erofs: move erofs out of staging

EROFS filesystem has been merged into linux-staging for a year.

EROFS is designed to be a better solution of saving extra storage
space with guaranteed end-to-end performance for read-only files
with the help of reduced metadata, fixed-sized output compression
and decompression inplace technologies.

In the past year, EROFS was greatly improved by many people as
a staging driver, self-tested, betaed by a large number of our
internal users, successfully applied to almost all in-service
HUAWEI smartphones as the part of EMUI 9.1 and proven to be stable
enough to be moved out of staging.

EROFS is a self-contained filesystem driver. Although there are
still some TODOs to be more generic, we have a dedicated team
actively keeping on working on EROFS in order to make it better
with the evolution of Linux kernel as the other in-kernel filesystems.

As Pavel suggested, it's better to do as one commit since git
can do moves and all histories will be saved in this way.

Let's promote it from staging and enhance it more actively as
a "real" part of kernel for more wider scenarios!

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Pavel Machek <pavel@denx.de>
Cc: David Sterba <dsterba@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Darrick J . Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Richard Weinberger <richard@nod.at>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Chao Yu <yuchao0@huawei.com>
Cc: Miao Xie <miaoxie@huawei.com>
Cc: Li Guifu <bluce.liguifu@huawei.com>
Cc: Fang Wei <fangwei1@huawei.com>
Change-Id: I16111e83bd97a64b13fa67354f2ee437d7b16fc5
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190822213659.5501-1-hsiangkao@aol.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/filesystems/erofs.txt

@@ -49,10 +49,6 @@ Bugs and patches are welcome, please kindly help us and send to the following
 linux-erofs mailing list:
 >> linux-erofs mailing list   <linux-erofs@lists.ozlabs.org>
 
-Note that EROFS is still working in progress as a Linux staging driver,
-Cc the staging mailing list as well is highly recommended:
->> Linux Driver Project Developer List <devel@driverdev.osuosl.org>
-
 Mount options
 =============
 

MAINTAINERS

@@ -5488,6 +5488,13 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/kristoffer/linux-hpc.git
 F:	drivers/video/fbdev/s1d13xxxfb.c
 F:	include/video/s1d13xxxfb.h
 
+EROFS FILE SYSTEM
+M:	Gao Xiang <gaoxiang25@huawei.com>
+M:	Chao Yu <yuchao0@huawei.com>
+L:	linux-erofs@lists.ozlabs.org
+S:	Maintained
+F:	fs/erofs/
+
 ERRSEQ ERROR TRACKING INFRASTRUCTURE
 M:	Jeff Layton <jlayton@kernel.org>
 S:	Maintained
@@ -13829,13 +13836,6 @@ M:	H Hartley Sweeten <hsweeten@visionengravers.com>
 S:	Odd Fixes
 F:	drivers/staging/comedi/
 
-STAGING - EROFS FILE SYSTEM
-M:	Gao Xiang <gaoxiang25@huawei.com>
-M:	Chao Yu <yuchao0@huawei.com>
-L:	linux-erofs@lists.ozlabs.org
-S:	Maintained
-F:	drivers/staging/erofs/
-
 STAGING - FLARION FT1000 DRIVERS
 M:	Marek Belisko <marek.belisko@gmail.com>
 S:	Odd Fixes

fs/erofs/TODO

@@ -1,45 +0,0 @@
-
-EROFS is still working in progress, thus it is not suitable
-for all productive uses. play at your own risk :)
-
-TODO List:
- - add the missing error handling code
-   (mainly existed in xattr and decompression submodules);
-
- - finalize erofs ondisk format design  (which means that
-   minor on-disk revisions could happen later);
-
- - documentation and detailed technical analysis;
-
- - general code review and clean up
-   (including confusing variable names and code snippets);
-
- - support larger compressed clustersizes for selection
-   (currently erofs only works as expected with the page-sized
-    compressed cluster configuration, usually 4KB);
-
- - support more lossless data compression algorithms
-   in addition to LZ4 algorithms in VLE approach;
-
- - data deduplication and other useful features.
-
-erofs-mkfs (preview version) binaries for i386 / x86_64 are available at:
-
-   https://github.com/hsiangkao/erofs_mkfs_binary
-
-It is still in progress opening mkfs source code to public,
-in any case an open-source mkfs will be released in the near future.
-
-
-Code, suggestions, etc, are welcome. Please feel free to
-ask and send patches,
-
-To:
-  linux-erofs mailing list   <linux-erofs@lists.ozlabs.org>
-  Gao Xiang                  <gaoxiang25@huawei.com>
-  Chao Yu                    <yuchao0@huawei.com>
-
-Cc: (for linux-kernel upstream patches)
-  Greg Kroah-Hartman         <gregkh@linuxfoundation.org>
-  linux-staging mailing list <devel@driverdev.osuosl.org>
-

fs/erofs/erofs_fs.h

@@ -8,7 +8,6 @@
 #ifndef __EROFS_FS_H
 #define __EROFS_FS_H
 
-#define EROFS_SUPER_MAGIC_V1	0xE0F5E1E2
 #define EROFS_SUPER_OFFSET      1024
 
 #define EROFS_FEATURE_COMPAT_SB_CHKSUM          0x00000001

include/uapi/linux/magic.h

@@ -19,6 +19,7 @@
 #define SQUASHFS_MAGIC		0x73717368
 #define ECRYPTFS_SUPER_MAGIC	0xf15f
 #define EFS_SUPER_MAGIC		0x414A53
+#define EROFS_SUPER_MAGIC_V1	0xE0F5E1E2
 #define EXT2_SUPER_MAGIC	0xEF53
 #define EXT3_SUPER_MAGIC	0xEF53
 #define XENFS_SUPER_MAGIC	0xabba1974