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Nick Piggin 9db5579be4 rewrite rd 
This is a rewrite of the ramdisk block device driver.

The old one is really difficult because it effectively implements a block
device which serves data out of its own buffer cache.  It relies on the dirty
bit being set, to pin its backing store in cache, however there are non
trivial paths which can clear the dirty bit (eg.  try_to_free_buffers()),
which had recently lead to data corruption.  And in general it is completely
wrong for a block device driver to do this.

The new one is more like a regular block device driver.  It has no idea about
vm/vfs stuff.  It's backing store is similar to the buffer cache (a simple
radix-tree of pages), but it doesn't know anything about page cache (the pages
in the radix tree are not pagecache pages).

There is one slight downside -- direct block device access and filesystem
metadata access goes through an extra copy and gets stored in RAM twice.
However, this downside is only slight, because the real buffercache of the
device is now reclaimable (because we're not playing crazy games with it), so
under memory intensive situations, footprint should effectively be the same --
maybe even a slight advantage to the new driver because it can also reclaim
buffer heads.

The fact that it now goes through all the regular vm/fs paths makes it
much more useful for testing, too.

   text    data     bss     dec     hex filename
   2837     849     384    4070     fe6 drivers/block/rd.o
   3528     371      12    3911     f47 drivers/block/brd.o

Text is larger, but data and bss are smaller, making total size smaller.

A few other nice things about it:
- Similar structure and layout to the new loop device handlinag.
- Dynamic ramdisk creation.
- Runtime flexible buffer head size (because it is no longer part of the
  ramdisk code).
- Boot / load time flexible ramdisk size, which could easily be extended
  to a per-ramdisk runtime changeable size (eg. with an ioctl).
- Can use highmem for the backing store.

[akpm@linux-foundation.org: fix build]
[byron.bbradley@gmail.com: make rd_size non-static]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Byron Bradley <byron.bbradley@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2008-02-08 09:22:30 -08:00
..
9p Convert ERR_PTR(PTR_ERR(p)) instances to ERR_CAST(p) 2008-02-07 08:42:26 -08:00
adfs Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
affs iget: stop AFFS from using iget() and read_inode() 2008-02-07 08:42:27 -08:00
afs iget: use iget_failed() in AFS 2008-02-07 08:42:26 -08:00
autofs iget: stop autofs from using iget() and read_inode() 2008-02-07 08:42:27 -08:00
autofs4 pid namespaces: round up the API 2007-10-19 11:53:37 -07:00
befs iget: stop BEFS from using iget() and read_inode() 2008-02-07 08:42:27 -08:00
bfs iget: stop BFS from using iget() and read_inode() 2008-02-07 08:42:27 -08:00
cifs iget: stop CIFS from using iget() and read_inode() 2008-02-07 08:42:27 -08:00
coda coda: convert struct class_device to struct device 2008-01-24 20:40:05 -08:00
configfs configfs: file.c fix possible recursive locking 2008-01-25 15:05:47 -08:00
cramfs fs/cramfs/inode.c: replace hardcoded value with preprocessor constant 2007-10-18 14:37:29 -07:00
debugfs Kobject: convert fs/* from kobject_unregister() to kobject_put() 2008-01-24 20:40:40 -08:00
devpts
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dlm dlm: static initialization improvements 2008-01-30 11:04:43 -06:00
ecryptfs ecryptfs: check for existing key_tfm at mount time 2008-02-06 10:41:13 -08:00
efs iget: stop EFS from using iget() and read_inode() 2008-02-07 08:42:27 -08:00
exportfs exportfs: update documentation 2007-10-22 08:13:21 -07:00
ext2 iget: stop EXT2 from using iget() and read_inode() 2008-02-07 08:42:27 -08:00
ext3 iget: stop EXT3 from using iget() and read_inode() 2008-02-07 08:42:27 -08:00
ext4 iget: stop EXT4 from using iget() and read_inode() 2008-02-07 08:42:27 -08:00
fat iget: stop FAT from using iget() and read_inode() 2008-02-07 08:42:28 -08:00
freevxfs iget: stop FreeVXFS from using iget() and read_inode() 2008-02-07 08:42:28 -08:00
fuse iget: stop FUSE from using iget() and read_inode() 2008-02-07 08:42:28 -08:00
gfs2 iget: use iget_failed() in GFS2 2008-02-07 08:42:27 -08:00
hfs hfs: update comment to reflect actual init and exit routines 2008-02-06 10:41:05 -08:00
hfsplus iget: stop HFSPLUS from using iget() and read_inode() 2008-02-07 08:42:28 -08:00
hostfs iget: stop HOSTFS from using iget() and read_inode() 2008-02-07 08:42:29 -08:00
hpfs Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
hppfs iget: stop HPPFS from using iget() and read_inode() 2008-02-07 08:42:29 -08:00
hugetlbfs hugetlb: allow sticky directory mount option 2008-02-05 09:44:14 -08:00
isofs iget: stop ISOFS from using read_inode() 2008-02-07 08:42:28 -08:00
jbd make jbd/journal.c:__journal_abort_hard() static 2008-02-06 10:41:20 -08:00
jbd2 BKL-removal: remove incorrect comment refering to lock_kernel() from jbd/jbd2 2008-02-06 10:41:20 -08:00
jffs2 Merge git://git.infradead.org/mtd-2.6 2008-02-07 10:20:31 -08:00
jfs BKL-removal: Implement a compat_ioctl handler for JFS 2008-02-07 13:45:29 -06:00
lockd NLM: tear down RPC clients in nlm_shutdown_hosts 2008-02-01 16:42:15 -05:00
minix iget: stop the MINIX filesystem from using iget() and read_inode() 2008-02-07 08:42:28 -08:00
msdos
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ncpfs NCPFS: update diagnostic strings to match routine names. 2008-02-06 10:41:05 -08:00
nfs NFS: Fix a potential file corruption issue when writing 2008-02-07 19:20:20 -05:00
nfs_common
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nfsd Convert ERR_PTR(PTR_ERR(p)) instances to ERR_CAST(p) 2008-02-07 08:42:26 -08:00
nls sparse pointer use of zero as null 2007-10-18 14:37:31 -07:00
ntfs is_vmalloc_addr(): Check if an address is within the vmalloc boundaries 2008-02-05 09:44:14 -08:00
ocfs2 ocfs2: Negotiate locking protocol versions. 2008-02-06 16:11:29 -08:00
openpromfs iget: stop OPENPROMFS from using iget() and read_inode() 2008-02-07 08:42:29 -08:00
partitions Block: Fix whole_disk attribute bug 2008-02-07 11:31:46 -08:00
proc aout: remove unnecessary inclusions of {asm, linux}/a.out.h 2008-02-08 09:22:30 -08:00
qnx4 iget: stop QNX4 from using iget() and read_inode() 2008-02-07 08:42:28 -08:00
ramfs Remove valueless definition of hard-selected RAMFS option 2007-10-17 08:42:56 -07:00
reiserfs Convert ERR_PTR(PTR_ERR(p)) instances to ERR_CAST(p) 2008-02-07 08:42:26 -08:00
romfs iget: stop ROMFS from using iget() and read_inode() 2008-02-07 08:42:28 -08:00
smbfs smbfs: fix calculation of kernel_recvmsg size parameter in smb_receive() 2008-02-06 10:41:02 -08:00
sysfs sysfs: remove BUG_ON() from sysfs_remove_group() 2008-02-07 11:31:46 -08:00
sysv iget: stop the SYSV filesystem from using iget() and read_inode() 2008-02-07 08:42:29 -08:00
udf fs/udf/balloc.c: mark a variable as uninitialized_var() 2007-10-17 08:43:00 -07:00
ufs iget: stop UFS from using iget() and read_inode() 2008-02-07 08:42:29 -08:00
vfat Convert ERR_PTR(PTR_ERR(p)) instances to ERR_CAST(p) 2008-02-07 08:42:26 -08:00
xfs Merge branch 'for-linus' of git://oss.sgi.com:8090/xfs/xfs-2.6 2008-02-07 19:12:12 -08:00
Kconfig SUNRPC xptrdma: simplify build configuration 2008-02-07 19:58:08 -05:00
Kconfig.binfmt aout: suppress A.OUT library support if !CONFIG_ARCH_SUPPORTS_AOUT 2008-02-08 09:22:30 -08:00
Makefile x86: compat_binfmt_elf Kconfig 2008-01-30 13:31:46 +01:00
aio.c core: remove last users of empty FASTCALL macro 2008-01-30 13:31:17 +01:00
anon_inodes.c anon-inodes use open coded atomic_inc for the shared inode 2007-10-17 08:43:00 -07:00
attr.c VFS: make notify_change pass ATTR_KILL_S*ID to setattr operations 2007-10-18 14:37:22 -07:00
bad_inode.c iget: introduce a function to register iget failure 2008-02-07 08:42:26 -08:00
binfmt_aout.c aout: suppress A.OUT library support if !CONFIG_ARCH_SUPPORTS_AOUT 2008-02-08 09:22:30 -08:00
binfmt_elf.c aout: suppress A.OUT library support if !CONFIG_ARCH_SUPPORTS_AOUT 2008-02-08 09:22:30 -08:00
binfmt_elf_fdpic.c pid namespaces: changes to show virtual ids to user 2007-10-19 11:53:40 -07:00
binfmt_em86.c Convert files to UTF-8 and some cleanups 2007-10-19 23:21:04 +02:00
binfmt_flat.c aout: remove unnecessary inclusions of {asm, linux}/a.out.h 2008-02-08 09:22:30 -08:00
binfmt_misc.c Convert files to UTF-8 and some cleanups 2007-10-19 23:21:04 +02:00
binfmt_script.c Convert files to UTF-8 and some cleanups 2007-10-19 23:21:04 +02:00
binfmt_som.c aout: remove unnecessary inclusions of {asm, linux}/a.out.h 2008-02-08 09:22:30 -08:00
bio.c __bio_clone: don't calculate hw/phys segment counts 2008-01-28 10:04:46 +01:00
block_dev.c kill an unused PTR_ERR in bdev_cache_init() 2008-02-06 10:41:06 -08:00
buffer.c rewrite rd 2008-02-08 09:22:30 -08:00
char_dev.c Kobject: rename kobject_init_ng() to kobject_init() 2008-01-24 20:40:38 -08:00
compat.c fs: remove dead config CONFIG_HAS_COMPAT_EPOLL_EVENT symbol 2008-02-06 10:41:03 -08:00
compat_binfmt_elf.c x86: compat_binfmt_elf 2008-01-30 13:31:46 +01:00
compat_ioctl.c dm ioctl: move compat code 2008-02-08 02:09:56 +00:00
dcache.c inotify: remove debug code 2008-02-06 10:41:07 -08:00
dcookies.c
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direct-io.c Pagecache zeroing: zero_user_segment, zero_user_segments and zero_user 2008-02-05 09:44:13 -08:00
dnotify.c
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dquot.c quota: improve inode list scanning in add_dquot_ref() 2008-02-06 10:41:07 -08:00
drop_caches.c
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eventfd.c fs/eventfd.c should #include <linux/syscalls.h> 2008-02-06 10:41:03 -08:00
eventpoll.c lockdep: annotate epoll 2008-02-05 09:44:07 -08:00
exec.c aout: suppress A.OUT library support if !CONFIG_ARCH_SUPPORTS_AOUT 2008-02-08 09:22:30 -08:00
fcntl.c Pidns: make full use of xxx_vnr() calls 2008-02-08 09:22:29 -08:00
fifo.c
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file.c get rid of NR_OPEN and introduce a sysctl_nr_open 2008-02-06 10:41:06 -08:00
file_table.c fs/file_table.c: use list_for_each_entry() instead of list_for_each() 2007-10-19 11:53:38 -07:00
filesystems.c
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fs-writeback.c fs: use list_for_each_entry_reverse and kill sb_entry 2008-02-06 10:41:05 -08:00
generic_acl.c
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inode.c iget: remove iget() and the read_inode() super op as being obsolete 2008-02-07 08:42:29 -08:00
inotify.c inotify: remove debug code 2008-02-06 10:41:07 -08:00
inotify_user.c inotify: fix check for one-shot watches before destroying them 2008-02-08 09:22:22 -08:00
internal.h
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ioctl.c VFS: factor out three helpers for FIBMAP/FIONBIO/FIOASYNC file ioctls 2008-02-07 08:42:16 -08:00
ioprio.c cfq-iosched: relax IOPRIO_CLASS_IDLE restrictions 2008-01-28 11:38:15 +01:00
libfs.c Pagecache zeroing: zero_user_segment, zero_user_segments and zero_user 2008-02-05 09:44:13 -08:00
locks.c Pidns: make full use of xxx_vnr() calls 2008-02-08 09:22:29 -08:00
mbcache.c fs: Fix to correct the mbcache entries counter 2007-10-25 15:18:29 -07:00
mpage.c Pagecache zeroing: zero_user_segment, zero_user_segments and zero_user 2008-02-05 09:44:13 -08:00
namei.c inotify: send IN_ATTRIB events when link count changes 2008-02-06 10:41:05 -08:00
namespace.c Use ilog2() in fs/namespace.c 2008-02-06 10:41:09 -08:00
nfsctl.c
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no-block.c
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open.c mark sys_open/sys_read exports unused 2007-11-14 18:45:42 -08:00
pipe.c sched: affine sync wakeups 2007-10-15 17:00:19 +02:00
pnode.c MNT_UNBINDABLE fix 2008-02-06 10:41:02 -08:00
pnode.h [PATCH] new helpers - collect_mounts() and release_collected_mounts() 2007-10-21 02:37:25 -04:00
posix_acl.c
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quota.c Convert ERR_PTR(PTR_ERR(p)) instances to ERR_CAST(p) 2008-02-07 08:42:26 -08:00
quota_v1.c
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quota_v2.c
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read_write.c ext4: export iov_shorten from kernel for ext4's use 2008-01-28 23:58:27 -05:00
read_write.h
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readdir.c Use mutex_lock_killable in vfs_readdir 2007-12-06 17:39:54 -05:00
select.c make sys_poll() wait at least timeout ms 2008-02-06 10:41:09 -08:00
seq_file.c [FS] seq_file: Introduce the seq_open_private() 2007-10-10 16:55:33 -07:00
signalfd.c fs/signalfd.c should #include <linux/syscalls.h> 2008-02-06 10:41:03 -08:00
splice.c splice: always updated atime in direct splice 2008-02-01 09:26:32 +01:00
stack.c
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stat.c
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super.c Convert files to UTF-8 and some cleanups 2007-10-19 23:21:04 +02:00
sync.c
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timerfd.c timerfd: new timerfd API 2008-02-05 09:44:07 -08:00
utimes.c fs/utimes.c should #include <linux/syscalls.h> 2008-02-06 10:41:03 -08:00
xattr.c VFS: Reorder vfs_getxattr to avoid unnecessary calls to the LSM 2008-02-05 09:44:20 -08:00
xattr_acl.c
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