[PATCH] BLOCK: Make it possible to disable the block layer [try #6]
Make it possible to disable the block layer. Not all embedded devices require
it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require
the block layer to be present.
This patch does the following:
(*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev
support.
(*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls
an item that uses the block layer. This includes:
(*) Block I/O tracing.
(*) Disk partition code.
(*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS.
(*) The SCSI layer. As far as I can tell, even SCSI chardevs use the
block layer to do scheduling. Some drivers that use SCSI facilities -
such as USB storage - end up disabled indirectly from this.
(*) Various block-based device drivers, such as IDE and the old CDROM
drivers.
(*) MTD blockdev handling and FTL.
(*) JFFS - which uses set_bdev_super(), something it could avoid doing by
taking a leaf out of JFFS2's book.
(*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and
linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is,
however, still used in places, and so is still available.
(*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and
parts of linux/fs.h.
(*) Makes a number of files in fs/ contingent on CONFIG_BLOCK.
(*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK.
(*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK
is not enabled.
(*) fs/no-block.c is created to hold out-of-line stubs and things that are
required when CONFIG_BLOCK is not set:
(*) Default blockdev file operations (to give error ENODEV on opening).
(*) Makes some /proc changes:
(*) /proc/devices does not list any blockdevs.
(*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK.
(*) Makes some compat ioctl handling contingent on CONFIG_BLOCK.
(*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if
given command other than Q_SYNC or if a special device is specified.
(*) In init/do_mounts.c, no reference is made to the blockdev routines if
CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2.
(*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return
error ENOSYS by way of cond_syscall if so).
(*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if
CONFIG_BLOCK is not set, since they can't then happen.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/Kconfig b/fs/Kconfig
index 4fd9efa..1453d2d 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -4,6 +4,8 @@
menu "File systems"
+if BLOCK
+
config EXT2_FS
tristate "Second extended fs support"
help
@@ -399,6 +401,8 @@
If you don't know whether you need it, then you don't need it:
answer N.
+endif
+
config INOTIFY
bool "Inotify file change notification support"
default y
@@ -530,6 +534,7 @@
If you want to develop a userspace FS, or if you want to use
a filesystem based on FUSE, answer Y or M.
+if BLOCK
menu "CD-ROM/DVD Filesystems"
config ISO9660_FS
@@ -597,7 +602,9 @@
depends on (UDF_FS=m && NLS) || (UDF_FS=y && NLS=y)
endmenu
+endif
+if BLOCK
menu "DOS/FAT/NT Filesystems"
config FAT_FS
@@ -782,6 +789,7 @@
It is perfectly safe to say N here.
endmenu
+endif
menu "Pseudo filesystems"
@@ -939,7 +947,7 @@
config ADFS_FS
tristate "ADFS file system support (EXPERIMENTAL)"
- depends on EXPERIMENTAL
+ depends on BLOCK && EXPERIMENTAL
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
@@ -967,7 +975,7 @@
config AFFS_FS
tristate "Amiga FFS file system support (EXPERIMENTAL)"
- depends on EXPERIMENTAL
+ depends on BLOCK && EXPERIMENTAL
help
The Fast File System (FFS) is the common file system used on hard
disks by Amiga(tm) systems since AmigaOS Version 1.3 (34.20). Say Y
@@ -989,7 +997,7 @@
config HFS_FS
tristate "Apple Macintosh file system support (EXPERIMENTAL)"
- depends on EXPERIMENTAL
+ depends on BLOCK && EXPERIMENTAL
select NLS
help
If you say Y here, you will be able to mount Macintosh-formatted
@@ -1002,6 +1010,7 @@
config HFSPLUS_FS
tristate "Apple Extended HFS file system support"
+ depends on BLOCK
select NLS
select NLS_UTF8
help
@@ -1015,7 +1024,7 @@
config BEFS_FS
tristate "BeOS file system (BeFS) support (read only) (EXPERIMENTAL)"
- depends on EXPERIMENTAL
+ depends on BLOCK && EXPERIMENTAL
select NLS
help
The BeOS File System (BeFS) is the native file system of Be, Inc's
@@ -1042,7 +1051,7 @@
config BFS_FS
tristate "BFS file system support (EXPERIMENTAL)"
- depends on EXPERIMENTAL
+ depends on BLOCK && EXPERIMENTAL
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
@@ -1064,7 +1073,7 @@
config EFS_FS
tristate "EFS file system support (read only) (EXPERIMENTAL)"
- depends on EXPERIMENTAL
+ depends on BLOCK && EXPERIMENTAL
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
@@ -1079,7 +1088,7 @@
config JFFS_FS
tristate "Journalling Flash File System (JFFS) support"
- depends on MTD
+ depends on MTD && BLOCK
help
JFFS is the Journaling Flash File System developed by Axis
Communications in Sweden, aimed at providing a crash/powerdown-safe
@@ -1264,6 +1273,7 @@
config CRAMFS
tristate "Compressed ROM file system support (cramfs)"
+ depends on BLOCK
select ZLIB_INFLATE
help
Saying Y here includes support for CramFs (Compressed ROM File
@@ -1283,6 +1293,7 @@
config VXFS_FS
tristate "FreeVxFS file system support (VERITAS VxFS(TM) compatible)"
+ depends on BLOCK
help
FreeVxFS is a file system driver that support the VERITAS VxFS(TM)
file system format. VERITAS VxFS(TM) is the standard file system
@@ -1300,6 +1311,7 @@
config HPFS_FS
tristate "OS/2 HPFS file system support"
+ depends on BLOCK
help
OS/2 is IBM's operating system for PC's, the same as Warp, and HPFS
is the file system used for organizing files on OS/2 hard disk
@@ -1316,6 +1328,7 @@
config QNX4FS_FS
tristate "QNX4 file system support (read only)"
+ depends on BLOCK
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).
@@ -1343,6 +1356,7 @@
config SYSV_FS
tristate "System V/Xenix/V7/Coherent file system support"
+ depends on BLOCK
help
SCO, Xenix and Coherent are commercial Unix systems for Intel
machines, and Version 7 was used on the DEC PDP-11. Saying Y
@@ -1381,6 +1395,7 @@
config UFS_FS
tristate "UFS file system support (read only)"
+ depends on BLOCK
help
BSD and derivate versions of Unix (such as SunOS, FreeBSD, NetBSD,
OpenBSD and NeXTstep) use a file system called UFS. Some System V
@@ -1959,11 +1974,13 @@
endmenu
+if BLOCK
menu "Partition Types"
source "fs/partitions/Kconfig"
endmenu
+endif
source "fs/nls/Kconfig"