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| author |   Gao Xiang <gaoxiang25@huawei.com> | 2019-06-24 15:22:51 +0800 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-06-26 09:44:39 +0800 |
| commit | ec8c24420501d4cf3ed495c4d026984194897276 (patch) | |
| tree | 9ecde9f14e9b774cd311059f78e710afe756b816 /drivers/staging/erofs/Makefile | |
| parent | staging: comedi: use dma_mmap_coherent for DMA-able buffer mmap (diff) | |
| download | linux-dev-ec8c24420501d4cf3ed495c4d026984194897276.tar.xz linux-dev-ec8c24420501d4cf3ed495c4d026984194897276.zip | |
staging: erofs: add compacted ondisk compression indexes
This patch introduces new compacted compression indexes.
In contract to legacy compression indexes that
each 4k logical cluster has an 8-byte index,
compacted ondisk compression indexes will have
amortized 2 bytes for each 4k logical cluster (compacted 2B)
amortized 4 bytes for each 4k logical cluster (compacted 4B)
In detail, several continuous clusters will be encoded in
a compacted pack with cluster types, offsets, and one blkaddr
at the end of the pack to leave 4-byte margin for better
decoding performance, as illustrated below:
_____________________________________________
|___@_____ encoded bits __________|_ blkaddr _|
0 . amortized * vcnt
. .
. . amortized * vcnt - 4
. .
.___________________.
|_type_|_clusterofs_|
Note that compacted 2 / 4B should be aligned with 32 / 8 bytes
in order to avoid each pack crossing page boundary.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/erofs/Makefile')
0 files changed, 0 insertions, 0 deletions