When the delayed refs for a head are all run, eventually
cleanup_ref_head is called which (in case of deletion) obtains a
reference for the relevant btrfs_space_info struct by querying the bg
for the range. This is problematic because when the last extent of a
bg is deleted a race window emerges between removal of that bg and the
subsequent invocation of cleanup_ref_head. This can result in cache being null
and either a null pointer dereference or assertion failure.

	task: ffff8d04d31ed080 task.stack: ffff9e5dc10cc000
	RIP: 0010:assfail.constprop.78+0x18/0x1a [btrfs]
	RSP: 0018:ffff9e5dc10cfbe8 EFLAGS: 00010292
	RAX: 0000000000000044 RBX: 0000000000000000 RCX: 0000000000000000
	RDX: ffff8d04ffc1f868 RSI: ffff8d04ffc178c8 RDI: ffff8d04ffc178c8
	RBP: ffff8d04d29e5ea0 R08: 00000000000001f0 R09: 0000000000000001
	R10: ffff9e5dc0507d58 R11: 0000000000000001 R12: ffff8d04d29e5ea0
	R13: ffff8d04d29e5f08 R14: ffff8d04efe29b40 R15: ffff8d04efe203e0
	FS:  00007fbf58ead500(0000) GS:ffff8d04ffc00000(0000) knlGS:0000000000000000
	CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
	CR2: 00007fe6c6975648 CR3: 0000000013b2a000 CR4: 00000000000006f0
	DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
	DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
	Call Trace:
	 __btrfs_run_delayed_refs+0x10e7/0x12c0 [btrfs]
	 btrfs_run_delayed_refs+0x68/0x250 [btrfs]
	 btrfs_should_end_transaction+0x42/0x60 [btrfs]
	 btrfs_truncate_inode_items+0xaac/0xfc0 [btrfs]
	 btrfs_evict_inode+0x4c6/0x5c0 [btrfs]
	 evict+0xc6/0x190
	 do_unlinkat+0x19c/0x300
	 do_syscall_64+0x74/0x140
	 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
	RIP: 0033:0x7fbf589c57a7

To fix this, introduce a new flag "is_system" to head_ref structs,
which is populated at insertion time. This allows to decouple the
querying for the spaceinfo from querying the possibly deleted bg.

Fixes: d7eae340 ("Btrfs: rework delayed ref total_bytes_pinned accounting")
CC: stable@vger.kernel.org # 4.14+
Suggested-by: NOmar Sandoval <osandov@osandov.com>
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The last update to readdir introduced a temporary buffer to store the
emitted readdir data, but as there are file names of variable length,
there's a lot of unaligned access.

This was observed on a sparc64 machine:

  Kernel unaligned access at TPC[102f3080] btrfs_real_readdir+0x51c/0x718 [btrfs]

Fixes: 23b5ec74 ("btrfs: fix readdir deadlock with pagefault")
CC: stable@vger.kernel.org # 4.14+
Reported-and-tested-by: NRené Rebe <rene@exactcode.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Commit 43b18595 ("btrfs: qgroup: Use separate meta reservation type
for delalloc") merged into mainline is not the latest version submitted
to mail list in Dec 2017.

It has a fatal wrong @qgroup_free parameter, which results increasing
qgroup metadata pertrans reserved space, and causing a lot of early EDQUOT.

Fix it by applying the correct diff on top of current branch.

Fixes: 43b18595 ("btrfs: qgroup: Use separate meta reservation type for delalloc")
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Commit 4f5427cc ("btrfs: delayed-inode: Use new qgroup meta rsv for
delayed inode and item") merged into mainline was not latest version
submitted to the mail list in Dec 2017.

Which lacks the following fixes:

1) Remove btrfs_qgroup_convert_reserved_meta() call in
   btrfs_delayed_item_release_metadata()
2) Remove btrfs_qgroup_reserve_meta_prealloc() call in
   btrfs_delayed_inode_reserve_metadata()

Those fixes will resolve unexpected EDQUOT problems.

Fixes: 4f5427cc ("btrfs: delayed-inode: Use new qgroup meta rsv for delayed inode and item")
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Unlike reservation calculation used in inode rsv for metadata, qgroup
doesn't really need to care about things like csum size or extent usage
for the whole tree COW.

Qgroups care more about net change of the extent usage.
That's to say, if we're going to insert one file extent, it will mostly
find its place in COWed tree block, leaving no change in extent usage.
Or causing a leaf split, resulting in one new net extent and increasing
qgroup number by nodesize.
Or in an even more rare case, increase the tree level, increasing qgroup
number by 2 * nodesize.

So here instead of using the complicated calculation for extent
allocator, which cares more about accuracy and no error, qgroup doesn't
need that over-estimated reservation.

This patch will maintain 2 new members in btrfs_block_rsv structure for
qgroup, using much smaller calculation for qgroup rsv, reducing false
EDQUOT.
Signed-off-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NQu Wenruo <wqu@suse.com>

Unlike previous method that tries to commit transaction inside
qgroup_reserve(), this time we will try to commit transaction using
fs_info->transaction_kthread to avoid nested transaction and no need to
worry about locking context.

Since it's an asynchronous function call and we won't wait for
transaction commit, unlike previous method, we must call it before we
hit the qgroup limit.

So this patch will use the ratio and size of qgroup meta_pertrans
reservation as indicator to check if we should trigger a transaction
commit.  (meta_prealloc won't be cleaned in transaction committ, it's
useless anyway)
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When looping btrfs/074 with many cpus (>= 8), it's possible to trigger
kernel warning due to first key verification:

[ 4239.523446] WARNING: CPU: 5 PID: 2381 at fs/btrfs/disk-io.c:460 btree_read_extent_buffer_pages+0x1ad/0x210
[ 4239.523830] Modules linked in:
[ 4239.524630] RIP: 0010:btree_read_extent_buffer_pages+0x1ad/0x210
[ 4239.527101] Call Trace:
[ 4239.527251]  read_tree_block+0x42/0x70
[ 4239.527434]  read_node_slot+0xd2/0x110
[ 4239.527632]  push_leaf_right+0xad/0x1b0
[ 4239.527809]  split_leaf+0x4ea/0x700
[ 4239.527988]  ? leaf_space_used+0xbc/0xe0
[ 4239.528192]  ? btrfs_set_lock_blocking_rw+0x99/0xb0
[ 4239.528416]  btrfs_search_slot+0x8cc/0xa40
[ 4239.528605]  btrfs_insert_empty_items+0x71/0xc0
[ 4239.528798]  __btrfs_run_delayed_refs+0xa98/0x1680
[ 4239.529013]  btrfs_run_delayed_refs+0x10b/0x1b0
[ 4239.529205]  btrfs_commit_transaction+0x33/0xaf0
[ 4239.529445]  ? start_transaction+0xa8/0x4f0
[ 4239.529630]  btrfs_alloc_data_chunk_ondemand+0x1b0/0x4e0
[ 4239.529833]  btrfs_check_data_free_space+0x54/0xa0
[ 4239.530045]  btrfs_delalloc_reserve_space+0x25/0x70
[ 4239.531907]  btrfs_direct_IO+0x233/0x3d0
[ 4239.532098]  generic_file_direct_write+0xcb/0x170
[ 4239.532296]  btrfs_file_write_iter+0x2bb/0x5f4
[ 4239.532491]  aio_write+0xe2/0x180
[ 4239.532669]  ? lock_acquire+0xac/0x1e0
[ 4239.532839]  ? __might_fault+0x3e/0x90
[ 4239.533032]  do_io_submit+0x594/0x860
[ 4239.533223]  ? do_io_submit+0x594/0x860
[ 4239.533398]  SyS_io_submit+0x10/0x20
[ 4239.533560]  ? SyS_io_submit+0x10/0x20
[ 4239.533729]  do_syscall_64+0x75/0x1d0
[ 4239.533979]  entry_SYSCALL_64_after_hwframe+0x42/0xb7
[ 4239.534182] RIP: 0033:0x7f8519741697

The problem here is, at btree_read_extent_buffer_pages() we don't have
acquired read/write lock on that extent buffer, only basic info like
level/bytenr is reliable.

So race condition leads to such false alert.

However in current call site, it's impossible to acquire proper lock
without race window.
To fix the problem, we only verify first key for committed tree blocks
(whose generation is no larger than fs_info->last_trans_committed), so
the content of such tree blocks will not change and there is no need to
get read/write lock.
Reported-by: NNikolay Borisov <nborisov@suse.com>
Fixes: 581c1760 ("btrfs: Validate child tree block's level and first key")
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Signed-off-by: NDavid Sterba <dsterba@suse.com>

Remove GPL boilerplate text (long, short, one-line) and keep the rest,
ie. personal, company or original source copyright statements. Add the
SPDX header.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Remove GPL boilerplate text (long, short, one-line) and keep the rest,
ie. personal, company or original source copyright statements. Add the
SPDX header.

Unify the include protection macros to match the file names.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Currently if we allocate extents beyond an inode's i_size (through the
fallocate system call) and then fsync the file, we log the extents but
after a power failure we replay them and then immediately drop them.
This behaviour happens since about 2009, commit c71bf099 ("Btrfs:
Avoid orphan inodes cleanup while replaying log"), because it marks
the inode as an orphan instead of dropping any extents beyond i_size
before replaying logged extents, so after the log replay, and while
the mount operation is still ongoing, we find the inode marked as an
orphan and then perform a truncation (drop extents beyond the inode's
i_size). Because the processing of orphan inodes is still done
right after replaying the log and before the mount operation finishes,
the intention of that commit does not make any sense (at least as
of today). However reverting that behaviour is not enough, because
we can not simply discard all extents beyond i_size and then replay
logged extents, because we risk dropping extents beyond i_size created
in past transactions, for example:

  add prealloc extent beyond i_size
  fsync - clears the flag BTRFS_INODE_NEEDS_FULL_SYNC from the inode
  transaction commit
  add another prealloc extent beyond i_size
  fsync - triggers the fast fsync path
  power failure

In that scenario, we would drop the first extent and then replay the
second one. To fix this just make sure that all prealloc extents
beyond i_size are logged, and if we find too many (which is far from
a common case), fallback to a full transaction commit (like we do when
logging regular extents in the fast fsync path).

Trivial reproducer:

 $ mkfs.btrfs -f /dev/sdb
 $ mount /dev/sdb /mnt
 $ xfs_io -f -c "pwrite -S 0xab 0 256K" /mnt/foo
 $ sync
 $ xfs_io -c "falloc -k 256K 1M" /mnt/foo
 $ xfs_io -c "fsync" /mnt/foo
 <power failure>

 # mount to replay log
 $ mount /dev/sdb /mnt
 # at this point the file only has one extent, at offset 0, size 256K

A test case for fstests follows soon, covering multiple scenarios that
involve adding prealloc extents with previous shrinking truncates and
without such truncates.

Fixes: c71bf099 ("Btrfs: Avoid orphan inodes cleanup while replaying log")
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Currently if some fatal errors occur, like all IO get -EIO, resources
would be cleaned up when
a) transaction is being committed or
b) BTRFS_FS_STATE_ERROR is set

However, in some rare cases, resources may be left alone after transaction
gets aborted and umount may run into some ASSERT(), e.g.
ASSERT(list_empty(&block_group->dirty_list));

For case a), in btrfs_commit_transaciton(), there're several places at the
beginning where we just call btrfs_end_transaction() without cleaning up
resources.  For case b), it is possible that the trans handle doesn't have
any dirty stuff, then only trans hanlde is marked as aborted while
BTRFS_FS_STATE_ERROR is not set, so resources remain in memory.

This makes btrfs also check BTRFS_FS_STATE_TRANS_ABORTED to make sure that
all resources won't stay in memory after umount.
Signed-off-by: NLiu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

do_chunk_alloc implements a loop checking whether there is a pending
chunk allocation and if so causes the caller do loop. Generally this
loop is executed only once, however testing with btrfs/072 on a single
core vm machines uncovered an extreme case where the system could loop
indefinitely. This is due to a missing cond_resched when loop which
doesn't give a chance to the previous chunk allocator finish its job.

The fix is to simply add the missing cond_resched.

Fixes: 6d74119f ("Btrfs: avoid taking the chunk_mutex in do_chunk_alloc")
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

If errors were returned by btrfs_next_leaf(), replay_dir_deletes needs
to bail out, otherwise @ret would be forced to be 0 after 'break;' and
the caller won't be aware of it.

Fixes: e02119d5 ("Btrfs: Add a write ahead tree log to optimize synchronous operations")
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NLiu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

0, 1 and <0 can be returned by btrfs_next_leaf(), and when <0 is
returned, path->nodes[0] could be NULL, log_dir_items lacks such a
check for <0 and we may run into a null pointer dereference panic.

Fixes: e02119d5 ("Btrfs: Add a write ahead tree log to optimize synchronous operations")
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NLiu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The missing error handling in add_extent_changeset was hidden, so make
it at least visible in the callers.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When mount fails to read trees like fs tree, checksum tree, extent
tree, etc, there is not enough information about where went wrong.

With this, messages like

"BTRFS warning (device sdf): failed to read root (objectid=7): -5"

would help us a bit.
Signed-off-by: NLiu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

All users pass a local unsigned int and not the __uXX types that are
supposed to be used for userspace interfaces.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The current calls are unclear in what way btrfs_dev_replace_lock takes
the locks, so drop the argument, split the helpers and use similar
naming as for read and write locks.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The fs_mutex has been killed in 2008, a2135011 ("Btrfs: Replace
the big fs_mutex with a collection of other locks"), still remembered in
some comments.

We don't have any extra needs for locking in the ACL handlers.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The show_devname callback is used to print device name in
/proc/self/mounts, we need to traverse the device list consistently and
read the name that's copied to a seq buffer so we don't need further
locking.

If the first device is being deleted at the same time, the RCU will
allow us to read the device name, though it will become stale right
after the RCU protection ends. This is unavoidable and the user can
expect that the device will disappear from the filesystem's list at some
point.

The device_list_mutex was pretty heavy as it is used eg. for writing
superblock and a few other IO related contexts. This can stall any
application that reads the proc file for no reason.
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Once there was a simple int force_cow that was used with the plain
barriers, and then converted to a bit, so we should use the appropriate
barrier helper.

Other variables in the complex if condition do not depend on a barrier,
so we should be fine in case the atomic barrier becomes a no-op.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Using lockdep_assert_held is preferred, replace mutex_is_locked.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Using lockdep_assert_held is preferred, replace assert_spin_locked.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We have several reports about node pointer points to incorrect child
tree blocks, which could have even wrong owner and level but still with
valid generation and checksum.

Although btrfs check could handle it and print error message like:
leaf parent key incorrect 60670574592

Kernel doesn't have enough check on this type of corruption correctly.
At least add such check to read_tree_block() and btrfs_read_buffer(),
where we need two new parameters @level and @first_key to verify the
child tree block.

The new @level check is mandatory and all call sites are already
modified to extract expected level from its call chain.

While @first_key is optional, the following call sites are skipping such
check:
1) Root node/leaf
   As ROOT_ITEM doesn't contain the first key, skip @first_key check.
2) Direct backref
   Only parent bytenr and level is known and we need to resolve the key
   all by ourselves, skip @first_key check.

Another note of this verification is, it needs extra info from nodeptr
or ROOT_ITEM, so it can't fit into current tree-checker framework, which
is limited to node/leaf boundary.
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The extent tree of the test fs is like the following:

 BTRFS info (device (null)): leaf 16327509003777336587 total ptrs 1 free space 3919
  item 0 key (4096 168 4096) itemoff 3944 itemsize 51
          extent refs 1 gen 1 flags 2
          tree block key (68719476736 0 0) level 1
                                           ^^^^^^^
          ref#0: tree block backref root 5

And it's using an empty tree for fs tree, so there is no way that its
level can be 1.

For REAL (created by mkfs) fs tree backref with no skinny metadata, the
result should look like:

 item 3 key (30408704 EXTENT_ITEM 4096) itemoff 3845 itemsize 51
         refs 1 gen 4 flags TREE_BLOCK
         tree block key (256 INODE_ITEM 0) level 0
                                           ^^^^^^^
         tree block backref root 5

Fix the level to 0, so it won't break later tree level checker.

Fixes: faa2dbf0 ("Btrfs: add sanity tests for new qgroup accounting code")
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When logging an inode, at tree-log.c:copy_items(), if we call
btrfs_next_leaf() at the loop which checks for the need to log holes, we
need to make sure copy_items() returns the value 1 to its caller and
not 0 (on success). This is because the path the caller passed was
released and is now different from what is was before, and the caller
expects a return value of 0 to mean both success and that the path
has not changed, while a return value of 1 means both success and
signals the caller that it can not reuse the path, it has to perform
another tree search.

Even though this is a case that should not be triggered on normal
circumstances or very rare at least, its consequences can be very
unpredictable (especially when replaying a log tree).

Fixes: 16e7549f ("Btrfs: incompatible format change to remove hole extents")
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When we have the no-holes mode enabled and fsync a file after punching a
hole in it, we can end up not logging the whole hole range in the log tree.
This happens if the file has extent items that span more than one leaf and
we punch a hole that covers a range that starts in a leaf but does not go
beyond the offset of the first extent in the next leaf.

Example:

  $ mkfs.btrfs -f -O no-holes -n 65536 /dev/sdb
  $ mount /dev/sdb /mnt
  $ for ((i = 0; i <= 831; i++)); do
	offset=$((i * 2 * 256 * 1024))
	xfs_io -f -c "pwrite -S 0xab -b 256K $offset 256K" \
		/mnt/foobar >/dev/null
    done
  $ sync

  # We now have 2 leafs in our filesystem fs tree, the first leaf has an
  # item corresponding the extent at file offset 216530944 and the second
  # leaf has a first item corresponding to the extent at offset 217055232.
  # Now we punch a hole that partially covers the range of the extent at
  # offset 216530944 but does go beyond the offset 217055232.

  $ xfs_io -c "fpunch $((216530944 + 128 * 1024 - 4000)) 256K" /mnt/foobar
  $ xfs_io -c "fsync" /mnt/foobar

  <power fail>

  # mount to replay the log
  $ mount /dev/sdb /mnt

  # Before this patch, only the subrange [216658016, 216662016[ (length of
  # 4000 bytes) was logged, leaving an incorrect file layout after log
  # replay.

Fix this by checking if there is a hole between the last extent item that
we processed and the first extent item in the next leaf, and if there is
one, log an explicit hole extent item.

Fixes: 16e7549f ("Btrfs: incompatible format change to remove hole extents")
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We have a nice helper to do proper casting of a qgroup to a ulist aux
value. And several places that could make use of it.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

This reverts commit 48a89bc4.

The idea to commit transaction and free some space after hitting qgroup
limit is good, although the problem is it can easily cause deadlocks.

One deadlock example is caused by trying to flush data while still
holding it:

Call Trace:
 __schedule+0x49d/0x10f0
 schedule+0xc6/0x290
 schedule_timeout+0x187/0x1c0
 wait_for_completion+0x204/0x3a0
 btrfs_wait_ordered_extents+0xa40/0xaf0 [btrfs]
 qgroup_reserve+0x913/0xa10 [btrfs]
 btrfs_qgroup_reserve_data+0x3ef/0x580 [btrfs]
 btrfs_check_data_free_space+0x96/0xd0 [btrfs]
 __btrfs_buffered_write+0x3ac/0xd40 [btrfs]
 btrfs_file_write_iter+0x62a/0xba0 [btrfs]
 __vfs_write+0x320/0x430
 vfs_write+0x107/0x270
 SyS_write+0xbf/0x150
 do_syscall_64+0x1b0/0x3d0
 entry_SYSCALL64_slow_path+0x25/0x25

Another can be caused by trying to commit one transaction while nesting
with trans handle held by ourselves:

btrfs_start_transaction()
|- btrfs_qgroup_reserve_meta_pertrans()
   |- qgroup_reserve()
      |- btrfs_join_transaction()
      |- btrfs_commit_transaction()

The retry is causing more problems than exppected when limit is enabled.
At least a graceful EDQUOT is way better than deadlock.
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Now trace_qgroup_meta_reserve() will have extra type parameter.

And introduce two new trace events:

1) trace_qgroup_meta_free_all_pertrans()
   For btrfs_qgroup_free_meta_all_pertrans()

2) trace_qgroup_meta_convert()
   For btrfs_qgroup_convert_reserved_meta()
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

For quota disabled->enable case, it's possible that at reservation time
quota was not enabled so no bytes were really reserved, while at release
time, quota was enabled so we will try to release some bytes we didn't
really own.

Such situation can cause metadata reserveation underflow, for both types,
also less possible for per-trans type since quota enable will commit
transaction.

To address this, record qgroup meta reserved bytes into
root::qgroup_meta_rsv_pertrans and ::prealloc.
So at releasing time we won't free any bytes we didn't reserve.

For DATA, it's already handled by io_tree, so nothing needs to be done
there.
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Quite similar for delalloc, some modification to delayed-inode and
delayed-item reservation.  Also needs extra parameter for release case
to distinguish normal release and error release.
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Before this patch, btrfs qgroup is mixing per-transcation meta rsv with
preallocated meta rsv, making it quite easy to underflow qgroup meta
reservation.

Since we have the new qgroup meta rsv types, apply it to delalloc
reservation.

Now for delalloc, most of its reserved space will use META_PREALLOC qgroup
rsv type.

And for callers reducing outstanding extent like btrfs_finish_ordered_io(),
they will convert corresponding META_PREALLOC reservation to
META_PERTRANS.

This is mainly due to the fact that current qgroup numbers will only be
updated in btrfs_commit_transaction(), that's to say if we don't keep
such placeholder reservation, we can exceed qgroup limitation.

And for callers freeing outstanding extent in error handler, we will
just free META_PREALLOC bytes.

This behavior makes callers of btrfs_qgroup_release_meta() or
btrfs_qgroup_convert_meta() to be aware of which type they are.
So in this patch, btrfs_delalloc_release_metadata() and its callers get
an extra parameter to info qgroup to do correct meta convert/release.

The good news is, even we use the wrong type (convert or free), it won't
cause obvious bug, as prealloc type is always in good shape, and the
type only affects how per-trans meta is increased or not.

So the worst case will be at most metadata limitation can be sometimes
exceeded (no convert at all) or metadata limitation is reached too soon
(no free at all).
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

For meta_prealloc reservation users, after btrfs_join_transaction()
caller will modify tree so part (or even all) meta_prealloc reservation
should be converted to meta_pertrans until transaction commit time.

This patch introduces a new function,
btrfs_qgroup_convert_reserved_meta() to do this for META_PREALLOC
reservation user.
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Since qgroup has seperate metadata reservation types now, we can
completely get rid of the old root->qgroup_meta_rsv, which mostly acts
as current META_PERTRANS reservation type.
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Btrfs uses 2 different methods to reseve metadata qgroup space.

1) Reserve at btrfs_start_transaction() time
   This is quite straightforward, caller will use the trans handler
   allocated to modify b-trees.

   In this case, reserved metadata should be kept until qgroup numbers
   are updated.

2) Reserve by using block_rsv first, and later btrfs_join_transaction()
   This is more complicated, caller will reserve space using block_rsv
   first, and then later call btrfs_join_transaction() to get a trans
   handle.

   In this case, before we modify trees, the reserved space can be
   modified on demand, and after btrfs_join_transaction(), such reserved
   space should also be kept until qgroup numbers are updated.

Since these two types behave differently, split the original "META"
reservation type into 2 sub-types:

  META_PERTRANS:
    For above case 1)

  META_PREALLOC:
    For reservations that happened before btrfs_join_transaction() of
    case 2)

NOTE: This patch will only convert existing qgroup meta reservation
callers according to its situation, not ensuring all callers are at
correct timing.
Such fix will be added in later patches.
Signed-off-by: NQu Wenruo <wqu@suse.com>
[ update comments ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

So qgroup is switched to new separate types reservation system.
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When modifying qgroup relationship, for qgroup which only owns exclusive
extents, we will go through quick update path.

In this path, we will add/subtract exclusive and reference number for
parent qgroup, since the source (child) qgroup only has exclusive
extents, destination (parent) qgroup will also own or lose those extents
exclusively.

The same should be the same for reservation, since later reservation
adding/releasing will also affect parent qgroup, without the reservation
carried from child, parent will underflow reservation or have dead
reservation which will never be freed.

However original code doesn't do the same thing for reservation.
It handles qgroup reservation quite differently:

It removes qgroup reservation, as it's allocating space from the
reserved qgroup for relationship adding.
But does nothing for qgroup reservation if we're removing a qgroup
relationship.

According to the original code, it looks just like because we're adding
qgroup->rfer, the code assumes we're writing new data, so it's follows
the normal write routine, by reducing qgroup->reserved and adding
qgroup->rfer/excl.

This old behavior is wrong, and should be fixed to follow the same
excl/rfer behavior.

Just fix it by using the correct behavior described above.

Fixes: 31193213 ("Btrfs: qgroup: Introduce a may_use to account space_info->bytes_may_use.")
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>