• Vyacheslav Dubeyko's avatar
    nilfs2: add /sys/fs/nilfs2/features group · aebe17f6
    Vyacheslav Dubeyko authored
    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: default avatarMichael L. Semon <mlsemon35@gmail.com>
    Signed-off-by: default avatarVyacheslav Dubeyko <Vyacheslav.Dubeyko@hgst.com>
    Cc: Vyacheslav Dubeyko <slava@dubeyko.com>
    Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    aebe17f6
sysfs.c 3.04 KB