zio: remove io_cmd and DKIOCFLUSHWRITECACHE

There's no other options, so we can just always assume its a flush.

Includes some light refactoring where a switch statement was doing
control flow that no longer works.

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Alexander Motin <[email protected]>
Signed-off-by: Rob Norris <[email protected]>
Closes #16064

4 files changed, 51 insertions, 84 deletions

diff --git a/module/os/freebsd/zfs/vdev_file.c b/module/os/freebsd/zfs/vdev_file.c
index a65dfec86..888c8e7f8 100644
--- a/module/os/freebsd/zfs/vdev_file.c
+++ b/module/os/freebsd/zfs/vdev_file.c
@@ -255,14 +255,7 @@ vdev_file_io_start(zio_t *zio)
 			return;
 		}
 
-		switch (zio->io_cmd) {
-		case DKIOCFLUSHWRITECACHE:
-			zio->io_error = zfs_file_fsync(vf->vf_file,
-			    O_SYNC|O_DSYNC);
-			break;
-		default:
-			zio->io_error = SET_ERROR(ENOTSUP);
-		}
+		zio->io_error = zfs_file_fsync(vf->vf_file, O_SYNC|O_DSYNC);
 
 		zio_execute(zio);
 		return;
diff --git a/module/os/freebsd/zfs/vdev_geom.c b/module/os/freebsd/zfs/vdev_geom.c
index 196d67b4b..264dfa5c9 100644
--- a/module/os/freebsd/zfs/vdev_geom.c
+++ b/module/os/freebsd/zfs/vdev_geom.c
@@ -1153,42 +1153,31 @@ vdev_geom_io_start(zio_t *zio)
 
 	vd = zio->io_vd;
 
-	switch (zio->io_type) {
-	case ZIO_TYPE_IOCTL:
+	if (zio->io_type == ZIO_TYPE_IOCTL) {
 		/* XXPOLICY */
 		if (!vdev_readable(vd)) {
 			zio->io_error = SET_ERROR(ENXIO);
 			zio_interrupt(zio);
 			return;
-		} else {
-			switch (zio->io_cmd) {
-			case DKIOCFLUSHWRITECACHE:
-				if (zfs_nocacheflush ||
-				    vdev_geom_bio_flush_disable)
-					break;
-				if (vd->vdev_nowritecache) {
-					zio->io_error = SET_ERROR(ENOTSUP);
-					break;
-				}
-				goto sendreq;
-			default:
-				zio->io_error = SET_ERROR(ENOTSUP);
-			}
 		}
 
-		zio_execute(zio);
-		return;
-	case ZIO_TYPE_TRIM:
-		if (!vdev_geom_bio_delete_disable) {
-			goto sendreq;
+		if (zfs_nocacheflush || vdev_geom_bio_flush_disable) {
+			zio_execute(zio);
+			return;
+		}
+
+		if (vd->vdev_nowritecache) {
+			zio->io_error = SET_ERROR(ENOTSUP);
+			zio_execute(zio);
+			return;
+		}
+	} else if (zio->io_type == ZIO_TYPE_TRIM) {
+		if (vdev_geom_bio_delete_disable) {
+			zio_execute(zio);
+			return;
 		}
-		zio_execute(zio);
-		return;
-	default:
-			;
-		/* PASSTHROUGH --- placate compiler */
 	}
-sendreq:
+
 	ASSERT(zio->io_type == ZIO_TYPE_READ ||
 	    zio->io_type == ZIO_TYPE_WRITE ||
 	    zio->io_type == ZIO_TYPE_TRIM ||
diff --git a/module/os/linux/zfs/vdev_disk.c b/module/os/linux/zfs/vdev_disk.c
index f3f0c0875..554ed22b9 100644
--- a/module/os/linux/zfs/vdev_disk.c
+++ b/module/os/linux/zfs/vdev_disk.c
@@ -1403,38 +1403,29 @@ vdev_disk_io_start(zio_t *zio)
 	case ZIO_TYPE_IOCTL:
 
 		if (!vdev_readable(v)) {
-			rw_exit(&vd->vd_lock);
-			zio->io_error = SET_ERROR(ENXIO);
-			zio_interrupt(zio);
-			return;
-		}
-
-		switch (zio->io_cmd) {
-		case DKIOCFLUSHWRITECACHE:
-
-			if (zfs_nocacheflush)
-				break;
-
-			if (v->vdev_nowritecache) {
-				zio->io_error = SET_ERROR(ENOTSUP);
-				break;
-			}
-
+			/* Drive not there, can't flush */
+			error = SET_ERROR(ENXIO);
+		} else if (zfs_nocacheflush) {
+			/* Flushing disabled by operator, declare success */
+			error = 0;
+		} else if (v->vdev_nowritecache) {
+			/* This vdev not capable of flushing */
+			error = SET_ERROR(ENOTSUP);
+		} else {
+			/*
+			 * Issue the flush. If successful, the response will
+			 * be handled in the completion callback, so we're done.
+			 */
 			error = vdev_disk_io_flush(BDH_BDEV(vd->vd_bdh), zio);
 			if (error == 0) {
 				rw_exit(&vd->vd_lock);
 				return;
 			}
-
-			zio->io_error = error;
-
-			break;
-
-		default:
-			zio->io_error = SET_ERROR(ENOTSUP);
 		}
 
+		/* Couldn't issue the flush, so set the error and return it */
 		rw_exit(&vd->vd_lock);
+		zio->io_error = error;
 		zio_execute(zio);
 		return;
 
diff --git a/module/os/linux/zfs/vdev_file.c b/module/os/linux/zfs/vdev_file.c
index 5abc0426d..2b483c9a9 100644
--- a/module/os/linux/zfs/vdev_file.c
+++ b/module/os/linux/zfs/vdev_file.c
@@ -250,33 +250,27 @@ vdev_file_io_start(zio_t *zio)
 			return;
 		}
 
-		switch (zio->io_cmd) {
-		case DKIOCFLUSHWRITECACHE:
-
-			if (zfs_nocacheflush)
-				break;
-
-			/*
-			 * We cannot safely call vfs_fsync() when PF_FSTRANS
-			 * is set in the current context.  Filesystems like
-			 * XFS include sanity checks to verify it is not
-			 * already set, see xfs_vm_writepage().  Therefore
-			 * the sync must be dispatched to a different context.
-			 */
-			if (__spl_pf_fstrans_check()) {
-				VERIFY3U(taskq_dispatch(vdev_file_taskq,
-				    vdev_file_io_fsync, zio, TQ_SLEEP), !=,
-				    TASKQID_INVALID);
-				return;
-			}
-
-			zio->io_error = zfs_file_fsync(vf->vf_file,
-			    O_SYNC | O_DSYNC);
-			break;
-		default:
-			zio->io_error = SET_ERROR(ENOTSUP);
+		if (zfs_nocacheflush) {
+			zio_execute(zio);
+			return;
 		}
 
+		/*
+		 * We cannot safely call vfs_fsync() when PF_FSTRANS
+		 * is set in the current context.  Filesystems like
+		 * XFS include sanity checks to verify it is not
+		 * already set, see xfs_vm_writepage().  Therefore
+		 * the sync must be dispatched to a different context.
+		 */
+		if (__spl_pf_fstrans_check()) {
+			VERIFY3U(taskq_dispatch(vdev_file_taskq,
+			    vdev_file_io_fsync, zio, TQ_SLEEP), !=,
+			    TASKQID_INVALID);
+			return;
+		}
+
+		zio->io_error = zfs_file_fsync(vf->vf_file, O_SYNC | O_DSYNC);
+
 		zio_execute(zio);
 		return;
 	} else if (zio->io_type == ZIO_TYPE_TRIM) {