Since the subpage support of scrub, scrub_sector is in fact just
representing one sector.

Thus the name scrub_page is no longer correct, rename it to
scrub_sector.

This also involves the following renames:

- spage -> sector
  Normally we would just replace "page" with "sector" and result
  something like "ssector".
  But the repeating 's' is not really eye friendly.

  So here we just simple use "sector", as there is nothing from MM layer
  called "sector" to cause any confusion.

- scrub_parity::spages -> sectors_list
  Normally we use plural to indicate an array, not a list.
  Rename it to @sectors_list to be more explicit on the list part.

- Also reformat and update comments that get changed
Signed-off-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The following will be renamed in this patch:

- scrub_block::pagev -> sectors

- scrub_block::page_count -> sector_count

- SCRUB_MAX_PAGES_PER_BLOCK -> SCRUB_MAX_SECTORS_PER_BLOCK

- page_num -> sector_num to iterate scrub_block::sectors

For now scrub_page is not yet renamed to keep the patch reasonable and
it will be updated in a followup.
Signed-off-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The function btrfs_read_buffer() is useless, it just calls
btree_read_extent_buffer_pages() with exactly the same arguments.

So remove it and rename btree_read_extent_buffer_pages() to
btrfs_read_extent_buffer(), which is a shorter name, has the "btrfs_"
prefix (since it's used outside disk-io.c) and the name is clear enough
about what it does.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The comment at the top of read_block_for_search() is very outdated, as it
refers to the blocking versus spinning path locking modes. We no longer
have these two locking modes after we switched the btree locks from custom
code to rw semaphores. So update the comment to stop referring to the
blocking mode and put it more up to date.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When reading a btree node (or leaf), at read_block_for_search(), if we
can't find its extent buffer in the cache (the fs_info->buffer_radix
radix tree), then we unlock all upper level nodes before reading the
btree node/leaf from disk, to prevent blocking other tasks for too long.

However if we find that the extent buffer is in the cache but it is not
up to date, we don't unlock upper level nodes before reading it from disk,
potentially blocking other tasks on upper level nodes for too long.

Fix this inconsistent behaviour by unlocking upper level nodes if we need
to read a node/leaf from disk because its in-memory extent buffer is not
up to date. If we unlocked upper level nodes then we must return -EAGAIN
to the caller, just like the case where the extent buffer is not cached in
memory. And like that case, we determine if upper level nodes are locked
by checking only if the parent node is locked - if it isn't, then no other
upper level nodes are locked.

This is actually a rare case, as if we have an extent buffer in memory,
it typically has the uptodate flag set and passes all the checks done by
btrfs_buffer_uptodate().
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When reading a btree node, at read_block_for_search(), if we don't find
the node's (or leaf) extent buffer in the cache, we will read it from
disk. Since that requires waiting on IO, we release all upper level nodes
from our path before reading the target node/leaf, and then return -EAGAIN
to the caller, which will make the caller restart the while btree search.

However we are causing the restart of btree search even for cases where
it is not necessary:

1) We have a path with ->skip_locking set to true, typically when doing
   a search on a commit root, so we are never holding locks on any node;

2) We are doing a read search (the "ins_len" argument passed to
   btrfs_search_slot() is 0), or we are doing a search to modify an
   existing key (the "cow" argument passed to btrfs_search_slot() has
   a value of 1 and "ins_len" is 0), in which case we never hold locks
   for upper level nodes;

3) We are doing a search to insert or delete a key, in which case we may
   or may not have upper level nodes locked. That depends on the current
   minimum write lock levels at btrfs_search_slot(), if we had to split
   or merge parent nodes, if we had to COW upper level nodes and if
   we ever visited slot 0 of an upper level node. It's still common to
   not have upper level nodes locked, but our current node must be at
   least at level 1, for insertions, or at least at level 2 for deletions.
   In these cases when we have locks on upper level nodes, they are always
   write locks.

These cases where we are not holding locks on upper level nodes far
outweigh the cases where we are holding locks, so it's completely wasteful
to retry the whole search when we have no upper nodes locked.

So change the logic to not return -EAGAIN, and make the caller retry the
search, when we don't have the parent node locked - when it's not locked
it means no other upper level nodes are locked as well.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

btrfs_new_inode() inherits the inode flags from the parent directory and
the mount options _after_ we fill the inode item. This works because all
of the callers of btrfs_new_inode() make further changes to the inode
and then call btrfs_update_inode(). It'd be better to fully initialize
the inode once to avoid the extra update, so as a first step, set the
inode flags _before_ filling the inode item.
Reviewed-by: NSweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Every call of btrfs_new_inode() is immediately preceded by a call to
btrfs_get_free_objectid(). Since getting an inode number is part of
creating a new inode, this is better off being moved into
btrfs_new_inode(). While we're here, get rid of the comment about
reclaiming inode numbers, since we only did that when using the ino
cache, which was removed by commit 5297199a ("btrfs: remove inode
number cache feature").
Reviewed-by: NSweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

For everything other than a subvolume root inode, we get the parent
objectid from the parent directory. For the subvolume root inode, the
parent objectid is the same as the inode's objectid. We can find this
within btrfs_new_inode() instead of passing it.
Reviewed-by: NSweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The passed dentry already contains the name.
Reviewed-by: NSweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Commit 4a8b34af ("btrfs: handle ACLs on idmapped mounts") added this
parameter but didn't use it. __btrfs_set_acl() is the low-level helper
that writes an ACL to disk. The higher-level btrfs_set_acl() is the one
that translates the ACL based on the user namespace.
Reviewed-by: NSweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

btrfs_new_inode() already returns an inode with nlink set to 1 (via
inode_init_always()). Get rid of the unnecessary set.
Reviewed-by: NSweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

new_inode() always returns an inode with i_blocks and i_bytes set to 0
(via inode_init_always()). Remove the unnecessary call to
inode_set_bytes() in btrfs_new_inode().
Reviewed-by: NSweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

btrfs_new_inode() always returns an inode with i_size and disk_i_size
set to 0 (via inode_init_always() and btrfs_alloc_inode(),
respectively). Remove the unnecessary calls to btrfs_i_size_write() in
btrfs_mkdir() and btrfs_create_subvol_root().
Reviewed-by: NSweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This is a trivial wrapper around btrfs_add_link(). The only thing it
does other than moving arguments around is translating a > 0 return
value to -EEXIST. As far as I can tell, btrfs_add_link() won't return >
0 (and if it did, the existing callsites in, e.g., btrfs_mkdir() would
be broken). The check itself dates back to commit 2c90e5d6 ("Btrfs:
still corruption hunting"), so it's probably left over from debugging.
Let's just get rid of btrfs_add_nondir().
Reviewed-by: NSweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When btrfs_qgroup_inherit(), btrfs_alloc_tree_block, or
btrfs_insert_root() fail in create_subvol(), we return without freeing
anon_dev. Reorganize the error handling in create_subvol() to fix this.
Reviewed-by: NSweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

btrfs_rename() and btrfs_rename_exchange() don't account for enough
items. Replace the incorrect explanations with a specific breakdown of
the number of items and account them accurately.

Note that this glosses over RENAME_WHITEOUT because the next commit is
going to rework that, too.
Reviewed-by: NSweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

__btrfs_unlink_inode() calls btrfs_update_inode() on the parent
directory in order to update its size and sequence number. Make sure we
account for it.
Reviewed-by: NSweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Merge tag 'driver-core-5.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core fixes from Greg KH:
 "Here is one fix, and three documentation updates for 5.18-rc7.

  The fix is for the firmware loader which resolves a long-reported
  problem where the credentials of the firmware loader could be set to a
  userspace process without enough permissions to actually load the
  firmware image. Many Android vendors have been reporting this for
  quite some time.

  The documentation updates are for the embargoed-hardware-issues.rst
  file to add a new entry, change an existing one, and sort the list to
  make changes easier in the future.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'driver-core-5.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  Documentation/process: Update ARM contact for embargoed hardware issues
  Documentation/process: Add embargoed HW contact for Ampere Computing
  Documentation/process: Make groups alphabetical and use tabs consistently
  firmware_loader: use kernel credentials when reading firmware

Pull char/misc driver fixes from Greg KH:
 "Here are two small driver fixes for 5.18-rc7 that resolve reported
  problems:

   - slimbus driver irq bugfix

   - interconnect sync state bugfix

  Both of these have been in linux-next with no reported problems"

* tag 'char-misc-5.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  slimbus: qcom: Fix IRQ check in qcom_slim_probe
  interconnect: Restore sync state by ignoring ipa-virt in provider count

Pull tty/serial driver fixes from Greg KH:
 "Here are some small tty n_gsm and serial driver fixes for 5.18-rc7
  that resolve reported problems. They include:

   - n_gsm fixes for reported issues

   - 8250_mtk driver fixes for some platforms

   - fsl_lpuart driver fix for reported problem.

   - digicolor driver fix for reported problem.

  All have been in linux-next for a while with no reported problems"

* tag 'tty-5.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  fsl_lpuart: Don't enable interrupts too early
  tty: n_gsm: fix invalid gsmtty_write_room() result
  tty: n_gsm: fix mux activation issues in gsm_config()
  tty: n_gsm: fix buffer over-read in gsm_dlci_data()
  serial: 8250_mtk: Fix register address for XON/XOFF character
  serial: 8250_mtk: Make sure to select the right FEATURE_SEL
  serial: 8250_mtk: Fix UART_EFR register address
  tty/serial: digicolor: fix possible null-ptr-deref in digicolor_uart_probe()

Pull USB fixes from Greg KH:
 "Here are some small fixes for reported issues with some USB drivers.
  They include:

   - xhci fixes for xhci-mtk platform driver

   - typec driver fixes for reported problems.

   - cdc-wdm read-stuck fix

   - gadget driver fix for reported race condition

   - new usb-serial driver ids

  All of these have been in linux-next with no reported problems"

* tag 'usb-5.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usb: xhci-mtk: remove bandwidth budget table
  usb: xhci-mtk: fix fs isoc's transfer error
  usb: gadget: fix race when gadget driver register via ioctl
  usb: typec: tcpci_mt6360: Update for BMC PHY setting
  usb: gadget: uvc: allow for application to cleanly shutdown
  usb: typec: tcpci: Don't skip cleanup in .remove() on error
  usb: cdc-wdm: fix reading stuck on device close
  USB: serial: qcserial: add support for Sierra Wireless EM7590
  USB: serial: option: add Fibocom MA510 modem
  USB: serial: option: add Fibocom L610 modem
  USB: serial: pl2303: add device id for HP LM930 Display

Pull powerpc fix from Michael Ellerman:

 - Fix KVM PR on 32-bit, which was broken by some MMU code refactoring.

Thanks to: Alexander Graf, and Matt Evans.

* tag 'powerpc-5.18-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  KVM: PPC: Book3S PR: Enable MSR_DR for switch_mmu_context()

Pull x86 fix from Thomas Gleixner:
 "A single fix for the handling of unpopulated sub-pmd spaces.

  The copy & pasta from the corresponding s390 code screwed up the
  address calculation for marking the sub-pmd ranges via memset by
  omitting the ALIGN_DOWN() to calculate the proper start address.

  It's a mystery why this code is not generic and shared because there
  is nothing architecture specific in there, but that's too intrusive
  for a backportable fix"

* tag 'x86-urgent-2022-05-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mm: Fix marking of unused sub-pmd ranges

Pull scheduler fix from Thomas Gleixner:
 "The recent expansion of the sched switch tracepoint inserted a new
  argument in the middle of the arguments. This reordering broke BPF
  programs which relied on the old argument list.

  While tracepoints are not considered stable ABI, it's not trivial to
  make BPF cope with such a change, but it's being worked on. For now
  restore the original argument order and move the new argument to the
  end of the argument list"

* tag 'sched-urgent-2022-05-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/tracing: Append prev_state to tp args instead

Pull irq fix from Thomas Gleixner:
 "A single fix for a recent (introduced in 5.16) regression in the core
  interrupt code.

  The consolidation of the interrupt handler invocation code added an
  unconditional warning when generic_handle_domain_irq() is invoked from
  outside hard interrupt context. That's overbroad as the requirement
  for invoking these handlers in hard interrupt context is only required
  for certain interrupt types. The subsequently called code already
  contains a warning which triggers conditionally for interrupt chips
  which indicate this requirement in their properties.

  Remove the overbroad one"

* tag 'irq-urgent-2022-05-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq: Remove WARN_ON_ONCE() in generic_handle_domain_irq()

Merge tag 'perf-tools-fixes-for-v5.18-2022-05-14' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux

Pull perf tools fixes from Arnaldo Carvalho de Melo:

 - Fix two NDEBUG warnings in 'perf bench numa'

 - Fix ARM coresight `perf test` failure

 - Sync linux/kvm.h with the kernel sources

 - Add James and Mike as Arm64 performance events reviewers

* tag 'perf-tools-fixes-for-v5.18-2022-05-14' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux:
  MAINTAINERS: Add James and Mike as Arm64 performance events reviewers
  tools headers UAPI: Sync linux/kvm.h with the kernel sources
  perf tests: Fix coresight `perf test` failure.
  perf bench: Fix two numa NDEBUG warnings

Pull more drm fixes from Dave Airlie:
 "Turns out I was right, some fixes hadn't made it to me yet. The vmwgfx
  ones also popped up later, but all seem like bad enough things to fix.
  The dma-buf, vc4 and nouveau ones are all pretty small.

  The fbdev fixes are a bit more complicated: a fix to cleanup fbdev
  devices properly, uncovered some use-after-free bugs in existing
  drivers. Then the fix for those bugs wasn't correct. This reverts that
  fix, and puts the proper fixes in place in the drivers to avoid the
  use-after-frees.

  This has had a fair number of eyes on it at this stage, and I'm
  confident enough that it puts things in the right place, and is less
  dangerous than reverting our way out of the initial change at this
  stage.

  fbdev:
   - revert NULL deref fix that turned into a use-after-free
   - prevent use-after-free in fbdev
   - efifb/simplefb/vesafb: fix cleanup paths to avoid use-after-frees

  dma-buf:
   - fix panic in stats setup

  vc4:
   - fix hdmi build

  nouveau:
   - tegra iommu present fix
   - fix leak in backlight name

  vmwgfx:
   - Black screen due to fences using FIFO checks on SVGA3
   - Random black screens on boot due to uninitialized drm_mode_fb_cmd2
   - Hangs on SVGA3 due to command buffers being used with gbobjects"

* tag 'drm-fixes-2022-05-14' of git://anongit.freedesktop.org/drm/drm:
  drm/vmwgfx: Disable command buffers on svga3 without gbobjects
  drm/vmwgfx: Initialize drm_mode_fb_cmd2
  drm/vmwgfx: Fix fencing on SVGAv3
  drm/vc4: hdmi: Fix build error for implicit function declaration
  dma-buf: call dma_buf_stats_setup after dmabuf is in valid list
  fbdev: efifb: Fix a use-after-free due early fb_info cleanup
  drm/nouveau: Fix a potential theorical leak in nouveau_get_backlight_name()
  drm/nouveau/tegra: Stop using iommu_present()
  fbdev: vesafb: Cleanup fb_info in .fb_destroy rather than .remove
  fbdev: efifb: Cleanup fb_info in .fb_destroy rather than .remove
  fbdev: simplefb: Cleanup fb_info in .fb_destroy rather than .remove
  fbdev: Prevent possible use-after-free in fb_release()
  Revert "fbdev: Make fb_release() return -ENODEV if fbdev was unregistered"

Multiple fixes to fbdev to address a regression at unregistration, an
iommu detection improvement for nouveau, a memory leak fix for nouveau,
pointer dereference fix for dma_buf_file_release(), and a build breakage
fix for vc4
Signed-off-by: NDave Airlie <airlied@redhat.com>

From: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220513073044.ymayac7x7bzatrt7@houat

Merge tag 'vmwgfx-drm-fixes-5.18-2022-05-13' of https://gitlab.freedesktop.org/zack/vmwgfx into drm-fixes

vmwgfx fixes for:
- Black screen due to fences using FIFO checks on SVGA3
- Random black screens on boot due to uninitialized drm_mode_fb_cmd2
- Hangs on SVGA3 due to command buffers being used with gbobjects
Signed-off-by: NDave Airlie <airlied@redhat.com>
From: Zack Rusin <zackr@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/a1d32799e4c74b8540216376d7576bb783ca07ba.camel@vmware.com

Pull gfs2 fixes from Andreas Gruenbacher:
 "We've finally identified commit dc732906 ("gfs2: Introduce flag
  for glock holder auto-demotion") to be the other cause of the
  filesystem corruption we've been seeing. This feature isn't strictly
  necessary anymore, so we've decided to stop using it for now.

  With this and the gfs_iomap_end rounding fix you've already seen
  ("gfs2: Fix filesystem block deallocation for short writes" in this
  pull request), we're corruption free again now.

   - Fix filesystem block deallocation for short writes.

   - Stop using glock holder auto-demotion for now.

   - Get rid of buffered writes inefficiencies due to page faults being
     disabled.

   - Minor other cleanups"

* tag 'gfs2-v5.18-rc4-fix3' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
  gfs2: Stop using glock holder auto-demotion for now
  gfs2: buffered write prefaulting
  gfs2: Align read and write chunks to the page cache
  gfs2: Pull return value test out of should_fault_in_pages
  gfs2: Clean up use of fault_in_iov_iter_{read,write}able
  gfs2: Variable rename
  gfs2: Fix filesystem block deallocation for short writes

We're having unresolved issues with the glock holder auto-demotion mechanism
introduced in commit dc732906.  This mechanism was assumed to be essential
for avoiding frequent short reads and writes until commit 296abc0d
("gfs2: No short reads or writes upon glock contention").  Since then,
when the inode glock is lost, it is simply re-acquired and the operation
is resumed.  This means that apart from the performance penalty, we
might as well drop the inode glock before faulting in pages, and
re-acquire it afterwards.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>

In gfs2_file_buffered_write, to increase the likelihood that all the
user memory we're trying to write will be resident in memory, carry out
the write in chunks and fault in each chunk of user memory before trying
to write it.  Otherwise, some workloads will trigger frequent short
"internal" writes, causing filesystem blocks to be allocated and then
partially deallocated again when writing into holes, which is wasteful
and breaks reservations.

Neither the chunked writes nor any of the short "internal" writes are
user visible.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>

Pull SCSI fixes from James Bottomley:
 "Four fixes, all in drivers.

  These patches mosly fix error legs and exceptional conditions
  (scsi_dh_alua, qla2xxx). The lpfc fixes are for coding issues with
  lpfc features"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: lpfc: Correct BDE DMA address assignment for GEN_REQ_WQE
  scsi: lpfc: Fix split code for FLOGI on FCoE
  scsi: qla2xxx: Fix missed DMA unmap for aborted commands
  scsi: scsi_dh_alua: Properly handle the ALUA transitioning state

Align the chunks that reads and writes are carried out in to the page
cache rather than the user buffers.  This will be more efficient in
general, especially for allocating writes.  Optimizing the case that the
user buffer is gfs2 backed isn't very useful; we only need to make sure
we won't deadlock.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>

Pull the return value test of the previous read or write operation out
of should_fault_in_pages().  In a following patch, we'll fault in pages
before the I/O and there will be no return value to check.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>

No need to store the return value of the fault_in functions in separate
variables.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>

Instead of counting the number of bytes read from the filesystem,
functions gfs2_file_direct_read and gfs2_file_read_iter count the number
of bytes written into the user buffer.  Conversely, functions
gfs2_file_direct_write and gfs2_file_buffered_write count the number of
bytes read from the user buffer.  This is nothing but confusing, so
change the read functions to count how many bytes they have read, and
the write functions to count how many bytes they have written.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>

When a write cannot be carried out in full, gfs2_iomap_end() releases
blocks that have been allocated for this write but haven't been used.

To compute the end of the allocation, gfs2_iomap_end() incorrectly
rounded the end of the attempted write down to the next block boundary
to arrive at the end of the allocation.  It would have to round up, but
the end of the allocation is also available as iomap->offset +
iomap->length, so just use that instead.

In addition, use round_up() for computing the start of the unused range.

Fixes: 64bc06bb ("gfs2: iomap buffered write support")
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>