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linux-next/fs/Kconfig
Damien Le Moal 8dcc1a9d90 fs: New zonefs file system 
zonefs is a very simple file system exposing each zone of a zoned block
device as a file. Unlike a regular file system with zoned block device
support (e.g. f2fs), zonefs does not hide the sequential write
constraint of zoned block devices to the user. Files representing
sequential write zones of the device must be written sequentially
starting from the end of the file (append only writes).

As such, zonefs is in essence closer to a raw block device access
interface than to a full featured POSIX file system. The goal of zonefs
is to simplify the implementation of zoned block device support in
applications by replacing raw block device file accesses with a richer
file API, avoiding relying on direct block device file ioctls which may
be more obscure to developers. One example of this approach is the
implementation of LSM (log-structured merge) tree structures (such as
used in RocksDB and LevelDB) on zoned block devices by allowing SSTables
to be stored in a zone file similarly to a regular file system rather
than as a range of sectors of a zoned device. The introduction of the
higher level construct "one file is one zone" can help reducing the
amount of changes needed in the application as well as introducing
support for different application programming languages.

Zonefs on-disk metadata is reduced to an immutable super block to
persistently store a magic number and optional feature flags and
values. On mount, zonefs uses blkdev_report_zones() to obtain the device
zone configuration and populates the mount point with a static file tree
solely based on this information. E.g. file sizes come from the device
zone type and write pointer offset managed by the device itself.

The zone files created on mount have the following characteristics.
1) Files representing zones of the same type are grouped together
   under a common sub-directory:
     * For conventional zones, the sub-directory "cnv" is used.
     * For sequential write zones, the sub-directory "seq" is used.
  These two directories are the only directories that exist in zonefs.
  Users cannot create other directories and cannot rename nor delete
  the "cnv" and "seq" sub-directories.
2) The name of zone files is the number of the file within the zone
   type sub-directory, in order of increasing zone start sector.
3) The size of conventional zone files is fixed to the device zone size.
   Conventional zone files cannot be truncated.
4) The size of sequential zone files represent the file's zone write
   pointer position relative to the zone start sector. Truncating these
   files is allowed only down to 0, in which case, the zone is reset to
   rewind the zone write pointer position to the start of the zone, or
   up to the zone size, in which case the file's zone is transitioned
   to the FULL state (finish zone operation).
5) All read and write operations to files are not allowed beyond the
   file zone size. Any access exceeding the zone size is failed with
   the -EFBIG error.
6) Creating, deleting, renaming or modifying any attribute of files and
   sub-directories is not allowed.
7) There are no restrictions on the type of read and write operations
   that can be issued to conventional zone files. Buffered, direct and
   mmap read & write operations are accepted. For sequential zone files,
   there are no restrictions on read operations, but all write
   operations must be direct IO append writes. mmap write of sequential
   files is not allowed.

Several optional features of zonefs can be enabled at format time.
* Conventional zone aggregation: ranges of contiguous conventional
  zones can be aggregated into a single larger file instead of the
  default one file per zone.
* File ownership: The owner UID and GID of zone files is by default 0
  (root) but can be changed to any valid UID/GID.
* File access permissions: the default 640 access permissions can be
  changed.

The mkzonefs tool is used to format zoned block devices for use with
zonefs. This tool is available on Github at:

git@github.com:damien-lemoal/zonefs-tools.git.

zonefs-tools also includes a test suite which can be run against any
zoned block device, including null_blk block device created with zoned
mode.

Example: the following formats a 15TB host-managed SMR HDD with 256 MB
zones with the conventional zones aggregation feature enabled.

$ sudo mkzonefs -o aggr_cnv /dev/sdX
$ sudo mount -t zonefs /dev/sdX /mnt
$ ls -l /mnt/
total 0
dr-xr-xr-x 2 root root     1 Nov 25 13:23 cnv
dr-xr-xr-x 2 root root 55356 Nov 25 13:23 seq

The size of the zone files sub-directories indicate the number of files
existing for each type of zones. In this example, there is only one
conventional zone file (all conventional zones are aggregated under a
single file).

$ ls -l /mnt/cnv
total 137101312
-rw-r----- 1 root root 140391743488 Nov 25 13:23 0

This aggregated conventional zone file can be used as a regular file.

$ sudo mkfs.ext4 /mnt/cnv/0
$ sudo mount -o loop /mnt/cnv/0 /data

The "seq" sub-directory grouping files for sequential write zones has
in this example 55356 zones.

$ ls -lv /mnt/seq
total 14511243264
-rw-r----- 1 root root 0 Nov 25 13:23 0
-rw-r----- 1 root root 0 Nov 25 13:23 1
-rw-r----- 1 root root 0 Nov 25 13:23 2
...
-rw-r----- 1 root root 0 Nov 25 13:23 55354
-rw-r----- 1 root root 0 Nov 25 13:23 55355

For sequential write zone files, the file size changes as data is
appended at the end of the file, similarly to any regular file system.

$ dd if=/dev/zero of=/mnt/seq/0 bs=4K count=1 conv=notrunc oflag=direct
1+0 records in
1+0 records out
4096 bytes (4.1 kB, 4.0 KiB) copied, 0.000452219 s, 9.1 MB/s

$ ls -l /mnt/seq/0
-rw-r----- 1 root root 4096 Nov 25 13:23 /mnt/seq/0

The written file can be truncated to the zone size, preventing any
further write operation.

$ truncate -s 268435456 /mnt/seq/0
$ ls -l /mnt/seq/0
-rw-r----- 1 root root 268435456 Nov 25 13:49 /mnt/seq/0

Truncation to 0 size allows freeing the file zone storage space and
restart append-writes to the file.

$ truncate -s 0 /mnt/seq/0
$ ls -l /mnt/seq/0
-rw-r----- 1 root root 0 Nov 25 13:49 /mnt/seq/0

Since files are statically mapped to zones on the disk, the number of
blocks of a file as reported by stat() and fstat() indicates the size
of the file zone.

$ stat /mnt/seq/0
  File: /mnt/seq/0
  Size: 0       Blocks: 524288     IO Block: 4096   regular empty file
Device: 870h/2160d      Inode: 50431       Links: 1
Access: (0640/-rw-r-----)  Uid: (    0/    root)   Gid: (    0/  root)
Access: 2019-11-25 13:23:57.048971997 +0900
Modify: 2019-11-25 13:52:25.553805765 +0900
Change: 2019-11-25 13:52:25.553805765 +0900
 Birth: -

The number of blocks of the file ("Blocks") in units of 512B blocks
gives the maximum file size of 524288 * 512 B = 256 MB, corresponding
to the device zone size in this example. Of note is that the "IO block"
field always indicates the minimum IO size for writes and corresponds
to the device physical sector size.

This code contains contributions from:
* Johannes Thumshirn <jthumshirn@suse.de>,
* Darrick J. Wong <darrick.wong@oracle.com>,
* Christoph Hellwig <hch@lst.de>,
* Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> and
* Ting Yao <tingyao@hust.edu.cn>.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
2020-02-07 14:39:38 +09:00

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# SPDX-License-Identifier: GPL-2.0-only
#
# File system configuration
#
menu "File systems"
# Use unaligned word dcache accesses
config DCACHE_WORD_ACCESS
bool
config VALIDATE_FS_PARSER
bool "Validate filesystem parameter description"
help
Enable this to perform validation of the parameter description for a
filesystem when it is registered.
if BLOCK
config FS_IOMAP
bool
source "fs/ext2/Kconfig"
source "fs/ext4/Kconfig"
source "fs/jbd2/Kconfig"
config FS_MBCACHE
# Meta block cache for Extended Attributes (ext2/ext3/ext4)
tristate
default y if EXT2_FS=y && EXT2_FS_XATTR
default y if EXT4_FS=y
default m if EXT2_FS_XATTR || EXT4_FS
source "fs/reiserfs/Kconfig"
source "fs/jfs/Kconfig"
source "fs/xfs/Kconfig"
source "fs/gfs2/Kconfig"
source "fs/ocfs2/Kconfig"
source "fs/btrfs/Kconfig"
source "fs/nilfs2/Kconfig"
source "fs/f2fs/Kconfig"
source "fs/zonefs/Kconfig"
config FS_DAX
bool "Direct Access (DAX) support"
depends on MMU
depends on !(ARM || MIPS || SPARC)
select DEV_PAGEMAP_OPS if (ZONE_DEVICE && !FS_DAX_LIMITED)
select FS_IOMAP
select DAX
help
Direct Access (DAX) can be used on memory-backed block devices.
If the block device supports DAX and the filesystem supports DAX,
then you can avoid using the pagecache to buffer I/Os. Turning
on this option will compile in support for DAX; you will need to
mount the filesystem using the -o dax option.
If you do not have a block device that is capable of using this,
or if unsure, say N. Saying Y will increase the size of the kernel
by about 5kB.
config FS_DAX_PMD
bool
default FS_DAX
depends on FS_DAX
depends on ZONE_DEVICE
depends on TRANSPARENT_HUGEPAGE
# Selected by DAX drivers that do not expect filesystem DAX to support
# get_user_pages() of DAX mappings. I.e. "limited" indicates no support
# for fork() of processes with MAP_SHARED mappings or support for
# direct-I/O to a DAX mapping.
config FS_DAX_LIMITED
bool
endif # BLOCK
# Posix ACL utility routines
#
# Note: Posix ACLs can be implemented without these helpers. Never use
# this symbol for ifdefs in core code.
#
config FS_POSIX_ACL
def_bool n
config EXPORTFS
tristate
config EXPORTFS_BLOCK_OPS
bool "Enable filesystem export operations for block IO"
help
This option enables the export operations for a filesystem to support
external block IO.
config FILE_LOCKING
bool "Enable POSIX file locking API" if EXPERT
default y
help
This option enables standard file locking support, required
for filesystems like NFS and for the flock() system
call. Disabling this option saves about 11k.
config MANDATORY_FILE_LOCKING
bool "Enable Mandatory file locking"
depends on FILE_LOCKING
default y
help
This option enables files appropriately marked files on appropriely
mounted filesystems to support mandatory locking.
To the best of my knowledge this is dead code that no one cares about.
source "fs/crypto/Kconfig"
source "fs/verity/Kconfig"
source "fs/notify/Kconfig"
source "fs/quota/Kconfig"
source "fs/autofs/Kconfig"
source "fs/fuse/Kconfig"
source "fs/overlayfs/Kconfig"
menu "Caches"
source "fs/fscache/Kconfig"
source "fs/cachefiles/Kconfig"
endmenu
if BLOCK
menu "CD-ROM/DVD Filesystems"
source "fs/isofs/Kconfig"
source "fs/udf/Kconfig"
endmenu
endif # BLOCK
if BLOCK
menu "DOS/FAT/NT Filesystems"
source "fs/fat/Kconfig"
source "fs/ntfs/Kconfig"
endmenu
endif # BLOCK
menu "Pseudo filesystems"
source "fs/proc/Kconfig"
source "fs/kernfs/Kconfig"
source "fs/sysfs/Kconfig"
config TMPFS
bool "Tmpfs virtual memory file system support (former shm fs)"
depends on SHMEM
help
Tmpfs is a file system which keeps all files in virtual memory.
Everything in tmpfs is temporary in the sense that no files will be
created on your hard drive. The files live in memory and swap
space. If you unmount a tmpfs instance, everything stored therein is
lost.
See <file:Documentation/filesystems/tmpfs.txt> for details.
config TMPFS_POSIX_ACL
bool "Tmpfs POSIX Access Control Lists"
depends on TMPFS
select TMPFS_XATTR
select FS_POSIX_ACL
help
POSIX Access Control Lists (ACLs) support additional access rights
for users and groups beyond the standard owner/group/world scheme,
and this option selects support for ACLs specifically for tmpfs
filesystems.
If you've selected TMPFS, it's possible that you'll also need
this option as there are a number of Linux distros that require
POSIX ACL support under /dev for certain features to work properly.
For example, some distros need this feature for ALSA-related /dev
files for sound to work properly. In short, if you're not sure,
say Y.
config TMPFS_XATTR
bool "Tmpfs extended attributes"
depends on TMPFS
default n
help
Extended attributes are name:value pairs associated with inodes by
the kernel or by users (see the attr(5) manual page for details).
Currently this enables support for the trusted.* and
security.* namespaces.
You need this for POSIX ACL support on tmpfs.
If unsure, say N.
config HUGETLBFS
bool "HugeTLB file system support"
depends on X86 || IA64 || SPARC64 || (S390 && 64BIT) || \
SYS_SUPPORTS_HUGETLBFS || BROKEN
help
hugetlbfs is a filesystem backing for HugeTLB pages, based on
ramfs. For architectures that support it, say Y here and read
<file:Documentation/admin-guide/mm/hugetlbpage.rst> for details.
If unsure, say N.
config HUGETLB_PAGE
def_bool HUGETLBFS
config MEMFD_CREATE
def_bool TMPFS || HUGETLBFS
config ARCH_HAS_GIGANTIC_PAGE
bool
source "fs/configfs/Kconfig"
source "fs/efivarfs/Kconfig"
endmenu
menuconfig MISC_FILESYSTEMS
bool "Miscellaneous filesystems"
default y
---help---
Say Y here to get to see options for various miscellaneous
filesystems, such as filesystems that came from other
operating systems.
This option alone does not add any kernel code.
If you say N, all options in this submenu will be skipped and
disabled; if unsure, say Y here.
if MISC_FILESYSTEMS
source "fs/orangefs/Kconfig"
source "fs/adfs/Kconfig"
source "fs/affs/Kconfig"
source "fs/ecryptfs/Kconfig"
source "fs/hfs/Kconfig"
source "fs/hfsplus/Kconfig"
source "fs/befs/Kconfig"
source "fs/bfs/Kconfig"
source "fs/efs/Kconfig"
source "fs/jffs2/Kconfig"
# UBIFS File system configuration
source "fs/ubifs/Kconfig"
source "fs/cramfs/Kconfig"
source "fs/squashfs/Kconfig"
source "fs/freevxfs/Kconfig"
source "fs/minix/Kconfig"
source "fs/omfs/Kconfig"
source "fs/hpfs/Kconfig"
source "fs/qnx4/Kconfig"
source "fs/qnx6/Kconfig"
source "fs/romfs/Kconfig"
source "fs/pstore/Kconfig"
source "fs/sysv/Kconfig"
source "fs/ufs/Kconfig"
source "fs/erofs/Kconfig"
endif # MISC_FILESYSTEMS
menuconfig NETWORK_FILESYSTEMS
bool "Network File Systems"
default y
depends on NET
---help---
Say Y here to get to see options for network filesystems and
filesystem-related networking code, such as NFS daemon and
RPCSEC security modules.
This option alone does not add any kernel code.
If you say N, all options in this submenu will be skipped and
disabled; if unsure, say Y here.
if NETWORK_FILESYSTEMS
source "fs/nfs/Kconfig"
source "fs/nfsd/Kconfig"
config GRACE_PERIOD
tristate
config LOCKD
tristate
depends on FILE_LOCKING
select GRACE_PERIOD
config LOCKD_V4
bool
depends on NFSD_V3 || NFS_V3
depends on FILE_LOCKING
default y
config NFS_ACL_SUPPORT
tristate
select FS_POSIX_ACL
config NFS_COMMON
bool
depends on NFSD || NFS_FS || LOCKD
default y
source "net/sunrpc/Kconfig"
source "fs/ceph/Kconfig"
source "fs/cifs/Kconfig"
source "fs/coda/Kconfig"
source "fs/afs/Kconfig"
source "fs/9p/Kconfig"
endif # NETWORK_FILESYSTEMS
source "fs/nls/Kconfig"
source "fs/dlm/Kconfig"
source "fs/unicode/Kconfig"
config IO_WQ
bool
endmenu
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