[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>

1 files changed, 18 insertions, 0 deletions

diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index e1a56437040a..64b34533edea 100644
--- a/fs/compat_ioctl.c
+++ b/fs/compat_ioctl.c
@@ -645,6 +645,7 @@ out:
 }
 #endif
 
+#ifdef CONFIG_BLOCK
 struct hd_geometry32 {
 	unsigned char heads;
 	unsigned char sectors;
@@ -869,6 +870,7 @@ static int sg_grt_trans(unsigned int fd, unsigned int cmd, unsigned long arg)
 	}
 	return err;
 }
+#endif /* CONFIG_BLOCK */
 
 struct sock_fprog32 {
 	unsigned short	len;
@@ -992,6 +994,7 @@ static int ppp_ioctl_trans(unsigned int fd, unsigned int cmd, unsigned long arg)
 }
 
 
+#ifdef CONFIG_BLOCK
 struct mtget32 {
 	compat_long_t	mt_type;
 	compat_long_t	mt_resid;
@@ -1164,6 +1167,7 @@ static int cdrom_ioctl_trans(unsigned int fd, unsigned int cmd, unsigned long ar
 
 	return err;
 }
+#endif /* CONFIG_BLOCK */
 
 #ifdef CONFIG_VT
 
@@ -1491,6 +1495,7 @@ ret_einval(unsigned int fd, unsigned int cmd, unsigned long arg)
 	return -EINVAL;
 }
 
+#ifdef CONFIG_BLOCK
 static int broken_blkgetsize(unsigned int fd, unsigned int cmd, unsigned long arg)
 {
 	/* The mkswap binary hard codes it to Intel value :-((( */
@@ -1525,12 +1530,14 @@ static int blkpg_ioctl_trans(unsigned int fd, unsigned int cmd, unsigned long ar
 
 	return sys_ioctl(fd, cmd, (unsigned long)a);
 }
+#endif
 
 static int ioc_settimeout(unsigned int fd, unsigned int cmd, unsigned long arg)
 {
 	return rw_long(fd, AUTOFS_IOC_SETTIMEOUT, arg);
 }
 
+#ifdef CONFIG_BLOCK
 /* Fix sizeof(sizeof()) breakage */
 #define BLKBSZGET_32   _IOR(0x12,112,int)
 #define BLKBSZSET_32   _IOW(0x12,113,int)
@@ -1551,6 +1558,7 @@ static int do_blkgetsize64(unsigned int fd, unsigned int cmd,
 {
        return sys_ioctl(fd, BLKGETSIZE64, (unsigned long)compat_ptr(arg));
 }
+#endif
 
 /* Bluetooth ioctls */
 #define HCIUARTSETPROTO	_IOW('U', 200, int)
@@ -1571,6 +1579,7 @@ static int do_blkgetsize64(unsigned int fd, unsigned int cmd,
 #define HIDPGETCONNLIST	_IOR('H', 210, int)
 #define HIDPGETCONNINFO	_IOR('H', 211, int)
 
+#ifdef CONFIG_BLOCK
 struct floppy_struct32 {
 	compat_uint_t	size;
 	compat_uint_t	sect;
@@ -1895,6 +1904,7 @@ out:
 	kfree(karg);
 	return err;
 }
+#endif
 
 struct mtd_oob_buf32 {
 	u_int32_t start;
@@ -1936,6 +1946,7 @@ static int mtd_rw_oob(unsigned int fd, unsigned int cmd, unsigned long arg)
 	return err;
 }	
 
+#ifdef CONFIG_BLOCK
 struct raw32_config_request
 {
         compat_int_t    raw_minor;
@@ -2000,6 +2011,7 @@ static int raw_ioctl(unsigned fd, unsigned cmd, unsigned long arg)
         }
         return ret;
 }
+#endif /* CONFIG_BLOCK */
 
 struct serial_struct32 {
         compat_int_t    type;
@@ -2606,6 +2618,7 @@ HANDLE_IOCTL(SIOCBRDELIF, dev_ifsioc)
 HANDLE_IOCTL(SIOCRTMSG, ret_einval)
 HANDLE_IOCTL(SIOCGSTAMP, do_siocgstamp)
 #endif
+#ifdef CONFIG_BLOCK
 HANDLE_IOCTL(HDIO_GETGEO, hdio_getgeo)
 HANDLE_IOCTL(BLKRAGET, w_long)
 HANDLE_IOCTL(BLKGETSIZE, w_long)
@@ -2631,14 +2644,17 @@ HANDLE_IOCTL(FDGETFDCSTAT32, fd_ioctl_trans)
 HANDLE_IOCTL(FDWERRORGET32, fd_ioctl_trans)
 HANDLE_IOCTL(SG_IO,sg_ioctl_trans)
 HANDLE_IOCTL(SG_GET_REQUEST_TABLE, sg_grt_trans)
+#endif
 HANDLE_IOCTL(PPPIOCGIDLE32, ppp_ioctl_trans)
 HANDLE_IOCTL(PPPIOCSCOMPRESS32, ppp_ioctl_trans)
 HANDLE_IOCTL(PPPIOCSPASS32, ppp_sock_fprog_ioctl_trans)
 HANDLE_IOCTL(PPPIOCSACTIVE32, ppp_sock_fprog_ioctl_trans)
+#ifdef CONFIG_BLOCK
 HANDLE_IOCTL(MTIOCGET32, mt_ioctl_trans)
 HANDLE_IOCTL(MTIOCPOS32, mt_ioctl_trans)
 HANDLE_IOCTL(CDROMREADAUDIO, cdrom_ioctl_trans)
 HANDLE_IOCTL(CDROM_SEND_PACKET, cdrom_ioctl_trans)
+#endif
 #define AUTOFS_IOC_SETTIMEOUT32 _IOWR(0x93,0x64,unsigned int)
 HANDLE_IOCTL(AUTOFS_IOC_SETTIMEOUT32, ioc_settimeout)
 #ifdef CONFIG_VT
@@ -2677,12 +2693,14 @@ HANDLE_IOCTL(SONET_SETFRAMING, do_atm_ioctl)
 HANDLE_IOCTL(SONET_GETFRAMING, do_atm_ioctl)
 HANDLE_IOCTL(SONET_GETFRSENSE, do_atm_ioctl)
 /* block stuff */
+#ifdef CONFIG_BLOCK
 HANDLE_IOCTL(BLKBSZGET_32, do_blkbszget)
 HANDLE_IOCTL(BLKBSZSET_32, do_blkbszset)
 HANDLE_IOCTL(BLKGETSIZE64_32, do_blkgetsize64)
 /* Raw devices */
 HANDLE_IOCTL(RAW_SETBIND, raw_ioctl)
 HANDLE_IOCTL(RAW_GETBIND, raw_ioctl)
+#endif
 /* Serial */
 HANDLE_IOCTL(TIOCGSERIAL, serial_struct_ioctl)
 HANDLE_IOCTL(TIOCSSERIAL, serial_struct_ioctl)