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linux/Documentation/ABI/testing/sysfs-fs-nilfs2

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nilfs2: add /sys/fs/nilfs2/features group This patchset implements creation of sysfs groups and attributes with the purpose to show NILFS2 volume details, internal state of the driver and to manage internal state of NILFS2 driver. Sysfs is a virtual file system that exports information about devices and drivers from the kernel device model to user space, and is also used for configuration. NILFS2 is a complex file system that has segctor thread, GC thread, checkpoint/snapshot model and so on. Sysfs namespace provides native and easy way for: (1) getting info and statistics about volume state; (2) getting info and configuration of internal subsystems (segctor thread); (3) snapshots management. Suggested patchset provides basis for managing segctor thread behaviour and manipulation by snapshots. Currently, it informs only about segctor thread's internal parameters and about mounted snapshots. But sysfs interface can provide easy and simple way for deep management of segctor thread and snapshots. This patchset provides opportunity to manage interval of periodical update of superblock (in seconds). Default value is 10 seconds. Now a user can increase this value by means of nilfs2/<device>/superblock/sb_update_frequency attribute in the case of necessity. Also the patchset provides opportunity to get information easily about key volumes's parameters (free blocks, superblock write count, superblock update frequency, latest segment info, dirty data blocks count, count of clean segments, count of dirty segments and so on) in real time manner. Such information can be used in scripts for subtle management of filesystem. Implemented functionality creates such groups: (1) /sys/fs/nilfs2 - root group (2) /sys/fs/nilfs2/features - group contains attributes that describe NILFS file system driver features (3) /sys/fs/nilfs2/<device> - group contains attributes that describe file system partition's details (4) /sys/fs/nilfs2/<device>/superblock - group contains attributes that describe superblock's details (5) /sys/fs/nilfs2/<device>/segctor - group contains attributes that describe segctor thread activity details (6) /sys/fs/nilfs2/<device>/segments - group contains attributes that describe details about volume's segments (7) /sys/fs/nilfs2/<device>/checkpoints - group contains attributes that describe details about volume's checkpoints (8) /sys/fs/nilfs2/<device>/mounted_snapshots - group contains group for every mounted snapshot (9) /sys/fs/nilfs2/<device>/mounted_snapshots/<snapshot> - group contains details about mounted snapshot This patch (of 9): This patch adds code of creation /sys/fs/nilfs2 group and /sys/fs/nilfs2/features group. The features group contains attributes that describe NILFS file system driver features: (1) revision - show current revision of NILFS file system driver. There are two formats of timestamp output - seconds and human-readable format. Every showed timestamp has two sysfs files (time-<xxx> and time-<xxx>-secs). One sysfs file (time-<xxx>) shows time in human-readable format. Another sysfs file (time-<xxx>-secs) shows time in seconds. It was reported by Michael Semon that timestamp output in human-readable format should be changed from "2014-4-12 14:5:38" to "2014-04-12 14:05:38". Second version of the patch fixes this issue. Reported-by: Michael L. Semon <mlsemon35@gmail.com> Signed-off-by: Vyacheslav Dubeyko <Vyacheslav.Dubeyko@hgst.com> Cc: Vyacheslav Dubeyko <slava@dubeyko.com> Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-08 21:20:37 +00:00
What: /sys/fs/nilfs2/features/revision
Date: April 2014
Contact: "Vyacheslav Dubeyko" <slava@dubeyko.com>
Description:
Show current revision of NILFS file system driver.
This value informs about file system revision that
driver is ready to support.
What: /sys/fs/nilfs2/features/README
Date: April 2014
Contact: "Vyacheslav Dubeyko" <slava@dubeyko.com>
Description:
Describe attributes of /sys/fs/nilfs2/features group.
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