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docs: filesystems: convert nilfs2.txt to ReST
- Add a SPDX header; - Add a document title; - Adjust document title; - Mark literal blocks as such; - use :field: markup; - Add table markups; - Add it to filesystems/index.rst. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/f7989ca501585f5990fffd2d365cfca4fe9fdd6f.1581955849.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Mauro Carvalho Chehab
Jonathan Corbet
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76f216855b
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@ -70,9 +70,10 @@ Documentation for filesystem implementations.
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hfs
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hfsplus
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hpfs
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fuse
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inotify
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isofs
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fuse
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nilfs2
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overlayfs
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virtiofs
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vfat
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@ -1,5 +1,8 @@
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.. SPDX-License-Identifier: GPL-2.0
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======
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NILFS2
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------
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======
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NILFS2 is a log-structured file system (LFS) supporting continuous
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snapshotting. In addition to versioning capability of the entire file
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@ -25,9 +28,9 @@ available from the following download page. At least "mkfs.nilfs2",
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cleaner or garbage collector) are required. Details on the tools are
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described in the man pages included in the package.
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Project web page: https://nilfs.sourceforge.io/
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Download page: https://nilfs.sourceforge.io/en/download.html
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List info: http://vger.kernel.org/vger-lists.html#linux-nilfs
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:Project web page: https://nilfs.sourceforge.io/
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:Download page: https://nilfs.sourceforge.io/en/download.html
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:List info: http://vger.kernel.org/vger-lists.html#linux-nilfs
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Caveats
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=======
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@ -47,6 +50,7 @@ Mount options
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NILFS2 supports the following mount options:
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(*) == default
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======================= =======================================================
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barrier(*) This enables/disables the use of write barriers. This
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nobarrier requires an IO stack which can support barriers, and
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if nilfs gets an error on a barrier write, it will
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@ -79,6 +83,7 @@ discard This enables/disables the use of discard/TRIM commands.
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nodiscard(*) The discard/TRIM commands are sent to the underlying
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block device when blocks are freed. This is useful
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for SSD devices and sparse/thinly-provisioned LUNs.
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======================= =======================================================
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Ioctls
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======
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@ -87,9 +92,11 @@ There is some NILFS2 specific functionality which can be accessed by application
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through the system call interfaces. The list of all NILFS2 specific ioctls are
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shown in the table below.
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Table of NILFS2 specific ioctls
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..............................................................................
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Table of NILFS2 specific ioctls:
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============================== ===============================================
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Ioctl Description
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============================== ===============================================
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NILFS_IOCTL_CHANGE_CPMODE Change mode of given checkpoint between
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checkpoint and snapshot state. This ioctl is
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used in chcp and mkcp utilities.
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@ -142,11 +149,12 @@ Table of NILFS2 specific ioctls
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NILFS_IOCTL_SET_ALLOC_RANGE Define lower limit of segments in bytes and
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upper limit of segments in bytes. This ioctl
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is used by nilfs_resize utility.
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============================== ===============================================
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NILFS2 usage
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============
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To use nilfs2 as a local file system, simply:
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To use nilfs2 as a local file system, simply::
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# mkfs -t nilfs2 /dev/block_device
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# mount -t nilfs2 /dev/block_device /dir
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@ -157,18 +165,20 @@ This will also invoke the cleaner through the mount helper program
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Checkpoints and snapshots are managed by the following commands.
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Their manpages are included in the nilfs-utils package above.
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==== ===========================================================
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lscp list checkpoints or snapshots.
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mkcp make a checkpoint or a snapshot.
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chcp change an existing checkpoint to a snapshot or vice versa.
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rmcp invalidate specified checkpoint(s).
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==== ===========================================================
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To mount a snapshot,
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To mount a snapshot::
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# mount -t nilfs2 -r -o cp=<cno> /dev/block_device /snap_dir
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where <cno> is the checkpoint number of the snapshot.
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To unmount the NILFS2 mount point or snapshot, simply:
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To unmount the NILFS2 mount point or snapshot, simply::
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# umount /dir
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@ -181,7 +191,7 @@ Disk format
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A nilfs2 volume is equally divided into a number of segments except
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for the super block (SB) and segment #0. A segment is the container
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of logs. Each log is composed of summary information blocks, payload
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blocks, and an optional super root block (SR):
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blocks, and an optional super root block (SR)::
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______________________________________________________
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| |SB| | Segment | Segment | Segment | ... | Segment | |
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@ -200,7 +210,7 @@ blocks, and an optional super root block (SR):
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|_blocks__|_________________|__|
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The payload blocks are organized per file, and each file consists of
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data blocks and B-tree node blocks:
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data blocks and B-tree node blocks::
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|<--- File-A --->|<--- File-B --->|
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_______________________________________________________________
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@ -213,7 +223,7 @@ files without data blocks or B-tree node blocks.
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The organization of the blocks is recorded in the summary information
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blocks, which contains a header structure (nilfs_segment_summary), per
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file structures (nilfs_finfo), and per block structures (nilfs_binfo):
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file structures (nilfs_finfo), and per block structures (nilfs_binfo)::
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_________________________________________________________________________
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| Summary | finfo | binfo | ... | binfo | finfo | binfo | ... | binfo |...
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@ -223,7 +233,7 @@ file structures (nilfs_finfo), and per block structures (nilfs_binfo):
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The logs include regular files, directory files, symbolic link files
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and several meta data files. The mata data files are the files used
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to maintain file system meta data. The current version of NILFS2 uses
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the following meta data files:
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the following meta data files::
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1) Inode file (ifile) -- Stores on-disk inodes
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2) Checkpoint file (cpfile) -- Stores checkpoints
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@ -232,7 +242,7 @@ the following meta data files:
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(DAT) block numbers. This file serves to
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make on-disk blocks relocatable.
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The following figure shows a typical organization of the logs:
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The following figure shows a typical organization of the logs::
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_________________________________________________________________________
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| Summary | regular file | file | ... | ifile | cpfile | sufile | DAT |SR|
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@ -250,7 +260,7 @@ three special inodes, inodes for the DAT, cpfile, and sufile. Inodes
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of regular files, directories, symlinks and other special files, are
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included in the ifile. The inode of ifile itself is included in the
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corresponding checkpoint entry in the cpfile. Thus, the hierarchy
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among NILFS2 files can be depicted as follows:
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among NILFS2 files can be depicted as follows::
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Super block (SB)
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