When cifsacl mount option is used, retain the ACEs which
should not be modified during chmod. Following is the approach taken:

1. Retain all explicit (non-inherited) ACEs, unless the SID is one
of owner/group/everyone/authenticated-users. We're going to set new
ACEs for these SIDs anyways.
2. At the end of the list of explicit ACEs, place the new list of
ACEs obtained by necessary conversion/encoding.
3. Once the converted/encoded ACEs are set, copy all the remaining
ACEs (inherited) into the new ACL.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

A two line fix which I made while testing my prev fix with
cifsacl mode conversions seem to have gone missing in the final fix
that was submitted. This is that fix.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

/proc/fs/cifs/DebugData called the ip address for server sessions
"Name" which is confusing since it is not a hostname. Change
this field name to "Address" and for the list of servers add
new field "Hostname" which is populated from the hostname used
to connect to the server.  See below. And also don't print
[NONE] when the interface list is empty as it is not clear
what 'NONE' referred to.

Servers:
1) ConnectionId: 0x1 Hostname: localhost
Number of credits: 389 Dialect 0x311
TCP status: 1 Instance: 1
Local Users To Server: 1 SecMode: 0x1 Req On Wire: 0
In Send: 0 In MaxReq Wait: 0

	Sessions:
	1) Address: 127.0.0.1
...
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

ses->serverName is not the server name, but the string form
of the ip address of the server.  Change the name to ip_addr
to avoid confusion (and fix the array length to match
maximum length of ipv6 address).
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

Fix inconsistent IS_ERR and PTR_ERR in cifs_find_swn_reg(). The proper
pointer to be passed as argument to PTR_ERR() is share_name.

This bug was detected with the help of Coccinelle.

Fixes: bf80e5d4 ("cifs: Send witness register and unregister commands to userspace daemon")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Samuel Cabrero <scabrero@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>

Reformat the output of /proc/fs/cifs/DebugData to print the
conn_id for each connection. Also reordered and numbered the data
into a more reader-friendly format.

This is what the new format looks like:
$ cat /proc/fs/cifs/DebugData
Display Internal CIFS Data Structures for Debugging
---------------------------------------------------
CIFS Version 2.30
Features: DFS,FSCACHE,STATS,DEBUG,ALLOW_INSECURE_LEGACY,WEAK_PW_HASH,CIFS_POSIX,UPCALL(SPNEGO),XATTR,ACL
CIFSMaxBufSize: 16384
Active VFS Requests: 0

Servers:
1) ConnectionId: 0x1
Number of credits: 371 Dialect 0x300
TCP status: 1 Instance: 1
Local Users To Server: 1 SecMode: 0x1 Req On Wire: 0 In Send: 0 In MaxReq Wait: 0

        Sessions:
        1) Name: 10.10.10.10 Uses: 1 Capability: 0x300077     Session Status: 1
        Security type: RawNTLMSSP  SessionId: 0x785560000019
        User: 1000 Cred User: 0

        Shares:
        0) IPC: \\10.10.10.10\IPC$ Mounts: 1 DevInfo: 0x0 Attributes: 0x0
        PathComponentMax: 0 Status: 1 type: 0 Serial Number: 0x0
        Share Capabilities: None        Share Flags: 0x30
        tid: 0x1        Maximal Access: 0x11f01ff

        1) \\10.10.10.10\shyam_test2 Mounts: 1 DevInfo: 0x20020 Attributes: 0xc706ff
        PathComponentMax: 255 Status: 1 type: DISK Serial Number: 0xd4723975
        Share Capabilities: None Aligned, Partition Aligned,    Share Flags: 0x0
        tid: 0x5        Optimal sector size: 0x1000     Maximal Access: 0x1f01ff

        MIDs:

        Server interfaces: 3
        1)      Speed: 10000000000 bps
                Capabilities: rss
                IPv4: 10.10.10.1

        2)      Speed: 10000000000 bps
                Capabilities: rss
                IPv6: fe80:0000:0000:0000:18b4:0000:0000:0000

        3)      Speed: 1000000000 bps
                Capabilities: rss
                IPv4: 10.10.10.10
                [CONNECTED]
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

Introduced a new field conn_id in TCP_Server_Info structure.
This is a non-persistent unique identifier maintained by the client
for a connection to a file server. For this, a global counter named
tcpSesNextId is maintained. On allocating a new TCP_Server_Info,
this counter is incremented and assigned.

Changed the dynamic tracepoints related to reconnects and
crediting to be more informative (with conn_id printed).
Debugging a crediting issue helped me understand the
important things to print here.

Always call dynamic tracepoints outside the scope of spinlocks.
To do this, copy out the credits and in_flight fields of the
server struct before dropping the lock.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

For failure by timeout waiting for credits, changed the error
returned to the app with EBUSY, instead of ENOTSUPP. This is done
because this situation is possible even in non-buggy cases. i.e.
overloaded server can return 0 credits until done with outstanding
requests. And this feels like a better error to return to the app.

For cases of zero credits found even when there are no requests
in flight, replaced ENOTSUPP with EDEADLK, since we're avoiding
deadlock here by returning error.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

We used to share the CIFS_NEG_OP flag between negotiate and
session authentication. There was an assumption in the code that
CIFS_NEG_OP is used by negotiate only. So introcuded CIFS_SESS_OP
and used it for session setup optypes.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

Various minor changes to the admin-guide for cifs
Signed-off-by: Steve French <stfrench@microsoft.com>

Typo: exiting --> existing
Signed-off-by: Steve French <stfrench@microsoft.com>

SMB3.1.1 is the newest, and preferred dialect, and is included in
the requested dialect list by default (ie if no vers= is specified
on mount) but it should also be requested if SMB3 or later is requested
(vers=3 instead of a specific dialect: vers=2.1, vers=3.02 or vers=3.0).

Currently specifying "vers=3" only requests smb3.0 and smb3.02 but this
patch fixes it to also request smb3.1.1 dialect, as it is the newest
and most secure dialect and is a "version 3 or later" dialect (the intent
of "vers=3").
Signed-off-by: Steve French <stfrench@microsoft.com>
Suggested-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

Pull LED fix from Pavel Machek:
 "One-liner fixing a build problem"

* 'for-rc8-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/pavel/linux-leds:
  leds: rt8515: add V4L2_FLASH_LED_CLASS dependency

Merge tag 'kbuild-fixes-v5.11-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - Fix CONFIG_TRIM_UNUSED_KSYMS build for ppc64

 - Use pkg-config for scripts/sign-file.c CFLAGS

* tag 'kbuild-fixes-v5.11-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  scripts: set proper OpenSSL include dir also for sign-file
  sparc: remove wrong comment from arch/sparc/include/asm/Kbuild
  kbuild: fix CONFIG_TRIM_UNUSED_KSYMS build for ppc64

Pull x86 fixes from Borislav Petkov:
 "I kinda knew while typing 'I hope this is the last batch of x86/urgent
  updates' last week, Murphy was reading too and uttered 'Hold my
  beer!'.

  So here's more fixes... Thanks Murphy.

  Anyway, three more x86/urgent fixes for 5.11 final. We should be
  finally ready (famous last words). :-)

   - An SGX use after free fix

   - A fix for the fix to disable CET instrumentation generation for
     kernel code. We forgot 32-bit, which we seem to do very often
     nowadays

   - A Xen PV fix to irqdomain init ordering"

* tag 'x86_urgent_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/pci: Create PCI/MSI irqdomain after x86_init.pci.arch_init()
  x86/build: Disable CET instrumentation in the kernel for 32-bit too
  x86/sgx: Maintain encl->refcount for each encl->mm_list entry

The leds-rt8515 driver can optionall use the v4l2 flash led class,
but it causes a link error when that class is in a loadable module
and the rt8515 driver itself is built-in:

ld.lld: error: undefined symbol: v4l2_flash_init
>>> referenced by leds-rt8515.c
>>>               leds/flash/leds-rt8515.o:(rt8515_probe) in archive
drivers/built-in.a

Adding 'depends on V4L2_FLASH_LED_CLASS' in Kconfig would avoid that,
but it would make it impossible to use the driver without the
v4l2 support.

Add the same dependency that the other users of this class have
instead, which just prevents the broken configuration.

Fixes: e1c6edcb ("leds: rt8515: Add Richtek RT8515 LED driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

Fixes: 2cea4a7a ("scripts: use pkg-config to locate libcrypto")
Signed-off-by: Rolf Eike Beer <eb@emlix.com>
Cc: stable@vger.kernel.org # 5.6.x
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

These are NOT exported to userspace.

The headers listed in arch/sparc/include/uapi/asm/Kbuild are exported.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Pull clk fix from Stephen Boyd:
 "One small fix for the Allwinner clk driver so that display clks figure
  out the correct rate to use.

  This fixes displays running 4k@60Hz and some other resolutions that
  haven't been exercised and fully understood until now"

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk: sunxi-ng: mp: fix parent rate change flag check

Pull SCSI fix from James Bottomley:
 "One fix for scsi_debug that fixes a memory leak on module removal"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: scsi_debug: Fix a memory leak

Pull cgroup fixes from Tejun Heo:
 "Two cgroup fixes:

   - fix a NULL deref when trying to poll PSI in the root cgroup

   - fix confusing controller parsing corner case when mounting cgroup
     v1 hierarchies

  And doc / maintainer file updates"

* 'for-5.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: update PSI file description in docs
  cgroup: fix psi monitor for root cgroup
  MAINTAINERS: Update my email address
  MAINTAINERS: Remove stale URLs for cpuset
  cgroup-v1: add disabled controller check in cgroup1_parse_param()

Merge fixes from Andrew Morton:
 "6 patches.

  Subsystems affected by this patch series: mm/pagemap, scripts,
  MAINTAINERS, and h8300"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  h8300: fix PREEMPTION build, TI_PRE_COUNT undefined
  MAINTAINERS: add Andrey Konovalov to KASAN reviewers
  MAINTAINERS: update Andrey Konovalov's email address
  MAINTAINERS: update KASAN file list
  scripts/recordmcount.pl: support big endian for ARCH sh
  m68k: make __pfn_to_phys() and __phys_to_pfn() available for !MMU

Pull i2c fix from Wolfram Sang:
 "One more I2C driver bugfix"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: stm32f7: fix configuration of the digital filter

Pull btrfs fix from David Sterba:
 "A regression fix caused by a refactoring in 5.11.

  A corrupted superblock wouldn't be detected by checksum verification
  due to wrongly placed initialization of the checksum length, thus
  making memcmp always work"

* tag 'for-5.11-rc7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: initialize fs_info::csum_size earlier in open_ctree

Fix a build error for undefined 'TI_PRE_COUNT' by adding it to
asm-offsets.c.

  h8300-linux-ld: arch/h8300/kernel/entry.o: in function `resume_kernel': (.text+0x29a): undefined reference to `TI_PRE_COUNT'

Link: https://lkml.kernel.org/r/20210212021650.22740-1-rdunlap@infradead.org
Fixes: df2078b8 ("h8300: Low level entry")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add my personal email address to KASAN reviewers list.

Link: https://lkml.kernel.org/r/c1ce89a7aae0e2d6852249c280b1eb59aeac30c0.1613150186.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Use my personal email address.

Link: https://lkml.kernel.org/r/b0ec98dabbc12336c162788f5ccde97045a0d65e.1613150186.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Account for the following files:

 - lib/Kconfig.kasan

 - lib/test_kasan_module.c

 - arch/arm64/include/asm/mte-kasan.h

Link: https://lkml.kernel.org/r/7f9771d97b34d396bfdc4e288ad93486bb865a06.1613150186.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The kernel test robot reported the following issue:

    CC [M]  drivers/soc/litex/litex_soc_ctrl.o
  sh4-linux-objcopy: Unable to change endianness of input file(s)
  sh4-linux-ld: cannot find drivers/soc/litex/.tmp_gl_litex_soc_ctrl.o: No such file or directory
  sh4-linux-objcopy: 'drivers/soc/litex/.tmp_mx_litex_soc_ctrl.o': No such file

The problem is that the format of input file is elf32-shbig-linux, but
sh4-linux-objcopy wants to output a file which format is elf32-sh-linux:

  $ sh4-linux-objdump -d drivers/soc/litex/litex_soc_ctrl.o | grep format
  drivers/soc/litex/litex_soc_ctrl.o:     file format elf32-shbig-linux

Link: https://lkml.kernel.org/r/20210210150435.2171567-1-rong.a.chen@intel.com
Link: https://lore.kernel.org/linux-mm/202101261118.GbbYSlHu-lkp@intel.comSigned-off-by: Rong Chen <rong.a.chen@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Yoshinori Sato <ysato@users.osdn.me>
Cc: Rich Felker <dalias@libc.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Recent changes that obsoleted DISCONTIGMEM on m68k switched the MMU
variant to use generic definitions of __pfn_to_phys() and __phys_to_pfn(),
but missed the !MMU variant which caused a build failure:

   drivers/media/common/videobuf2/videobuf2-dma-contig.c: In function 'vb2_dc_get_userptr':
   drivers/media/common/videobuf2/videobuf2-dma-contig.c:509:5: error: implicit declaration of function '__pfn_to_phys' [-Werror=implicit-function-declaration]
     509 |     __pfn_to_phys(nums[0]), size, buf->dma_dir, 0);
         |     ^~~~~~~~~~~~~
   cc1: some warnings being treated as errors

Enable __pfn_to_phys() and __phys_to_pfn() on !MMU builds.

Link: https://lkml.kernel.org/r/20210211232202.GS299309@linux.ibm.com
Fixes: 4bfc848e ("m68k/mm: enable use of generic memory_model.h for !DISCONTIGMEM")
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull cifs fixes from Steve French:
 "Four small smb3 fixes to the new mount API (including a particularly
  important one for DFS links).

  These were found in testing this week of additional DFS scenarios, and
  a user testing of an apache container problem"

* tag '5.11-rc7-smb3-github' of git://github.com/smfrench/smb3-kernel:
  cifs: Set CIFS_MOUNT_USE_PREFIX_PATH flag on setting cifs_sb->prepath.
  cifs: In the new mount api we get the full devname as source=
  cifs: do not disable noperm if multiuser mount option is not provided
  cifs: fix dfs-links

Pull io_uring fix from Jens Axboe:
 "Revert of a patch from this release that caused a regression"

* tag 'io_uring-5.11-2021-02-12' of git://git.kernel.dk/linux-block:
  Revert "io_uring: don't take fs for recvmsg/sendmsg"

Pull drm fixes from Dave Airlie:
 "Regular fixes for final, there is a ttm regression fix, dp-mst fix,
  one amdgpu revert, two i915 fixes, and some misc fixes for sun4i,
  xlnx, and vc4.

  All pretty quiet and don't think we have any known outstanding
  regressions.

  ttm:
   - page pool regression fix.

  dp_mst:
   - don't report un-attached ports as connected

  amdgpu:
   - blank screen fix

  i915:
   - ensure Type-C FIA is powered when initializing
   - fix overlay frontbuffer tracking

  sun4i:
   - tcon1 sync polarity fix
   - always set HDMI clock rate
   - fix H6 HDMI PHY config
   - fix H6 max frequency

  vc4:
   - fix buffer overflow

  xlnx:
   - fix memory leak"

* tag 'drm-fixes-2021-02-12' of git://anongit.freedesktop.org/drm/drm:
  drm/ttm: make sure pool pages are cleared
  drm/sun4i: dw-hdmi: Fix max. frequency for H6
  drm/sun4i: Fix H6 HDMI PHY configuration
  drm/sun4i: dw-hdmi: always set clock rate
  drm/sun4i: tcon: set sync polarity for tcon1 channel
  drm/i915: Fix overlay frontbuffer tracking
  Revert "drm/amd/display: Update NV1x SR latency values"
  drm/i915/tgl+: Make sure TypeC FIA is powered up when initializing it
  drm/dp_mst: Don't report ports connected if nothing is attached to them
  drm/xlnx: fix kmemleak by sending vblank_event in atomic_disable
  drm/vc4: hvs: Fix buffer overflow with the dlist handling

Pull tracing fix from Steven Rostedt:
 "Fix buffer overflow in trace event filter.

  It was reported that if an trace event was larger than a page and was
  filtered, that it caused memory corruption. The reason is that
  filtered events first go into a buffer to test the filter before being
  written into the ring buffer. Unfortunately, this write did not check
  the size"

* tag 'trace-v5.11-rc7-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Check length before giving out the filter buffer

Pull xen fix from Juergen Gross:
 "A single fix for an issue introduced this development cycle: when
  running as a Xen guest on Arm systems the kernel will hang during
  boot"

* tag 'for-linus-5.11-rc8-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  arm/xen: Don't probe xenbus as part of an early initcall

Pull RISC-V fix from Palmer Dabbelt:
 "A single fix this week: the removal of the GPIO reset method for the
  Ethernet phy on the HiFive Unleashed.

  This returns to relying on the bootloader's phy reset sequence, which
  we'll have to continue doing until we can sort out how to get the
  Linux phy driver to perform the special reset dance required for this
  phy"

* tag 'riscv-for-linus-5.11-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  Revert "dts: phy: add GPIO number and active state used for phy reset"

Pull arm64 fix from Catalin Marinas:
 "Fix PTRACE_PEEKMTETAGS access to an mmapped region before the first
  write"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: mte: Allow PTRACE_PEEKMTETAGS access to the zero page

The ptrace(PTRACE_PEEKMTETAGS) implementation checks whether the user
page has valid tags (mapped with PROT_MTE) by testing the PG_mte_tagged
page flag. If this bit is cleared, ptrace(PTRACE_PEEKMTETAGS) returns
-EIO.

A newly created (PROT_MTE) mapping points to the zero page which had its
tags zeroed during cpu_enable_mte(). If there were no prior writes to
this mapping, ptrace(PTRACE_PEEKMTETAGS) fails with -EIO since the zero
page does not have the PG_mte_tagged flag set.

Set PG_mte_tagged on the zero page when its tags are cleared during
boot. In addition, to avoid ptrace(PTRACE_PEEKMTETAGS) succeeding on
!PROT_MTE mappings pointing to the zero page, change the
__access_remote_tags() check to (vm_flags & VM_MTE) instead of
PG_mte_tagged.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Fixes: 34bfeea4 ("arm64: mte: Clear the tags when a page is mapped in user-space with PROT_MTE")
Cc: <stable@vger.kernel.org> # 5.10.x
Cc: Will Deacon <will@kernel.org>
Reported-by: Luis Machado <luis.machado@linaro.org>
Tested-by: Luis Machado <luis.machado@linaro.org>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20210210180316.23654-1-catalin.marinas@arm.com

User reported that btrfs-progs misc-tests/028-superblock-recover fails:

      [TEST/misc]   028-superblock-recover
  unexpected success: mounted fs with corrupted superblock
  test failed for case 028-superblock-recover

The test case expects that a broken image with bad superblock will be
rejected to be mounted. However, the test image just passed csum check
of superblock and was successfully mounted.

Commit 55fc29be ("btrfs: use cached value of fs_info::csum_size
everywhere") replaces all calls to btrfs_super_csum_size by
fs_info::csum_size. The calls include the place where fs_info->csum_size
is not initialized. So btrfs_check_super_csum() passes because memcmp()
with len 0 always returns 0.

Fix it by caching csum size in btrfs_fs_info::csum_size once we know the
csum type in superblock is valid in open_ctree().

Link: https://github.com/kdave/btrfs-progs/issues/250
Fixes: 55fc29be ("btrfs: use cached value of fs_info::csum_size everywhere")
Signed-off-by: Su Yue <l@damenly.su>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>