From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Gao Xiang <gaoxiang25@huawei.com>
Cc: devel@driverdev.osuosl.org, hsiangkao@aol.com,
linux-erofs@lists.ozlabs.org, yuchao0@huawei.com,
linux-kernel@vger.kernel.org, weidu.du@huawei.com,
linux-fsdevel@vger.kernel.org, miaoxie@huawei.com,
chao@kernel.org
Subject: Re: [PATCH 00/25] staging: erofs: introduce erofs file system
Date: Sat, 28 Jul 2018 09:25:48 +0200 [thread overview]
Message-ID: <20180728072548.GA1500@kroah.com> (raw)
In-Reply-To: <1532607728-103372-1-git-send-email-gaoxiang25@huawei.com>
On Thu, Jul 26, 2018 at 08:21:43PM +0800, Gao Xiang wrote:
> Hi,
>
> This is actually the 2nd patchset of erofs file system,
> the original patchset can be found at
>
> Link: https://marc.info/?l=linux-fsdevel&m=152776480425624
>
> In order to keep up with the mainline linux-kernel changes and
> improve it in a more active and timely manner, we put forword
> this upstream proposal for linux-staging.
>
> EROFS file system is a read-only file system with compression
> support designed for certain devices (especially embeded
> devices) with very limited physical memory and lots of memory
> consumers, such as Android devices. It aimes to provide
> a complete compression solution for such devices focuing
> on high performance and little extra memory overhead.
>
> It is perferred to select larger compressed cluster sizes
> (generally >= 128k) for traditional compression file systems.
> It reads and decompresses a large compressed cluster at once,
> which has a good-looking random read number when memory
> is sufficient because all historial decompressed data
> is expected to be cached in memory. However, it also
> induces destructive effects when such devices have no enough
> spare memory for caching and decompression.
>
> EROFS file system acts in some different way. It uses
> fixed-sized compressed size rather than fixed-sized input
> size, namely VLE (variable-length extent) compression,
> which has at least three adventages:
>
> 1) all data read from block device at once can be
> utilized, and read amplification can be easier to
> estimate and control;
> 2) generally, it has a better compression ratio than
> fixed-sized input compression approaches configured
> with the same size;
> 3) aggressively optimized paths such as partial page
> read can be implemented to gain better performance
> for page-unaligned read (unimplemented yet, in TODO list).
>
> As can be seen, VLE compression does a great job in small
> compressed cluster sizes, which is of course suitable for
> devices with limited memory. In this patchset, an in-place
> decompresion is also introduced to minimize extra memory usage.
>
>
> Apart from compression, EROFS also has the following features
> available and some limits:
> o page-sized block support (currently, and no buffer-head);
> o 32-bit block address (16TB for 4KB block);
> o selectable v1 (32 bytes) / v2 (64 bytes) inode;
> o 32-bit / 64-bit file size;
> o 64-bit node number for addressing inodes;
> o 64-bit s and 32-bit ns timestamps;
> o inline data support;
> o inline and shared xattr support;
> o metadata and data can be mixed (optional);
> o special inode support;
> o posix acl support.
>
>
> The file system is still actively WIP, see _TODO_ for more details.
>
> Any comments are welcome. :)
Thanks for submitting this, the filesystem looks very interesting. I've
queued it all up now in the staging-next tree.
greg k-h
next prev parent reply other threads:[~2018-07-28 7:25 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-31 11:06 [NOMERGE] [RFC PATCH 00/12] erofs: introduce erofs file system Gao Xiang
2018-06-01 7:48 ` Richard Weinberger
2018-06-01 9:11 ` Gao Xiang
2018-06-01 9:28 ` Richard Weinberger
2018-06-01 11:16 ` Gao Xiang
2018-06-07 10:26 ` Pavel Machek
2018-07-27 0:55 ` Joey Pabalinas
2018-07-27 0:57 ` Joey Pabalinas
2018-07-26 12:21 ` [PATCH 00/25] staging: " Gao Xiang
2018-07-26 12:21 ` [PATCH 01/25] staging: erofs: add on-disk layout Gao Xiang
2018-07-26 12:21 ` [PATCH 02/25] staging: erofs: add erofs in-memory stuffs Gao Xiang
2018-07-26 12:21 ` [PATCH 03/25] staging: erofs: add super block operations Gao Xiang
2018-07-26 12:21 ` [PATCH 04/25] staging: erofs: add raw address_space operations Gao Xiang
2018-07-26 12:21 ` [PATCH 05/25] staging: erofs: add inode operations Gao Xiang
2018-07-26 12:21 ` [PATCH 06/25] staging: erofs: add directory operations Gao Xiang
2018-07-26 12:21 ` [PATCH 07/25] staging: erofs: add namei functions Gao Xiang
2018-07-26 12:21 ` [PATCH 08/25] staging: erofs: update Kconfig and Makefile Gao Xiang
2018-07-26 12:21 ` [PATCH 09/25] staging: erofs: introduce xattr & acl support Gao Xiang
2018-07-26 12:21 ` [PATCH 10/25] staging: erofs: support special inode Gao Xiang
2018-07-26 12:21 ` [PATCH 11/25] staging: erofs: introduce error injection infrastructure Gao Xiang
2018-07-26 12:21 ` [PATCH 12/25] staging: erofs: support tracepoint Gao Xiang
2018-07-26 12:21 ` [PATCH 13/25] staging: erofs: <linux/tagptr.h>: introduce tagged pointer Gao Xiang
2018-07-26 12:21 ` [PATCH 14/25] staging: erofs: introduce pagevec for unzip subsystem Gao Xiang
2018-07-26 12:21 ` [PATCH 15/25] staging: erofs: add erofs_map_blocks_iter Gao Xiang
2018-07-26 12:21 ` [PATCH 16/25] staging: erofs: add erofs_allocpage Gao Xiang
2018-07-26 12:22 ` [PATCH 17/25] staging: erofs: globalize prepare_bio and __submit_bio Gao Xiang
2018-07-26 12:22 ` [PATCH 18/25] staging: erofs: introduce a customized LZ4 decompression Gao Xiang
2018-07-26 12:22 ` [PATCH 19/25] staging: erofs: add a generic z_erofs VLE decompressor Gao Xiang
2018-07-26 12:22 ` [PATCH 20/25] staging: erofs: introduce superblock registration Gao Xiang
2018-07-26 12:22 ` [PATCH 21/25] staging: erofs: introduce erofs shrinker Gao Xiang
2018-07-26 12:22 ` [PATCH 22/25] staging: erofs: introduce workstation for decompression Gao Xiang
2018-07-26 12:22 ` [PATCH 23/25] staging: erofs: introduce VLE decompression support Gao Xiang
2018-07-26 12:22 ` [PATCH 24/25] staging: erofs: introduce cached decompression Gao Xiang
2018-07-26 12:22 ` [PATCH 25/25] staging: erofs: add a TODO and update MAINTAINERS for staging Gao Xiang
2018-07-28 7:10 ` [PATCH] staging: erofs: fix a compile warning of Z_EROFS_VLE_VMAP_ONSTACK_PAGES Gao Xiang
2018-07-28 10:43 ` Chao Yu
2018-07-29 5:34 ` [PATCH 1/2] staging: erofs: fix compile error without built-in decompression support Gao Xiang
2018-07-29 5:37 ` [PATCH 2/2] staging: erofs: fix conditional uninitialized `pcn' in z_erofs_map_blocks_iter Gao Xiang
2018-07-30 1:51 ` [PATCH] staging: erofs: use the wrapped PTR_ERR_OR_ZERO instead of open code Gao Xiang
2018-07-30 6:58 ` Chao Yu
2018-08-01 6:38 ` [PATCH 1/2] staging: erofs: add the missing break in z_erofs_map_blocks_iter Gao Xiang
2018-08-01 6:38 ` [PATCH 2/2] staging: erofs: remove a redundant marco in xattr Gao Xiang
2018-08-01 9:02 ` [PATCH 1/2] staging: erofs: add the missing break in z_erofs_map_blocks_iter Dan Carpenter
2018-08-01 9:19 ` Gao Xiang
2018-08-01 9:36 ` [PATCH RESEND " Gao Xiang
2018-08-01 11:36 ` Dan Carpenter
2018-08-01 12:08 ` Gao Xiang
2018-07-30 2:07 ` [PATCH 2/2] staging: erofs: fix conditional uninitialized `pcn' " Chao Yu
2018-07-30 2:07 ` [PATCH 1/2] staging: erofs: fix compile error without built-in decompression support Chao Yu
2018-07-30 2:32 ` Gao Xiang
2018-07-30 3:07 ` Chao Yu
2018-07-30 3:55 ` Gao Xiang
2018-07-27 0:25 ` [PATCH 00/25] staging: erofs: introduce erofs file system Christian Kujau
2018-07-27 1:39 ` Gao Xiang
2018-07-27 1:56 ` Gao Xiang
2018-07-28 7:25 ` Greg Kroah-Hartman [this message]
2018-07-28 9:33 ` Gao Xiang
2018-07-28 10:34 ` Chao Yu
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