From: Gao Xiang <gaoxiang25@huawei.com>
To: Alexander Viro <viro@zeniv.linux.org.uk>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Theodore Ts'o <tytso@mit.edu>, "David Sterba" <dsterba@suse.cz>,
Amir Goldstein <amir73il@gmail.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: <linux-fsdevel@vger.kernel.org>, <devel@driverdev.osuosl.org>,
LKML <linux-kernel@vger.kernel.org>,
<linux-erofs@lists.ozlabs.org>, Chao Yu <yuchao0@huawei.com>,
Miao Xie <miaoxie@huawei.com>,
Li Guifu <bluce.liguifu@huawei.com>,
Fang Wei <fangwei1@huawei.com>, Gao Xiang <gaoxiang25@huawei.com>
Subject: [PATCH v4 21/24] erofs: introduce LZ4 decompression inplace
Date: Thu, 25 Jul 2019 17:56:55 +0800 [thread overview]
Message-ID: <20190725095658.155779-22-gaoxiang25@huawei.com> (raw)
In-Reply-To: <20190725095658.155779-1-gaoxiang25@huawei.com>
compressed data will be usually loaded into last pages of
the extent (the last page for 4k) for in-place decompression
(more specifically, in-place IO), as ilustration below,
start of compressed logical extent
| end of this logical extent
| |
______v___________________________v________
... | page 6 | page 7 | page 8 | page 9 | ...
|__________|__________|__________|__________|
. ^ . ^
. |compressed|
. | data |
. . .
|< dstsize >|<margin>|
oend iend
op ip
Therefore, it's possible to do decompression inplace (thus no
memcpy at all) if the margin is sufficient and safe enough [1],
and it can be implemented only for fixed-size output compression
compared with fixed-size input compression.
No memcpy for most of in-place IO (about 99% of enwik9) after
decompression inplace is implemented and sequential read will
be improved of course (see the following patches for test results).
[1] https://github.com/lz4/lz4/commit/b17f578a919b7e6b078cede2d52be29dd48c8e8c
https://github.com/lz4/lz4/commit/5997e139f53169fa3a1c1b4418d2452a90b01602
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
fs/erofs/decompressor.c | 36 ++++++++++++++++++++++++++++++++----
fs/erofs/erofs_fs.h | 2 +-
2 files changed, 33 insertions(+), 5 deletions(-)
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index 2523f6ab552b..e882a8ff0903 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -15,6 +15,9 @@
#endif
#define LZ4_MAX_DISTANCE_PAGES (DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) + 1)
+#ifndef LZ4_DECOMPRESS_INPLACE_MARGIN
+#define LZ4_DECOMPRESS_INPLACE_MARGIN(srcsize) (((srcsize) >> 8) + 32)
+#endif
struct z_erofs_decompressor {
/*
@@ -117,7 +120,7 @@ static int lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
{
unsigned int inputmargin, inlen;
u8 *src;
- bool copied;
+ bool copied, support_0padding;
int ret;
if (rq->inputsize > PAGE_SIZE)
@@ -125,13 +128,38 @@ static int lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
src = kmap_atomic(*rq->in);
inputmargin = 0;
+ support_0padding = false;
+
+ /* decompression inplace is only safe when 0padding is enabled */
+ if (EROFS_SB(rq->sb)->requirements & EROFS_REQUIREMENT_LZ4_0PADDING) {
+ support_0padding = true;
+
+ while (!src[inputmargin & ~PAGE_MASK])
+ if (!(++inputmargin & ~PAGE_MASK))
+ break;
+
+ if (inputmargin >= rq->inputsize) {
+ kunmap_atomic(src);
+ return -EIO;
+ }
+ }
copied = false;
inlen = rq->inputsize - inputmargin;
if (rq->inplace_io) {
- src = generic_copy_inplace_data(rq, src, inputmargin);
- inputmargin = 0;
- copied = true;
+ const uint oend = (rq->pageofs_out +
+ rq->outputsize) & ~PAGE_MASK;
+ const uint nr = PAGE_ALIGN(rq->pageofs_out +
+ rq->outputsize) >> PAGE_SHIFT;
+
+ if (rq->partial_decoding || !support_0padding ||
+ rq->out[nr - 1] != rq->in[0] ||
+ rq->inputsize - oend <
+ LZ4_DECOMPRESS_INPLACE_MARGIN(inlen)) {
+ src = generic_copy_inplace_data(rq, src, inputmargin);
+ inputmargin = 0;
+ copied = true;
+ }
}
ret = LZ4_decompress_safe_partial(src + inputmargin, out,
diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h
index b307060dd220..25bda459f2e6 100644
--- a/fs/erofs/erofs_fs.h
+++ b/fs/erofs/erofs_fs.h
@@ -17,7 +17,7 @@
* incompatible with this kernel version.
*/
#define EROFS_REQUIREMENT_LZ4_0PADDING 0x00000001
-#define EROFS_ALL_REQUIREMENTS 0
+#define EROFS_ALL_REQUIREMENTS EROFS_REQUIREMENT_LZ4_0PADDING
struct erofs_super_block {
/* 0 */__le32 magic; /* in the little endian */
--
2.17.1
next prev parent reply other threads:[~2019-07-25 9:58 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 9:56 [PATCH v4 00/24] erofs: promote erofs from staging Gao Xiang
2019-07-25 9:56 ` [PATCH v4 01/24] erofs: add on-disk layout Gao Xiang
2019-07-25 9:56 ` [PATCH v4 02/24] erofs: add erofs in-memory stuffs Gao Xiang
2019-07-25 9:56 ` [PATCH v4 03/24] erofs: add super block operations Gao Xiang
2019-07-25 9:56 ` [PATCH v4 04/24] erofs: add raw address_space operations Gao Xiang
2019-07-25 9:56 ` [PATCH v4 05/24] erofs: add inode operations Gao Xiang
2019-07-25 9:56 ` [PATCH v4 06/24] erofs: support special inode Gao Xiang
2019-07-25 9:56 ` [PATCH v4 07/24] erofs: add directory operations Gao Xiang
2019-07-25 9:56 ` [PATCH v4 08/24] erofs: add namei functions Gao Xiang
2019-07-25 9:56 ` [PATCH v4 09/24] erofs: support tracepoint Gao Xiang
2019-07-25 9:56 ` [PATCH v4 10/24] erofs: update Kconfig and Makefile Gao Xiang
2019-07-25 9:56 ` [PATCH v4 11/24] erofs: introduce xattr & posixacl support Gao Xiang
2019-07-25 9:56 ` [PATCH v4 12/24] erofs: introduce tagged pointer Gao Xiang
2019-07-25 9:56 ` [PATCH v4 13/24] erofs: add compression indexes support Gao Xiang
2019-07-25 9:56 ` [PATCH v4 14/24] erofs: introduce superblock registration Gao Xiang
2019-07-25 9:56 ` [PATCH v4 15/24] erofs: introduce erofs shrinker Gao Xiang
2019-07-25 9:56 ` [PATCH v4 16/24] erofs: introduce workstation for decompression Gao Xiang
2019-07-25 9:56 ` [PATCH v4 17/24] erofs: introduce per-CPU buffers implementation Gao Xiang
2019-07-25 9:56 ` [PATCH v4 18/24] erofs: introduce pagevec for decompression subsystem Gao Xiang
2019-07-25 9:56 ` [PATCH v4 19/24] erofs: add erofs_allocpage() Gao Xiang
2019-07-25 9:56 ` [PATCH v4 20/24] erofs: introduce generic decompression backend Gao Xiang
2019-07-25 9:56 ` Gao Xiang [this message]
2019-07-25 9:56 ` [PATCH v4 22/24] erofs: introduce the decompression frontend Gao Xiang
2019-07-25 9:56 ` [PATCH v4 23/24] erofs: introduce cached decompression Gao Xiang
2019-07-25 9:56 ` [PATCH v4 24/24] erofs: add document Gao Xiang
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