linux/Documentation/ABI/testing/sysfs-fs-erofs
Jingbo Xu 839f075aab erofs: add sysfs feature entry for xattr prefixes
Let /sys/fs/erofs/features/xattr_prefixes advertise that this kernel
supports the EROFS_FEATURE_INCOMPAT_XATTR_PREFIXES on-disk format.

Fixes: 6a318ccd7e ("erofs: enable long extended attribute name prefixes")
Cc: stable@vger.kernel.org # 6.4+
Reviewed-by: Gao Xiang <xiang@kernel.org>
Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Gao Xiang <xiang@kernel.org>
2026-09-02 10:03:30 +08:00

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What: /sys/fs/erofs/features/
Date: November 2021
Contact: "Huang Jianan" <huangjianan@oppo.com>
Description: Shows all enabled kernel features.
Supported features:
compr_cfgs, big_pcluster, chunked_file, device_table,
compr_head2, sb_chksum, ztailpacking, dedupe, fragments,
xattr_prefixes, 48bit, metabox.
What: /sys/fs/erofs/<disk>/sync_decompress
Date: November 2021
Contact: "Huang Jianan" <huangjianan@oppo.com>
Description: Control strategy of synchronous decompression. Synchronous
decompression tries to decompress in the reader thread for
synchronous reads and small asynchronous reads (<= 12 KiB):
- 0 (auto, default): apply to synchronous reads only, but will
switch to 1 (force on) if any decompression
request is detected in atomic contexts;
- 1 (force on): apply to synchronous reads and small
asynchronous reads;
- 2 (force off): disable synchronous decompression completely.
What: /sys/fs/erofs/<disk>/drop_caches
Date: November 2024
Contact: "Guo Chunhai" <guochunhai@vivo.com>
Description: Writing to this will drop compression-related caches,
currently used to drop in-memory pclusters and cached
compressed folios:
- 1 : invalidate cached compressed folios
- 2 : drop in-memory pclusters
- 3 : drop in-memory pclusters and cached compressed folios
What: /sys/fs/erofs/accel
Date: May 2025
Contact: "Bo Liu" <liubo03@inspur.com>
Description: Used to set or show hardware accelerators in effect
and multiple accelerators are separated by '\n'.
Supported accelerator(s): qat_deflate.
Disable all accelerators with an empty string (echo > accel).
What: /sys/fs/erofs/<disk>/dir_ra_bytes
Date: July 2025
Contact: "Chao Yu" <chao@kernel.org>
Description: Used to set or show readahead bytes during readdir(), by
default the value is 16384.
- 0: disable readahead.