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Copyright (C) 2019, Western Digital Corporation or its affiliates.

zonefs tools

This project provides the mkzonefs command line utility which allows formatting zoned block devices for use with the zonefs file system.

The zonefs File System

zonefs is a very simple file system exposing each zone of a zoned block device as a file. zonefs does not have complex on-disk metadata. Its implementation relies solely on a super block stored at LBA 0 of the device. On mount, zonefs uses zone configuration information obtained directly from the device to populate the mount point with files representing the device zones.

By default, the files created have the following characteristics.

  1. The files mapped to zones of the same type are grouped together under a directory.

    • For conventional zones, the directory "cnv" is used.
    • For all sequential write zones, the directory "seq" is used.

  2. The name of each file is by default the number of the file, corresponding to the number of the backing zone for the file.

  3. The size of conventional zone files is fixed to the zone size. Conventional zone files cannot be truncated.

  4. The size of sequential zone files represent the zones write pointer position relative to the zone start sector. Truncating these files is allowed only down to a 0 size, in wich case, the zone is reset to rewind its write pointer position to the start of the zone.

  5. All read and write operations to files are not allowed beyond the file zone size.

  6. Creating, deleting, renaming etc files and directories is not allowed.

  7. All files are by default owned by the root user with access permissions set to 640 ("-rw-r-----").

The on-disk super block allows specifying optional features which change the default file system operation:

  1. File names: the start sector value of a file backing zone can be used as a file name.

  2. File owner UID and GID and access permissions can be changed.

  3. Contiguous conventional zones can be aggregated into a single file instead of the default one file per zone.

License

The zonefs-tools project source code is distributed under the terms of the GNU General Public License v2.0 or later (GPL-v2). A copy of this license with zonefs-tools copyright can be found in the files LICENSES/GPL-2.0-or-later.txt and COPYING.GPL.

All source files in zonefs-tools contain the SPDX short identifier for the GPL-2.0-or-later license in place of the full license text.

SPDX-License-Identifier: GPL-2.0-or-later

Some files such as the Makefile.am files and the .gitignore file are public domain specified by the CC0 1.0 Universal (CC0 1.0) Public Domain Dedication. These files are identified with the following SPDX short identifier header.

SPDX-License-Identifier: CC0-1.0

See LICENSES/CC0-1.0.txt for the full text of this license.

Requirements

The following packages must be installed prior to compiling mkzonefs.

  • m4
  • autoconf
  • automake
  • libtool
  • libuuid library and its development headers (libuuid and libuuid-devel packages)
  • libblkid library and its development headers (libblkid and libblkid-devel packages)

The kernel header file /usr/include/linux/blkzoned.h must also be present.

Compilation and Installation

The following commands will compile the mkzonefs tool.

> sh ./autogen.sh
> ./configure
> make

To install the compiled executable files, simply execute as root the following command.

> sudo make install

The default installation directory is /usr/sbin. This default location can be changed using the configure script. Executing the following command displays the options used to control the installation path.

> ./configure --help

Building RPM Packages

The rpm and rpmbuild utilities are necessary to build zonefs-tools RPM packages. Once these utilities are installed, the RPM packages can be built using the following command.

$ sh ./autogen.sh
$ ./configure
$ make rpm

Four RPM packages are built: a binary package providing mkzonefs executable and its documentation and license files, a source RPM package, a debuginfo RPM package and a debugsource RPM package.

The source RPM package can be used to build the binary and debug RPM packages outside of zonefs-tools source tree using the following command.

$ rpmbuild --rebuild zonefs-tools-<version>.src.rpm

Usage

mkzonefs detailed usage is as follows:

> mkzonefs -h 
Usage: mkzonefs [options] <device path>
Options:
  --help | -h   : General help message
  -v            : Verbose output
  -f            : Force overwrite of existing content
  -o <features>	: Optional features
See "man mkzonefs" for more information

To format a zoned block device for use with zonefs with all default settings, the following command can be used.

# mkzonefs /dev/<disk name>

Enabling optional features can be done with the -o option. For instance, to set the files owner UID and GID to user "1000", the following command can be used.

# mkzonefs -o uid=1000,gid=1000 /dev/<disk name>

Several optional features can be specified simultaneously as a comma separated list. The following features are defined.

Feature Description
aggr_cnv Aggregate contiguous conventional zones as a single file (default: off)
uid=int Set zone files user owner ID (default: 0)
gid=int Set zone files user group ID (default: 0)
perm=octal Set zone files access permissions (default: 640)

Running tests

zonefs tools also provide a test suite for testing the correct operation of zonefs with any zoned block device.

To enable the compilation of tools used for tests, zonefs-tools must be compiled as follows.

> sh ./autogen.sh
> ./configure --with-tests
> make

Running the tests for a particular device is done as follows.

> cd tests
> ./zonefs-tests.sh /dev/XXX

Where /dev/XXX is the device file for the target zoned block device to test with. The script zonefs-tests-nullblk.sh is also available to test a particular kernel against a nullblk device.

The zonefs-tests.sh script has several options that can be listed using the -h or --help options or by not specifying any argument.

> ./zonefs-tests.sh -h
Usage: zonefs-tests.sh [Options] <Zoned device node file>
Options:
  -l             : List all tests
  -g <file name> : Use file name for the test log file.
                   default: <dev name>-zonefs-tests.log
  -t <test num>  : Execute only the specified test case. Can be
                   specified multiple times.
  -s             : Short test (do not execute tests that take a
                   long time)
  -h, --help     : This help message

The lists of test cases executed can be listed with the -l option.

./zonefs-tests.sh -l
  Test 0010: mkzonefs (options)
  Test 0011: mkzonefs (force format)
  Test 0012: mkzonefs (invalid device)
  Test 0013: mkzonefs (super block zone state)
  Test 0020: mount (default)
  Test 0021: mount (invalid device)
  Test 0022: mount (check mount directory sub-directories)
  Test 0023: mount (options)
  Test 0030: Number of files (default)
  Test 0031: Number of files (aggr_cnv)
  Test 0032: Number of files using stat (default)
  Test 0033: Number of files using stat (aggr_cnv)
  Test 0034: Number of blocks using stat (default)
  Test 0035: Number of blocks using stat (aggr_cnv)
  Test 0040: Files permissions (default)
  Test 0041: Files permissions (aggr_cnv)
  Test 0042: Files permissions (set value)
  Test 0043: Files permissions (set value + aggr_cnv)
  Test 0050: Files owner (default)
  Test 0051: Files owner (aggr_cnv)
  Test 0052: Files owner (set value)
  Test 0053: Files owner (set value + aggr_cnv)
  Test 0060: Files size (default)
  Test 0061: Files size (aggr_cnv)
  Test 0070: Conventional file truncate
  Test 0071: Conventional file truncate (aggr_cnv)
  Test 0072: Conventional file unlink
  Test 0073: Conventional file unlink (aggr_cnv)
  Test 0074: Conventional file random write
  Test 0075: Conventional file random write (direct)
  Test 0076: Conventional file random write (aggr_cnv)
  Test 0077: Conventional file random write (aggr_cnv, direct)
  Test 0078: Conventional file mmap read/write
  Test 0079: Conventional file mmap read/write (aggr_cnv)
  Test 0080: Sequential file truncate
  Test 0081: Sequential file unlink
  Test 0082: Sequential file buffered write IO
  Test 0083: Sequential file overwrite
  Test 0084: Sequential file unaligned write (sync IO)
  Test 0085: Sequential file unaligned write (async IO)
  Test 0086: Sequential file append (sync)
  Test 0087: Sequential file append (async)
  Test 0088: Sequential file random read
  Test 0089: Sequential file mmap read/write
  Test 0090: sequential file 4K synchronous write
  Test 0091: Sequential file large synchronous write
  Test 0092: Sequential file explicit-open zone resources
  Test 0100: Swap file on conventional file
  Test 0101: Swap file on sequential file
  Test 0110: Sysfs attr after format
  Test 0111: Sysfs seq files active after mount (open zones)
  Test 0112: Sysfs seq files active after mount (active zones)
  Test 0113: Sysfs seq files write-open (default)
  Test 0114: Sysfs seq files write-open (explicit-open)
  Test 0115: Sysfs seq files active after write (default)
  Test 0116: Sysfs conv files write-open
  Test 0117: Sysfs conv files active after write

Contributing

Read the CONTRIBUTING file and send patches to:

Damien Le Moal <dlemoal@kernel.org>

If you believe your changes require kernel eyes or review, Cc the Linux kernel file system development mailing list:

linux-fsdevel@vger.kernel.org