zfs_file: rename zfs_file_fallocate to zfs_file_deallocate

We only use it on a specific way: to punch a hole in (make sparse) a
region of a file, in order to implement TRIM-like behaviour.

So, call the op "deallocate", and move the Linux-style mode flags down
into the Linux implementation, since they're an implementation detail.

FreeBSD gets a no-op stub (for the moment).

Sponsored-by: https://despairlabs.com/sponsor/
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes openzfs#16496

include/sys/zfs_file.h

@@ -53,7 +53,7 @@ int zfs_file_pread(zfs_file_t *fp, void *buf, size_t len, loff_t off,
 int zfs_file_seek(zfs_file_t *fp, loff_t *offp, int whence);
 int zfs_file_getattr(zfs_file_t *fp, zfs_file_attr_t *zfattr);
 int zfs_file_fsync(zfs_file_t *fp, int flags);
-int zfs_file_fallocate(zfs_file_t *fp, int mode, loff_t offset, loff_t len);
+int zfs_file_deallocate(zfs_file_t *fp, loff_t offset, loff_t len);
 loff_t zfs_file_off(zfs_file_t *fp);
 int zfs_file_unlink(const char *);
 

lib/libzpool/kernel.c

@@ -1364,24 +1364,26 @@ zfs_file_fsync(zfs_file_t *fp, int flags)
 }
 
 /*
- * fallocate - allocate or free space on disk
+ * deallocate - zero and/or deallocate file storage
  *
  * fp - file pointer
- * mode (non-standard options for hole punching etc)
- * offset - offset to start allocating or freeing from
- * len - length to free / allocate
- *
- * OPTIONAL
+ * offset - offset to start zeroing or deallocating
+ * len - length to zero or deallocate
  */
 int
-zfs_file_fallocate(zfs_file_t *fp, int mode, loff_t offset, loff_t len)
+zfs_file_deallocate(zfs_file_t *fp, loff_t offset, loff_t len)
 {
-#ifdef __linux__
-	return (fallocate(fp->f_fd, mode, offset, len));
+	int rc;
+#if defined(__linux__)
+	rc = fallocate(fp->f_fd,
+	    FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, offset, len);
 #else
-	(void) fp, (void) mode, (void) offset, (void) len;
-	return (EOPNOTSUPP);
+	(void) fp, (void) offset, (void) len;
+	rc = EOPNOTSUPP;
 #endif
+	if (rc)
+		return (SET_ERROR(rc));
+	return (0);
 }
 
 /*

module/os/freebsd/zfs/vdev_file.c

@@ -267,16 +267,9 @@ vdev_file_io_start(zio_t *zio)
 		zio_execute(zio);
 		return;
 	} else if (zio->io_type == ZIO_TYPE_TRIM) {
-#ifdef notyet
-		int mode = 0;
-
 		ASSERT3U(zio->io_size, !=, 0);
-
-		/* XXX FreeBSD has no fallocate routine in file ops */
-		zio->io_error = zfs_file_fallocate(vf->vf_file,
-		    mode, zio->io_offset, zio->io_size);
-#endif
-		zio->io_error = SET_ERROR(ENOTSUP);
+		zio->io_error = zfs_file_deallocate(vf->vf_file,
+		    zio->io_offset, zio->io_size);
 		zio_execute(zio);
 		return;
 	}

module/os/freebsd/zfs/zfs_file_os.c

@@ -288,6 +288,20 @@ zfs_file_fsync(zfs_file_t *fp, int flags)
 	return (zfs_vop_fsync(fp->f_vnode));
 }
 
+/*
+ * deallocate - zero and/or deallocate file storage
+ *
+ * fp - file pointer
+ * offset - offset to start zeroing or deallocating
+ * len - length to zero or deallocate
+ */
+int
+zfs_file_deallocate(zfs_file_t *fp, loff_t offset, loff_t len)
+{
+	(void) fp, (void) offset, (void) len;
+	return (SET_ERROR(EOPNOTSUPP));
+}
+
 zfs_file_t *
 zfs_file_get(int fd)
 {

module/os/linux/zfs/vdev_file.c

@@ -280,14 +280,9 @@ vdev_file_io_start(zio_t *zio)
 		zio_execute(zio);
 		return;
 	} else if (zio->io_type == ZIO_TYPE_TRIM) {
-		int mode = 0;
-
 		ASSERT3U(zio->io_size, !=, 0);
-#ifdef __linux__
-		mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
-#endif
-		zio->io_error = zfs_file_fallocate(vf->vf_file,
-		    mode, zio->io_offset, zio->io_size);
+		zio->io_error = zfs_file_deallocate(vf->vf_file,
+		    zio->io_offset, zio->io_size);
 		zio_execute(zio);
 		return;
 	}

module/os/linux/zfs/zfs_file_os.c

@@ -281,17 +281,14 @@ zfs_file_fsync(zfs_file_t *filp, int flags)
 }
 
 /*
- * fallocate - allocate or free space on disk
+ * deallocate - zero and/or deallocate file storage
  *
  * fp - file pointer
- * mode (non-standard options for hole punching etc)
- * offset - offset to start allocating or freeing from
- * len - length to free / allocate
- *
- * OPTIONAL
+ * offset - offset to start zeroing or deallocating
+ * len - length to zero or deallocate
  */
 int
-zfs_file_fallocate(zfs_file_t *fp, int mode, loff_t offset, loff_t len)
+zfs_file_deallocate(zfs_file_t *fp, loff_t offset, loff_t len)
 {
 	/*
 	 * May enter XFS which generates a warning when PF_FSTRANS is set.
@@ -307,12 +304,16 @@ zfs_file_fallocate(zfs_file_t *fp, int mode, loff_t offset, loff_t len)
 	 */
 	int error = EOPNOTSUPP;
 	if (fp->f_op->fallocate)
-		error = fp->f_op->fallocate(fp, mode, offset, len);
+		error = -fp->f_op->fallocate(fp,
+		    FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, offset, len);
 
 	if (fstrans)
 		current->flags |= __SPL_PF_FSTRANS;
 
-	return (error);
+	if (error)
+		return (SET_ERROR(error));
+
+	return (0);
 }
 
 /*