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

1 files changed, 19 insertions, 25 deletions

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) {