Linux 2.6.x compat, blkdev_compat.h

For legacy reasons the zvol.c and vdev_disk.c Linux compatibility
code ended up in sys/blkdev.h and sys/vdev_disk.h headers.  While
there are worse places for this code to live it should be in a
linux/blkdev_compat.h header.  This change moves this block device
Linux compatibility code in to the linux/blkdev_compat.h header
and updates all the correct #include locations.  This is not a
functional change or bug fix, it is just code cleanup.

include/linux/blkdev_compat.h

@@ -18,17 +18,16 @@
  *
  * CDDL HEADER END
  */
+
 /*
- * Copyright (C) 2008-2010 Lawrence Livermore National Security, LLC.
+ * Copyright (C) 2011 Lawrence Livermore National Security, LLC.
  * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
  * Written by Brian Behlendorf <behlendorf1@llnl.gov>.
  * LLNL-CODE-403049.
  */
 
-#ifndef	_SYS_BLKDEV_H
-#define	_SYS_BLKDEV_H
-
-#ifdef _KERNEL
+#ifndef _ZFS_BLKDEV_H
+#define _ZFS_BLKDEV_H
 
 #include <linux/blkdev.h>
 #include <linux/elevator.h>
@@ -212,6 +211,10 @@ struct req_iterator {
 		bio_for_each_segment(bvl, _iter.bio, _iter.i)
 #endif /* HAVE_RQ_FOR_EACH_SEGMENT */
 
+/*
+ * Portable helper for correctly setting the FAILFAST flags.  The
+ * correct usage has changed 3 times from 2.6.12 to 2.6.38.
+ */
 static inline void
 bio_set_flags_failfast(struct block_device *bdev, int *flags)
 {
@@ -255,10 +258,66 @@ bio_set_flags_failfast(struct block_device *bdev, int *flags)
 #endif /* HAVE_BIO_RW_FAILFAST_DTD */
 }
 
+/*
+ * Maximum disk label length, it may be undefined for some kernels.
+ */
 #ifndef DISK_NAME_LEN
 #define DISK_NAME_LEN	32
 #endif /* DISK_NAME_LEN */
 
-#endif /* KERNEL */
+/*
+ * 2.6.24 API change,
+ * The bio_end_io() prototype changed slightly.  These are helper
+ * macro's to ensure the prototype and return value are handled.
+ */
+#ifdef HAVE_2ARGS_BIO_END_IO_T
+# define BIO_END_IO_PROTO(fn, x, y, z)	static void fn(struct bio *x, int z)
+# define BIO_END_IO_RETURN(rc)		return
+#else
+# define BIO_END_IO_PROTO(fn, x, y, z)	static int fn(struct bio *x, \
+					              unsigned int y, int z)
+# define BIO_END_IO_RETURN(rc)		return rc
+#endif /* HAVE_2ARGS_BIO_END_IO_T */
 
-#endif	/* _SYS_BLKDEV_H */
+/*
+ * 2.6.28 API change
+ * Used to exclusively open a block device from within the kernel.
+ */
+#ifdef HAVE_OPEN_BDEV_EXCLUSIVE
+# define vdev_bdev_open(path, md, hld)	open_bdev_exclusive(path, md, hld)
+# define vdev_bdev_close(bdev, md)	close_bdev_exclusive(bdev, md)
+#else
+# define vdev_bdev_open(path, md, hld)	open_bdev_excl(path, md, hld)
+# define vdev_bdev_close(bdev, md)	close_bdev_excl(bdev)
+#endif /* HAVE_OPEN_BDEV_EXCLUSIVE */
+
+/*
+ * 2.6.22 API change
+ * The function invalidate_bdev() lost it's second argument because
+ * it was unused.
+ */
+#ifdef HAVE_1ARG_INVALIDATE_BDEV
+# define vdev_bdev_invalidate(bdev)	invalidate_bdev(bdev)
+#else
+# define vdev_bdev_invalidate(bdev)	invalidate_bdev(bdev, 1)
+#endif /* HAVE_1ARG_INVALIDATE_BDEV */
+
+/*
+ * 2.6.30 API change
+ * Change to make it explicit there this is the logical block size.
+ */
+#ifdef HAVE_BDEV_LOGICAL_BLOCK_SIZE
+# define vdev_bdev_block_size(bdev)	bdev_logical_block_size(bdev)
+#else
+# define vdev_bdev_block_size(bdev)	bdev_hardsect_size(bdev)
+#endif
+
+/*
+ * Default Linux IO Scheduler,
+ * Setting the scheduler to noop will allow the Linux IO scheduler to
+ * still perform front and back merging, while leaving the request
+ * ordering and prioritization to the ZFS IO scheduler.
+ */
+#define	VDEV_SCHEDULER			"noop"
+
+#endif /* _ZFS_BLKDEV_H */

include/sys/Makefile.am

@@ -72,7 +72,6 @@ COMMON_H = \
 	$(top_srcdir)/include/sys/zrlock.h
 
 KERNEL_H = \
-	$(top_srcdir)/include/sys/blkdev.h \
 	$(top_srcdir)/include/sys/zfs_ioctl.h \
 	$(top_srcdir)/include/sys/zfs_onexit.h \
 	${top_srcdir}/include/sys/zpl.h \

include/sys/Makefile.in

@@ -163,7 +163,6 @@ am__kernel_HEADERS_DIST = $(top_srcdir)/include/sys/arc.h \
 	$(top_srcdir)/include/sys/zio.h \
 	$(top_srcdir)/include/sys/zio_impl.h \
 	$(top_srcdir)/include/sys/zrlock.h \
-	$(top_srcdir)/include/sys/blkdev.h \
 	$(top_srcdir)/include/sys/zfs_ioctl.h \
 	$(top_srcdir)/include/sys/zfs_onexit.h \
 	${top_srcdir}/include/sys/zpl.h \
@@ -532,7 +531,6 @@ COMMON_H = \
 	$(top_srcdir)/include/sys/zrlock.h
 
 KERNEL_H = \
-	$(top_srcdir)/include/sys/blkdev.h \
 	$(top_srcdir)/include/sys/zfs_ioctl.h \
 	$(top_srcdir)/include/sys/zfs_onexit.h \
 	${top_srcdir}/include/sys/zpl.h \

include/sys/dmu.h

@@ -41,9 +41,6 @@
 #include <sys/cred.h>
 #include <sys/time.h>
 #include <sys/uio.h>
-#ifdef _KERNEL
-#include <sys/blkdev.h>
-#endif
 
 #ifdef	__cplusplus
 extern "C" {
@@ -514,6 +511,7 @@ void dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 void dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 	dmu_tx_t *tx);
 #ifdef _KERNEL
+#include <linux/blkdev_compat.h>
 int dmu_read_req(objset_t *os, uint64_t object, struct request *req);
 int dmu_write_req(objset_t *os, uint64_t object, struct request *req,
 	dmu_tx_t *tx);

include/sys/vdev_disk.h

@@ -28,15 +28,8 @@
 #ifndef _SYS_VDEV_DISK_H
 #define _SYS_VDEV_DISK_H
 
-#ifdef	__cplusplus
-extern "C" {
-#endif
-
 #ifdef _KERNEL
 #include <sys/vdev.h>
-#include <sys/ddi.h>
-#include <sys/sunldi.h>
-#include <sys/sunddi.h>
 
 typedef struct vdev_disk {
 	ddi_devid_t		vd_devid;
@@ -48,46 +41,5 @@ extern int vdev_disk_physio(struct block_device *, caddr_t,
 			    size_t, uint64_t, int);
 extern int vdev_disk_read_rootlabel(char *, char *, nvlist_t **);
 
-/* 2.6.24 API change */
-#ifdef HAVE_2ARGS_BIO_END_IO_T
-# define BIO_END_IO_PROTO(fn, x, y, z)	static void fn(struct bio *x, int z)
-# define BIO_END_IO_RETURN(rc)		return
-#else
-# define BIO_END_IO_PROTO(fn, x, y, z)	static int fn(struct bio *x, \
-					              unsigned int y, int z)
-# define BIO_END_IO_RETURN(rc)		return rc
-#endif /* HAVE_2ARGS_BIO_END_IO_T */
-
-/* 2.6.28 API change */
-#ifdef HAVE_OPEN_BDEV_EXCLUSIVE
-# define vdev_bdev_open(path, md, hld)	open_bdev_exclusive(path, md, hld)
-# define vdev_bdev_close(bdev, md)	close_bdev_exclusive(bdev, md)
-#else
-# define vdev_bdev_open(path, md, hld)	open_bdev_excl(path, md, hld)
-# define vdev_bdev_close(bdev, md)	close_bdev_excl(bdev)
-#endif /* HAVE_OPEN_BDEV_EXCLUSIVE */
-
-/* 2.6.22 API change */
-#ifdef HAVE_1ARG_INVALIDATE_BDEV
-# define vdev_bdev_invalidate(bdev)	invalidate_bdev(bdev)
-#else
-# define vdev_bdev_invalidate(bdev)	invalidate_bdev(bdev, 1)
-#endif /* HAVE_1ARG_INVALIDATE_BDEV */
-
-/* 2.6.30 API change */
-#ifdef HAVE_BDEV_LOGICAL_BLOCK_SIZE
-# define vdev_bdev_block_size(bdev)	bdev_logical_block_size(bdev)
-#else
-# define vdev_bdev_block_size(bdev)	bdev_hardsect_size(bdev)
-#endif
-
-/* Default Linux IO Scheduler */
-#define	VDEV_SCHEDULER			"noop"
-
 #endif /* _KERNEL */
-
-#ifdef	__cplusplus
-}
-#endif
-
 #endif /* _SYS_VDEV_DISK_H */

include/sys/zvol.h

@@ -33,8 +33,6 @@
 
 #ifdef _KERNEL
 
-#include <sys/blkdev.h>
-
 extern int zvol_check_volsize(uint64_t volsize, uint64_t blocksize);
 extern int zvol_check_volblocksize(uint64_t volblocksize);
 extern int zvol_get_stats(objset_t *os, nvlist_t *nv);

module/zfs/zvol.c

@@ -44,6 +44,7 @@
 #include <sys/zfs_rlock.h>
 #include <sys/zfs_znode.h>
 #include <sys/zvol.h>
+#include <linux/blkdev_compat.h>
 
 unsigned int zvol_major = ZVOL_MAJOR;
 unsigned int zvol_threads = 0;