sysv: Remove the filesystem

Since 2002 (change "Replace BKL for chain locking with sysvfs-private
rwlock") the sysv filesystem was doing IO under a rwlock in its
get_block() function (yes, a non-sleepable lock hold over a function
used to read inode metadata for all reads and writes).  Nobody noticed
until syzbot in 2023 [1]. This shows nobody is using the filesystem.
Just drop it.

[1] https://lore.kernel.org/all/0000000000000ccf9a05ee84f5b0@google.com/

Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20250220163940.10155-2-jack@suse.cz
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: jankara

Documentation/filesystems/index.rst

@@ -118,7 +118,6 @@ Documentation for filesystem implementations.
    spufs/index
    squashfs
    sysfs
-   sysv-fs
    tmpfs
    ubifs
    ubifs-authentication

Documentation/filesystems/sysv-fs.rst

@@ -23030,12 +23030,6 @@ L:	platform-driver-x86@vger.kernel.org
 S:	Maintained
 F:	drivers/platform/x86/system76_acpi.c
 
-SYSV FILESYSTEM
-S:	Orphan
-F:	Documentation/filesystems/sysv-fs.rst
-F:	fs/sysv/
-F:	include/linux/sysv_fs.h
-
 TASKSTATS STATISTICS INTERFACE
 M:	Balbir Singh <bsingharora@gmail.com>
 S:	Maintained

MAINTAINERS

@@ -981,7 +981,6 @@ CONFIG_MINIX_FS=m
 CONFIG_ROMFS_FS=m
 CONFIG_PSTORE=m
 CONFIG_PSTORE_COMPRESS=y
-CONFIG_SYSV_FS=m
 CONFIG_UFS_FS=m
 CONFIG_EROFS_FS=m
 CONFIG_EROFS_FS_ZIP_LZMA=y

arch/loongarch/configs/loongson3_defconfig

@@ -486,7 +486,6 @@ CONFIG_OMFS_FS=m
 CONFIG_HPFS_FS=m
 CONFIG_QNX4FS_FS=m
 CONFIG_QNX6FS_FS=m
-CONFIG_SYSV_FS=m
 CONFIG_UFS_FS=m
 CONFIG_EROFS_FS=m
 CONFIG_NFS_FS=y

arch/m68k/configs/amiga_defconfig

@@ -443,7 +443,6 @@ CONFIG_OMFS_FS=m
 CONFIG_HPFS_FS=m
 CONFIG_QNX4FS_FS=m
 CONFIG_QNX6FS_FS=m
-CONFIG_SYSV_FS=m
 CONFIG_UFS_FS=m
 CONFIG_EROFS_FS=m
 CONFIG_NFS_FS=y

arch/m68k/configs/apollo_defconfig

@@ -463,7 +463,6 @@ CONFIG_OMFS_FS=m
 CONFIG_HPFS_FS=m
 CONFIG_QNX4FS_FS=m
 CONFIG_QNX6FS_FS=m
-CONFIG_SYSV_FS=m
 CONFIG_UFS_FS=m
 CONFIG_EROFS_FS=m
 CONFIG_NFS_FS=y

arch/m68k/configs/atari_defconfig

@@ -435,7 +435,6 @@ CONFIG_OMFS_FS=m
 CONFIG_HPFS_FS=m
 CONFIG_QNX4FS_FS=m
 CONFIG_QNX6FS_FS=m
-CONFIG_SYSV_FS=m
 CONFIG_UFS_FS=m
 CONFIG_EROFS_FS=m
 CONFIG_NFS_FS=y

arch/m68k/configs/bvme6000_defconfig

@@ -445,7 +445,6 @@ CONFIG_OMFS_FS=m
 CONFIG_HPFS_FS=m
 CONFIG_QNX4FS_FS=m
 CONFIG_QNX6FS_FS=m
-CONFIG_SYSV_FS=m
 CONFIG_UFS_FS=m
 CONFIG_EROFS_FS=m
 CONFIG_NFS_FS=y

arch/m68k/configs/hp300_defconfig

@@ -462,7 +462,6 @@ CONFIG_OMFS_FS=m
 CONFIG_HPFS_FS=m
 CONFIG_QNX4FS_FS=m
 CONFIG_QNX6FS_FS=m
-CONFIG_SYSV_FS=m
 CONFIG_UFS_FS=m
 CONFIG_EROFS_FS=m
 CONFIG_NFS_FS=y