erofs: fix inconsistent per-file compression format

EROFS can select compression algorithms on a per-file basis, and each
per-file compression algorithm needs to be marked in the on-disk
superblock for initialization.

However, syzkaller can generate inconsistent crafted images that use
an unsupported algorithmtype for specific inodes, e.g. use MicroLZMA
algorithmtype even it's not set in `sbi->available_compr_algs`. This
can lead to an unexpected "BUG: kernel NULL pointer dereference" if
the corresponding decompressor isn't built-in.

Fix this by checking against `sbi->available_compr_algs` for each
m_algorithmformat request. Incorrect !erofs_sb_has_compr_cfgs preset
bitmap is now fixed together since it was harmless previously.

Reported-by: <bugreport@ubisectech.com>
Fixes: 8f89926290c4 ("erofs: get compression algorithms directly on mapping")
Fixes: 622ceaddb764 ("erofs: lzma compression support")
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Link: https://lore.kernel.org/r/20240113150602.1471050-1-hsiangkao@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: fix up compacted indexes for block size < 4096

Previously, the block size always equaled to PAGE_SIZE, therefore
`lclusterbits` couldn't be less than 12.

Since sub-page compressed blocks are now considered, `lobits` for
a lcluster in each pack cannot always be `lclusterbits` as before.
Otherwise, there is no enough room for the special value
`Z_EROFS_LI_D0_CBLKCNT`.

To support smaller block sizes, `lobits` for each compacted lcluster is
now calculated as:
lobits = max(lclusterbits, ilog2(Z_EROFS_LI_D0_CBLKCNT) + 1)

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20231206091057.87027-4-hsiangkao@linux.alibaba.com

erofs: DEFLATE compression support

Add DEFLATE compression as the 3rd supported algorithm.

DEFLATE is a popular generic-purpose compression algorithm for quite
long time (many advanced formats like gzip, zlib, zip, png are all
based on that) as Apple documentation written "If you require
interoperability with non-Apple devices, use COMPRESSION_ZLIB. [1]".

Due to its popularity, there are several hardware on-market DEFLATE
accelerators, such as (s390) DFLTCC, (Intel) IAA/QAT, (HiSilicon) ZIP
accelerator, etc. In addition, there are also several high-performence
IP cores and even open-source FPGA approches available for DEFLATE.
Therefore, it's useful to support DEFLATE compression in order to find
a way to utilize these accelerators for asynchronous I/Os and get
benefits from these later.

Besides, it's a good choice to trade off between compression ratios
and performance compared to LZ4 and LZMA. The DEFLATE core format is
simple as well as easy to understand, therefore the code size of its
decompressor is small even for the bootloader use cases. The runtime
memory consumption is quite limited too (e.g. 32K + ~7K for each zlib
stream). As usual, EROFS ourperforms similar approaches too.

Alternatively, DEFLATE could still be used for some specific files
since EROFS supports multiple compression algorithms in one image.

[1] https://developer.apple.com/documentation/compression/compression_algorithm
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230810154859.118330-1-hsiangkao@linux.alibaba.com

erofs: clean up zmap.c

Several trivial cleanups which aren't quite necessary to split:

- Rename lcluster load functions as well as justify full indexes
since they are typically used for global deduplication for
compressed data;

- Avoid unnecessary lines, comments for simplicity.

No logic changes.

Reviewed-by: Guo Xuenan <guoxuenan@huaweicloud.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230615064421.103178-1-hsiangkao@linux.alibaba.com

erofs: fix compact 4B support for 16k block size

In compact 4B, two adjacent lclusters are packed together as a unit to
form on-disk indexes for effective random access, as below:

(amortized = 4, vcnt = 2)
_____________________________________________
|___@_____ encoded bits __________|_ blkaddr _|
0 . amortized * vcnt = 8
. .
. . amortized * vcnt - 4 = 4
. .
.____________________________.
|_type (2 bits)_|_clusterofs_|

Therefore, encoded bits for each pack are 32 bits (4 bytes). IOWs,
since each lcluster can get 16 bits for its type and clusterofs, the
maximum supported lclustersize for compact 4B format is 16k (14 bits).

Fix this to enable compact 4B format for 16k lclusters (blocks), which
is tested on an arm64 server with 16k page size.

Fixes: 152a333a5895 ("staging: erofs: add compacted compression indexes support")
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230601112341.56960-1-hsiangkao@linux.alibaba.com

erofs: sunset erofs_dbg()

Such debug messages are rarely used now. Let's get rid of these,
and revert locally if they are needed for debugging.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230414083027.12307-1-hsiangkao@linux.alibaba.com

erofs: get rid of z_erofs_fill_inode()

Prior to big pclusters, non-compact compression indexes could have
empty headers.

Let's just avoid the legacy path since it can be handled properly
as a specific compression header with z_erofs_fill_inode_lazy() too.

Tested with erofs-utils exist versions.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230413092241.73829-1-hsiangkao@linux.alibaba.com

erofs: stop parsing non-compact HEAD index if clusterofs is invalid

Syzbot generated a crafted image [1] with a non-compact HEAD index of
clusterofs 33024 while valid numbers should be 0 ~ lclustersize-1,
which causes the following unexpected behavior as below:

BUG: unable to handle page fault for address: fffff52101a3fff9
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 23ffed067 P4D 23ffed067 PUD 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 4398 Comm: kworker/u5:1 Not tainted 6.3.0-rc6-syzkaller-g09a9639e56c0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023
Workqueue: erofs_worker z_erofs_decompressqueue_work
RIP: 0010:z_erofs_decompress_queue+0xb7e/0x2b40
...
Call Trace:
<TASK>
z_erofs_decompressqueue_work+0x99/0xe0
process_one_work+0x8f6/0x1170
worker_thread+0xa63/0x1210
kthread+0x270/0x300
ret_from_fork+0x1f/0x30

Note that normal images or images using compact indexes are not
impacted. Let's fix this now.

[1] https://lore.kernel.org/r/000000000000ec75b005ee97fbaa@google.com

Reported-and-tested-by: syzbot+aafb3f37cfeb6534c4ac@syzkaller.appspotmail.com
Fixes: 02827e1796b3 ("staging: erofs: add erofs_map_blocks_iter")
Fixes: 152a333a5895 ("staging: erofs: add compacted compression indexes support")
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230410173714.104604-1-hsiangkao@linux.alibaba.com

erofs: tidy up EROFS on-disk naming

- Get rid of all "vle" (variable-length extents) expressions
since they only expand overall name lengths unnecessarily;
- Rename COMPRESSION_LEGACY to COMPRESSED_FULL;
- Move on-disk directory definitions ahead of compression;
- Drop unused extended attribute definitions;
- Move inode ondisk union `i_u` out as `union erofs_inode_i_u`.

No actual logical change.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230331063149.25611-1-hsiangkao@linux.alibaba.com

erofs: avoid hardcoded blocksize for subpage block support

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 <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
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 <hsiangkao@linux.alibaba.com>

erofs: get rid of a useless DBG_BUGON

`err` could be -EINTR and it should not be the case. Actually such
DBG_BUGON is useless.

Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230309053148.9223-2-hsiangkao@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: get rid of z_erofs_do_map_blocks() forward declaration

The code can be neater without forward declarations. Let's
get rid of z_erofs_do_map_blocks() forward declaration.

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230204093040.97967-5-hsiangkao@linux.alibaba.com

erofs: simplify iloc()

Actually we could pass in inodes directly to clean up all callers.
Also rename iloc() as erofs_iloc().

Link: https://lore.kernel.org/r/20230114150823.432069-1-xiang@kernel.org
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs/zmap.c: Fix incorrect offset calculation

Effective offset to add to length was being incorrectly calculated,
which resulted in iomap->length being set to 0, triggering a WARN_ON
in iomap_iter_done().

Fix that, and describe it in comments.

This was reported as a crash by syzbot under an issue about a warning
encountered in iomap_iter_done(), but unrelated to erofs.

C reproducer: https://syzkaller.appspot.com/text?tag=ReproC&x=1037a6b2880000
Kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=e2021a61197ebe02
Dashboard link: https://syzkaller.appspot.com/bug?extid=a8e049cd3abd342936b6

Reported-by: syzbot+a8e049cd3abd342936b6@syzkaller.appspotmail.com
Suggested-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Siddh Raman Pant <code@siddh.me>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20221209102151.311049-1-code@siddh.me
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: validate the extent length for uncompressed pclusters

syzkaller reported a KASAN use-after-free:
https://syzkaller.appspot.com/bug?extid=2ae90e873e97f1faf6f2

The referenced fuzzed image actually has two issues:
- m_pa == 0 as a non-inlined pcluster;
- The logical length is longer than its physical length.

The first issue has already been addressed. This patch addresses
the second issue by checking the extent length validity.

Reported-by: syzbot+2ae90e873e97f1faf6f2@syzkaller.appspotmail.com
Fixes: 02827e1796b3 ("staging: erofs: add erofs_map_blocks_iter")
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20221205150050.47784-2-hsiangkao@linux.alibaba.com

erofs: fix missing unmap if z_erofs_get_extent_compressedlen() fails

Otherwise, meta buffers could be leaked.

Fixes: cec6e93beadf ("erofs: support parsing big pcluster compress indexes")
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20221205150050.47784-1-hsiangkao@linux.alibaba.com

erofs: use kmap_local_page() only for erofs_bread()

Convert all mapped erofs_bread() users to use kmap_local_page()
instead of kmap() or kmap_atomic().

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-and-tested-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20221018105313.4940-1-hsiangkao@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: fix illegal unmapped accesses in z_erofs_fill_inode_lazy()

Note that we are still accessing 'h_idata_size' and 'h_fragmentoff'
after calling erofs_put_metabuf(), that is not correct. Fix it.

Fixes: ab92184ff8f1 ("erofs: add on-disk compressed tail-packing inline support")
Fixes: b15b2e307c3a ("erofs: support on-disk compressed fragments data")
Signed-off-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20221005013528.62977-1-zbestahu@163.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: clean up unnecessary code and comments

Some conditional macros and comments are useless.

Link: https://lore.kernel.org/r/20220927063607.54832-1-hsiangkao@linux.alibaba.com
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: fold in z_erofs_reload_indexes()

The name of this function looks not very accurate compared to it's
implementation and it's only a wrapper to erofs_read_metabuf(). So,
let's fold it directly instead.

Signed-off-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220927032518.25266-1-zbestahu@gmail.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: introduce partial-referenced pclusters

Due to deduplication for compressed data, pclusters can be partially
referenced with their prefixes.

Together with the user-space implementation, it enables EROFS
variable-length global compressed data deduplication with rolling
hash.

Link: https://lore.kernel.org/r/20220923014915.4362-1-hsiangkao@linux.alibaba.com
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: support on-disk compressed fragments data

Introduce on-disk compressed fragments data feature.

This approach adds a new field called `h_fragmentoff' in the per-file
compression header to indicate the fragment offset of each tail pcluster
or the whole file in the special packed inode.

Similar to ztailpacking, it will also find and record the 'headlcn'
of the tail pcluster when initializing per-inode zmap for making
follow-on requests more easy.

Signed-off-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/YzHKxcFTlHGgXeH9@B-P7TQMD6M-0146.local
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: support interlaced uncompressed data for compressed files

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 <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/8369112678604fdf4ef796626d59b1fdd0745a53.1663898962.git.huyue2@coolpad.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: avoid the potentially wrong m_plen for big pcluster

Actually, 'compressedlcs' stores compressed block count rather than
lcluster count. Therefore, the number of bits for shifting the count
should be 'LOG_BLOCK_SIZE' rather than 'lclusterbits' although current
lcluster size is 4K.

The value of 'm_plen' will be wrong once we enable the non 4K-sized
lcluster.

Signed-off-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20220812060150.8510-1-huyue2@coolpad.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: clean up z_erofs_extent_lookback

Avoid the unnecessary tail recursion since it can be converted into
a loop directly in order to prevent potential stack overflow.

It's a pretty straightforward conversion.

Link: https://lore.kernel.org/r/20220310182743.102365-1-hsiangkao@linux.alibaba.com
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: silence warnings related to impossible m_plen

Dan reported two smatch warnings [1],
.. warn: should '1 << lclusterbits' be a 64 bit type?
.. warn: should 'm->compressedlcs << lclusterbits' be a 64 bit type?

In practice, m_plen cannot be more than 1MiB due to on-disk constraint
for the compression mode, so we're always safe here.

In order to make static analyzers happy and not report again, let's
silence them instead.

[1] https://lore.kernel.org/r/202203091002.lJVzsX6e-lkp@intel.com

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20220310173448.19962-1-hsiangkao@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: fix small compressed files inlining

Prior to ztailpacking feature, it's enough that each lcluster has
two pclusters at most, and the last pcluster should be turned into
an uncompressed pcluster when necessary. For example,
_________________________________________________
|_ pcluster n-2 _|_ pcluster n-1 _|____ EOFed ____|

which should be converted into:
_________________________________________________
|_ pcluster n-2 _|_ pcluster n-1 (uncompressed)' _|

That is fine since either pcluster n-1 or (uncompressed)' takes one
physical block.

However, after ztailpacking was supported, the game is changed since
the last pcluster can be inlined now. And such case above is quite
common for inlining small files. Therefore, in order to inline more
effectively, special EOF lclusters are now supported which can have
three parts at most, as illustrated below:
_________________________________________________
|_ pcluster n-2 _|_ pcluster n-1 _|____ EOFed ____|
^ i_size

Actually similar code exists in Yue Hu's original patchset [1], but I
removed this part on purpose. After evaluating more real cases with
small files, I've changed my mind.

[1] https://lore.kernel.org/r/20211215094449.15162-1-huyue2@yulong.com

Link: https://lore.kernel.org/r/20220203190203.30794-1-xiang@kernel.org
Fixes: ab92184ff8f1 ("erofs: add on-disk compressed tail-packing inline support")
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: use meta buffers for zmap operations

Get rid of old erofs_get_meta_page() within zmap operations by
using on-stack meta buffers in order to prepare subpage and folio
features.

Finally, erofs_get_meta_page() is useless. Get rid of it!

Link: https://lore.kernel.org/r/20220102040017.51352-6-hsiangkao@linux.alibaba.com
Reviewed-by: Yue Hu <huyue2@yulong.com>
Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: add on-disk compressed tail-packing inline support

Introduces erofs compressed tail-packing inline support.

This approach adds a new field called `h_idata_size' in the
per-file compression header to indicate the encoded size of
each tail-packing pcluster.

At runtime, it will find the start logical offset of the tail
pcluster when initializing per-inode zmap and record such
extent (headlcn, idataoff) information to the in-memory inode.
Therefore, follow-on requests can directly recognize if one
pcluster is a tail-packing inline pcluster or not.

Link: https://lore.kernel.org/r/20211228054604.114518-6-hsiangkao@linux.alibaba.com
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Yue Hu <huyue2@yulong.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: lzma compression support

Add MicroLZMA support in order to maximize compression ratios for
specific scenarios. For example, it's useful for low-end embedded
boards and as a secondary algorithm in a file for specific access
patterns.

MicroLZMA is a new container format for raw LZMA1, which was created
by Lasse Collin aiming to minimize old LZMA headers and get rid of
unnecessary EOPM (end of payload marker) as well as to enable
fixed-sized output compression, especially for 4KiB pclusters.

Similar to LZ4, inplace I/O approach is used to minimize runtime
memory footprint when dealing with I/O. Overlapped decompression is
handled with 1) bounced buffer for data under processing or 2) extra
short-lived pages from the on-stack pagepool which will be shared in
the same read request (128KiB for example).

Link: https://lore.kernel.org/r/20211010213145.17462-8-xiang@kernel.org
Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: introduce the secondary compression head

Previously, for each HEAD lcluster, it can be either HEAD or PLAIN
lcluster to indicate whether the whole pcluster is compressed or not.

In this patch, a new HEAD2 head type is introduced to specify another
compression algorithm other than the primary algorithm for each
compressed file, which can be used for upcoming LZMA compression and
LZ4 range dictionary compression for various data patterns.

It has been stayed in the EROFS roadmap for years. Complete it now!

Link: https://lore.kernel.org/r/20211017165721.2442-1-xiang@kernel.org
Reviewed-by: Yue Hu <huyue2@yulong.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: get compression algorithms directly on mapping

Currently, z_erofs_map_blocks_iter() returns whether extents are
compressed or not, and the decompression frontend gets the specific
algorithms then.

It works but not quite well in many aspests, for example:
- The decompression frontend has to deal with whether extents are
compressed or not again and lookup the algorithms if compressed.
It's duplicated and too detailed about the on-disk mapping.

- A new secondary compression head will be introduced later so that
each file can have 2 compression algorithms at most for different
type of data. It could increase the complexity of the decompression
frontend if still handled in this way;

- A new readmore decompression strategy will be introduced to get
better performance for much bigger pcluster and lzma, which needs
the specific algorithm in advance as well.

Let's look up compression algorithms in z_erofs_map_blocks_iter()
directly instead.

Link: https://lore.kernel.org/r/20211008200839.24541-2-xiang@kernel.org
Reviewed-by: Chao Yu <chao@kernel.org>
Reviewed-by: Yue Hu <huyue2@yulong.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: clear compacted_2b if compacted_4b_initial > totalidx

Currently, the whole indexes will only be compacted 4B if
compacted_4b_initial > totalidx. So, the calculated compacted_2b
is worthless for that case. It may waste CPU resources.

No need to update compacted_4b_initial as mkfs since it's used to
fulfill the alignment of the 1st compacted_2b pack and would handle
the case above.

We also need to clarify compacted_4b_end here. It's used for the
last lclusters which aren't fitted in the previous compacted_2b
packs.

Some messages are from Xiang.

Link: https://lore.kernel.org/r/20210914035915.1190-1-zbestahu@gmail.com
Signed-off-by: Yue Hu <huyue2@yulong.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
[ Gao Xiang: it's enough to use "compacted_4b_initial < totalidx". ]
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: add fiemap support with iomap

This adds fiemap support for both uncompressed files and compressed
files by using iomap infrastructure.

Link: https://lore.kernel.org/r/20210813052931.203280-3-hsiangkao@linux.alibaba.com
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: add support for the full decompressed length

Previously, there is no need to get the full decompressed length since
EROFS supports partial decompression. However for some other cases
such as fiemap, the full decompressed length is necessary for iomap to
make it work properly.

This patch adds a way to get the full decompressed length. Note that
it takes more metadata overhead and it'd be avoided if possible in the
performance sensitive scenario.

Link: https://lore.kernel.org/r/20210818152231.243691-1-hsiangkao@linux.alibaba.com
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: clean up file headers & footers

- Remove my outdated misleading email address;

- Get rid of all unnecessary trailing newline by accident.

Link: https://lore.kernel.org/r/20210602160634.10757-1-xiang@kernel.org
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

erofs: fix 1 lcluster-sized pcluster for big pcluster

If the 1st NONHEAD lcluster of a pcluster isn't CBLKCNT lcluster type
rather than a HEAD or PLAIN type instead, which means its pclustersize
_must_ be 1 lcluster (since its uncompressed size < 2 lclusters),
as illustrated below:

HEAD HEAD / PLAIN lcluster type
____________ ____________
|_:__________|_________:__| file data (uncompressed)
. .
.____________.
|____________| pcluster data (compressed)

Such on-disk case was explained before [1] but missed to be handled
properly in the runtime implementation.

It can be observed if manually generating 1 lcluster-sized pcluster
with 2 lclusters (thus CBLKCNT doesn't exist.) Let's fix it now.

[1] https://lore.kernel.org/r/20210407043927.10623-1-xiang@kernel.org

Link: https://lore.kernel.org/r/20210510064715.29123-1-xiang@kernel.org
Fixes: cec6e93beadf ("erofs: support parsing big pcluster compress indexes")
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <xiang@kernel.org>

erofs: support parsing big pcluster compact indexes

Different from non-compact indexes, several lclusters are packed
as the compact form at once and an unique base blkaddr is stored for
each pack, so each lcluster index would take less space on avarage
(e.g. 2 bytes for COMPACT_2B.) btw, that is also why BIG_PCLUSTER
switch should be consistent for compact head0/1.

Prior to big pcluster, the size of all pclusters was 1 lcluster.
Therefore, when a new HEAD lcluster was scanned, blkaddr would be
bumped by 1 lcluster. However, that way doesn't work anymore for
big pcluster since we actually don't know the compressed size of
pclusters in advance (before reading CBLKCNT lcluster).

So, instead, let blkaddr of each pack be the first pcluster blkaddr
with a valid CBLKCNT, in detail,

1) if CBLKCNT starts at the pack, this first valid pcluster is
itself, e.g.
_____________________________________________________________
|_CBLKCNT0_|_NONHEAD_| .. |_HEAD_|_CBLKCNT1_| ... |_HEAD_| ...
^ = blkaddr base ^ += CBLKCNT0 ^ += CBLKCNT1

2) if CBLKCNT doesn't start at the pack, the first valid pcluster
is the next pcluster, e.g.
_________________________________________________________
| NONHEAD_| .. |_HEAD_|_CBLKCNT0_| ... |_HEAD_|_HEAD_| ...
^ = blkaddr base ^ += CBLKCNT0
^ += 1

When a CBLKCNT is found, blkaddr will be increased by CBLKCNT
lclusters, or a new HEAD is found immediately, bump blkaddr by 1
instead (see the picture above.)

Also noted if CBLKCNT is the end of the pack, instead of storing
delta1 (distance of the next HEAD lcluster) as normal NONHEADs,
it still uses the compressed block count (delta0) since delta1
can be calculated indirectly but the block count can't.

Adjust decoding logic to fit big pcluster compact indexes as well.

Link: https://lore.kernel.org/r/20210407043927.10623-9-xiang@kernel.org
Acked-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>

erofs: support parsing big pcluster compress indexes

When INCOMPAT_BIG_PCLUSTER sb feature is enabled, legacy compress indexes
will also have the same on-disk header compact indexes to keep per-file
configurations instead of leaving it zeroed.

If ADVISE_BIG_PCLUSTER is set for a file, CBLKCNT will be loaded for each
pcluster in this file by parsing 1st non-head lcluster.

Link: https://lore.kernel.org/r/20210407043927.10623-8-xiang@kernel.org
Acked-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>

erofs: reserve physical_clusterbits[]

Formal big pcluster design is actually more powerful / flexable than
the previous thought whose pclustersize was fixed as power-of-2 blocks,
which was obviously inefficient and space-wasting. Instead, pclustersize
can now be set independently for each pcluster, so various pcluster
sizes can also be used together in one file if mkfs wants (for example,
according to data type and/or compression ratio).

Let's get rid of previous physical_clusterbits[] setting (also notice
that corresponding on-disk fields are still 0 for now). Therefore,
head1/2 can be used for at most 2 different algorithms in one file and
again pclustersize is now independent of these.

Link: https://lore.kernel.org/r/20210407043927.10623-2-xiang@kernel.org
Acked-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>

erofs: Clean up spelling mistakes found in fs/erofs

zmap.c: s/correspoinding/corresponding
zdata.c: s/endding/ending

Link: https://lore.kernel.org/r/20210331093920.31923-1-gongruiqi1@huawei.com
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Ruiqi Gong <gongruiqi1@huawei.com>
Reviewed-by: Gao Xiang <hsiangkao@redhat.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>

erofs: initialized fields can only be observed after bit is set

Currently, although set_bit() & test_bit() pairs are used as a fast-
path for initialized configurations. However, these atomic ops are
actually relaxed forms. Instead, load-acquire & store-release form is
needed to make sure uninitialized fields won't be observed in advance
here (yet no such corresponding bitops so use full barriers instead.)

Link: https://lore.kernel.org/r/20210209130618.15838-1-hsiangkao@aol.com
Fixes: 62dc45979f3f ("staging: erofs: fix race of initializing xattrs of a inode at the same time")
Fixes: 152a333a5895 ("staging: erofs: add compacted compression indexes support")
Cc: <stable@vger.kernel.org> # 5.3+
Reported-by: Huang Jianan <huangjianan@oppo.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>

treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

erofs: Replace HTTP links with HTTPS ones

Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.

Deterministic algorithm:
For each file:
If not .svg:
For each line:
If doesn't contain `\bxmlns\b`:
For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`:
If both the HTTP and HTTPS versions
return 200 OK and serve the same content:
Replace HTTP with HTTPS.

Reviewed-by: Gao Xiang <hsiangkao@redhat.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Link: https://lore.kernel.org/r/20200713130944.34419-1-grandmaster@al2klimov.de
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>

erofs: drop all vle annotations for runtime names

VLE was an old informal name of fixed-sized output
compression which came from published ATC'19 paper [1].

Drop those old annotations since erofs can handle
all encoded clusters in block-aligned basis, which
is wider than fixed-sized output compression after
larger clustersize feature is fully implemented.

Unaligned encoding won't be considered in EROFS
since it's not friendly to inplace I/O and perhaps
decompression inplace.

a) Fixed-sized output compression with 16KB pcluster:
___________________________________
|xxxxxxxx|xxxxxxxx|xxxxxxxx|xxxxxxxx|
|___ 0___|___ 1___|___ 2___|___ 3___| physical blocks

b) Block-aligned fixed-sized input compression with
16KB pcluster:
___________________________________
|xxxxxxxx|xxxxxxxx|xxxxxxxx|xxx00000|
|___ 0___|___ 1___|___ 2___|___ 3___| physical blocks

c) Block-unaligned fixed-sized input compression with
16KB compression unit:
____________________________________________
|..xxxxxx|xxxxxxxx|xxxxxxxx|xxxxxxxx|x.......|
|___ 0___|___ 1___|___ 2___|___ 3___|___ 4___| physical blocks

Refine better names for those as well.

[1] https://www.usenix.org/conference/atc19/presentation/gao

Link: https://lore.kernel.org/r/20191108033733.63919-1-gaoxiang25@huawei.com
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>

erofs: rename errln/infoln/debugln to erofs_{err, info, dbg}

Add prefix "erofs_" to these functions and print
sb->s_id as a prefix to erofs_{err, info} so that
the user knows which file system is affected.

Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-23-gaoxiang25@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

erofs: kill prio and nofail of erofs_get_meta_page()

As Christoph pointed out [1],
"Why is there __erofs_get_meta_page with the two weird
booleans instead of a single erofs_get_meta_page that
gets and gfp_t for additional flags and an unsigned int
for additional bio op flags."

And since all callers can handle errors, let's kill
prio and nofail and erofs_get_inline_page() now.

[1] https://lore.kernel.org/r/20190830162812.GA10694@infradead.org/
Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-17-gaoxiang25@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

erofs: use erofs_inode naming

As Christoph suggested [1], "Why is this called vnode instead
of inode? That seems like a rather odd naming for a Linux
file system."

[1] https://lore.kernel.org/r/20190829101545.GC20598@infradead.org/
Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-10-gaoxiang25@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

erofs: better naming for erofs inode related stuffs

updates inode naming
- kill is_inode_layout_compression [1]
- kill magic underscores [2] [3]
- better naming for datamode & data_mapping_mode [3]
- better naming erofs_inode_{compact, extended} [4]

[1] https://lore.kernel.org/r/20190829102426.GE20598@infradead.org/
[2] https://lore.kernel.org/r/20190829102426.GE20598@infradead.org/
[3] https://lore.kernel.org/r/20190902122627.GN15931@infradead.org/
[4] https://lore.kernel.org/r/20190902125438.GA17750@infradead.org/
Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-8-gaoxiang25@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

erofs: remove all likely/unlikely annotations

As Dan Carpenter suggested [1], I have to remove
all erofs likely/unlikely annotations.

[1] https://lore.kernel.org/linux-fsdevel/20190829154346.GK23584@kadam/
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190829163827.203274-1-gaoxiang25@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

erofs: move erofs out of staging

EROFS filesystem has been merged into linux-staging for a year.

EROFS is designed to be a better solution of saving extra storage
space with guaranteed end-to-end performance for read-only files
with the help of reduced metadata, fixed-sized output compression
and decompression inplace technologies.

In the past year, EROFS was greatly improved by many people as
a staging driver, self-tested, betaed by a large number of our
internal users, successfully applied to almost all in-service
HUAWEI smartphones as the part of EMUI 9.1 and proven to be stable
enough to be moved out of staging.

EROFS is a self-contained filesystem driver. Although there are
still some TODOs to be more generic, we have a dedicated team
actively keeping on working on EROFS in order to make it better
with the evolution of Linux kernel as the other in-kernel filesystems.

As Pavel suggested, it's better to do as one commit since git
can do moves and all histories will be saved in this way.

Let's promote it from staging and enhance it more actively as
a "real" part of kernel for more wider scenarios!

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Pavel Machek <pavel@denx.de>
Cc: David Sterba <dsterba@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Darrick J . Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Richard Weinberger <richard@nod.at>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Chao Yu <yuchao0@huawei.com>
Cc: Miao Xie <miaoxie@huawei.com>
Cc: Li Guifu <bluce.liguifu@huawei.com>
Cc: Fang Wei <fangwei1@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190822213659.5501-1-hsiangkao@aol.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>