *bio) +{ + struct completion done; + + init_completion(&done); + bio->bi_private = &done; + bio->bi_end_io = submit_bio_wait_endio; + bio->bi_opf |= REQ_SYNC; + submit_bio(bio); + wait_for_completion(&done); + + return blk_status_to_errno(bio->bi_status); +} + +int blkdev_issue_discard(struct block_device *bdev, + sector_t sector, sector_t nr_sects, + gfp_t gfp_mask) +{ + return 0; +} + +int blkdev_issue_zeroout(struct block_device *bdev, + sector_t sector, sector_t nr_sects, + gfp_t gfp_mask, unsigned flags) +{ + /* Not yet implemented: */ + BUG(); +} + +unsigned bdev_logical_block_size(struct block_device *bdev) +{ + struct stat statbuf; + unsigned blksize; + int ret; + + ret = fstat(bdev->bd_fd, &statbuf); + BUG_ON(ret); + + if (!S_ISBLK(statbuf.st_mode)) + return statbuf.st_blksize; + + xioctl(bdev->bd_fd, BLKPBSZGET, &blksize); + return blksize; +} + +sector_t get_capacity(struct gendisk *disk) +{ + struct block_device *bdev = + container_of(disk, struct block_device, __bd_disk); + struct stat statbuf; + u64 bytes; + int ret; + + ret = fstat(bdev->bd_fd, &statbuf); + BUG_ON(ret); + + if (!S_ISBLK(statbuf.st_mode)) + return statbuf.st_size >> 9; + + ret = ioctl(bdev->bd_fd, BLKGETSIZE64, &bytes); + BUG_ON(ret); + + return bytes >> 9; +} + +void blkdev_put(struct block_device *bdev, void *holder) +{ + fdatasync(bdev->bd_fd); + close(bdev->bd_fd); + free(bdev); +} + +struct block_device *blkdev_get_by_path(const char *path, blk_mode_t mode, + void *holder, const struct blk_holder_ops *hop) +{ + struct block_device *bdev; + int fd, flags = 0; + + if ((mode & (BLK_OPEN_READ|BLK_OPEN_WRITE)) == (BLK_OPEN_READ|BLK_OPEN_WRITE)) + flags = O_RDWR; + else if (mode & BLK_OPEN_READ) + flags = O_RDONLY; + else if (mode & BLK_OPEN_WRITE) + flags = O_WRONLY; + + if (!(mode & BLK_OPEN_BUFFERED)) + flags |= O_DIRECT; + + if (mode & BLK_OPEN_EXCL) + flags |= O_EXCL; + + fd = open(path, flags); + if (fd < 0) + return ERR_PTR(-errno); + + bdev = malloc(sizeof(*bdev)); + memset(bdev, 0, sizeof(*bdev)); + + strncpy(bdev->name, path, sizeof(bdev->name)); + bdev->name[sizeof(bdev->name) - 1] = '\0'; + + bdev->bd_dev = xfstat(fd).st_rdev; + bdev->bd_fd = fd; + bdev->bd_holder = holder; + bdev->bd_disk = &bdev->__bd_disk; + bdev->bd_disk->bdi = &bdev->bd_disk->__bdi; + bdev->queue.backing_dev_info = bdev->bd_disk->bdi; + + return bdev; +} + +void bdput(struct block_device *bdev) +{ + BUG(); +} + +int lookup_bdev(const char *path, dev_t *dev) +{ + return -EINVAL; +} + +static void io_fallback(void) +{ + fops++; + if (fops->init == NULL) + die("no fallback possible, something is very wrong"); + fops->init(); +} + +static void sync_check(struct bio *bio, int ret) +{ + if (ret != bio->bi_iter.bi_size) { + die("IO error: %s\n", strerror(-ret)); + } + + if (bio->bi_opf & REQ_FUA) { + ret = fdatasync(bio->bi_bdev->bd_fd); + if (ret) + die("fsync error: %s\n", strerror(-ret)); + } + bio_endio(bio); +} + +static void sync_init(void) {} + +static void sync_cleanup(void) +{ + /* not necessary? */ + sync(); +} + +static void sync_read(struct bio *bio, struct iovec * iov, unsigned i) +{ + + ssize_t ret = preadv(bio->bi_bdev->bd_fd, iov, i, + bio->bi_iter.bi_sector << 9); + sync_check(bio, ret); +} + +static void sync_write(struct bio *bio, struct iovec * iov, unsigned i) +{ + ssize_t ret = pwritev2(bio->bi_bdev->bd_fd, iov, i, + bio->bi_iter.bi_sector << 9, + bio->bi_opf & REQ_FUA ? RWF_SYNC : 0); + sync_check(bio, ret); +} + +static DECLARE_WAIT_QUEUE_HEAD(aio_events_completed); + +static int aio_completion_thread(void *arg) +{ + struct io_event events[8], *ev; + int ret; + bool stop = false; + + while (!stop) { + ret = io_getevents(aio_ctx, 1, ARRAY_SIZE(events), + events, NULL); + + if (ret < 0 && ret == -EINTR) + continue; + if (ret < 0) + die("io_getevents() error: %s", strerror(-ret)); + if (ret) + wake_up(&aio_events_completed); + + for (ev = events; ev < events + ret; ev++) { + struct bio *bio = (struct bio *) ev->data; + + /* This should only happen during blkdev_cleanup() */ + if (!bio) { + BUG_ON(atomic_read(&running_requests) != 0); + stop = true; + continue; + } + + if (ev->res != bio->bi_iter.bi_size) + bio->bi_status = BLK_STS_IOERR; + + bio_endio(bio); + atomic_dec(&running_requests); + } + } + + return 0; +} + +static struct task_struct *aio_task = NULL; + +static void aio_init(void) +{ + struct task_struct *p; + long err = io_setup(256, &aio_ctx); + if (!err) { + p = kthread_run(aio_completion_thread, NULL, "aio_completion"); + BUG_ON(IS_ERR(p)); + + aio_task = p; + + } else if (err == -ENOSYS) { + io_fallback(); + } else { + die("io_setup() error: %s", strerror(err)); + } +} + +static void aio_cleanup(void) +{ + struct task_struct *p = NULL; + swap(aio_task, p); + get_task_struct(p); + + /* I mean, really?! IO_CMD_NOOP is even defined, but not implemented. */ + int fds[2]; + int ret = pipe(fds); + if (ret != 0) + die("pipe err: %s", strerror(ret)); + + /* Wake up the completion thread with spurious work. */ + int junk = 0; + struct iocb iocb = { + .aio_lio_opcode = IO_CMD_PWRITE, + .data = NULL, /* Signal to stop */ + .aio_fildes = fds[1], + .u.c.buf = &junk, + .u.c.nbytes = 1, + }, *iocbp = &iocb; + ret = io_submit(aio_ctx, 1, &iocbp); + if (ret != 1) + die("io_submit cleanup err: %s", strerror(-ret)); + + ret = kthread_stop(p); + BUG_ON(ret); + + put_task_struct(p); + + close(fds[0]); + close(fds[1]); +} + +static void aio_op(struct bio *bio, struct iovec *iov, unsigned i, int opcode) +{ + ssize_t ret; + struct iocb iocb = { + .data = bio, + .aio_fildes = bio->bi_bdev->bd_fd, + .aio_rw_flags = bio->bi_opf & REQ_FUA ? RWF_SYNC : 0, + .aio_lio_opcode = opcode, + .u.c.buf = iov, + .u.c.nbytes = i, + .u.c.offset = bio->bi_iter.bi_sector << 9, + + }, *iocbp = &iocb; + + atomic_inc(&running_requests); + + wait_event(aio_events_completed, + (ret = io_submit(aio_ctx, 1, &iocbp)) != -EAGAIN);; + + if (ret != 1) + die("io_submit err: %s", strerror(-ret)); +} + +static void aio_read(struct bio *bio, struct iovec *iov, unsigned i) +{ + aio_op(bio, iov, i, IO_CMD_PREADV); +} + +static void aio_write(struct bio *bio, struct iovec * iov, unsigned i) +{ + aio_op(bio, iov, i, IO_CMD_PWRITEV); +} + + +/* not implemented */ +static void uring_init(void) { + io_fallback(); +} + +struct fops fops_list[] = { + { + .init = uring_init, + }, { + .init = aio_init, + .cleanup = aio_cleanup, + .read = aio_read, + .write = aio_write, + }, { + .init = sync_init, + .cleanup = sync_cleanup, + .read = sync_read, + .write = sync_write, + }, { + /* NULL */ + } +}; + +__attribute__((constructor(102))) +static void blkdev_init(void) +{ + fops = fops_list; + fops->init(); +} + +__attribute__((destructor(102))) +static void blkdev_cleanup(void) +{ + fops->cleanup(); +} |