If a subvolume still exists, forbid deleting its qgroup 0/subvolid.
This behavior generally leads to incorrect behavior in squotas and
doesn't have a legitimate purpose.
Fixes: cecbb533b5 ("btrfs: record simple quota deltas in delayed refs")
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
A reservation goes through a 3 step lifetime:
- generated during delalloc
- released/counted by ordered_extent allocation
- freed by running delayed ref
That third step depends on must_insert_reserved on the head ref, so the
head ref with that field set owns the reservation. Once you prepare to
run the head ref, must_insert_reserved is unset, which means that
running the ref must free the reservation, whether or not it succeeds,
or else the reservation is leaked. That results in either a risk of
spurious ENOSPC if the fs stays writeable or a warning on unmount if it
is readonly.
The existing squota code was aware of these invariants, but missed a few
cases. Improve it by adding a helper function to use in the cleanup
paths and call it from the existing early returns in running delayed
refs. This also simplifies btrfs_record_squota_delta and struct
btrfs_quota_delta.
This fixes (or at least improves the reliability of) generic/475 with
"mkfs -O squota". On my machine, that test failed ~4/10 times without
this patch and passed 100/100 times with it.
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
If we abort a transaction, we never run the code that frees the pertrans
qgroup reservation. This results in warnings on unmount as that
reservation has been leaked. The leak isn't a huge issue since the fs is
read-only, but it's better to clean it up when we know we can/should. Do
it during the cleanup_transaction step of aborting.
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
The reserved data counter and input parameter is a u64, but we
inadvertently accumulate it in an int. Overflowing that int results in
freeing the wrong amount of data and breaking reserve accounting.
Unfortunately, this overflow rot spreads from there, as the qgroup
release/free functions rely on returning an int to take advantage of
negative values for error codes.
Therefore, the full fix is to return the "released" or "freed" amount by
a u64 argument and to return 0 or negative error code via the return
value.
Most of the call sites simply ignore the return value, though some
of them handle the error and count the returned bytes. Change all of
them accordingly.
CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When using simple quotas we are not supposed to allocate qgroup records
when adding delayed references. However we allocate them if either mode
of quotas is enabled (the new simple one or the old one), but then we
never free them because running the accounting, which frees the records,
is only run when using the old quotas (at btrfs_qgroup_account_extents()),
resulting in a memory leak of the records allocated when adding delayed
references.
Fix this by allocating the records only if the old quotas mode is enabled.
Also fix btrfs_qgroup_trace_extent_nolock() to return 1 if the old quotas
mode is not enabled - meaning the caller has to free the record.
Fixes: 182940f4f4 ("btrfs: qgroup: add new quota mode for simple quotas")
Reported-by: syzbot+d3ddc6dcc6386dea398b@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/00000000000004769106097f9a34@google.com/
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing qgroup accounting for an extent, we take the spinlock
fs_info->qgroup_lock and then add qgroups to the local list (iterator)
named "qgroups". These qgroups are found in the fs_info->qgroup_tree
rbtree. After we're done, we unlock fs_info->qgroup_lock and then call
qgroup_iterator_nested_clean(), which will iterate over all the qgroups
added to the local list "qgroups" and then delete them from the list.
Deleting a qgroup from the list can however result in a use-after-free
if a qgroup remove operation happens after we unlock fs_info->qgroup_lock
and before or while we are at qgroup_iterator_nested_clean().
Fix this by calling qgroup_iterator_nested_clean() while still holding
the lock fs_info->qgroup_lock - we don't need it under the 'out' label
since before taking the lock the "qgroups" list is always empty. This
guarantees safety because btrfs_remove_qgroup() takes that lock before
removing a qgroup from the rbtree fs_info->qgroup_tree.
This was reported by syzbot with the following stack traces:
BUG: KASAN: slab-use-after-free in __list_del_entry_valid_or_report+0x2f/0x130 lib/list_debug.c:49
Read of size 8 at addr ffff888027e420b0 by task kworker/u4:3/48
CPU: 1 PID: 48 Comm: kworker/u4:3 Not tainted 6.6.0-syzkaller-10396-g4652b8e4f3ff #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
Workqueue: btrfs-qgroup-rescan btrfs_work_helper
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0x163/0x540 mm/kasan/report.c:475
kasan_report+0x175/0x1b0 mm/kasan/report.c:588
__list_del_entry_valid_or_report+0x2f/0x130 lib/list_debug.c:49
__list_del_entry_valid include/linux/list.h:124 [inline]
__list_del_entry include/linux/list.h:215 [inline]
list_del_init include/linux/list.h:287 [inline]
qgroup_iterator_nested_clean fs/btrfs/qgroup.c:2623 [inline]
btrfs_qgroup_account_extent+0x18b/0x1150 fs/btrfs/qgroup.c:2883
qgroup_rescan_leaf fs/btrfs/qgroup.c:3543 [inline]
btrfs_qgroup_rescan_worker+0x1078/0x1c60 fs/btrfs/qgroup.c:3604
btrfs_work_helper+0x37c/0xbd0 fs/btrfs/async-thread.c:315
process_one_work kernel/workqueue.c:2630 [inline]
process_scheduled_works+0x90f/0x1400 kernel/workqueue.c:2703
worker_thread+0xa5f/0xff0 kernel/workqueue.c:2784
kthread+0x2d3/0x370 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
</TASK>
Allocated by task 6355:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:721 [inline]
btrfs_quota_enable+0xee9/0x2060 fs/btrfs/qgroup.c:1209
btrfs_ioctl_quota_ctl+0x143/0x190 fs/btrfs/ioctl.c:3705
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xf8/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
Freed by task 6355:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522
____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
kasan_slab_free include/linux/kasan.h:164 [inline]
slab_free_hook mm/slub.c:1800 [inline]
slab_free_freelist_hook mm/slub.c:1826 [inline]
slab_free mm/slub.c:3809 [inline]
__kmem_cache_free+0x263/0x3a0 mm/slub.c:3822
btrfs_remove_qgroup+0x764/0x8c0 fs/btrfs/qgroup.c:1787
btrfs_ioctl_qgroup_create+0x185/0x1e0 fs/btrfs/ioctl.c:3811
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xf8/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
Last potentially related work creation:
kasan_save_stack+0x3f/0x60 mm/kasan/common.c:45
__kasan_record_aux_stack+0xad/0xc0 mm/kasan/generic.c:492
__call_rcu_common kernel/rcu/tree.c:2667 [inline]
call_rcu+0x167/0xa70 kernel/rcu/tree.c:2781
kthread_worker_fn+0x4ba/0xa90 kernel/kthread.c:823
kthread+0x2d3/0x370 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
Second to last potentially related work creation:
kasan_save_stack+0x3f/0x60 mm/kasan/common.c:45
__kasan_record_aux_stack+0xad/0xc0 mm/kasan/generic.c:492
__call_rcu_common kernel/rcu/tree.c:2667 [inline]
call_rcu+0x167/0xa70 kernel/rcu/tree.c:2781
kthread_worker_fn+0x4ba/0xa90 kernel/kthread.c:823
kthread+0x2d3/0x370 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
The buggy address belongs to the object at ffff888027e42000
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 176 bytes inside of
freed 512-byte region [ffff888027e42000, ffff888027e42200)
The buggy address belongs to the physical page:
page:ffffea00009f9000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x27e40
head:ffffea00009f9000 order:2 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888012c41c80 ffffea0000a5ba00 dead000000000002
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4514, tgid 4514 (udevadm), ts 24598439480, free_ts 23755696267
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1536
prep_new_page mm/page_alloc.c:1543 [inline]
get_page_from_freelist+0x31db/0x3360 mm/page_alloc.c:3170
__alloc_pages+0x255/0x670 mm/page_alloc.c:4426
alloc_slab_page+0x6a/0x160 mm/slub.c:1870
allocate_slab mm/slub.c:2017 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2070
___slab_alloc+0xc85/0x1310 mm/slub.c:3223
__slab_alloc mm/slub.c:3322 [inline]
__slab_alloc_node mm/slub.c:3375 [inline]
slab_alloc_node mm/slub.c:3468 [inline]
__kmem_cache_alloc_node+0x19d/0x270 mm/slub.c:3517
kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:721 [inline]
kernfs_fop_open+0x3e7/0xcc0 fs/kernfs/file.c:670
do_dentry_open+0x8fd/0x1590 fs/open.c:948
do_open fs/namei.c:3622 [inline]
path_openat+0x2845/0x3280 fs/namei.c:3779
do_filp_open+0x234/0x490 fs/namei.c:3809
do_sys_openat2+0x13e/0x1d0 fs/open.c:1440
do_sys_open fs/open.c:1455 [inline]
__do_sys_openat fs/open.c:1471 [inline]
__se_sys_openat fs/open.c:1466 [inline]
__x64_sys_openat+0x247/0x290 fs/open.c:1466
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1136 [inline]
free_unref_page_prepare+0x8c3/0x9f0 mm/page_alloc.c:2312
free_unref_page+0x37/0x3f0 mm/page_alloc.c:2405
discard_slab mm/slub.c:2116 [inline]
__unfreeze_partials+0x1dc/0x220 mm/slub.c:2655
put_cpu_partial+0x17b/0x250 mm/slub.c:2731
__slab_free+0x2b6/0x390 mm/slub.c:3679
qlink_free mm/kasan/quarantine.c:166 [inline]
qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x14b/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x23/0x70 mm/kasan/common.c:305
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x67/0x3d0 mm/slab.h:762
slab_alloc_node mm/slub.c:3478 [inline]
slab_alloc mm/slub.c:3486 [inline]
__kmem_cache_alloc_lru mm/slub.c:3493 [inline]
kmem_cache_alloc+0x104/0x2c0 mm/slub.c:3502
getname_flags+0xbc/0x4f0 fs/namei.c:140
do_sys_openat2+0xd2/0x1d0 fs/open.c:1434
do_sys_open fs/open.c:1455 [inline]
__do_sys_openat fs/open.c:1471 [inline]
__se_sys_openat fs/open.c:1466 [inline]
__x64_sys_openat+0x247/0x290 fs/open.c:1466
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
Memory state around the buggy address:
ffff888027e41f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888027e42000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888027e42080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888027e42100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888027e42180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
Reported-by: syzbot+e0b615318f8fcfc01ceb@syzkaller.appspotmail.com
Fixes: dce28769a3 ("btrfs: qgroup: use qgroup_iterator_nested to in qgroup_update_refcnt()")
CC: stable@vger.kernel.org # 6.6
Link: https://lore.kernel.org/linux-btrfs/00000000000091a5b2060936bf6d@google.com/
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In open_ctree, we set BTRFS_FS_QUOTA_ENABLED as soon as we see a
quota_root, as opposed to after we are done setting up the qgroup
structures. In the quota_enable path, we wait until after the structures
are set up. Likewise, in disable, we clear the bit before tearing down
the structures. I feel that this organization is less surprising for the
open_ctree path.
I don't believe this fixes any actual bug, but avoids potential
confusion when using btrfs_qgroup_mode in an intermediate state where we
are enabled but haven't yet setup the qgroup status flags. It also
avoids any risk of calling a qgroup function and attempting to use the
qgroup rbtrees before they exist/are setup.
This all occurs before we do rw setup, so I believe it should be mostly
a no-op.
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
Simple quotas count extents only from the moment the feature is enabled.
Therefore, if we do something like:
1. create subvol S
2. write F in S
3. enable quotas
4. remove F
5. write G in S
then after 3. and 4. we would expect the simple quota usage of S to be 0
(putting aside some metadata extents that might be written) and after
5., it should be the size of G plus metadata. Therefore, we need to be
able to determine whether a particular quota delta we are processing
predates simple quota enablement.
To do this, store the transaction id when quotas were enabled. In
fs_info for immediate use and in the quota status item to make it
recoverable on mount. When we see a delta, check if the generation of
the extent item is less than that of quota enablement. If so, we should
ignore the delta from this extent.
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
Consider the following sequence:
- enable quotas
- create subvol S id 256 at dir outer/
- create a qgroup 1/100
- add 0/256 (S's auto qgroup) to 1/100
- create subvol T id 257 at dir outer/inner/
With full qgroups, there is no relationship between 0/257 and either of
0/256 or 1/100. There is an inherit feature that the creator of inner/
can use to specify it ought to be in 1/100.
Simple quotas are targeted at container isolation, where such automatic
inheritance for not necessarily trusted/controlled nested subvol
creation would be quite helpful. Therefore, add a new default behavior
for simple quotas: when you create a nested subvol, automatically
inherit as parents any parents of the qgroup of the subvol the new inode
is going in.
In our example, 257/0 would also be under 1/100, allowing easy control
of a total quota over an arbitrary hierarchy of subvolumes.
I think this _might_ be a generally useful behavior, so it could be
interesting to put it behind a new inheritance flag that simple quotas
always use while traditional quotas let the user specify, but this is a
minimally intrusive change to start.
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
Rather than re-computing shared/exclusive ownership based on backrefs
and walking roots for implicit backrefs, simple quotas does an increment
when creating an extent and a decrement when deleting it. Add the API
for the extent item code to use to track those events.
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
Pull creating the qgroup earlier in the snapshot. This allows simple
quotas qgroups to see all the metadata writes related to the snapshot
being created and to be born with the root node accounted.
Note this has an impact on transaction commit where the qgroup creation
can do a lot of work, allocate memory and take locks. The change is done
for correctness, potential performance issues will be fixed in the
future.
Signed-off-by: Boris Burkov <boris@bur.io>
[ add note ]
Signed-off-by: David Sterba <dsterba@suse.com>
The following sequence:
enable simple quotas
do some writes
reserve space
create ordered_extent
release rsv (store rsv_bytes in OE, mark QGROUP_RESERVED bits)
disable quotas
enable simple quotas
set qgroup rsv to 0 on all subvolumes
ordered_extent finishes
create delayed ref with rsv_bytes from before
run delayed ref
record_simple_quota_delta
free rsv_bytes (0 -> -rsv_delta)
results in us reliably underflowing the subvolume's qgroup rsv counter,
because disabling/re-enabling quotas toggles reservation counters down
to 0, but does not remove other file system state which represents
successful acquisition of qgroup rsv space. Specifically metadata rsv
counters on the root object and rsv_bytes on ordered_extent objects that
have released their reservation as well as the corresponding
QGROUP_RESERVED extent bits.
Normal qgroups gets away with this, I believe because it forces more
work to happen on transaction commit, but I am not certain it is totally
safe from the ordered_extent/leaked extent bit variant. Simple quotas
hits this reliably.
The intent of the fix is to make disable take the time to clear that
external to qgroups state as well: after flipping off the quota bit on
fs_info, flush delalloc and ordered extents, clearing the extent bits
along the way. This makes it so there are no ordered extents or meta
prealloc hanging around from the first enablement period during the second.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
Add a new quota mode called "simple quotas". It can be enabled by the
existing quota enable ioctl via a new command, and sets an incompat
bit, as the implementation of simple quotas will make backwards
incompatible changes to the disk format of the extent tree.
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
In preparation for introducing simple quotas, change from a binary
setting for quotas to an enum based mode. Initially, the possible modes
are disabled/full. Full quotas is normal btrfs qgroups.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There are two callbacks defined in btrfs_work but only two actually make
use of them, otherwise there are NULLs. We can get rid of the freeing
callback making it a special case of the normal work. This reduces the
size of btrfs_work by 8 bytes, final layout:
struct btrfs_work {
btrfs_func_t func; /* 0 8 */
btrfs_ordered_func_t ordered_func; /* 8 8 */
struct work_struct normal_work; /* 16 32 */
struct list_head ordered_list; /* 48 16 */
/* --- cacheline 1 boundary (64 bytes) --- */
struct btrfs_workqueue * wq; /* 64 8 */
long unsigned int flags; /* 72 8 */
/* size: 80, cachelines: 2, members: 6 */
/* last cacheline: 16 bytes */
};
This in turn reduces size of other structures (on a release config):
- async_chunk 160 -> 152
- async_submit_bio 152 -> 144
- btrfs_async_delayed_work 104 -> 96
- btrfs_caching_control 176 -> 168
- btrfs_delalloc_work 144 -> 136
- btrfs_fs_info 3608 -> 3600
- btrfs_ordered_extent 440 -> 424
- btrfs_writepage_fixup 104 -> 96
Signed-off-by: David Sterba <dsterba@suse.com>
When marking an extent buffer as dirty, at btrfs_mark_buffer_dirty(),
we check if its generation matches the running transaction and if not we
just print a warning. Such mismatch is an indicator that something really
went wrong and only printing a warning message (and stack trace) is not
enough to prevent a corruption. Allowing a transaction to commit with such
an extent buffer will trigger an error if we ever try to read it from disk
due to a generation mismatch with its parent generation.
So abort the current transaction with -EUCLEAN if we notice a generation
mismatch. For this we need to pass a transaction handle to
btrfs_mark_buffer_dirty() which is always available except in test code,
in which case we can pass NULL since it operates on dummy extent buffers
and all test roots have a single node/leaf (root node at level 0).
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We keep the comments next to the implementation, there were some left
to move.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
These functions are defined in the qgroup.c file, but not called
anymore since commit "btrfs: qgroup: use qgroup_iterator_nested to in
qgroup_update_refcnt()" so we can delete them.
fs/btrfs/qgroup.c:149:19: warning: unused function 'qgroup_to_aux'.
fs/btrfs/qgroup.c:154:36: warning: unused function 'unode_aux_to_qgroup'.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=6566
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently we go GFP_ATOMIC allocation for qgroup relation add, this
includes the following 3 call sites:
- btrfs_read_qgroup_config()
This is not really needed, as at that time we're still in single
thread mode, and no spin lock is held.
- btrfs_add_qgroup_relation()
This one is holding a spinlock, but we're ensured to add at most one
relation, thus we can easily do a preallocation and use the
preallocated memory to avoid GFP_ATOMIC.
- btrfs_qgroup_inherit()
This is a little more tricky, as we may have as many relationships as
inherit::num_qgroups.
Thus we have to properly allocate an array then preallocate all the
memory.
This patch would remove the GFP_ATOMIC allocation for above involved
call sites, by doing preallocation before holding the spinlock, and let
__add_relation_rb() to handle the freeing of the structure.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qgroup is the heaviest user of GFP_ATOMIC, but one call site does not
really need GFP_ATOMIC, that is add_qgroup_rb().
That function only searches the rbtree to find if we already have such
entry. If not, then it would try to allocate memory for it.
This means we can afford to pre-allocate such structure unconditionally,
then free the memory if it's not needed.
Considering this function is not a hot path, only utilized by the
following functions:
- btrfs_qgroup_inherit()
For "btrfs subvolume snapshot -i" option.
- btrfs_read_qgroup_config()
At mount time, and we're ensured there would be no existing rb tree
entry for each qgroup.
- btrfs_create_qgroup()
Thus we're completely safe to pre-allocate the extra memory for btrfs_qgroup
structure, and reduce unnecessary GFP_ATOMIC usage.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The ulist @qgroups is utilized to record all involved qgroups from both
old and new roots inside btrfs_qgroup_account_extent().
Due to the fact that qgroup_update_refcnt() itself is already utilizing
qgroup_iterator, here we have to introduce another list_head,
btrfs_qgroup::nested_iterator, allowing nested iteration.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For function qgroup_update_refcnt(), we use @tmp list to iterate all the
involved qgroups of a subvolume.
It's a perfect match for qgroup_iterator facility, as that @tmp ulist
has a very limited lifespan (just inside the while() loop).
By migrating to qgroup_iterator, we can get rid of the GFP_ATOMIC memory
allocation and no error handling is needed.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
With the new qgroup_iterator_add() and qgroup_iterator_clean(), we can
get rid of the ulist and its GFP_ATOMIC memory allocation.
Furthermore we can merge the code handling the initial and parent
qgroups into one loop, and drop the @tmp ulist parameter for involved
call sites.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
With the new qgroup_iterator_add() and qgroup_iterator_clean(), we can
get rid of the ulist and its GFP_ATOMIC memory allocation.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
With the new qgroup_iterator_add() and qgroup_iterator_clean(), we can
get rid of the ulist and its GFP_ATOMIC memory allocation.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qgroup heavily relies on ulist to go through all the involved
qgroups, but since we're using ulist inside fs_info->qgroup_lock
spinlock, this means we're doing a lot of GFP_ATOMIC allocations.
This patch reduces the GFP_ATOMIC usage for qgroup_reserve() by
eliminating the memory allocation completely.
This is done by moving the needed memory to btrfs_qgroup::iterator
list_head, so that we can put all the involved qgroup into a on-stack
list, thus eliminating the need to allocate memory while holding
spinlock.
The only cost is the slightly higher memory usage, but considering the
reduce GFP_ATOMIC during a hot path, it should still be acceptable.
Function qgroup_reserve() is the perfect start point for this
conversion.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When flushing qgroups, we try to join a running transaction, with
btrfs_join_transaction(), and then commit the transaction. However using
btrfs_join_transaction() will result in creating a new transaction in case
there isn't any running or if there's an existing one already committing.
This is pointless as we only need to attach to an existing one that is
not committing and in case there's an existing one committing, wait for
its commit to complete. Creating and committing an empty transaction is
wasteful, pointless IO and unnecessary rotation of the backup roots.
So use btrfs_attach_transaction_barrier() instead, to avoid creating and
committing empty transactions.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When starting a qgroup rescan, we try to join a running transaction, with
btrfs_join_transaction(), and then commit the transaction. However using
btrfs_join_transaction() will result in creating a new transaction in case
there isn't any running or if there's an existing one already committing.
This is pointless as we only need to attach to an existing one that is
not committing and in case there's an existing one committing, wait for
its commit to complete. Creating and committing an empty transaction is
wasteful, pointless IO and unnecessary rotation of the backup roots.
So use btrfs_attach_transaction_barrier() instead, to avoid creating and
committing empty transactions.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we disable quotas while we have a relocation of a metadata block group
that has extents belonging to the quota root, we can cause the relocation
to fail with -ENOENT. This is because relocation builds backref nodes for
extents of the quota root and later needs to walk the backrefs and access
the quota root - however if in between a task disables quotas, it results
in deleting the quota root from the root tree (with btrfs_del_root(),
called from btrfs_quota_disable().
This can be sporadically triggered by test case btrfs/255 from fstests:
$ ./check btrfs/255
FSTYP -- btrfs
PLATFORM -- Linux/x86_64 debian0 6.4.0-rc6-btrfs-next-134+ #1 SMP PREEMPT_DYNAMIC Thu Jun 15 11:59:28 WEST 2023
MKFS_OPTIONS -- /dev/sdc
MOUNT_OPTIONS -- /dev/sdc /home/fdmanana/btrfs-tests/scratch_1
btrfs/255 6s ... _check_dmesg: something found in dmesg (see /home/fdmanana/git/hub/xfstests/results//btrfs/255.dmesg)
- output mismatch (see /home/fdmanana/git/hub/xfstests/results//btrfs/255.out.bad)
--- tests/btrfs/255.out 2023-03-02 21:47:53.876609426 +0000
+++ /home/fdmanana/git/hub/xfstests/results//btrfs/255.out.bad 2023-06-16 10:20:39.267563212 +0100
@@ -1,2 +1,4 @@
QA output created by 255
+ERROR: error during balancing '/home/fdmanana/btrfs-tests/scratch_1': No such file or directory
+There may be more info in syslog - try dmesg | tail
Silence is golden
...
(Run 'diff -u /home/fdmanana/git/hub/xfstests/tests/btrfs/255.out /home/fdmanana/git/hub/xfstests/results//btrfs/255.out.bad' to see the entire diff)
Ran: btrfs/255
Failures: btrfs/255
Failed 1 of 1 tests
To fix this make the quota disable operation take the cleaner mutex, as
relocation of a block group also takes this mutex. This is also what we
do when deleting a subvolume/snapshot, we take the cleaner mutex in the
cleaner kthread (at cleaner_kthread()) and then we call btrfs_del_root()
at btrfs_drop_snapshot() while under the protection of the cleaner mutex.
Fixes: bed92eae26 ("Btrfs: qgroup implementation and prototypes")
CC: stable@vger.kernel.org # 5.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_clean_tree_block is a misnomer, it's just
clear_extent_buffer_dirty with some extra accounting around it. Rename
this to btrfs_clear_buffer_dirty to make it more clear it belongs with
it's setter, btrfs_mark_buffer_dirty.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We check the header generation in the extent buffer against the current
running transaction id to see if it's safe to clear DIRTY on this
buffer. Generally speaking if we're clearing the buffer dirty we're
holding the transaction open, but in the case of cleaning up an aborted
transaction we don't, so we have extra checks in that path to check the
transid. To allow for a future cleanup go ahead and pass in the trans
handle so we don't have to rely on ->running_transaction being set.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we have one task trying to start the quota rescan worker while another
one is trying to disable quotas, we can end up hitting a race that results
in the quota rescan worker doing a NULL pointer dereference. The steps for
this are the following:
1) Quotas are enabled;
2) Task A calls the quota rescan ioctl and enters btrfs_qgroup_rescan().
It calls qgroup_rescan_init() which returns 0 (success) and then joins a
transaction and commits it;
3) Task B calls the quota disable ioctl and enters btrfs_quota_disable().
It clears the bit BTRFS_FS_QUOTA_ENABLED from fs_info->flags and calls
btrfs_qgroup_wait_for_completion(), which returns immediately since the
rescan worker is not yet running.
Then it starts a transaction and locks fs_info->qgroup_ioctl_lock;
4) Task A queues the rescan worker, by calling btrfs_queue_work();
5) The rescan worker starts, and calls rescan_should_stop() at the start
of its while loop, which results in 0 iterations of the loop, since
the flag BTRFS_FS_QUOTA_ENABLED was cleared from fs_info->flags by
task B at step 3);
6) Task B sets fs_info->quota_root to NULL;
7) The rescan worker tries to start a transaction and uses
fs_info->quota_root as the root argument for btrfs_start_transaction().
This results in a NULL pointer dereference down the call chain of
btrfs_start_transaction(). The stack trace is something like the one
reported in Link tag below:
general protection fault, probably for non-canonical address 0xdffffc0000000041: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000208-0x000000000000020f]
CPU: 1 PID: 34 Comm: kworker/u4:2 Not tainted 6.1.0-syzkaller-13872-gb6bb9676f216 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Workqueue: btrfs-qgroup-rescan btrfs_work_helper
RIP: 0010:start_transaction+0x48/0x10f0 fs/btrfs/transaction.c:564
Code: 48 89 fb 48 (...)
RSP: 0018:ffffc90000ab7ab0 EFLAGS: 00010206
RAX: 0000000000000041 RBX: 0000000000000208 RCX: ffff88801779ba80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: dffffc0000000000 R08: 0000000000000001 R09: fffff52000156f5d
R10: fffff52000156f5d R11: 1ffff92000156f5c R12: 0000000000000000
R13: 0000000000000001 R14: 0000000000000001 R15: 0000000000000003
FS: 0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2bea75b718 CR3: 000000001d0cc000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
btrfs_qgroup_rescan_worker+0x3bb/0x6a0 fs/btrfs/qgroup.c:3402
btrfs_work_helper+0x312/0x850 fs/btrfs/async-thread.c:280
process_one_work+0x877/0xdb0 kernel/workqueue.c:2289
worker_thread+0xb14/0x1330 kernel/workqueue.c:2436
kthread+0x266/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>
Modules linked in:
So fix this by having the rescan worker function not attempt to start a
transaction if it didn't do any rescan work.
Reported-by: syzbot+96977faa68092ad382c4@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/000000000000e5454b05f065a803@google.com/
Fixes: e804861bd4 ("btrfs: fix deadlock between quota disable and qgroup rescan worker")
CC: stable@vger.kernel.org # 5.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
There are some reports from the mailing list that since v6.1 kernel, the
WARN_ON() inside btrfs_qgroup_account_extent() gets triggered during
rescan:
WARNING: CPU: 3 PID: 6424 at fs/btrfs/qgroup.c:2756 btrfs_qgroup_account_extents+0x1ae/0x260 [btrfs]
CPU: 3 PID: 6424 Comm: snapperd Tainted: P OE 6.1.2-1-default #1 openSUSE Tumbleweed 05c7a1b1b61d5627475528f71f50444637b5aad7
RIP: 0010:btrfs_qgroup_account_extents+0x1ae/0x260 [btrfs]
Call Trace:
<TASK>
btrfs_commit_transaction+0x30c/0xb40 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6]
? start_transaction+0xc3/0x5b0 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6]
btrfs_qgroup_rescan+0x42/0xc0 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6]
btrfs_ioctl+0x1ab9/0x25c0 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6]
? __rseq_handle_notify_resume+0xa9/0x4a0
? mntput_no_expire+0x4a/0x240
? __seccomp_filter+0x319/0x4d0
__x64_sys_ioctl+0x90/0xd0
do_syscall_64+0x5b/0x80
? syscall_exit_to_user_mode+0x17/0x40
? do_syscall_64+0x67/0x80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fd9b790d9bf
</TASK>
[CAUSE]
Since commit e15e9f43c7 ("btrfs: introduce
BTRFS_QGROUP_RUNTIME_FLAG_NO_ACCOUNTING to skip qgroup accounting"), if
our qgroup is already in inconsistent state, we will no longer do the
time-consuming backref walk.
This can leave some qgroup records without a valid old_roots ulist.
Normally this is fine, as btrfs_qgroup_account_extents() would also skip
those records if we have NO_ACCOUNTING flag set.
But there is a small window, if we have NO_ACCOUNTING flag set, and
inserted some qgroup_record without a old_roots ulist, but then the user
triggered a qgroup rescan.
During btrfs_qgroup_rescan(), we firstly clear NO_ACCOUNTING flag, then
commit current transaction.
And since we have a qgroup_record with old_roots = NULL, we trigger the
WARN_ON() during btrfs_qgroup_account_extents().
[FIX]
Unfortunately due to the introduction of NO_ACCOUNTING flag, the
assumption that every qgroup_record would have its old_roots populated
is no longer correct.
Fix the false alerts and drop the WARN_ON().
Reported-by: Lukas Straub <lukasstraub2@web.de>
Reported-by: HanatoK <summersnow9403@gmail.com>
Fixes: e15e9f43c7 ("btrfs: introduce BTRFS_QGROUP_RUNTIME_FLAG_NO_ACCOUNTING to skip qgroup accounting")
CC: stable@vger.kernel.org # 6.1
Link: https://lore.kernel.org/linux-btrfs/2403c697-ddaf-58ad-3829-0335fc89df09@gmail.com/
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In the patch a2c8d27e5e ("btrfs: use a structure to pass arguments to
backref walking functions") Filipe converted everybody to using a new
context struct to use for backref lookups, but accidentally dropped the
BTRFS_SEQ_LAST usage that exists for qgroups. Add this back so we have
the previous behavior.
Fixes: a2c8d27e5e ("btrfs: use a structure to pass arguments to backref walking functions")
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move struct btrfs_tree_parent_check out of disk-io.h so that volumes.h
an various .c files don't have to include disk-io.h just for it.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
[ use tree-checker.h for the structure ]
Signed-off-by: David Sterba <dsterba@suse.com>
There are several different tree block parentness check parameters used
across several helpers:
- level
Mandatory
- transid
Under most cases it's mandatory, but there are several backref cases
which skips this check.
- owner_root
- first_key
Utilized by most top-down tree search routine. Otherwise can be
skipped.
Those four members are not always mandatory checks, and some of them are
the same u64, which means if some arguments got swapped compiler will
not catch it.
Furthermore if we're going to further expand the parentness check, we
need to modify quite some helpers just to add one more parameter.
This patch will concentrate all these members into a structure called
btrfs_tree_parent_check, and pass that structure for the following
helpers:
- btrfs_read_extent_buffer()
- read_tree_block()
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The public backref walking functions have quite a lot of arguments that
are passed down the call stack to find_parent_nodes(), the core function
of the backref walking code.
The next patches in series will need to add even arguments to these
functions that should be passed not only to find_parent_nodes(), but also
to other functions used by the later (directly or even lower in the call
stack).
So create a structure to hold all these arguments and state used by the
main backref walking function, find_parent_nodes(), and use it as the
argument for the public backref walking functions iterate_extent_inodes(),
btrfs_find_all_leafs() and btrfs_find_all_roots().
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move all the root-tree.c prototypes to root-tree.h, and then update all
the necessary files to include the new header.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move all the extent tree related prototypes to extent-tree.h out of
ctree.h, and then go include it everywhere needed so everything
compiles.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
All callers pass GFP_NOFS, we can drop the parameter and use it
directly.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This is a large patch, but because they're all macros it's impossible to
split up. Simply copy all of the item accessors in ctree.h and paste
them in accessors.h, and then update any files to include the header so
everything compiles.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ reformat comments, style fixups ]
Signed-off-by: David Sterba <dsterba@suse.com>
We have several fs wide related helpers in ctree.h. The bulk of these
are the incompat flag test helpers, but there are things such as
btrfs_fs_closing() and the read only helpers that also aren't directly
related to the ctree code. Move these into a fs.h header, which will
serve as the location for file system wide related helpers.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Syzkaller reported BUG as follows:
BUG: sleeping function called from invalid context at
include/linux/sched/mm.h:274
Call Trace:
<TASK>
dump_stack_lvl+0xcd/0x134
__might_resched.cold+0x222/0x26b
kmem_cache_alloc+0x2e7/0x3c0
update_qgroup_limit_item+0xe1/0x390
btrfs_qgroup_inherit+0x147b/0x1ee0
create_subvol+0x4eb/0x1710
btrfs_mksubvol+0xfe5/0x13f0
__btrfs_ioctl_snap_create+0x2b0/0x430
btrfs_ioctl_snap_create_v2+0x25a/0x520
btrfs_ioctl+0x2a1c/0x5ce0
__x64_sys_ioctl+0x193/0x200
do_syscall_64+0x35/0x80
Fix this by calling qgroup_dirty() on @dstqgroup, and update limit item in
btrfs_run_qgroups() later outside of the spinlock context.
CC: stable@vger.kernel.org # 4.9+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add a missing 'r'. s/qgoup/qgroup/ . Codespell does not catch that for
some reason.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Btrfs qgroup has a long history of bringing performance penalty in
btrfs_commit_transaction().
Although we tried our best to migrate such impact, there is still an
unsolved call site, btrfs_drop_snapshot().
This function will find the highest shared tree block and modify its
extent ownership to do a subvolume/snapshot dropping.
Such change will affect the whole subtree, and cause tons of qgroup
dirty extents and stall btrfs_commit_transaction().
To avoid such problem, here we introduce a new sysfs interface,
/sys/fs/btrfs/<uuid>/qgroups/drop_subptree_threshold, to determine at
whether and at which level we should skip qgroup accounting for subtree
dropping.
The default value is BTRFS_MAX_LEVEL, thus every subtree drop will go
through qgroup accounting, to ensure qgroup numbers are kept as
consistent as possible.
While for performance sensitive cases, add a way to change the values to
more reasonable values like 3, to make any subtree, which is at or higher
than level 3, to mark qgroup inconsistent and skip the accounting.
The cost is obvious, the qgroup number is no longer consistent, but at
least performance is more reasonable, and users have the control.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The new flag will make btrfs qgroup skip all its time consuming
qgroup accounting.
The lifespan is the same as BTRFS_QGROUP_RUNTIME_FLAG_CANCEL_RESCAN,
only get cleared after a new rescan.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
