fs: add CONFIG_BUFFER_HEAD

Add a new config option that controls building the buffer_head code, and
select it from all file systems and stacking drivers that need it.

For the block device nodes and alternative iomap based buffered I/O path
is provided when buffer_head support is not enabled, and iomap needs a
a small tweak to define the IOMAP_F_BUFFER_HEAD flag to 0 to not call
into the buffer_head code when it doesn't exist.

Otherwise this is just Kconfig and ifdef changes.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20230801172201.1923299-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

31 files changed, 34 insertions, 1 deletions

diff --git a/fs/Kconfig b/fs/Kconfig
index 18d034ec7953..e8b17c81b83a 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -18,8 +18,12 @@ config VALIDATE_FS_PARSER
 config FS_IOMAP
 	bool
 
+config BUFFER_HEAD
+	bool
+
 # old blockdev_direct_IO implementation.  Use iomap for new code instead
 config LEGACY_DIRECT_IO
+	depends on BUFFER_HEAD
 	bool
 
 if BLOCK
diff --git a/fs/Makefile b/fs/Makefile
index e513aaee0603..f9541f40be4e 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -17,7 +17,7 @@ obj-y :=	open.o read_write.o file_table.o super.o \
 		fs_types.o fs_context.o fs_parser.o fsopen.o init.o \
 		kernel_read_file.o mnt_idmapping.o remap_range.o
 
-obj-$(CONFIG_BLOCK)		+= buffer.o mpage.o
+obj-$(CONFIG_BUFFER_HEAD)	+= buffer.o mpage.o
 obj-$(CONFIG_PROC_FS)		+= proc_namespace.o
 obj-$(CONFIG_LEGACY_DIRECT_IO)	+= direct-io.o
 obj-y				+= notify/
diff --git a/fs/adfs/Kconfig b/fs/adfs/Kconfig
index 44738fed6625..1b97058f0c4a 100644
--- a/fs/adfs/Kconfig
+++ b/fs/adfs/Kconfig
@@ -2,6 +2,7 @@
 config ADFS_FS
 	tristate "ADFS file system support"
 	depends on BLOCK
+	select BUFFER_HEAD
 	help
 	  The Acorn Disc Filing System is the standard file system of the
 	  RiscOS operating system which runs on Acorn's ARM-based Risc PC
diff --git a/fs/affs/Kconfig b/fs/affs/Kconfig
index 962b86374e1c..1ae432d266c3 100644
--- a/fs/affs/Kconfig
+++ b/fs/affs/Kconfig
@@ -2,6 +2,7 @@
 config AFFS_FS
 	tristate "Amiga FFS file system support"
 	depends on BLOCK
+	select BUFFER_HEAD
 	select LEGACY_DIRECT_IO
 	help
 	  The Fast File System (FFS) is the common file system used on hard
diff --git a/fs/befs/Kconfig b/fs/befs/Kconfig
index 9550b6462b81..5fcfc4024ffe 100644
--- a/fs/befs/Kconfig
+++ b/fs/befs/Kconfig
@@ -2,6 +2,7 @@
 config BEFS_FS
 	tristate "BeOS file system (BeFS) support (read only)"
 	depends on BLOCK
+	select BUFFER_HEAD
 	select NLS
 	help
 	  The BeOS File System (BeFS) is the native file system of Be, Inc's
diff --git a/fs/bfs/Kconfig b/fs/bfs/Kconfig
index 3a757805b585..8e7ef866b62a 100644
--- a/fs/bfs/Kconfig
+++ b/fs/bfs/Kconfig
@@ -2,6 +2,7 @@
 config BFS_FS
 	tristate "BFS file system support"
 	depends on BLOCK
+	select BUFFER_HEAD
 	help
 	  Boot File System (BFS) is a file system used under SCO UnixWare to
 	  allow the bootloader access to the kernel image and other important
diff --git a/fs/efs/Kconfig b/fs/efs/Kconfig
index 2df1bac8b375..0833e533df9d 100644
--- a/fs/efs/Kconfig
+++ b/fs/efs/Kconfig
@@ -2,6 +2,7 @@
 config EFS_FS
 	tristate "EFS file system support (read only)"
 	depends on BLOCK
+	select BUFFER_HEAD
 	help
 	  EFS is an older file system used for non-ISO9660 CD-ROMs and hard
 	  disk partitions by SGI's IRIX operating system (IRIX 6.0 and newer
diff --git a/fs/exfat/Kconfig b/fs/exfat/Kconfig
index 147edeb04469..cbeca8e44d9b 100644
--- a/fs/exfat/Kconfig
+++ b/fs/exfat/Kconfig
@@ -2,6 +2,7 @@
 
 config EXFAT_FS
 	tristate "exFAT filesystem support"
+	select BUFFER_HEAD
 	select NLS
 	select LEGACY_DIRECT_IO
 	help
diff --git a/fs/ext2/Kconfig b/fs/ext2/Kconfig
index 77393fda99af..74d98965902e 100644
--- a/fs/ext2/Kconfig
+++ b/fs/ext2/Kconfig
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 config EXT2_FS
 	tristate "Second extended fs support"
+	select BUFFER_HEAD
 	select FS_IOMAP
 	select LEGACY_DIRECT_IO
 	help
diff --git a/fs/ext4/Kconfig b/fs/ext4/Kconfig
index 86699c8cab28..e20d59221fc0 100644
--- a/fs/ext4/Kconfig
+++ b/fs/ext4/Kconfig
@@ -28,6 +28,7 @@ config EXT3_FS_SECURITY
 
 config EXT4_FS
 	tristate "The Extended 4 (ext4) filesystem"
+	select BUFFER_HEAD
 	select JBD2
 	select CRC16
 	select CRYPTO
diff --git a/fs/f2fs/Kconfig b/fs/f2fs/Kconfig
index 03ef087537c7..68a1e23e1557 100644
--- a/fs/f2fs/Kconfig
+++ b/fs/f2fs/Kconfig
@@ -2,6 +2,7 @@
 config F2FS_FS
 	tristate "F2FS filesystem support"
 	depends on BLOCK
+	select BUFFER_HEAD
 	select NLS
 	select CRYPTO
 	select CRYPTO_CRC32
diff --git a/fs/fat/Kconfig b/fs/fat/Kconfig
index afe83b4e7172..25fae1c83725 100644
--- a/fs/fat/Kconfig
+++ b/fs/fat/Kconfig
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 config FAT_FS
 	tristate
+	select BUFFER_HEAD
 	select NLS
 	select LEGACY_DIRECT_IO
 	help
diff --git a/fs/freevxfs/Kconfig b/fs/freevxfs/Kconfig
index 0e2fc08f7de4..912107ebea6f 100644
--- a/fs/freevxfs/Kconfig
+++ b/fs/freevxfs/Kconfig
@@ -2,6 +2,7 @@
 config VXFS_FS
 	tristate "FreeVxFS file system support (VERITAS VxFS(TM) compatible)"
 	depends on BLOCK
+	select BUFFER_HEAD
 	help
 	  FreeVxFS is a file system driver that support the VERITAS VxFS(TM)
 	  file system format.  VERITAS VxFS(TM) is the standard file system
diff --git a/fs/gfs2/Kconfig b/fs/gfs2/Kconfig
index 03c966840422..be7f87a8e11a 100644
--- a/fs/gfs2/Kconfig
+++ b/fs/gfs2/Kconfig
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 config GFS2_FS
 	tristate "GFS2 file system support"
+	select BUFFER_HEAD
 	select FS_POSIX_ACL
 	select CRC32
 	select LIBCRC32C
diff --git a/fs/hfs/Kconfig b/fs/hfs/Kconfig
index d985066006d5..5ea5cd8ecea9 100644
--- a/fs/hfs/Kconfig
+++ b/fs/hfs/Kconfig
@@ -2,6 +2,7 @@
 config HFS_FS
 	tristate "Apple Macintosh file system support"
 	depends on BLOCK
+	select BUFFER_HEAD
 	select NLS
 	select LEGACY_DIRECT_IO
 	help
diff --git a/fs/hfsplus/Kconfig b/fs/hfsplus/Kconfig
index 8034e7827a69..8ce4a33a9ac7 100644
--- a/fs/hfsplus/Kconfig
+++ b/fs/hfsplus/Kconfig
@@ -2,6 +2,7 @@
 config HFSPLUS_FS
 	tristate "Apple Extended HFS file system support"
 	depends on BLOCK
+	select BUFFER_HEAD
 	select NLS
 	select NLS_UTF8
 	select LEGACY_DIRECT_IO
diff --git a/fs/hpfs/Kconfig b/fs/hpfs/Kconfig
index ec975f466877..ac1e9318e65a 100644
--- a/fs/hpfs/Kconfig
+++ b/fs/hpfs/Kconfig
@@ -2,6 +2,7 @@
 config HPFS_FS
 	tristate "OS/2 HPFS file system support"
 	depends on BLOCK
+	select BUFFER_HEAD
 	select FS_IOMAP
 	help
 	  OS/2 is IBM's operating system for PC's, the same as Warp, and HPFS
diff --git a/fs/isofs/Kconfig b/fs/isofs/Kconfig
index 08ffd37b9bb8..51434f2a471b 100644
--- a/fs/isofs/Kconfig
+++ b/fs/isofs/Kconfig
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 config ISO9660_FS
 	tristate "ISO 9660 CDROM file system support"
+	select BUFFER_HEAD
 	help
 	  This is the standard file system used on CD-ROMs.  It was previously
 	  known as "High Sierra File System" and is called "hsfs" on other
diff --git a/fs/jfs/Kconfig b/fs/jfs/Kconfig
index 51e856f0e4b8..17488440eef1 100644
--- a/fs/jfs/Kconfig
+++ b/fs/jfs/Kconfig
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 config JFS_FS
 	tristate "JFS filesystem support"
+	select BUFFER_HEAD
 	select NLS
 	select CRC32
 	select LEGACY_DIRECT_IO
diff --git a/fs/minix/Kconfig b/fs/minix/Kconfig
index de2003974ff0..90ddfad2a75e 100644
--- a/fs/minix/Kconfig
+++ b/fs/minix/Kconfig
@@ -2,6 +2,7 @@
 config MINIX_FS
 	tristate "Minix file system support"
 	depends on BLOCK
+	select BUFFER_HEAD
 	help
 	  Minix is a simple operating system used in many classes about OS's.
 	  The minix file system (method to organize files on a hard disk
diff --git a/fs/nilfs2/Kconfig b/fs/nilfs2/Kconfig
index 7d59567465e1..7dae168e346e 100644
--- a/fs/nilfs2/Kconfig
+++ b/fs/nilfs2/Kconfig
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 config NILFS2_FS
 	tristate "NILFS2 file system support"
+	select BUFFER_HEAD
 	select CRC32
 	select LEGACY_DIRECT_IO
 	help
diff --git a/fs/ntfs/Kconfig b/fs/ntfs/Kconfig
index f93e69a61283..7b2509741735 100644
--- a/fs/ntfs/Kconfig
+++ b/fs/ntfs/Kconfig
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 config NTFS_FS
 	tristate "NTFS file system support"
+	select BUFFER_HEAD
 	select NLS
 	help
 	  NTFS is the file system of Microsoft Windows NT, 2000, XP and 2003.
diff --git a/fs/ntfs3/Kconfig b/fs/ntfs3/Kconfig
index 96cc236f7f7b..cdfdf51e55d7 100644
--- a/fs/ntfs3/Kconfig
+++ b/fs/ntfs3/Kconfig
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 config NTFS3_FS
 	tristate "NTFS Read-Write file system support"
+	select BUFFER_HEAD
 	select NLS
 	select LEGACY_DIRECT_IO
 	help
diff --git a/fs/ocfs2/Kconfig b/fs/ocfs2/Kconfig
index 3123da7cfb30..2514d36cbe01 100644
--- a/fs/ocfs2/Kconfig
+++ b/fs/ocfs2/Kconfig
@@ -2,6 +2,7 @@
 config OCFS2_FS
 	tristate "OCFS2 file system support"
 	depends on INET && SYSFS && CONFIGFS_FS
+	select BUFFER_HEAD
 	select JBD2
 	select CRC32
 	select QUOTA
diff --git a/fs/omfs/Kconfig b/fs/omfs/Kconfig
index 42b2ec35a05b..8470f6c3e64e 100644
--- a/fs/omfs/Kconfig
+++ b/fs/omfs/Kconfig
@@ -2,6 +2,7 @@
 config OMFS_FS
 	tristate "SonicBlue Optimized MPEG File System support"
 	depends on BLOCK
+	select BUFFER_HEAD
 	select CRC_ITU_T
 	help
 	  This is the proprietary file system used by the Rio Karma music
diff --git a/fs/qnx4/Kconfig b/fs/qnx4/Kconfig
index 45b5b98376c4..a2eb826e76c6 100644
--- a/fs/qnx4/Kconfig
+++ b/fs/qnx4/Kconfig
@@ -2,6 +2,7 @@
 config QNX4FS_FS
 	tristate "QNX4 file system support (read only)"
 	depends on BLOCK
+	select BUFFER_HEAD
 	help
 	  This is the file system used by the real-time operating systems
 	  QNX 4 and QNX 6 (the latter is also called QNX RTP).
diff --git a/fs/qnx6/Kconfig b/fs/qnx6/Kconfig
index 6a9d6bce1586..8e865d72204e 100644
--- a/fs/qnx6/Kconfig
+++ b/fs/qnx6/Kconfig
@@ -2,6 +2,7 @@
 config QNX6FS_FS
 	tristate "QNX6 file system support (read only)"
 	depends on BLOCK && CRC32
+	select BUFFER_HEAD
 	help
 	  This is the file system used by the real-time operating systems
 	  QNX 6 (also called QNX RTP).
diff --git a/fs/reiserfs/Kconfig b/fs/reiserfs/Kconfig
index 4d22ecfe0fab..0e6fe26458fe 100644
--- a/fs/reiserfs/Kconfig
+++ b/fs/reiserfs/Kconfig
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 config REISERFS_FS
 	tristate "Reiserfs support (deprecated)"
+	select BUFFER_HEAD
 	select CRC32
 	select LEGACY_DIRECT_IO
 	help
diff --git a/fs/sysv/Kconfig b/fs/sysv/Kconfig
index b4e23e03fbeb..67b3f90afbfd 100644
--- a/fs/sysv/Kconfig
+++ b/fs/sysv/Kconfig
@@ -2,6 +2,7 @@
 config SYSV_FS
 	tristate "System V/Xenix/V7/Coherent file system support"
 	depends on BLOCK
+	select BUFFER_HEAD
 	help
 	  SCO, Xenix and Coherent are commercial Unix systems for Intel
 	  machines, and Version 7 was used on the DEC PDP-11. Saying Y
diff --git a/fs/udf/Kconfig b/fs/udf/Kconfig
index 82e8bfa2dfd9..8f7ce30d47fd 100644
--- a/fs/udf/Kconfig
+++ b/fs/udf/Kconfig
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 config UDF_FS
 	tristate "UDF file system support"
+	select BUFFER_HEAD
 	select CRC_ITU_T
 	select NLS
 	select LEGACY_DIRECT_IO
diff --git a/fs/ufs/Kconfig b/fs/ufs/Kconfig
index 6d30adb6b890..9301e7ecd092 100644
--- a/fs/ufs/Kconfig
+++ b/fs/ufs/Kconfig
@@ -2,6 +2,7 @@
 config UFS_FS
 	tristate "UFS file system support (read only)"
 	depends on BLOCK
+	select BUFFER_HEAD
 	help
 	  BSD and derivate versions of Unix (such as SunOS, FreeBSD, NetBSD,
 	  OpenBSD and NeXTstep) use a file system called UFS. Some System V