Change the request initialisation function to return an error code so that
the network filesystem can return a failure (ENOMEM, for example).

This will also allow ceph to abort a ->readahead() op if the server refuses
to give it a cap allowing local caching from within the netfslib framework
(errors aren't passed back through ->readahead(), so returning, say,
-ENOBUFS will cause the op to be aborted).
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/164678212401.1200972.16537041523832944934.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692905398.2099075.5238033621684646524.stgit@warthog.procyon.org.uk/ # v3

Pass start and len to the rreq allocator. This should ensure that the
fields are set so that ->init_request() can use them.

Also add a parameter to indicates the origin of the request.  Ceph can use
this to tell whether to get caps.

Changes
=======
ver #3)
 - Change the author to me as Jeff feels that most of the patch is my
   changes now.

ver #2)
 - Show the request origin in the netfs_rreq tracepoint.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Co-developed-by: David Howells <dhowells@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/164622989020.3564931.17517006047854958747.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678208569.1200972.12153682697842916557.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692904155.2099075.14717645623034355995.stgit@warthog.procyon.org.uk/ # v3

Adjust the netfs_failure tracepoint to indicate a subrequest number of -1
when it's a full-request failure unrelated to any particular subrequest,
such as a failure to encrypt its data buffer.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/164623001948.3564931.2353852999649380059.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678204587.1200972.14893513018190383961.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692903233.2099075.15414355147237641274.stgit@warthog.procyon.org.uk/ # v3

Add refcount tracing for the netfs_io_subrequest structure.

Changes
=======
ver #3)
 - Switch 'W=' to 'R=' in the traceline to match other request debug IDs.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/164622998584.3564931.5052255990645723639.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678202603.1200972.14726007419792315578.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692901860.2099075.4845820886851239935.stgit@warthog.procyon.org.uk/ # v3

Add refcount tracing for the netfs_io_request structure.

Changes
=======
ver #3)
 - Switch 'W=' to 'R=' in the traceline to match other request debug IDs.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/164622997668.3564931.14456171619219324968.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678200943.1200972.7241495532327787765.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692900920.2099075.11847712419940675791.stgit@warthog.procyon.org.uk/ # v3

Adjust the netfs_rreq tracepoint to include the origin of the request and
to increase the size of the "what trace" output strings by a character so
that "ENCRYPT" and "DECRYPT" will fit without abbreviation.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/164622996715.3564931.4252319907990358129.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678199468.1200972.17275585970238114726.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692898684.2099075.12153225958137716567.stgit@warthog.procyon.org.uk/ # v3

Split netfs_io_* object handling out into a file that's going to contain
object allocation, get and put routines.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/164622995118.3564931.6089530629052064470.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678197044.1200972.11511937252083343775.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692894693.2099075.7831091294248735173.stgit@warthog.procyon.org.uk/ # v3

Adjust helper function names and comments after mass rename of
struct netfs_read_*request to struct netfs_io_*request.

Changes
=======
ver #2)
 - Make the changes in the docs also.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/164622992433.3564931.6684311087845150271.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678196111.1200972.5001114956865989528.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692892567.2099075.13895804222087028813.stgit@warthog.procyon.org.uk/ # v3

Rename netfs_read_*request to netfs_io_*request so that the same structures
can be used for the write helpers too.

perl -p -i -e 's/netfs_read_(request|subrequest)/netfs_io_$1/g' \
   `git grep -l 'netfs_read_\(sub\|\)request'`
perl -p -i -e 's/nr_rd_ops/nr_outstanding/g' \
   `git grep -l nr_rd_ops`
perl -p -i -e 's/nr_wr_ops/nr_copy_ops/g' \
   `git grep -l nr_wr_ops`
perl -p -i -e 's/netfs_read_source/netfs_io_source/g' \
   `git grep -l 'netfs_read_source'`
perl -p -i -e 's/netfs_io_request_ops/netfs_request_ops/g' \
   `git grep -l 'netfs_io_request_ops'`
perl -p -i -e 's/init_rreq/init_request/g' \
   `git grep -l 'init_rreq'`
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/164622988070.3564931.7089670190434315183.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678195157.1200972.366609966927368090.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692891535.2099075.18435198075367420588.stgit@warthog.procyon.org.uk/ # v3

netfs has a number of lists of symbols for use in tracing, listed in an
enum and then listed again in a symbol->string mapping for use with
__print_symbolic().  This is, however, redundant.

Instead, use the symbol->string mapping list to also generate the enum
where the enum is in the same file.

Changes
=======
ver #3)
 - #undef EM and E_ at the end of the trace file[1].
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/c2f4b3dc107b106e04c48f54945a12715cccfdf3.camel@redhat.com/ [1]
Link: https://lore.kernel.org/r/164622980839.3564931.5673300162465266909.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678192454.1200972.4428834328108580460.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/CALF+zOkB38_MB5QwNUtqTU4WjMaLUJ5+Piwsn3pMxkO3d4J7Kg@mail.gmail.com/ # v2
Link: https://lore.kernel.org/r/164692890614.2099075.12960653141802151575.stgit@warthog.procyon.org.uk/ # v3

Export fscache_end_operation() to avoid code duplication.

Besides, considering the paired fscache_begin_read_operation() is
already exported, it shall make sense to also export
fscache_end_operation().
Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/20220302125134.131039-2-jefflexu@linux.alibaba.com/ # Jeffle's v4
Link: https://lore.kernel.org/r/164622971432.3564931.12184135678781328146.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678190346.1200972.7453733431978569479.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692888334.2099075.5166283293894267365.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/20220316131723.111553-2-jefflexu@linux.alibaba.com/ # v5

To make the logs more readable such as for log likes:

ceph: will move 00000000a42b796b to split realm 100000003ed 000000007146df45

With this it will always show the inode numbers instead the inode
addresses.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

This will reduce very possible but unnecessary frequently memory
allocate/free in this loop.

URL: https://tracker.ceph.com/issues/44100Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

The global snaprealm would be created and then destroyed immediately
every time when updating it.

URL: https://tracker.ceph.com/issues/54362Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Ceph have removed this macro and the 0x3 will be use for global dummy
snaprealm.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Xiubo has been doing stellar kernel work lately, and has graciously
volunteered to help with maintainer duties. Add him on as co-maintainer
in for ceph.ko and libceph.ko.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Use a list instead of recursion to avoid possible stack overflow.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

We will only track the uppest parent snapshot realm from which we
need to rebuild the snapshot contexts _downward_ in hierarchy. For
all the others having no new snapshot we will do nothing.

This fix will avoid calling ceph_queue_cap_snap() on some inodes
inappropriately. For example, with the code in mainline, suppose there
are 2 directory hierarchies (with 6 directories total), like this:

/dir_X1/dir_X2/dir_X3/
/dir_Y1/dir_Y2/dir_Y3/

Firstly, make a snapshot under /dir_X1/dir_X2/.snap/snap_X2, then make a
root snapshot under /.snap/root_snap. Every time we make snapshots under
/dir_Y1/..., the kclient will always try to rebuild the snap context for
snap_X2 realm and finally will always try to queue cap snaps for dir_Y2
and dir_Y3, which makes no sense.

That's because the snap_X2's seq is 2 and root_snap's seq is 3. So when
creating a new snapshot under /dir_Y1/... the new seq will be 4, and
the mds will send the kclient a snapshot backtrace in _downward_
order: seqs 4, 3.

When ceph_update_snap_trace() is called, it will always rebuild the from
the last realm, that's the root_snap. So later when rebuilding the snap
context, the current logic will always cause it to rebuild the snap_X2
realm and then try to queue cap snaps for all the inodes related in that
realm, even though it's not necessary.

This is accompanied by a lot of these sorts of dout messages:

    "ceph:  queue_cap_snap 00000000a42b796b nothing dirty|writing"

Fix the logic to avoid this situation.

Also, the 'invalidate' word is not precise here. In actuality, it will
cause a rebuild of the existing snapshot contexts or just build
non-existent ones. Rename it to 'rebuild_snapcs'.

URL: https://tracker.ceph.com/issues/44100Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

This potentially will cause a bug in future if using an old ceph
version that sends a smaller inode struct, which can cause some members
to be skipped in handle_reply.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

There could be huge number of capsnaps around at any given time. On
x86_64 the structure is 248 bytes, which will be rounded up to 256 bytes
by kzalloc. Move this to a dedicated slabcache to save 8 bytes for each.

[ jlayton: use kmem_cache_zalloc ]
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Problem:
Some directory vxattrs (e.g. ceph.dir.pin.random) are governed by
information that isn't necessarily shared with the client. Add support
for the new GETVXATTR operation, which allows the client to query the
MDS directly for vxattrs.
When the client is queried for a vxattr that doesn't have a special
handler, have it issue a GETVXATTR to the MDS directly.

Solution:
Adds new getvxattr op to fetch ceph.dir.pin*, ceph.dir.layout* and
ceph.file.layout* vxattrs.
If the entire layout for a dir or a file is being set, then it is
expected that the layout be set in standard JSON format. Individual
field value retrieval is not wrapped in JSON. The JSON format also
applies while setting the vxattr if the entire layout is being set in
one go.
As a temporary measure, setting a vxattr can also be done in the old
format. The old format will be deprecated in the future.

URL: https://tracker.ceph.com/issues/51062Signed-off-by: Milind Changire <mchangir@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Just call set_in_bvec in the non-conditional part.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

inode->i_mutex has been replaced with inode->i_rwsem long ago. Fix
comments still mentioning i_mutex.
Signed-off-by: hongnanli <hongnan.li@linux.alibaba.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

If MDS return ESTALE, that means the MDS has already iterated all the
possible active MDSes including the auth MDS or the inode is under
purging. No need to retry in auth MDS and will just return ESTALE
directly. Retrying in this situation will cause an infinite loop.

Also, retrying like this would prevent the kernel VFS layer ESTALE
handling from working properly. An ESTALE error is usually an indication
that the dcache is wrong, so we want to allow the VFS to redo the lookup
and revalidate it properly.

URL: https://tracker.ceph.com/issues/53504Signed-off-by: Xiubo Li <xiubli@redhat.com>
Acked-by: Greg Farnum <gfarnum@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Currently, we only wake the waiters if we got a req->r_target_inode
out of the reply. In the case where the create fails though, we may not
have one.

If there is a non-zero result from the create, then ensure that we wake
anything waiting on the inode after we shut it down.

URL: https://tracker.ceph.com/issues/54067Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

If we haven't received a reply to an async create request, then we don't
want to send any cap messages to the MDS for that inode yet.

Just have ceph_check_caps  and __kick_flushing_caps return without doing
anything, and have ceph_write_inode wait for the reply if we were asked
to wait on the inode writeback.

URL: https://tracker.ceph.com/issues/54107Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Patrick Donnelly <pdonnell@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

...and instead just pass the wait function on the stack.

Make ceph_mdsc_wait_request non-static, and add an argument for wait for
completion. Then have ceph_lock_message call ceph_mdsc_submit_request,
and ceph_mdsc_wait_request and pass in the pointer to
ceph_lock_wait_for_completion.

While we're in there, rearrange some fields in ceph_mds_request, so we
save a total of 24 bytes per.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

If a ceph file is made up of inline data, uninline that in the ceph_open()
rather than in ceph_page_mkwrite(), ceph_write_iter(), ceph_fallocate() or
ceph_write_begin().

This makes it easier to convert to using the netfs library for VM write
hooks.

Should this also take the inode lock for the duration on uninlining to
prevent a race with truncation?

[ jlayton: fix up folio locking, update i_inline_version after write ]
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Make ceph_netfs_issue_op() handle inlined data on page 0.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

One fewer pointer dereference, and in the future we may not be able to
count on the mapping pointer being populated (e.g. in the DIO case).
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Pull irq fix from Thomas Gleixner:
 "A single fix for a regression caused by the recent PCI/MSI rework
  which resulted in a recursive locking problem in the VMD driver.

  The cure is to cache the relevant information upfront instead of
  retrieving it at runtime"

* tag 'irq-urgent-2022-02-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  PCI: vmd: Prevent recursive locking on interrupt allocation

Pull dma-mapping fix from Christoph Hellwig:

 - fix a swiotlb info leak (Halil Pasic)

* tag 'dma-mapping-5.17-1' of git://git.infradead.org/users/hch/dma-mapping:
  swiotlb: fix info leak with DMA_FROM_DEVICE

Pull pin control fixes from Linus Walleij:

 - Fix some drive strength and pull-up code in the K210 driver.

 - Add the Alder Lake-M ACPI ID so it starts to work properly.

 - Use a static name for the StarFive GPIO irq_chip, forestalling an
   upcoming fixes series from Marc Zyngier.

 - Fix an ages old bug in the Tegra 186 driver where we were indexing at
   random into struct and being lucky getting the right member.

* tag 'pinctrl-v5-17-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  gpio: tegra186: Fix chip_data type confusion
  pinctrl: starfive: Use a static name for the GPIO irq_chip
  pinctrl: tigerlake: Revert "Add Alder Lake-M ACPI ID"
  pinctrl: k210: Fix bias-pull-up
  pinctrl: fix loop in k210_pinconf_get_drive()

Pull tracing fixes from Steven Rostedt:

 - rtla (Real-Time Linux Analysis tool):
    - fix typo in man page
    - Update API -e to -E before it is released
    - Error message fix and memory leak fix

 - Partially uninline trace event soft disable to shrink text

 - Fix function graph start up test

 - Have triggers affect the trace instance they are in and not top level

 - Have osnoise sleep in the units it says it uses

 - Remove unused ftrace stub function

 - Remove event probe redundant info from event in the buffer

 - Fix group ownership setting in tracefs

 - Ensure trace buffer is minimum size to prevent crashes

* tag 'trace-v5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  rtla/osnoise: Fix error message when failing to enable trace instance
  rtla/osnoise: Free params at the exit
  rtla/hist: Make -E the short version of --entries
  tracing: Fix selftest config check for function graph start up test
  tracefs: Set the group ownership in apply_options() not parse_options()
  tracing/osnoise: Make osnoise_main to sleep for microseconds
  ftrace: Remove unused ftrace_startup_enable() stub
  tracing: Ensure trace buffer is at least 4096 bytes large
  tracing: Uninline trace_trigger_soft_disabled() partly
  eprobes: Remove redundant event type information
  tracing: Have traceon and traceoff trigger honor the instance
  tracing: Dump stacktrace trigger to the corresponding instance
  rtla: Fix systme -> system typo on man page

Pull memblock fix from Mike Rapoport:
 "Use kfree() to release kmalloced memblock regions

  memblock.{reserved,memory}.regions may be allocated using kmalloc()
  in memblock_double_array(). Use kfree() to release these kmalloced
  regions"

* tag 'fixes-2022-02-26' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock:
  memblock: use kfree() to release kmalloced memblock regions

Merge misc fixes from Andrew Morton:
 "12 patches.

  Subsystems affected by this patch series: MAINTAINERS, mailmap, memfd,
  and mm (hugetlb, kasan, hugetlbfs, pagemap, selftests, memcg, and
  slab)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  selftests/memfd: clean up mapping in mfd_fail_write
  mailmap: update Roman Gushchin's email
  MAINTAINERS, SLAB: add Roman as reviewer, git tree
  MAINTAINERS: add Shakeel as a memcg co-maintainer
  MAINTAINERS: remove Vladimir from memcg maintainers
  MAINTAINERS: add Roman as a memcg co-maintainer
  selftest/vm: fix map_fixed_noreplace test failure
  mm: fix use-after-free bug when mm->mmap is reused after being freed
  hugetlbfs: fix a truncation issue in hugepages parameter
  kasan: test: prevent cache merging in kmem_cache_double_destroy
  mm/hugetlb: fix kernel crash with hugetlb mremap
  MAINTAINERS: add sysctl-next git tree

Pull RISC-V fixes from Palmer Dabbelt:

 - A fix for the K210 sdcard defconfig, to avoid using a
   fixed delay for the root FS

 - A fix to make sure there's a proper call frame for
   trace_hardirqs_{on,off}().

* tag 'riscv-for-linus-5.17-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: fix oops caused by irqsoff latency tracer
  riscv: fix nommu_k210_sdcard_defconfig

Pull xfs fixes from Darrick Wong:
 "Nothing exciting, just more fixes for not returning sync_filesystem
  error values (and eliding it when it's not necessary).

  Summary:

   - Only call sync_filesystem when we're remounting the filesystem
     readonly readonly, and actually check its return value"

* tag 'xfs-5.17-fixes-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: only bother with sync_filesystem during readonly remount

Running the memfd script ./run_hugetlbfs_test.sh will often end in error
as follows:

    memfd-hugetlb: CREATE
    memfd-hugetlb: BASIC
    memfd-hugetlb: SEAL-WRITE
    memfd-hugetlb: SEAL-FUTURE-WRITE
    memfd-hugetlb: SEAL-SHRINK
    fallocate(ALLOC) failed: No space left on device
    ./run_hugetlbfs_test.sh: line 60: 166855 Aborted                 (core dumped) ./memfd_test hugetlbfs
    opening: ./mnt/memfd
    fuse: DONE

If no hugetlb pages have been preallocated, run_hugetlbfs_test.sh will
allocate 'just enough' pages to run the test.  In the SEAL-FUTURE-WRITE
test the mfd_fail_write routine maps the file, but does not unmap.  As a
result, two hugetlb pages remain reserved for the mapping.  When the
fallocate call in the SEAL-SHRINK test attempts allocate all hugetlb
pages, it is short by the two reserved pages.

Fix by making sure to unmap in mfd_fail_write.

Link: https://lkml.kernel.org/r/20220219004340.56478-1-mike.kravetz@oracle.comSigned-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>