linux.git/fs/erofs/decompressor.c, branch v6.5

erofs: simplify z_erofs_transform_plain()

2023-07-11T16:50:15+00:00

Use memcpy_to_page() instead of open-coding them.

In addition, add a missing flush_dcache_page() even though almost all
modern architectures clear `PG_dcache_clean` flag for new file cache
pages so that it doesn't change anything in practice.

Signed-off-by: Gao Xiang 
Reviewed-by: Yue Hu 
Reviewed-by: Chao Yu 
Link: https://lore.kernel.org/r/20230627161240.331-2-hsiangkao@linux.alibaba.com
Signed-off-by: Gao Xiang

erofs: get rid of the remaining kmap_atomic()

2023-07-11T16:49:39+00:00

It's unnecessary to use kmap_atomic() compared with kmap_local_page().
In addition, kmap_atomic() is deprecated now.

Signed-off-by: Gao Xiang 
Reviewed-by: Yue Hu 
Reviewed-by: Chao Yu 
Link: https://lore.kernel.org/r/20230627161240.331-1-hsiangkao@linux.alibaba.com
Signed-off-by: Gao Xiang

erofs: fold in z_erofs_decompress()

2023-05-29T07:54:49+00:00

No need this helper since it's just a simple wrapper for decompress
method and only one caller.  So, let's fold in directly instead.

Signed-off-by: Yue Hu 
Reviewed-by: Gao Xiang 
Link: https://lore.kernel.org/r/20230426084449.12781-1-zbestahu@gmail.com
Signed-off-by: Gao Xiang

erofs: avoid hardcoded blocksize for subpage block support

2023-04-16T17:15:44+00:00

As the first step of converting hardcoded blocksize to that specified in
on-disk superblock, convert all call sites of hardcoded blocksize to
sb->s_blocksize except for:

1) use sbi->blkszbits instead of sb->s_blocksize in
erofs_superblock_csum_verify() since sb->s_blocksize has not been
updated with the on-disk blocksize yet when the function is called.

2) use inode->i_blkbits instead of sb->s_blocksize in erofs_bread(),
since the inode operated on may be an anonymous inode in fscache mode.
Currently the anonymous inode is allocated from an anonymous mount
maintained in erofs, while in the near future we may allocate anonymous
inodes from a generic API directly and thus have no access to the
anonymous inode's i_sb.  Thus we keep the block size in i_blkbits for
anonymous inodes in fscache mode.

Be noted that this patch only gets rid of the hardcoded blocksize, in
preparation for actually setting the on-disk block size in the following
patch.  The hard limit of constraining the block size to PAGE_SIZE still
exists until the next patch.

Signed-off-by: Jingbo Xu 
Reviewed-by: Gao Xiang 
Reviewed-by: Yue Hu 
Reviewed-by: Chao Yu 
Link: https://lore.kernel.org/r/20230313135309.75269-2-jefflexu@linux.alibaba.com
[ Gao Xiang: fold a patch to fix incorrect truncated offsets. ]
Link: https://lore.kernel.org/r/20230413035734.15457-1-zhujia.zj@bytedance.com
Signed-off-by: Gao Xiang

erofs: support interlaced uncompressed data for compressed files

2022-09-23T02:55:56+00:00

Currently, uncompressed data is all handled in the shifted way, which
means we have to shift the whole on-disk plain pcluster to get the
logical data.   However, since we are also using in-place I/O for
uncompressed data, data copy will be reduced a lot if pcluster is
recorded in the interlaced way as illustrated below:
 _______________________________________________________________
|               |    |               |_ tail part |_ head part _|
|<-   blk0    ->| .. |<-   blkn-2  ->|<-         blkn-1       ->|

The logical data then becomes:
 ________________________________________________________
|_ head part _|_  blk0  _| .. |_  blkn-2  _|_ tail part _|

In addition, non-4k plain pclusters are also survived by the
interlaced way, which can be used for non-4k lclusters as well.

However, it's almost impossible to de-duplicate uncompressed data
in the interlaced way, therefore shifted uncompressed data is still
useful.

Signed-off-by: Yue Hu 
Reviewed-by: Gao Xiang 
Link: https://lore.kernel.org/r/8369112678604fdf4ef796626d59b1fdd0745a53.1663898962.git.huyue2@coolpad.com
Signed-off-by: Gao Xiang

erofs: introduce multi-reference pclusters (fully-referenced)

2022-07-22T13:44:27+00:00

Let's introduce multi-reference pclusters at runtime. In details,
if one pcluster is requested by multiple extents at almost the same
time (even belong to different files), the longest extent will be
decompressed as representative and the other extents are actually
copied from the longest one in one round.

After this patch, fully-referenced extents can be correctly handled
and the full decoding check needs to be bypassed for
partial-referenced extents.

Acked-by: Chao Yu 
Signed-off-by: Gao Xiang 
Link: https://lore.kernel.org/r/20220715154203.48093-17-hsiangkao@linux.alibaba.com

erofs: avoid consecutive detection for Highmem memory

2022-07-08T22:35:09+00:00

Currently, vmap()s are avoided if physical addresses are
consecutive for decompressed buffers.

I observed that is very common for 4KiB pclusters since the
numbers of decompressed pages are almost 2 or 3.

However, such detection doesn't work for Highmem pages on
32-bit machines, let's fix it now.

Reported-by: Liu Jinbao 
Fixes: 7fc45dbc938a ("staging: erofs: introduce generic decompression backend")
Link: https://lore.kernel.org/r/20220708101001.21242-1-hsiangkao@linux.alibaba.com
Signed-off-by: Gao Xiang

erofs: fix buffer copy overflow of ztailpacking feature

2022-05-17T15:38:14+00:00

I got some KASAN report as below:

[   46.959738] ==================================================================
[   46.960430] BUG: KASAN: use-after-free in z_erofs_shifted_transform+0x2bd/0x370
[   46.960430] Read of size 4074 at addr ffff8880300c2f8e by task fssum/188
...
[   46.960430] Call Trace:
[   46.960430]  
[   46.960430]  dump_stack_lvl+0x41/0x5e
[   46.960430]  print_report.cold+0xb2/0x6b7
[   46.960430]  ? z_erofs_shifted_transform+0x2bd/0x370
[   46.960430]  kasan_report+0x8a/0x140
[   46.960430]  ? z_erofs_shifted_transform+0x2bd/0x370
[   46.960430]  kasan_check_range+0x14d/0x1d0
[   46.960430]  memcpy+0x20/0x60
[   46.960430]  z_erofs_shifted_transform+0x2bd/0x370
[   46.960430]  z_erofs_decompress_pcluster+0xaae/0x1080

The root cause is that the tail pcluster won't be a complete filesystem
block anymore. So if ztailpacking is used, the second part of an
uncompressed tail pcluster may not be ``rq->pageofs_out``.

Fixes: ab749badf9f4 ("erofs: support unaligned data decompression")
Fixes: cecf864d3d76 ("erofs: support inline data decompression")
Reviewed-by: Yue Hu 
Reviewed-by: Chao Yu 
Link: https://lore.kernel.org/r/20220512115833.24175-1-hsiangkao@linux.alibaba.com
Signed-off-by: Gao Xiang

erofs: do not prompt for risk any more when using big pcluster

2022-05-17T15:38:02+00:00

The big pcluster feature has been merged for a year, it has been mostly
stable now.

Signed-off-by: Yue Hu 
Reviewed-by: Gao Xiang 
Reviewed-by: Chao Yu 
Link: https://lore.kernel.org/r/20220407050505.12683-1-huyue2@coolpad.com
Signed-off-by: Gao Xiang

erofs: support unaligned data decompression

2021-12-30T16:48:43+00:00

Previously, compressed data was assumed as block-aligned. This
should be changed due to in-block tail-packing inline data.

Link: https://lore.kernel.org/r/20211228054604.114518-4-hsiangkao@linux.alibaba.com
Reviewed-by: Chao Yu 
Signed-off-by: Yue Hu 
Signed-off-by: Gao Xiang