PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.
This promise never materialized. And unlikely will.
We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE. And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.
Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.
Let's stop pretending that pages in page cache are special. They are
not.
The changes are pretty straight-forward:
- <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};
- page_cache_get() -> get_page();
- page_cache_release() -> put_page();
This patch contains automated changes generated with coccinelle using
script below. For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.
The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.
There are few places in the code where coccinelle didn't reach. I'll
fix them manually in a separate patch. Comments and documentation also
will be addressed with the separate patch.
virtual patch
@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT
@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE
@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK
@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)
@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)
@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are some op tables that can be easily made const, similarly the
sysfs feature and raid tables. This is motivated by PaX CONSTIFY plugin.
Signed-off-by: David Sterba <dsterba@suse.cz>
Don Bailey noticed that our page zeroing for compression at end-io time
isn't complete. This reworks a patch from Linus to push the zeroing
into the zlib and lzo specific functions instead of trying to handle the
corners inside btrfs_decompress_buf2page
Signed-off-by: Chris Mason <clm@fb.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Reported-by: Don A. Bailey <donb@securitymouse.com>
cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The form
(value + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT
is equivalent to
(value + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE
The rest is a simple subsitution, no difference in the generated
assembly code.
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
The compression layer seems to have been built to return -1 and have
callers make up errors that make sense. This isn't great because there
are different errors that originate down in the compression layer.
Let's return real negative errnos from the compression layer so that
callers can pass on the error without having to guess what happened.
ENOMEM for allocation failure, E2BIG when compression exceeds the
uncompressed input, and EIO for everything else.
This helps a future path return errors from btrfs_decompress().
Signed-off-by: Zach Brown <zab@redhat.com>
Signed-off-by: Chris Mason <clm@fb.com>
Convert all applicable cases of printk and pr_* to the btrfs_* macros.
Fix all uses of the BTRFS prefix.
Signed-off-by: Frank Holton <fholton@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
With this fix the lzo code behaves like the zlib code by returning an
error
code when compression does not help reduce the size of the file.
This is currently not a bug since the compressed size is checked again
in
the calling method compress_file_range.
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Fix the code comments for lzo compression workspace.
The buf item is used to store the decompressed data
and cbuf is used to store the compressed data.
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
When decompressing a chunk of data, we'll copy the data out to
a working buffer if the data is stored in more than one page,
otherwise we'll use the mapped page directly to avoid memory
copy.
In the latter case, we'll end up accessing the kernel address
after we've unmapped the page in a corner case.
Reported-by: Juan Francisco Cantero Hurtado <iam@juanfra.info>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Lzo is a much faster compression algorithm than gzib, so would allow
more users to enable transparent compression, and some users can
choose from compression ratio and speed for different applications
Usage:
# mount -t btrfs -o compress[=<zlib,lzo>] dev /mnt
or
# mount -t btrfs -o compress-force[=<zlib,lzo>] dev /mnt
"-o compress" without argument is still allowed for compatability.
Compatibility:
If we mount a filesystem with lzo compression, it will not be able be
mounted in old kernels. One reason is, otherwise btrfs will directly
dump compressed data, which sits in inline extent, to user.
Performance:
The test copied a linux source tarball (~400M) from an ext4 partition
to the btrfs partition, and then extracted it.
(time in second)
lzo zlib nocompress
copy: 10.6 21.7 14.9
extract: 70.1 94.4 66.6
(data size in MB)
lzo zlib nocompress
copy: 185.87 108.69 394.49
extract: 193.80 132.36 381.21
Changelog:
v1 -> v2:
- Select LZO_COMPRESS and LZO_DECOMPRESS in btrfs Kconfig.
- Add incompability flag.
- Fix error handling in compress code.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
