Function need_sync is supposed to determine if a qd element needs to be
synced. If the "change" (qd_change) is zero, it does not need to be
synced because there's literally no change in the value. Before this
patch need_sync returned false if value < 0. That should be <= 0.
This patch changes the check to <=.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

This patch simplifies function need_sync by eliminating a variable in
favor of just returning the appropriate value as soon as we know it.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Function gfs2_write_disk_quota checks if its write overflows onto
another page, and if so, does a second write. Before this patch it kept
two variables for this, but only one is needed. This patch simplifies
it by eliminating pg_oflow.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Function gfs2_write_buf_to_page uses variable done to exit its loop, but
it's unnecessary if we just code an infinite loop and exit when we need.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

This patch passes the superblock pointer to gfs2_write_buf_to_page so it
becomes more apparent it's dealing with the system quota file.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Like the previous patch, we now pass the superblock pointer to function
gfs2_write_disk_quota. This makes the code more understandable, since it
only operates on the quota inode.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Before this change function gfs2_adjust_quota's first parameter was an
gfs2_inode pointer. But it always pointed to the quota inode. Here we
switch that to pass the superblock pointer, sdp, so it is easier to read
the code and understand that it's only dealing with the quota inode.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Since patch 845802b1 function gfs2_write_buf_to_page checks if the
target inode is jdata or ordered. This function only operates on the
system quota file, which is always jdata, so the check for jdata is
useless. This patch removes it.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

This patch adds a new mount option quota=quiet which is the same as
quota=on but it suppresses gfs2 quota error messages.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Add the device name to the names of the gfs2_logd and gfs2_quotad kernel
threads to allow for easier identification.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Rename the "gfs_recovery" workqueue to "gfs2_recovery", and
gfs_recovery_wq to gfs2_recovery_wq.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Function gfs2_withdraw() tries to synchronize concurrent callers by
atomically setting the SDF_WITHDRAWN flag in the first caller, setting
the SDF_WITHDRAW_IN_PROG flag to indicate that a withdraw is in
progress, performing the actual withdraw, and clearing the
SDF_WITHDRAW_IN_PROG flag when done.  All other callers wait for the
SDF_WITHDRAW_IN_PROG flag to be cleared before returning.

This leaves a small window in which callers can find the SDF_WITHDRAWN
flag set before the SDF_WITHDRAW_IN_PROG flag has been set, causing them
to return prematurely, before the withdraw has been completed.

Fix that by setting the SDF_WITHDRAWN and SDF_WITHDRAW_IN_PROG flags
atomically.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Immediately stop the logd and quotad kernel threads when a filesystem
withdraw is detected: those threads aren't doing anything useful after a
withdraw.  (Depends on the extra logd and quotad task struct references
held since commit 7a109f383fa3 ("gfs2: Fix asynchronous thread
destruction").)

In addition, check for kthread_should_stop() in the wait condition in
gfs2_quotad() to stop immediately when kthread_stop() is called.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

In gfs2_quotad(), switch from an open-coded wait loop to
wait_event_interruptible_timeout().
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

The kernel threads are currently stopped and destroyed synchronously by
gfs2_make_fs_ro() and gfs2_put_super(), and asynchronously by
signal_our_withdraw(), with no synchronization, so the synchronous and
asynchronous contexts can race with each other.

First, when creating the kernel threads, take an extra task struct
reference so that the task struct won't go away immediately when they
terminate.  This allows those kthreads to terminate immediately when
they're done rather than hanging around as zombies until they are reaped
by kthread_stop().  When kthread_stop() is called on a terminated
kthread, it will return immediately.

Second, in signal_our_withdraw(), once the SDF_JOURNAL_LIVE flag has
been cleared, wake up the logd and quotad wait queues instead of
stopping the logd and quotad kthreads.  The kthreads are then expected
to terminate automatically within short time, but if they cannot, they
will not block the withdraw.

For example, if a user process and one of the kthread decide to withdraw
at the same time, only one of them will perform the actual withdraw and
the other will wait for it to be done.  If the kthread ends up being the
one to wait, the withdrawing user process won't be able to stop it.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

[   81.372851][ T5532] CPU: 1 PID: 5532 Comm: syz-executor.0 Not tainted 6.2.0-rc1-syzkaller-dirty #0
[   81.382080][ T5532] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
[   81.392343][ T5532] Call Trace:
[   81.395654][ T5532]  <TASK>
[   81.398603][ T5532]  dump_stack_lvl+0x1b1/0x290
[   81.418421][ T5532]  gfs2_assert_warn_i+0x19a/0x2e0
[   81.423480][ T5532]  gfs2_quota_cleanup+0x4c6/0x6b0
[   81.428611][ T5532]  gfs2_make_fs_ro+0x517/0x610
[   81.457802][ T5532]  gfs2_withdraw+0x609/0x1540
[   81.481452][ T5532]  gfs2_inode_refresh+0xb2d/0xf60
[   81.506658][ T5532]  gfs2_instantiate+0x15e/0x220
[   81.511504][ T5532]  gfs2_glock_wait+0x1d9/0x2a0
[   81.516352][ T5532]  do_sync+0x485/0xc80
[   81.554943][ T5532]  gfs2_quota_sync+0x3da/0x8b0
[   81.559738][ T5532]  gfs2_sync_fs+0x49/0xb0
[   81.564063][ T5532]  sync_filesystem+0xe8/0x220
[   81.568740][ T5532]  generic_shutdown_super+0x6b/0x310
[   81.574112][ T5532]  kill_block_super+0x79/0xd0
[   81.578779][ T5532]  deactivate_locked_super+0xa7/0xf0
[   81.584064][ T5532]  cleanup_mnt+0x494/0x520
[   81.593753][ T5532]  task_work_run+0x243/0x300
[   81.608837][ T5532]  exit_to_user_mode_loop+0x124/0x150
[   81.614232][ T5532]  exit_to_user_mode_prepare+0xb2/0x140
[   81.619820][ T5532]  syscall_exit_to_user_mode+0x26/0x60
[   81.625287][ T5532]  do_syscall_64+0x49/0xb0
[   81.629710][ T5532]  entry_SYSCALL_64_after_hwframe+0x63/0xcd

In this backtrace, gfs2_quota_sync() takes quota data references and
then calls do_sync().  Function do_sync() encounters filesystem
corruption and withdraws the filesystem, which (among other things) calls
gfs2_quota_cleanup().  Function gfs2_quota_cleanup() wrongly assumes
that nobody is holding any quota data references anymore, and destroys
all quota data objects.  When gfs2_quota_sync() then resumes and
dereferences the quota data objects it is holding, those objects are no
longer there.

Function gfs2_quota_cleanup() deals with resource deallocation and can
easily be delayed until gfs2_put_super() in the case of a filesystem
withdraw.  In fact, most of the other work gfs2_make_fs_ro() does is
unnecessary during a withdraw as well, so change signal_our_withdraw()
to skip gfs2_make_fs_ro() and perform the necessary steps directly
instead.

Thanks to Edward Adam Davis <eadavis@sina.com> for the initial patches.

Link: https://lore.kernel.org/all/0000000000002b5e2405f14e860f@google.com
Reported-by: syzbot+3f6a670108ce43356017@syzkaller.appspotmail.com
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

In gfs2_quota_cleanup(), wait for the quota data objects to be freed
before returning.  Otherwise, there is no guarantee that the quota data
objects will be gone when their kmem cache is destroyed.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Fix the refcount of quota data objects created directly by
gfs2_quota_init(): those are placed into the in-memory quota "database"
for eventual syncing to the main quota file, but they are not actively
held and should thus have an initial refcount of 0.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Once a filesystem is withdrawn, don't complain about quota changes
that can't be synced to the main quota file anymore.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Rename gfs2_qd_dispose() to gfs2_qd_dispose_list().  Move some code
duplicated in gfs2_qd_dispose_list() and gfs2_quota_cleanup() into a
new gfs2_qd_dispose() function.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Change gfs2_quota_cleanup() to move the quota data objects to dispose of
on a dispose list and call gfs2_qd_dispose() on that list, like
gfs2_qd_shrink_scan() does, instead of disposing of the quota data
objects directly.

This may look a bit pointless by itself, but it will make more sense in
combination with a fix that follows.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Function gfs2_qd_isolate must only return LRU_REMOVED when removing the
item from the lru list; otherwise, the number of items on the list will
go wrong.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Rename the SDF_DEACTIVATING flag to SDF_KILL to make it more obvious
that this relates to the kill_sb filesystem operation.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Rename sd_glock_wait to sd_kill_wait: we'll use it for other things
related to "killing" a filesystem on unmount soon (kill_sb).
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Before this patch many of the functions in quota.c got their superblock
pointer, sdp, from the quota_data's glock pointer. That's silly because
the qd already has its own pointer to the superblock (qd_sbd).

This patch changes references to use that instead, eliminating a level
of indirection.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Commit f07b3520 ("GFS2: Made logd daemon take into account log
demand") changed gfs2_ail_flush_reqd() and gfs2_jrnl_flush_reqd() to
take sd_log_blks_needed into account, but the checks in
gfs2_log_commit() were not updated correspondingly.

Once that is fixed, gfs2_jrnl_flush_reqd() and gfs2_ail_flush_reqd() can
be used in gfs2_log_commit().  Make those two helpers available to
gfs2_log_commit() by defining them above gfs2_log_commit().
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

When quotad detects an I/O error, it sets sd_log_error and then it wakes
up logd to withdraw the filesystem.  However, logd doesn't wake up when
sd_log_error is set.  Fix that.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

First, function gfs2_ail_flush_reqd checks the SDF_FORCE_AIL_FLUSH flag
to determine if an AIL flush should be forced in low-memory situations.
However, it also immediately clears the flag, and when called repeatedly
as in function gfs2_logd, the flag will be lost.  Fix that by pulling
the SDF_FORCE_AIL_FLUSH flag check out of gfs2_ail_flush_reqd.

Second, function gfs2_writepages sets the SDF_FORCE_AIL_FLUSH flag
whether or not enough pages were written.  If enough pages could be
written, flushing the AIL is unnecessary, though.

Third, gfs2_writepages doesn't wake up logd after setting the
SDF_FORCE_AIL_FLUSH flag, so it can take a long time for logd to react.
It would be preferable to wake up logd, but that hurts the performance
of some workloads and we don't quite understand why so far, so don't
wake up logd so far.

Fixes: b066a4ee ("gfs2: forcibly flush ail to relieve memory pressure")
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

In gfs2_logd(), switch from an open-coded wait loop to
wait_event_interruptible_timeout().
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Consider the following case:
1. A glock is held in shared mode.
2. A process requests the glock in exclusive mode (rename).
3. Before the lock is granted, more processes (read / ls) request the
   glock in shared mode again.
4. gfs2 sends a request to dlm for the lock in exclusive mode because
   that holder is at the head of the queue.
5. Somehow the dlm request gets canceled, so dlm sends us back a
   response with state == LM_ST_SHARED and LM_OUT_CANCELED.  So at that
   point, the glock is still held in shared mode.
6. finish_xmote gets called to process the response from dlm. It detects
   that the glock is not in the requested mode and no demote is in
   progress, so it moves the canceled holder to the tail of the queue
   and finds the new holder at the head of the queue.  That holder is
   requesting the glock in shared mode.
7. finish_xmote calls do_xmote to transition the glock into shared mode,
   but the glock is already in shared mode and so do_xmote complains
   about that with:
	GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);

Instead, in finish_xmote, after moving the canceled holder to the tail
of the queue, check if any new holders can be granted.  Only call
do_xmote to repeat the dlm request if the holder at the head of the
queue is requesting the glock in a mode that is incompatible with the
mode the glock is currently held in.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

The last user of this flag was removed in commit b77b4a48 ("gfs2:
Rework freeze / thaw logic").
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Change function do_promote to return true on success, and false
otherwise.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Revert the rest of commit 220cca2a ("GFS2: Change truncate page
allocation to be GFP_NOFS"):

In gfs2_unstuff_dinode(), there is no need to carry out the page cache
allocation under GFP_NOFS because inodes on the "regular" filesystem are
never un-inlined under memory pressure, so switch back from
find_or_create_page() to grab_cache_page() here as well.

Inodes on the "metadata" filesystem can theoretically be un-inlined
under memory pressure, but any page cache allocations in that context
would happen in GFP_NOFS context because those inodes have
inode->i_mapping->gfp_mask set to GFP_NOFS (see the previous patch).
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Set mapping->gfp mask to GFP_NOFS for all metadata inodes so that
allocating pages in the address space of those inodes won't call back
into the filesystem.  This allows to switch back from
find_or_create_page() to grab_cache_page() in two places.

Partially reverts commit 220cca2a ("GFS2: Change truncate page
allocation to be GFP_NOFS").

Thanks to Dan Carpenter <dan.carpenter@linaro.org> for pointing out a
Smatch static checker warning.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Simplify code pattern of 'folio->index + folio_nr_pages(folio)' by using
the existing helper folio_next_index().
Signed-off-by: Minjie Du <duminjie@vivo.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Pull gfs2 fixes from Andreas Gruenbacher:

 - Fix a freeze consistency check in gfs2_trans_add_meta()

 - Don't use filemap_splice_read as it can cause deadlocks on gfs2

* tag 'gfs2-v6.4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
  gfs2: Don't use filemap_splice_read
  gfs2: Fix freeze consistency check in gfs2_trans_add_meta

Pull xen netback buffer overflow fix from Juergen Gross:
 "The fix for XSA-423 added logic to Linux'es netback driver to deal
  with a frontend splitting a packet in a way such that not all of the
  headers would come in one piece.

  Unfortunately the logic introduced there didn't account for the
  extreme case of the entire packet being split into as many pieces as
  permitted by the protocol, yet still being smaller than the area
  that's specially dealt with to keep all (possible) headers together.

  Such an unusual packet would therefore trigger a buffer overrun in the
  driver"

* tag 'xsa432-6.5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/netback: Fix buffer overrun triggered by unusual packet

Pull x86/gds fixes from Dave Hansen:
 "Mitigate Gather Data Sampling issue:

   - Add Base GDS mitigation

   - Support GDS_NO under KVM

   - Fix a documentation typo"

* tag 'gds-for-linus-2023-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Documentation/x86: Fix backwards on/off logic about YMM support
  KVM: Add GDS_NO support to KVM
  x86/speculation: Add Kconfig option for GDS
  x86/speculation: Add force option to GDS mitigation
  x86/speculation: Add Gather Data Sampling mitigation

Pull x86/srso fixes from Borislav Petkov:
 "Add a mitigation for the speculative RAS (Return Address Stack)
  overflow vulnerability on AMD processors.

  In short, this is yet another issue where userspace poisons a
  microarchitectural structure which can then be used to leak privileged
  information through a side channel"

* tag 'x86_bugs_srso' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/srso: Tie SBPB bit setting to microcode patch detection
  x86/srso: Add a forgotten NOENDBR annotation
  x86/srso: Fix return thunks in generated code
  x86/srso: Add IBPB on VMEXIT
  x86/srso: Add IBPB
  x86/srso: Add SRSO_NO support
  x86/srso: Add IBPB_BRTYPE support
  x86/srso: Add a Speculative RAS Overflow mitigation
  x86/bugs: Increase the x86 bugs vector size to two u32s