X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=engines%2Fsplice.c;h=5a288b5532c013d7e3cb8d58a6c131b76c488d82;hp=f55e5c0703273357781f4af7e548ba2be629d94a;hb=28cfeb6851703cf12b54b3a06bf3ff611198933e;hpb=36167d82e5f49dee91c6d2cd426068edee90e36f

diff --git a/engines/splice.c b/engines/splice.c
index f55e5c07..5a288b55 100644
--- a/engines/splice.c
+++ b/engines/splice.c
@@ -1,5 +1,8 @@
 /*
- * splice io engine
+ * splice engine
+ *
+ * IO engine that transfers data by doing splices to/from pipes and
+ * the files.
  *
  */
 #include <stdio.h>
@@ -8,22 +11,24 @@
 #include <errno.h>
 #include <assert.h>
 #include <sys/poll.h>
+#include <sys/mman.h>
 
 #include "../fio.h"
-#include "../os.h"
 
 #ifdef FIO_HAVE_SPLICE
 
 struct spliceio_data {
 	int pipe[2];
+	int vmsplice_to_user;
+	int vmsplice_to_user_map;
 };
 
 /*
- * For splice reading, we unfortunately cannot (yet) vmsplice the other way.
- * So just splice the data from the file into the pipe, and use regular
- * read to fill the buffer. Doesn't make a lot of sense, but...
+ * vmsplice didn't use to support splicing to user space, this is the old
+ * variant of getting that job done. Doesn't make a lot of sense, but it
+ * uses splices to move data from the source into a pipe.
  */
-static int fio_splice_read(struct thread_data *td, struct io_u *io_u)
+static int fio_splice_read_old(struct thread_data *td, struct io_u *io_u)
 {
 	struct spliceio_data *sd = td->io_ops->data;
 	struct fio_file *f = io_u->file;
@@ -45,7 +50,7 @@ static int fio_splice_read(struct thread_data *td, struct io_u *io_u)
 			if (errno == ENODATA || errno == EAGAIN)
 				continue;
 
-			return errno;
+			return -errno;
 		}
 
 		buflen -= ret;
@@ -53,7 +58,7 @@ static int fio_splice_read(struct thread_data *td, struct io_u *io_u)
 		while (ret) {
 			ret2 = read(sd->pipe[0], p, ret);
 			if (ret2 < 0)
-				return errno;
+				return -errno;
 
 			ret -= ret2;
 			p += ret2;
@@ -63,6 +68,97 @@ static int fio_splice_read(struct thread_data *td, struct io_u *io_u)
 	return io_u->xfer_buflen;
 }
 
+/*
+ * We can now vmsplice into userspace, so do the transfer by splicing into
+ * a pipe and vmsplicing that into userspace.
+ */
+static int fio_splice_read(struct thread_data *td, struct io_u *io_u)
+{
+	struct spliceio_data *sd = td->io_ops->data;
+	struct fio_file *f = io_u->file;
+	struct iovec iov;
+	int ret , buflen, mmap_len;
+	off_t offset;
+	void *p, *map;
+
+restart:
+	ret = 0;
+	offset = io_u->offset;
+	mmap_len = buflen = io_u->xfer_buflen;
+
+	if (sd->vmsplice_to_user_map) {
+		map = mmap(io_u->xfer_buf, buflen, PROT_READ, MAP_PRIVATE|OS_MAP_ANON, 0, 0);
+		if (map == MAP_FAILED) {
+			td_verror(td, errno, "mmap io_u");
+			return -1;
+		}
+
+		p = map;
+	} else {
+		map = NULL;
+		p = io_u->xfer_buf;
+	}
+
+	while (buflen) {
+		int this_len = buflen;
+		int flags = 0;
+
+		if (this_len > SPLICE_DEF_SIZE) {
+			this_len = SPLICE_DEF_SIZE;
+			flags = SPLICE_F_MORE;
+		}
+
+		ret = splice(f->fd, &offset, sd->pipe[1], NULL, this_len,flags);
+		if (ret < 0) {
+			if (errno == ENODATA || errno == EAGAIN)
+				continue;
+
+			td_verror(td, errno, "splice-from-fd");
+			break;
+		}
+
+		buflen -= ret;
+		iov.iov_base = p;
+		iov.iov_len = ret;
+		p += ret;
+
+		while (iov.iov_len) {
+			ret = vmsplice(sd->pipe[0], &iov, 1, SPLICE_F_MOVE);
+			if (ret < 0) {
+				if (errno == EFAULT && sd->vmsplice_to_user_map) {
+					sd->vmsplice_to_user_map = 0;
+					munmap(map, mmap_len);
+					goto restart;
+				}
+				if (errno == EBADF) {
+					ret = -EBADF;
+					break;
+				}
+				td_verror(td, errno, "vmsplice");
+				break;
+			} else if (!ret) {
+				td_verror(td, ENODATA, "vmsplice");
+				ret = -1;
+				break;
+			}
+
+			iov.iov_len -= ret;
+			iov.iov_base += ret;
+		}
+		if (ret < 0)
+			break;
+	}
+
+	if (sd->vmsplice_to_user_map && munmap(map, mmap_len) < 0) {
+		td_verror(td, errno, "munnap io_u");
+		return -1;
+	}
+	if (ret < 0)
+		return ret;
+
+	return io_u->xfer_buflen;
+}
+
 /*
  * For splice writing, we can vmsplice our data buffer directly into a
  * pipe and then splice that to a file.
@@ -70,32 +166,30 @@ static int fio_splice_read(struct thread_data *td, struct io_u *io_u)
 static int fio_splice_write(struct thread_data *td, struct io_u *io_u)
 {
 	struct spliceio_data *sd = td->io_ops->data;
-	struct iovec iov[1] = {
-		{
-			.iov_base = io_u->xfer_buf,
-			.iov_len = io_u->xfer_buflen,
-		}
+	struct iovec iov = {
+		.iov_base = io_u->xfer_buf,
+		.iov_len = io_u->xfer_buflen,
 	};
 	struct pollfd pfd = { .fd = sd->pipe[1], .events = POLLOUT, };
 	struct fio_file *f = io_u->file;
 	off_t off = io_u->offset;
 	int ret, ret2;
 
-	while (iov[0].iov_len) {
+	while (iov.iov_len) {
 		if (poll(&pfd, 1, -1) < 0)
 			return errno;
 
-		ret = vmsplice(sd->pipe[1], iov, 1, SPLICE_F_NONBLOCK);
+		ret = vmsplice(sd->pipe[1], &iov, 1, SPLICE_F_NONBLOCK);
 		if (ret < 0)
-			return errno;
+			return -errno;
 
-		iov[0].iov_len -= ret;
-		iov[0].iov_base += ret;
+		iov.iov_len -= ret;
+		iov.iov_base += ret;
 
 		while (ret) {
 			ret2 = splice(sd->pipe[0], NULL, f->fd, &off, ret, 0);
 			if (ret2 < 0)
-				return errno;
+				return -errno;
 
 			ret -= ret2;
 		}
@@ -106,17 +200,31 @@ static int fio_splice_write(struct thread_data *td, struct io_u *io_u)
 
 static int fio_spliceio_queue(struct thread_data *td, struct io_u *io_u)
 {
+	struct spliceio_data *sd = td->io_ops->data;
 	int ret;
 
-	if (io_u->ddir == DDIR_READ)
-		ret = fio_splice_read(td, io_u);
-	else if (io_u->ddir == DDIR_WRITE)
+	fio_ro_check(td, io_u);
+
+	if (io_u->ddir == DDIR_READ) {
+		if (sd->vmsplice_to_user) {
+			ret = fio_splice_read(td, io_u);
+			/*
+			 * This kernel doesn't support vmsplice to user
+			 * space. Reset the vmsplice_to_user flag, so that
+			 * we retry below and don't hit this path again.
+			 */
+			if (ret == -EBADF)
+				sd->vmsplice_to_user = 0;
+		}
+		if (!sd->vmsplice_to_user)
+			ret = fio_splice_read_old(td, io_u);
+	} else if (io_u->ddir == DDIR_WRITE)
 		ret = fio_splice_write(td, io_u);
 	else
 		ret = fsync(io_u->file->fd);
 
 	if (ret != (int) io_u->xfer_buflen) {
-		if (ret > 0) {
+		if (ret >= 0) {
 			io_u->resid = io_u->xfer_buflen - ret;
 			io_u->error = 0;
 			return FIO_Q_COMPLETED;
@@ -125,7 +233,7 @@ static int fio_spliceio_queue(struct thread_data *td, struct io_u *io_u)
 	}
 
 	if (io_u->error)
-		td_verror(td, io_u->error);
+		td_verror(td, io_u->error, "xfer");
 
 	return FIO_Q_COMPLETED;
 }
@@ -147,11 +255,29 @@ static int fio_spliceio_init(struct thread_data *td)
 	struct spliceio_data *sd = malloc(sizeof(*sd));
 
 	if (pipe(sd->pipe) < 0) {
-		td_verror(td, errno);
+		td_verror(td, errno, "pipe");
 		free(sd);
 		return 1;
 	}
 
+	/*
+	 * Assume this work, we'll reset this if it doesn't
+	 */
+	sd->vmsplice_to_user = 1;
+
+	/*
+	 * Works with "real" vmsplice to user, eg mapping pages directly.
+	 * Reset if we fail.
+	 */
+	sd->vmsplice_to_user_map = 1;
+
+	/*
+	 * And if vmsplice_to_user works, we definitely need aligned
+	 * buffers. Just set ->odirect to force that.
+	 */
+	if (td_read(td))
+		td->o.odirect = 1;
+
 	td->io_ops->data = sd;
 	return 0;
 }
@@ -162,6 +288,8 @@ static struct ioengine_ops ioengine = {
 	.init		= fio_spliceio_init,
 	.queue		= fio_spliceio_queue,
 	.cleanup	= fio_spliceio_cleanup,
+	.open_file	= generic_open_file,
+	.close_file	= generic_close_file,
 	.flags		= FIO_SYNCIO,
 };