From dfeab2e95a75a424adf39992ac62dcb9e9517d4a Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Thu, 14 Oct 2021 16:10:10 +0800 Subject: 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 Reviewed-by: Liu Bo Signed-off-by: Gao Xiang --- Documentation/filesystems/erofs.rst | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/erofs.rst b/Documentation/filesystems/erofs.rst index b97579b7d8fb..01df283c7d04 100644 --- a/Documentation/filesystems/erofs.rst +++ b/Documentation/filesystems/erofs.rst @@ -19,9 +19,10 @@ It is designed as a better filesystem solution for the following scenarios: immutable and bit-for-bit identical to the official golden image for their releases due to security and other considerations and - - hope to save some extra storage space with guaranteed end-to-end performance - by using reduced metadata and transparent file compression, especially - for those embedded devices with limited memory (ex, smartphone); + - hope to minimize extra storage space with guaranteed end-to-end performance + by using compact layout, transparent file compression and direct access, + especially for those embedded devices with limited memory and high-density + hosts with numerous containers; Here is the main features of EROFS: @@ -51,7 +52,9 @@ Here is the main features of EROFS: - Support POSIX.1e ACLs by using xattrs; - Support transparent data compression as an option: - LZ4 algorithm with the fixed-sized output compression for high performance. + LZ4 algorithm with the fixed-sized output compression for high performance; + + - Multiple device support for multi-layer container images. The following git tree provides the file system user-space tools under development (ex, formatting tool mkfs.erofs): @@ -87,6 +90,7 @@ cache_strategy=%s Select a strategy for cached decompression from now on: dax={always,never} Use direct access (no page cache). See Documentation/filesystems/dax.rst. dax A legacy option which is an alias for ``dax=always``. +device=%s Specify a path to an extra device to be used together. =================== ========================================================= On-disk details -- cgit