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authorDavid Howells <dhowells@redhat.com>2006-09-30 20:45:40 +0200
committerJens Axboe <axboe@nelson.home.kernel.dk>2006-09-30 20:52:31 +0200
commit9361401eb7619c033e2394e4f9f6d410d6719ac7 (patch)
tree04b94a71f2366988c17740d1c16cfbdec41d5d2e /init/do_mounts.c
parentd366e40a1cabd453be6e2609caa7e12f9ca17b1f (diff)
downloadlinux-9361401eb7619c033e2394e4f9f6d410d6719ac7.tar.gz
[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>
Diffstat (limited to 'init/do_mounts.c')
-rw-r--r--init/do_mounts.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/init/do_mounts.c b/init/do_mounts.c
index b290aadb1d3..dc1ec0803ef 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -285,7 +285,11 @@ void __init mount_block_root(char *name, int flags)
{
char *fs_names = __getname();
char *p;
+#ifdef CONFIG_BLOCK
char b[BDEVNAME_SIZE];
+#else
+ const char *b = name;
+#endif
get_fs_names(fs_names);
retry:
@@ -304,7 +308,9 @@ retry:
* Allow the user to distinguish between failed sys_open
* and bad superblock on root device.
*/
+#ifdef CONFIG_BLOCK
__bdevname(ROOT_DEV, b);
+#endif
printk("VFS: Cannot open root device \"%s\" or %s\n",
root_device_name, b);
printk("Please append a correct \"root=\" boot option\n");
@@ -316,7 +322,10 @@ retry:
for (p = fs_names; *p; p += strlen(p)+1)
printk(" %s", p);
printk("\n");
- panic("VFS: Unable to mount root fs on %s", __bdevname(ROOT_DEV, b));
+#ifdef CONFIG_BLOCK
+ __bdevname(ROOT_DEV, b);
+#endif
+ panic("VFS: Unable to mount root fs on %s", b);
out:
putname(fs_names);
}
@@ -387,8 +396,10 @@ void __init mount_root(void)
change_floppy("root floppy");
}
#endif
+#ifdef CONFIG_BLOCK
create_dev("/dev/root", ROOT_DEV);
mount_block_root("/dev/root", root_mountflags);
+#endif
}
/*