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 04:19:49 -08:00
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include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 17:04:11 +09:00
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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 04:19:49 -08:00
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2008-02-08 04:19:50 -08:00
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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 04:19:49 -08:00
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2008-02-08 04:19:50 -08:00
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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 04:19:49 -08:00
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2008-02-08 04:19:50 -08:00
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2008-04-22 05:36:52 +02:00
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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 04:19:49 -08:00
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2010-05-26 15:41:14 +02:00
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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 04:19:49 -08:00
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2010-05-26 15:41:14 +02:00
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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 04:19:49 -08:00
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2009-04-15 10:32:07 +02:00
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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 04:19:49 -08:00
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|
2009-04-15 10:32:07 +02:00
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|
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 04:19:49 -08:00
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2010-05-26 15:41:14 +02:00
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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 04:19:49 -08:00
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2008-02-08 04:19:50 -08:00
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2010-05-26 15:41:14 +02:00
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2008-04-28 02:13:02 -07:00
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2008-02-08 04:19:50 -08:00
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2008-04-28 02:13:02 -07:00
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2008-02-08 04:19:50 -08:00
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2008-03-02 09:24:35 -05:00
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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 04:19:49 -08:00
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2009-09-21 17:01:13 -07:00
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2008-02-08 04:19:50 -08:00
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2008-03-02 09:24:35 -05:00
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2008-02-08 04:19:50 -08:00
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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 04:19:49 -08:00
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brd: modify ramdisk device to be able to manage partitions
This patch adds partition management for Block RAM Device (BRD).
This patch is done to keep in sync BRD and loop device drivers.
This patch adds a parameter to the module, max_part, to specify
the maximum number of partitions per RAM device.
Example:
# modprobe brd max_part=63
# ls -l /dev/ram*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:39 /dev/ram0
brw-rw---- 1 root disk 1, 64 2008-04-03 13:39 /dev/ram1
brw-rw---- 1 root disk 1, 640 2008-04-03 13:39 /dev/ram10
brw-rw---- 1 root disk 1, 704 2008-04-03 13:39 /dev/ram11
brw-rw---- 1 root disk 1, 768 2008-04-03 13:39 /dev/ram12
brw-rw---- 1 root disk 1, 832 2008-04-03 13:39 /dev/ram13
brw-rw---- 1 root disk 1, 896 2008-04-03 13:39 /dev/ram14
brw-rw---- 1 root disk 1, 960 2008-04-03 13:39 /dev/ram15
brw-rw---- 1 root disk 1, 128 2008-04-03 13:39 /dev/ram2
brw-rw---- 1 root disk 1, 192 2008-04-03 13:39 /dev/ram3
brw-rw---- 1 root disk 1, 256 2008-04-03 13:39 /dev/ram4
brw-rw---- 1 root disk 1, 320 2008-04-03 13:39 /dev/ram5
brw-rw---- 1 root disk 1, 384 2008-04-03 13:39 /dev/ram6
brw-rw---- 1 root disk 1, 448 2008-04-03 13:39 /dev/ram7
brw-rw---- 1 root disk 1, 512 2008-04-03 13:39 /dev/ram8
brw-rw---- 1 root disk 1, 576 2008-04-03 13:39 /dev/ram9
# fdisk /dev/ram0
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): o
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2, default 1): 1
Last cylinder or +size or +sizeM or +sizeK (1-2, default 2): 2
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
# ls -l /dev/ram0*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:40 /dev/ram0
brw-rw---- 1 root disk 1, 1 2008-04-03 13:40 /dev/ram0p1
# mkfs /dev/ram0p1
mke2fs 1.40-WIP (14-Nov-2006)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
4016 inodes, 16032 blocks
801 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=16515072
2 block groups
8192 blocks per group, 8192 fragments per group
2008 inodes per group
Superblock backups stored on blocks:
8193
Writing inode tables: done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 26 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
# mount /dev/ram0p1 /mnt
df /mnt
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/ram0p1 15521 138 14582 1% /mnt
# ls -l /mnt
total 12
drwx------ 2 root root 12288 2008-04-03 13:41 lost+found
# umount /mnt
# rmmod brd
Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-30 00:55:06 -07:00
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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 04:19:49 -08:00
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brd: modify ramdisk device to be able to manage partitions
This patch adds partition management for Block RAM Device (BRD).
This patch is done to keep in sync BRD and loop device drivers.
This patch adds a parameter to the module, max_part, to specify
the maximum number of partitions per RAM device.
Example:
# modprobe brd max_part=63
# ls -l /dev/ram*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:39 /dev/ram0
brw-rw---- 1 root disk 1, 64 2008-04-03 13:39 /dev/ram1
brw-rw---- 1 root disk 1, 640 2008-04-03 13:39 /dev/ram10
brw-rw---- 1 root disk 1, 704 2008-04-03 13:39 /dev/ram11
brw-rw---- 1 root disk 1, 768 2008-04-03 13:39 /dev/ram12
brw-rw---- 1 root disk 1, 832 2008-04-03 13:39 /dev/ram13
brw-rw---- 1 root disk 1, 896 2008-04-03 13:39 /dev/ram14
brw-rw---- 1 root disk 1, 960 2008-04-03 13:39 /dev/ram15
brw-rw---- 1 root disk 1, 128 2008-04-03 13:39 /dev/ram2
brw-rw---- 1 root disk 1, 192 2008-04-03 13:39 /dev/ram3
brw-rw---- 1 root disk 1, 256 2008-04-03 13:39 /dev/ram4
brw-rw---- 1 root disk 1, 320 2008-04-03 13:39 /dev/ram5
brw-rw---- 1 root disk 1, 384 2008-04-03 13:39 /dev/ram6
brw-rw---- 1 root disk 1, 448 2008-04-03 13:39 /dev/ram7
brw-rw---- 1 root disk 1, 512 2008-04-03 13:39 /dev/ram8
brw-rw---- 1 root disk 1, 576 2008-04-03 13:39 /dev/ram9
# fdisk /dev/ram0
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): o
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2, default 1): 1
Last cylinder or +size or +sizeM or +sizeK (1-2, default 2): 2
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
# ls -l /dev/ram0*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:40 /dev/ram0
brw-rw---- 1 root disk 1, 1 2008-04-03 13:40 /dev/ram0p1
# mkfs /dev/ram0p1
mke2fs 1.40-WIP (14-Nov-2006)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
4016 inodes, 16032 blocks
801 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=16515072
2 block groups
8192 blocks per group, 8192 fragments per group
2008 inodes per group
Superblock backups stored on blocks:
8193
Writing inode tables: done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 26 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
# mount /dev/ram0p1 /mnt
df /mnt
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/ram0p1 15521 138 14582 1% /mnt
# ls -l /mnt
total 12
drwx------ 2 root root 12288 2008-04-03 13:41 lost+found
# umount /mnt
# rmmod brd
Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-30 00:55:06 -07:00
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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 04:19:49 -08:00
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2008-06-04 17:18:42 +02:00
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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 04:19:49 -08:00
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2009-06-10 12:57:08 -07:00
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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 04:19:49 -08:00
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2009-04-15 10:27:07 +02:00
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2010-02-26 00:20:38 -05:00
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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 04:19:49 -08:00
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2010-05-26 15:41:14 +02:00
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brd: modify ramdisk device to be able to manage partitions
This patch adds partition management for Block RAM Device (BRD).
This patch is done to keep in sync BRD and loop device drivers.
This patch adds a parameter to the module, max_part, to specify
the maximum number of partitions per RAM device.
Example:
# modprobe brd max_part=63
# ls -l /dev/ram*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:39 /dev/ram0
brw-rw---- 1 root disk 1, 64 2008-04-03 13:39 /dev/ram1
brw-rw---- 1 root disk 1, 640 2008-04-03 13:39 /dev/ram10
brw-rw---- 1 root disk 1, 704 2008-04-03 13:39 /dev/ram11
brw-rw---- 1 root disk 1, 768 2008-04-03 13:39 /dev/ram12
brw-rw---- 1 root disk 1, 832 2008-04-03 13:39 /dev/ram13
brw-rw---- 1 root disk 1, 896 2008-04-03 13:39 /dev/ram14
brw-rw---- 1 root disk 1, 960 2008-04-03 13:39 /dev/ram15
brw-rw---- 1 root disk 1, 128 2008-04-03 13:39 /dev/ram2
brw-rw---- 1 root disk 1, 192 2008-04-03 13:39 /dev/ram3
brw-rw---- 1 root disk 1, 256 2008-04-03 13:39 /dev/ram4
brw-rw---- 1 root disk 1, 320 2008-04-03 13:39 /dev/ram5
brw-rw---- 1 root disk 1, 384 2008-04-03 13:39 /dev/ram6
brw-rw---- 1 root disk 1, 448 2008-04-03 13:39 /dev/ram7
brw-rw---- 1 root disk 1, 512 2008-04-03 13:39 /dev/ram8
brw-rw---- 1 root disk 1, 576 2008-04-03 13:39 /dev/ram9
# fdisk /dev/ram0
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): o
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2, default 1): 1
Last cylinder or +size or +sizeM or +sizeK (1-2, default 2): 2
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
# ls -l /dev/ram0*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:40 /dev/ram0
brw-rw---- 1 root disk 1, 1 2008-04-03 13:40 /dev/ram0p1
# mkfs /dev/ram0p1
mke2fs 1.40-WIP (14-Nov-2006)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
4016 inodes, 16032 blocks
801 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=16515072
2 block groups
8192 blocks per group, 8192 fragments per group
2008 inodes per group
Superblock backups stored on blocks:
8193
Writing inode tables: done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 26 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
# mount /dev/ram0p1 /mnt
df /mnt
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/ram0p1 15521 138 14582 1% /mnt
# ls -l /mnt
total 12
drwx------ 2 root root 12288 2008-04-03 13:41 lost+found
# umount /mnt
# rmmod brd
Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-30 00:55:06 -07:00
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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 04:19:49 -08:00
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brd: modify ramdisk device to be able to manage partitions
This patch adds partition management for Block RAM Device (BRD).
This patch is done to keep in sync BRD and loop device drivers.
This patch adds a parameter to the module, max_part, to specify
the maximum number of partitions per RAM device.
Example:
# modprobe brd max_part=63
# ls -l /dev/ram*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:39 /dev/ram0
brw-rw---- 1 root disk 1, 64 2008-04-03 13:39 /dev/ram1
brw-rw---- 1 root disk 1, 640 2008-04-03 13:39 /dev/ram10
brw-rw---- 1 root disk 1, 704 2008-04-03 13:39 /dev/ram11
brw-rw---- 1 root disk 1, 768 2008-04-03 13:39 /dev/ram12
brw-rw---- 1 root disk 1, 832 2008-04-03 13:39 /dev/ram13
brw-rw---- 1 root disk 1, 896 2008-04-03 13:39 /dev/ram14
brw-rw---- 1 root disk 1, 960 2008-04-03 13:39 /dev/ram15
brw-rw---- 1 root disk 1, 128 2008-04-03 13:39 /dev/ram2
brw-rw---- 1 root disk 1, 192 2008-04-03 13:39 /dev/ram3
brw-rw---- 1 root disk 1, 256 2008-04-03 13:39 /dev/ram4
brw-rw---- 1 root disk 1, 320 2008-04-03 13:39 /dev/ram5
brw-rw---- 1 root disk 1, 384 2008-04-03 13:39 /dev/ram6
brw-rw---- 1 root disk 1, 448 2008-04-03 13:39 /dev/ram7
brw-rw---- 1 root disk 1, 512 2008-04-03 13:39 /dev/ram8
brw-rw---- 1 root disk 1, 576 2008-04-03 13:39 /dev/ram9
# fdisk /dev/ram0
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): o
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2, default 1): 1
Last cylinder or +size or +sizeM or +sizeK (1-2, default 2): 2
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
# ls -l /dev/ram0*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:40 /dev/ram0
brw-rw---- 1 root disk 1, 1 2008-04-03 13:40 /dev/ram0p1
# mkfs /dev/ram0p1
mke2fs 1.40-WIP (14-Nov-2006)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
4016 inodes, 16032 blocks
801 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=16515072
2 block groups
8192 blocks per group, 8192 fragments per group
2008 inodes per group
Superblock backups stored on blocks:
8193
Writing inode tables: done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 26 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
# mount /dev/ram0p1 /mnt
df /mnt
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/ram0p1 15521 138 14582 1% /mnt
# ls -l /mnt
total 12
drwx------ 2 root root 12288 2008-04-03 13:41 lost+found
# umount /mnt
# rmmod brd
Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-30 00:55:06 -07:00
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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 04:19:49 -08:00
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2008-05-23 13:04:46 -07:00
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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 04:19:49 -08:00
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brd: modify ramdisk device to be able to manage partitions
This patch adds partition management for Block RAM Device (BRD).
This patch is done to keep in sync BRD and loop device drivers.
This patch adds a parameter to the module, max_part, to specify
the maximum number of partitions per RAM device.
Example:
# modprobe brd max_part=63
# ls -l /dev/ram*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:39 /dev/ram0
brw-rw---- 1 root disk 1, 64 2008-04-03 13:39 /dev/ram1
brw-rw---- 1 root disk 1, 640 2008-04-03 13:39 /dev/ram10
brw-rw---- 1 root disk 1, 704 2008-04-03 13:39 /dev/ram11
brw-rw---- 1 root disk 1, 768 2008-04-03 13:39 /dev/ram12
brw-rw---- 1 root disk 1, 832 2008-04-03 13:39 /dev/ram13
brw-rw---- 1 root disk 1, 896 2008-04-03 13:39 /dev/ram14
brw-rw---- 1 root disk 1, 960 2008-04-03 13:39 /dev/ram15
brw-rw---- 1 root disk 1, 128 2008-04-03 13:39 /dev/ram2
brw-rw---- 1 root disk 1, 192 2008-04-03 13:39 /dev/ram3
brw-rw---- 1 root disk 1, 256 2008-04-03 13:39 /dev/ram4
brw-rw---- 1 root disk 1, 320 2008-04-03 13:39 /dev/ram5
brw-rw---- 1 root disk 1, 384 2008-04-03 13:39 /dev/ram6
brw-rw---- 1 root disk 1, 448 2008-04-03 13:39 /dev/ram7
brw-rw---- 1 root disk 1, 512 2008-04-03 13:39 /dev/ram8
brw-rw---- 1 root disk 1, 576 2008-04-03 13:39 /dev/ram9
# fdisk /dev/ram0
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): o
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2, default 1): 1
Last cylinder or +size or +sizeM or +sizeK (1-2, default 2): 2
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
# ls -l /dev/ram0*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:40 /dev/ram0
brw-rw---- 1 root disk 1, 1 2008-04-03 13:40 /dev/ram0p1
# mkfs /dev/ram0p1
mke2fs 1.40-WIP (14-Nov-2006)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
4016 inodes, 16032 blocks
801 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=16515072
2 block groups
8192 blocks per group, 8192 fragments per group
2008 inodes per group
Superblock backups stored on blocks:
8193
Writing inode tables: done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 26 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
# mount /dev/ram0p1 /mnt
df /mnt
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/ram0p1 15521 138 14582 1% /mnt
# ls -l /mnt
total 12
drwx------ 2 root root 12288 2008-04-03 13:41 lost+found
# umount /mnt
# rmmod brd
Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-30 00:55:06 -07:00
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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 04:19:49 -08:00
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brd: modify ramdisk device to be able to manage partitions
This patch adds partition management for Block RAM Device (BRD).
This patch is done to keep in sync BRD and loop device drivers.
This patch adds a parameter to the module, max_part, to specify
the maximum number of partitions per RAM device.
Example:
# modprobe brd max_part=63
# ls -l /dev/ram*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:39 /dev/ram0
brw-rw---- 1 root disk 1, 64 2008-04-03 13:39 /dev/ram1
brw-rw---- 1 root disk 1, 640 2008-04-03 13:39 /dev/ram10
brw-rw---- 1 root disk 1, 704 2008-04-03 13:39 /dev/ram11
brw-rw---- 1 root disk 1, 768 2008-04-03 13:39 /dev/ram12
brw-rw---- 1 root disk 1, 832 2008-04-03 13:39 /dev/ram13
brw-rw---- 1 root disk 1, 896 2008-04-03 13:39 /dev/ram14
brw-rw---- 1 root disk 1, 960 2008-04-03 13:39 /dev/ram15
brw-rw---- 1 root disk 1, 128 2008-04-03 13:39 /dev/ram2
brw-rw---- 1 root disk 1, 192 2008-04-03 13:39 /dev/ram3
brw-rw---- 1 root disk 1, 256 2008-04-03 13:39 /dev/ram4
brw-rw---- 1 root disk 1, 320 2008-04-03 13:39 /dev/ram5
brw-rw---- 1 root disk 1, 384 2008-04-03 13:39 /dev/ram6
brw-rw---- 1 root disk 1, 448 2008-04-03 13:39 /dev/ram7
brw-rw---- 1 root disk 1, 512 2008-04-03 13:39 /dev/ram8
brw-rw---- 1 root disk 1, 576 2008-04-03 13:39 /dev/ram9
# fdisk /dev/ram0
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): o
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2, default 1): 1
Last cylinder or +size or +sizeM or +sizeK (1-2, default 2): 2
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
# ls -l /dev/ram0*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:40 /dev/ram0
brw-rw---- 1 root disk 1, 1 2008-04-03 13:40 /dev/ram0p1
# mkfs /dev/ram0p1
mke2fs 1.40-WIP (14-Nov-2006)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
4016 inodes, 16032 blocks
801 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=16515072
2 block groups
8192 blocks per group, 8192 fragments per group
2008 inodes per group
Superblock backups stored on blocks:
8193
Writing inode tables: done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 26 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
# mount /dev/ram0p1 /mnt
df /mnt
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/ram0p1 15521 138 14582 1% /mnt
# ls -l /mnt
total 12
drwx------ 2 root root 12288 2008-04-03 13:41 lost+found
# umount /mnt
# rmmod brd
Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-30 00:55:06 -07:00
|
|
|
|
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 04:19:49 -08:00
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2008-08-20 14:09:09 -07:00
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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 04:19:49 -08:00
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brd: modify ramdisk device to be able to manage partitions
This patch adds partition management for Block RAM Device (BRD).
This patch is done to keep in sync BRD and loop device drivers.
This patch adds a parameter to the module, max_part, to specify
the maximum number of partitions per RAM device.
Example:
# modprobe brd max_part=63
# ls -l /dev/ram*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:39 /dev/ram0
brw-rw---- 1 root disk 1, 64 2008-04-03 13:39 /dev/ram1
brw-rw---- 1 root disk 1, 640 2008-04-03 13:39 /dev/ram10
brw-rw---- 1 root disk 1, 704 2008-04-03 13:39 /dev/ram11
brw-rw---- 1 root disk 1, 768 2008-04-03 13:39 /dev/ram12
brw-rw---- 1 root disk 1, 832 2008-04-03 13:39 /dev/ram13
brw-rw---- 1 root disk 1, 896 2008-04-03 13:39 /dev/ram14
brw-rw---- 1 root disk 1, 960 2008-04-03 13:39 /dev/ram15
brw-rw---- 1 root disk 1, 128 2008-04-03 13:39 /dev/ram2
brw-rw---- 1 root disk 1, 192 2008-04-03 13:39 /dev/ram3
brw-rw---- 1 root disk 1, 256 2008-04-03 13:39 /dev/ram4
brw-rw---- 1 root disk 1, 320 2008-04-03 13:39 /dev/ram5
brw-rw---- 1 root disk 1, 384 2008-04-03 13:39 /dev/ram6
brw-rw---- 1 root disk 1, 448 2008-04-03 13:39 /dev/ram7
brw-rw---- 1 root disk 1, 512 2008-04-03 13:39 /dev/ram8
brw-rw---- 1 root disk 1, 576 2008-04-03 13:39 /dev/ram9
# fdisk /dev/ram0
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): o
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2, default 1): 1
Last cylinder or +size or +sizeM or +sizeK (1-2, default 2): 2
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
# ls -l /dev/ram0*
brw-rw---- 1 root disk 1, 0 2008-04-03 13:40 /dev/ram0
brw-rw---- 1 root disk 1, 1 2008-04-03 13:40 /dev/ram0p1
# mkfs /dev/ram0p1
mke2fs 1.40-WIP (14-Nov-2006)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
4016 inodes, 16032 blocks
801 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=16515072
2 block groups
8192 blocks per group, 8192 fragments per group
2008 inodes per group
Superblock backups stored on blocks:
8193
Writing inode tables: done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 26 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
# mount /dev/ram0p1 /mnt
df /mnt
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/ram0p1 15521 138 14582 1% /mnt
# ls -l /mnt
total 12
drwx------ 2 root root 12288 2008-04-03 13:41 lost+found
# umount /mnt
# rmmod brd
Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-30 00:55:06 -07:00
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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 04:19:49 -08:00
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