Commit Graph

32 Commits

Author SHA1 Message Date
Geert Uytterhoeven
ab74edaeb1 erofs: Fix EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS default logic
When NR_CPUS is less than 16, or when SMP is disabled, the default value
of 16 is invalid.

While actual configuration picks up a sensible and valid default
(NR_CPUS or 1), "make savedefconfig" will still write a line like

    CONFIG_EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS=1

to the defconfig file, even if that matches the sensible default.

Avoid needlessly enlarging the defconfig files, and reduce churn for
updating them, by specifying valid defaults depending on SMP and
NR_CPUS.

While at it, make the prompt depend on SMP, as there is no point in
asking the user about the maximum number of decompression streams if
there is only one valid answer.

Fixes: c9b47e6b23 ("erofs: cap LZMA stream pool size")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <xiang@kernel.org>
2026-08-24 12:20:11 +08:00
Gao Xiang
a64d500b00 erofs: fix EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS on some UP platforms
CONFIG_NR_CPUS doesn't define on some UP platforms (e.g.  arm), so this
can cause make oldconfig to loop indefinitely when CONFIG_SMP=n:

  $ make ARCH=arm allmodconfig
  $ sed -i "/CONFIG_SMP=y/d" .config
  $ sed -i "/CONFIG_EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS.*/d" .config

  EROFS LZMA default maximum decompression streams (EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS) [0] (NEW)
  EROFS LZMA default maximum decompression streams (EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS) [0] (NEW)
  ...

Let's guard NR_CPUS with SMP instead of using a hardcoded arbitrary CPU
uplimit here, similar to commit a334407810 ("mm: make SPLIT_PTE_PTLOCKS
depend on SMP").

The initial report from SJ Park was for m68k [1] (m68k is the only arch
without NR_CPUS in Kconfig), and that got fixed in commit 1fd495ef09
("m68k: Define NR_CPUS to 1")

Reported-by: SJ Park <sj@kernel.org>
Link: https://lore.kernel.org/all/anuyFHLUGDjZWY4K@XiangdeMacBook-Pro.local/T/#u [1]
Closes: https://lore.kernel.org/r/20260728065447.91511-1-sj@kernel.org
Reported-by: Guenter Roeck <groeck7@gmail.com>
Closes: https://lore.kernel.org/r/87853c96-cc8f-49e6-81b1-02bfe409e372@roeck-us.net
Fixes: c9b47e6b23 ("erofs: cap LZMA stream pool size")
Signed-off-by: Gao Xiang <xiang@kernel.org>
Tested-by: SJ Park <sj@kernel.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2026-08-14 07:44:41 -07:00
Michael Bommarito
c9b47e6b23 erofs: cap LZMA stream pool size
fs/erofs/decompressor_lzma.c sizes the module-global MicroLZMA stream
pool from num_possible_cpus() when the lzma_streams module parameter is
unset, then z_erofs_load_lzma_config() preallocates one image-supplied
dictionary per stream, accepting dictionaries up to 8 MiB.  On high-CPU
systems, a small EROFS image can pin hundreds of MiB of vmalloc-backed
decoder state until the erofs module is unloaded.

Impact: An EROFS image mounted by the system can pin up to 8 MiB of
vmalloc memory per LZMA stream, either as intended or unexpectedly.

Bound the default stream count by a new
CONFIG_EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS option, default 16, so the
worst-case default preallocation is 128 MiB if the number of CPUs is no
less than 16 while preserving the existing per-image dictionary limit.
An explicit lzma_streams module parameter is still honoured as-is, so
administrators who deliberately size the pool are not affected.

Fixes: 622ceaddb7 ("erofs: lzma compression support")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2026-07-27 12:31:11 +08:00
Gao Xiang
96b2dbbe58 erofs: ensure valid f_path for page cache sharing
Previously, backing files for page cache sharing were set up with
f_path left as NULL (only f_inode was valid).  It worked, but a recent
mincore fix relies on f_path.mnt and crashes (found by "erofs/028" on
7.2-rc4):

 BUG: kernel NULL pointer dereference, address: 0000000000000018
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: Oops: 0000 [#1] SMP PTI
 CPU: 3 UID: 0 PID: 675528 Comm: fincore Not tainted 7.2.0-rc4-00002-g[]-dirty #1 PREEMPT(lazy)
 Hardware name: Red Hat KVM, BIOS 1.16.0-4.al8 04/01/2014
 RIP: 0010:__do_sys_mincore+0xc0/0x2c0
 ...

Specify valid paths using valid disconnected dentries together with
erofs_ishare_mnt instead of leaving f_path empty, so they are more
like real backing files in a pseudo filesystem and standard
backing_file_open() can be used directly.

Fixes: e187bc02f8 ("mm: do file ownership checks with the proper mount idmap")
Acked-by: Hongbo Li <hongbohbli@tencent.com>
Signed-off-by: Gao Xiang <xiang@kernel.org>
2026-07-27 12:31:02 +08:00
Gao Xiang
c37460cd9b erofs: remove fscache backend entirely
EROFS over fscache was introduced to provide image lazy pulling
functionality. After the feature landed, the fscache subsystem made
netfs a new hard dependency, which is unexpected for a local filesystem
and has an kernel-defined caching hierarchy which could be inflexible
compared to the fanotify pre-content hooks. Therefore, this feature has
been deprecated for almost two years.

As EROFS file-backed mounts and fanotify pre-content hooks both upstream
for a while and already providing equivalent functionality (erofs-utils
has supported fanotify pre-content hooks), let's remove the fscache
backend now.

The main application of this feature is Nydus [1], and they plan to move
to use fanotify pre-content hooks in the near future too.

I hope this patch can be merged into Linux 7.2, which is also motivated
by newly found implementation issues [2][3] that are not worth
investigating given the deprecation and limited development resources.
The associated fscache/cachefiles cleanup patch will follow separately
through the vfs tree (netfs) later: it seems fine since the codebase is
isolated by CONFIG_CACHEFILES_ONDEMAND.

[1] https://github.com/dragonflyoss/nydus/blob/v2.1.0/docs/nydus-fscache.md
[2] https://github.com/dragonflyoss/nydus/pull/1824
[3] https://lore.kernel.org/r/20260619135800.1594811-1-michael.bommarito@gmail.com

Acked-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2026-06-22 11:00:06 +08:00
Gao Xiang
938c418422 erofs: update the Kconfig description
Refine the description to better highlight its features and use cases.

In addition, add instructions for building it as a module and clarify
the compression option.

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2026-03-25 00:04:41 +08:00
Gao Xiang
8f2fb72fd1 erofs: update compression algorithm status
The following changes are proposed in the upcoming Linux 7.0:

 - Enable LZMA support by default, as it's already in use by Fedora 42/43
   and some Android vendors for minimal filesystem sizes;

 - Promote DEFLATE and Zstandard out of EXPERIMENTAL status, given that
   they have been landed and well-tested for over a year and are
   already ready for general use.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2026-02-05 17:45:20 +08:00
Hongzhen Luo
e0bf7d1c07 erofs: support user-defined fingerprint name
When creating the EROFS image, users can specify the fingerprint name.
This is to prepare for the upcoming inode page cache share.

Signed-off-by: Hongzhen Luo <hongzhen@linux.alibaba.com>
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2026-01-23 20:01:13 +08:00
Geert Uytterhoeven
74da24f0ac erofs: Do not select tristate symbols from bool symbols
The EROFS filesystem has many configurable options, controlled through
boolean Kconfig symbols.  When enabled, these options may need to enable
additional library functionality elsewhere.  Currently this is done by
selecting the symbol for the additional functionality.  However, if
EROFS_FS itself is modular, and the target symbol is a tristate symbol,
the additional functionality is always forced built-in.

Selecting tristate symbols from a tristate symbol does keep modular
transitivity.  Hence fix this by moving selects of tristate symbols to
the main EROFS_FS symbol.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/da1b899e511145dd43fd2d398f64b2e03c6a39e7.1753879351.git.geert+renesas@glider.be
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2025-08-11 06:02:20 +08:00
Bo Liu (OpenAnolis)
5e0bf36fd1 erofs: fix build error with CONFIG_EROFS_FS_ZIP_ACCEL=y
fix build err:
 ld.lld: error: undefined symbol: crypto_req_done
   referenced by decompressor_crypto.c
       fs/erofs/decompressor_crypto.o:(z_erofs_crypto_decompress) in archive vmlinux.a
   referenced by decompressor_crypto.c
       fs/erofs/decompressor_crypto.o:(z_erofs_crypto_decompress) in archive vmlinux.a

 ld.lld: error: undefined symbol: crypto_acomp_decompress
   referenced by decompressor_crypto.c
       fs/erofs/decompressor_crypto.o:(z_erofs_crypto_decompress) in archive vmlinux.a

 ld.lld: error: undefined symbol: crypto_alloc_acomp
   referenced by decompressor_crypto.c
       fs/erofs/decompressor_crypto.o:(z_erofs_crypto_enable_engine) in archive vmlinux.a

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202507161032.QholMPtn-lkp@intel.com/
Fixes: b4a29efc51 ("erofs: support DEFLATE decompression by using Intel QAT")
Signed-off-by: Bo Liu (OpenAnolis) <liubo03@inspur.com>
Link: https://lore.kernel.org/r/20250718033039.3609-1-liubo03@inspur.com
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2025-07-24 19:43:04 +08:00
Bo Liu
b4a29efc51 erofs: support DEFLATE decompression by using Intel QAT
This patch introduces the use of the Intel QAT to offload EROFS data
decompression, aiming to improve the decompression performance.

A 285MiB dataset is used with the following command to create EROFS
images with different cluster sizes:
     $ mkfs.erofs -zdeflate,level=9 -C{4096,16384,65536,131072,262144}

Fio is used to test the following read patterns:
     $ fio -filename=testfile -bs=4k -rw=read -name=job1
     $ fio -filename=testfile -bs=4k -rw=randread -name=job1
     $ fio -filename=testfile -bs=4k -rw=randread --io_size=14m -name=job1

Here are some performance numbers for reference:

Processors: Intel(R) Xeon(R) 6766E (144 cores)
Memory:     512 GiB

|-----------------------------------------------------------------------------|
|           | Cluster size | sequential read | randread  | small randread(5%) |
|-----------|--------------|-----------------|-----------|--------------------|
| Intel QAT |    4096      |    538  MiB/s   | 112 MiB/s |     20.76 MiB/s    |
| Intel QAT |    16384     |    699  MiB/s   | 158 MiB/s |     21.02 MiB/s    |
| Intel QAT |    65536     |    917  MiB/s   | 278 MiB/s |     20.90 MiB/s    |
| Intel QAT |    131072    |    1056 MiB/s   | 351 MiB/s |     23.36 MiB/s    |
| Intel QAT |    262144    |    1145 MiB/s   | 431 MiB/s |     26.66 MiB/s    |
| deflate   |    4096      |    499  MiB/s   | 108 MiB/s |     21.50 MiB/s    |
| deflate   |    16384     |    422  MiB/s   | 125 MiB/s |     18.94 MiB/s    |
| deflate   |    65536     |    452  MiB/s   | 159 MiB/s |     13.02 MiB/s    |
| deflate   |    131072    |    452  MiB/s   | 177 MiB/s |     11.44 MiB/s    |
| deflate   |    262144    |    466  MiB/s   | 194 MiB/s |     10.60 MiB/s    |

Signed-off-by: Bo Liu <liubo03@inspur.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250522094931.28956-1-liubo03@inspur.com
[ Gao Xiang: refine the commit message. ]
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2025-05-25 15:27:40 +08:00
Eric Biggers
b261d22220 lib/crc: remove CONFIG_LIBCRC32C
Now that LIBCRC32C does nothing besides select CRC32, make every option
that selects LIBCRC32C instead select CRC32 directly.  Then remove
LIBCRC32C.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250401221600.24878-8-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2025-04-04 11:31:42 -07:00
Gao Xiang
0f24e3c05a erofs: enable 48-bit layout support
Both 48-bit block addressing and encoded extents are implemented,
let's enable them formally.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Acked-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20250310095625.2623817-1-hsiangkao@linux.alibaba.com
2025-03-17 14:02:16 +08:00
Gao Xiang
0d442ce0b3 erofs: mark experimental fscache backend deprecated
Although fscache is still described as "General Filesystem Caching" for
network filesystems and other things such as ISO9660 filesystems, it has
actually become a part of netfslib recently, which was unexpected at the
time when "EROFS over fscache" proposed (2021) since EROFS is entirely a
disk filesystem and the dependency is redundant.

Mark it deprecated and it will be removed after "fanotify pre-content
hooks" lands, which will provide the same functionality for EROFS.

Reviewed-by: Sandeep Dhavale <dhavale@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240830032840.3783206-4-hsiangkao@linux.alibaba.com
2024-09-10 15:27:11 +08:00
Gao Xiang
fb17675026 erofs: add file-backed mount support
It actually has been around for years: For containers and other sandbox
use cases, there will be thousands (and even more) of authenticated
(sub)images running on the same host, unlike OS images.

Of course, all scenarios can use the same EROFS on-disk format, but
bdev-backed mounts just work well for OS images since golden data is
dumped into real block devices.  However, it's somewhat hard for
container runtimes to manage and isolate so many unnecessary virtual
block devices safely and efficiently [1]: they just look like a burden
to orchestrators and file-backed mounts are preferred indeed.  There
were already enough attempts such as Incremental FS, the original
ComposeFS and PuzzleFS acting in the same way for immutable fses.  As
for current EROFS users, ComposeFS, containerd and Android APEXs will
be directly benefited from it.

On the other hand, previous experimental feature "erofs over fscache"
was once also intended to provide a similar solution (inspired by
Incremental FS discussion [2]), but the following facts show file-backed
mounts will be a better approach:
 - Fscache infrastructure has recently been moved into new Netfslib
   which is an unexpected dependency to EROFS really, although it
   originally claims "it could be used for caching other things such as
   ISO9660 filesystems too." [3]

 - It takes an unexpectedly long time to upstream Fscache/Cachefiles
   enhancements.  For example, the failover feature took more than
   one year, and the deamonless feature is still far behind now;

 - Ongoing HSM "fanotify pre-content hooks" [4] together with this will
   perfectly supersede "erofs over fscache" in a simpler way since
   developers (mainly containerd folks) could leverage their existing
   caching mechanism entirely in userspace instead of strictly following
   the predefined in-kernel caching tree hierarchy.

After "fanotify pre-content hooks" lands upstream to provide the same
functionality, "erofs over fscache" will be removed then (as an EROFS
internal improvement and EROFS will not have to bother with on-demand
fetching and/or caching improvements anymore.)

[1] https://github.com/containers/storage/pull/2039
[2] https://lore.kernel.org/r/CAOQ4uxjbVxnubaPjVaGYiSwoGDTdpWbB=w_AeM6YM=zVixsUfQ@mail.gmail.com
[3] https://docs.kernel.org/filesystems/caching/fscache.html
[4] https://lore.kernel.org/r/cover.1723670362.git.josef@toxicpanda.com

Closes: https://github.com/containers/composefs/issues/144
Reviewed-by: Sandeep Dhavale <dhavale@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240830032840.3783206-1-hsiangkao@linux.alibaba.com
2024-09-10 15:26:35 +08:00
Gao Xiang
7c35de4df1 erofs: Zstandard compression support
Add Zstandard compression as the 4th supported algorithm since it
becomes more popular now and some end users have asked this for
quite a while [1][2].

Each EROFS physical cluster contains only one valid standard
Zstandard frame as described in [3] so that decompression can be
performed on a per-pcluster basis independently.

Currently, it just leverages multi-call stream decompression APIs with
internal sliding window buffers.  One-shot or bufferless decompression
could be implemented later for even better performance if needed.

[1] https://github.com/erofs/erofs-utils/issues/6
[2] https://lore.kernel.org/r/Y08h+z6CZdnS1XBm@B-P7TQMD6M-0146.lan
[3] https://www.rfc-editor.org/rfc/rfc8478.txt

Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240508234453.17896-1-xiang@kernel.org
2024-05-09 07:46:56 +08:00
David Howells
915cd30cde netfs, fscache: Combine fscache with netfs
Now that the fscache code is moved to be colocated with the netfslib code
so that they combined into one module, do the combining.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Christian Brauner <christian@brauner.io>
cc: linux-fsdevel@vger.kernel.org
cc: linux-cachefs@redhat.com
cc: linux-nfs@vger.kernel.org,
cc: linux-erofs@lists.ozlabs.org
2023-12-24 15:08:46 +00:00
Gao Xiang
62b241efff MAINTAINERS: erofs: add EROFS webpage
Add a new `W:` field of the EROFS entry points to the documentation
site at <https://erofs.docs.kernel.org>.

In addition, update the in-tree documentation and Kconfig too.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20231117085329.1624223-1-hsiangkao@linux.alibaba.com
2023-11-17 19:55:46 +08:00
Gao Xiang
798eecaea0 erofs: don't warn MicroLZMA format anymore
The LZMA algorithm support has been landed for more than one year since
Linux 5.16.  Besides, the new XZ Utils 5.4 has been available in most
Linux distributions.

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20231021020137.1646959-1-hsiangkao@linux.alibaba.com
2023-10-31 06:56:47 +08:00
Jingbo Xu
fd73a4395d erofs: boost negative xattr lookup with bloom filter
Optimise the negative xattr lookup with bloom filter.

The bit value for the bloom filter map has a reverse semantics for
compatibility.  That is, the bit value of 0 indicates existence, while
the bit value of 1 indicates the absence of corresponding xattr.

The initial version is _only_ enabled when xattr_filter_reserved is
zero.  The filter map internals may change in the future, in which case
the reserved flag will be set non-zero and we don't need bothering the
compatible bits again at that time.  For now disable the optimization if
this reserved flag is non-zero.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230722094538.11754-3-jefflexu@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2023-08-11 12:11:44 +08:00
Gao Xiang
ffa09b3bd0 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
2023-08-11 12:11:17 +08:00
Gao Xiang
cf7f2732b4 erofs: use HIPRI by default if per-cpu kthreads are enabled
As Sandeep shown [1], high priority RT per-cpu kthreads are
typically helpful for Android scenarios to minimize the scheduling
latencies.

Switch EROFS_FS_PCPU_KTHREAD_HIPRI on by default if
EROFS_FS_PCPU_KTHREAD is on since it's the typical use cases for
EROFS_FS_PCPU_KTHREAD.

Also clean up unneeded sched_set_normal().

[1] https://lore.kernel.org/r/CAB=BE-SBtO6vcoyLNA9F-9VaN5R0t3o_Zn+FW8GbO6wyUqFneQ@mail.gmail.com

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Sandeep Dhavale <dhavale@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230522092141.124290-1-hsiangkao@linux.alibaba.com
2023-05-23 16:57:08 +08:00
Sandeep Dhavale
3fffb589b9 erofs: add per-cpu threads for decompression as an option
Using per-cpu thread pool we can reduce the scheduling latency compared
to workqueue implementation. With this patch scheduling latency and
variation is reduced as per-cpu threads are high priority kthread_workers.

The results were evaluated on arm64 Android devices running 5.10 kernel.

The table below shows resulting improvements of total scheduling latency
for the same app launch benchmark runs with 50 iterations. Scheduling
latency is the latency between when the task (workqueue kworker vs
kthread_worker) became eligible to run to when it actually started
running.
+-------------------------+-----------+----------------+---------+
|                         | workqueue | kthread_worker |  diff   |
+-------------------------+-----------+----------------+---------+
| Average (us)            |     15253 |           2914 | -80.89% |
| Median (us)             |     14001 |           2912 | -79.20% |
| Minimum (us)            |      3117 |           1027 | -67.05% |
| Maximum (us)            |     30170 |           3805 | -87.39% |
| Standard deviation (us) |      7166 |            359 |         |
+-------------------------+-----------+----------------+---------+

Background: Boot times and cold app launch benchmarks are very
important to the Android ecosystem as they directly translate to
responsiveness from user point of view. While EROFS provides
a lot of important features like space savings, we saw some
performance penalty in cold app launch benchmarks in few scenarios.
Analysis showed that the significant variance was coming from the
scheduling cost while decompression cost was more or less the same.

Having per-cpu thread pool we can see from the above table that this
variation is reduced by ~80% on average. This problem was discussed
at LPC 2022. Link to LPC 2022 slides and talk at [1]

[1] https://lpc.events/event/16/contributions/1338/

[ Gao Xiang: At least, we have to add this until WQ_UNBOUND workqueue
             issue [2] on many arm64 devices is resolved. ]
[2] https://lore.kernel.org/r/CAJkfWY490-m6wNubkxiTPsW59sfsQs37Wey279LmiRxKt7aQYg@mail.gmail.com

Signed-off-by: Sandeep Dhavale <dhavale@google.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230208093322.75816-1-hsiangkao@linux.alibaba.com
2023-02-15 08:11:26 +08:00
Jeffle Xu
c6be2bd0a5 erofs: register fscache volume
A new fscache based mode is going to be introduced for erofs, in which
case on-demand read semantics is implemented through fscache.

As the first step, register fscache volume for each erofs filesystem.
That means, data blobs can not be shared among erofs filesystems. In the
following iteration, we are going to introduce the domain semantics, in
which case several erofs filesystems can belong to one domain, and data
blobs can be shared among these erofs filesystems of one domain.

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220425122143.56815-12-jefflexu@linux.alibaba.com
Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2022-05-18 00:11:19 +08:00
Gao Xiang
622ceaddb7 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>
2021-10-19 23:44:30 +08:00
Gao Xiang
dfeab2e95a erofs: add multiple device support
In order to support multi-layer container images, add multiple
device feature to EROFS. Two ways are available to use for now:

 - Devices can be mapped into 32-bit global block address space;
 - Device ID can be specified with the chunk indexes format.

Note that it assumes no extent would cross device boundary and mkfs
should take care of it seriously.

In the future, a dedicated device manager could be introduced then
thus extra devices can be automatically scanned by UUID as well.

Link: https://lore.kernel.org/r/20211014081010.43485-1-hsiangkao@linux.alibaba.com
Reviewed-by: Chao Yu <chao@kernel.org>
Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2021-10-18 00:13:30 +08:00
Huang Jianan
a08e67a028 erofs: iomap support for non-tailpacking DIO
Add iomap support for non-tailpacking uncompressed data in order to
support DIO and DAX.

Direct I/O is useful in certain scenarios for uncompressed files.
For example, double pagecache can be avoid by direct I/O when
loop device is used for uncompressed files containing upper layer
compressed filesystem.

This adds iomap DIO support for non-tailpacking cases first and
tail-packing inline files are handled in the follow-up patch.

Link: https://lore.kernel.org/r/20210805003601.183063-2-hsiangkao@linux.alibaba.com
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Huang Jianan <huangjianan@oppo.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2021-08-10 00:14:42 +08:00
Gao Xiang
c5fcb51111 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>
2021-06-08 00:41:24 +08:00
Gao Xiang
9f6cc76e6f erofs: introduce physical cluster slab pools
Since multiple pcluster sizes could be used at once, the number of
compressed pages will become a variable factor. It's necessary to
introduce slab pools rather than a single slab cache now.

This limits the pclustersize to 1M (Z_EROFS_PCLUSTER_MAX_SIZE), and
get rid of the obsolete EROFS_FS_CLUSTER_PAGE_LIMIT, which has no
use now.

Link: https://lore.kernel.org/r/20210407043927.10623-4-xiang@kernel.org
Acked-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
2021-04-10 03:20:16 +08:00
Pratik Shinde
b858a4844c erofs: support superblock checksum
Introduce superblock checksum feature in order to
check at mounting time.

Note that the first 1024 bytes are ignore for x86
boot sectors and other oddities.

Link: https://lore.kernel.org/r/20191104024937.113939-1-gaoxiang25@huawei.com
Signed-off-by: Pratik Shinde <pratikshinde320@gmail.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
2019-11-24 11:02:41 +08:00
Gao Xiang
e2c71e74b2 erofs: kill all erofs specific fault injection
As Christoph suggested [1], "Please just use plain kmalloc
everywhere and let the normal kernel error injection code
take care of injeting any errors."

[1] https://lore.kernel.org/r/20190829102426.GE20598@infradead.org/
Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-20-gaoxiang25@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-09-05 20:10:08 +02:00
Gao Xiang
47e4937a4a 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>
2019-08-24 14:20:10 +02:00