btrfs: add additional parameters to btrfs_init_tree_ref/btrfs_init_data_ref

[ Upstream commit f42c5da6c12e990d8ec415199600b4d593c63bf5 ]

In order to make 'real_root' used only in ref-verify it's re

btrfs: add additional parameters to btrfs_init_tree_ref/btrfs_init_data_ref

[ Upstream commit f42c5da6c12e990d8ec415199600b4d593c63bf5 ]

In order to make 'real_root' used only in ref-verify it's required to
have the necessary context to perform the same checks that this member
is used for. So add 'mod_root' which will contain the root on behalf of
which a delayed ref was created and a 'skip_group' parameter which
will contain callsite-specific override of skip_qgroup.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

btrfs: add additional parameters to btrfs_init_tree_ref/btrfs_init_data_ref

[ Upstream commit f42c5da6c12e990d8ec415199600b4d593c63bf5 ]

In order to make 'real_root' used only in ref-verify it's re

btrfs: add additional parameters to btrfs_init_tree_ref/btrfs_init_data_ref

[ Upstream commit f42c5da6c12e990d8ec415199600b4d593c63bf5 ]

In order to make 'real_root' used only in ref-verify it's required to
have the necessary context to perform the same checks that this member
is used for. So add 'mod_root' which will contain the root on behalf of
which a delayed ref was created and a 'skip_group' parameter which
will contain callsite-specific override of skip_qgroup.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

btrfs: add additional parameters to btrfs_init_tree_ref/btrfs_init_data_ref

[ Upstream commit f42c5da6c12e990d8ec415199600b4d593c63bf5 ]

In order to make 'real_root' used only in ref-verify it's re

btrfs: add additional parameters to btrfs_init_tree_ref/btrfs_init_data_ref

[ Upstream commit f42c5da6c12e990d8ec415199600b4d593c63bf5 ]

In order to make 'real_root' used only in ref-verify it's required to
have the necessary context to perform the same checks that this member
is used for. So add 'mod_root' which will contain the root on behalf of
which a delayed ref was created and a 'skip_group' parameter which
will contain callsite-specific override of skip_qgroup.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

btrfs: add additional parameters to btrfs_init_tree_ref/btrfs_init_data_ref

[ Upstream commit f42c5da6c12e990d8ec415199600b4d593c63bf5 ]

In order to make 'real_root' used only in ref-verify it's re

btrfs: add additional parameters to btrfs_init_tree_ref/btrfs_init_data_ref

[ Upstream commit f42c5da6c12e990d8ec415199600b4d593c63bf5 ]

In order to make 'real_root' used only in ref-verify it's required to
have the necessary context to perform the same checks that this member
is used for. So add 'mod_root' which will contain the root on behalf of
which a delayed ref was created and a 'skip_group' parameter which
will contain callsite-specific override of skip_qgroup.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

btrfs: only let one thread pre-flush delayed refs in commit

I've been running a stress test that runs 20 workers in their own
subvolume, which are running an fsstress instance with 4 threads per
wor

btrfs: only let one thread pre-flush delayed refs in commit

I've been running a stress test that runs 20 workers in their own
subvolume, which are running an fsstress instance with 4 threads per
worker, which is 80 total fsstress threads. In addition to this I'm
running balance in the background as well as creating and deleting
snapshots. This test takes around 12 hours to run normally, going
slower and slower as the test goes on.

The reason for this is because fsstress is running fsync sometimes, and
because we're messing with block groups we often fall through to
btrfs_commit_transaction, so will often have 20-30 threads all calling
btrfs_commit_transaction at the same time.

These all get stuck contending on the extent tree while they try to run
delayed refs during the initial part of the commit.

This is suboptimal, really because the extent tree is a single point of
failure we only want one thread acting on that tree at once to reduce
lock contention.

Fix this by making the flushing mechanism a bit operation, to make it
easy to use test_and_set_bit() in order to make sure only one task does
this initial flush.

Once we're into the transaction commit we only have one thread doing
delayed ref running, it's just this initial pre-flush that is
problematic. With this patch my stress test takes around 90 minutes to
run, instead of 12 hours.

The memory barrier is not necessary for the flushing bit as it's
ordered, unlike plain int. The transaction state accessed in
btrfs_should_end_transaction could be affected by that too as it's not
always used under transaction lock. Upon Nikolay's analysis in [1]
it's not necessary:

In should_end_transaction it's read without holding any locks. (U)

It's modified in btrfs_cleanup_transaction without holding the
fs_info->trans_lock (U), but the STATE_ERROR flag is going to be set.

set in cleanup_transaction under fs_info->trans_lock (L)
set in btrfs_commit_trans to COMMIT_START under fs_info->trans_lock.(L)
set in btrfs_commit_trans to COMMIT_DOING under fs_info->trans_lock.(L)
set in btrfs_commit_trans to COMMIT_UNBLOCK under
fs_info->trans_lock.(L)

set in btrfs_commit_trans to COMMIT_COMPLETED without locks but at this
point the transaction is finished and fs_info->running_trans is NULL (U
but irrelevant).

So by the looks of it we can have a concurrent READ race with a WRITE,
due to reads not taking a lock. In this case what we want to ensure is
we either see new or old state. I consulted with Will Deacon and he said
that in such a case we'd want to annotate the accesses to ->state with
(READ|WRITE)_ONCE so as to avoid a theoretical tear, in this case I
don't think this could happen but I imagine at some point KCSAN would
flag such an access as racy (which it is).

[1] https://lore.kernel.org/linux-btrfs/e1fd5cc1-0f28-f670-69f4-e9958b4964e6@suse.com

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ add comments regarding memory barrier ]
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: handle space_info::total_bytes_pinned inside the delayed ref itself

Currently we pass things around to figure out if we maybe freeing data
based on the state of the delayed refs head. This m

btrfs: handle space_info::total_bytes_pinned inside the delayed ref itself

Currently we pass things around to figure out if we maybe freeing data
based on the state of the delayed refs head. This makes the accounting
sort of confusing and hard to follow, as it's distinctly separate from
the delayed ref heads stuff, but also depends on it entirely.

Fix this by explicitly adjusting the space_info->total_bytes_pinned in
the delayed refs code. We now have two places where we modify this
counter, once where we create the delayed and destroy the delayed refs,
and once when we pin and unpin the extents. This means there is a
slight overlap between delayed refs and the pin/unpin mechanisms, but
this is simply used by the ENOSPC infrastructure to determine if we need
to commit the transaction, so there's no adverse affect from this, we
might simply commit thinking it will give us enough space when it might
not.

CC: stable@vger.kernel.org # 5.10
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: handle space_info::total_bytes_pinned inside the delayed ref itself

commit 2187374f35fe9cadbddaa9fcf0c4121365d914e8 upstream.

Currently we pass things around to figure out if we maybe freein

btrfs: handle space_info::total_bytes_pinned inside the delayed ref itself

commit 2187374f35fe9cadbddaa9fcf0c4121365d914e8 upstream.

Currently we pass things around to figure out if we maybe freeing data
based on the state of the delayed refs head. This makes the accounting
sort of confusing and hard to follow, as it's distinctly separate from
the delayed ref heads stuff, but also depends on it entirely.

Fix this by explicitly adjusting the space_info->total_bytes_pinned in
the delayed refs code. We now have two places where we modify this
counter, once where we create the delayed and destroy the delayed refs,
and once when we pin and unpin the extents. This means there is a
slight overlap between delayed refs and the pin/unpin mechanisms, but
this is simply used by the ENOSPC infrastructure to determine if we need
to commit the transaction, so there's no adverse affect from this, we
might simply commit thinking it will give us enough space when it might
not.

CC: stable@vger.kernel.org # 5.10
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

btrfs: migrate the delayed refs rsv code

These belong with the delayed refs related code, not in extent-tree.c.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterb

btrfs: migrate the delayed refs rsv code

These belong with the delayed refs related code, not in extent-tree.c.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: remove unused parameter fs_info from btrfs_add_delayed_extent_op

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

btrfs: delayed-ref: Use btrfs_ref to refactor btrfs_add_delayed_data_ref()

Just like btrfs_add_delayed_tree_ref(), use btrfs_ref to refactor
btrfs_add_delayed_data_ref().

Signed-off-by: Qu Wenruo <

btrfs: delayed-ref: Use btrfs_ref to refactor btrfs_add_delayed_data_ref()

Just like btrfs_add_delayed_tree_ref(), use btrfs_ref to refactor
btrfs_add_delayed_data_ref().

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: delayed-ref: Use btrfs_ref to refactor btrfs_add_delayed_tree_ref()

btrfs_add_delayed_tree_ref() has a longer and longer parameter list, and
some callers like btrfs_inc_extent_ref() are using

btrfs: delayed-ref: Use btrfs_ref to refactor btrfs_add_delayed_tree_ref()

btrfs_add_delayed_tree_ref() has a longer and longer parameter list, and
some callers like btrfs_inc_extent_ref() are using @owner as level for
delayed tree ref.

Instead of making the parameter list longer, use btrfs_ref to refactor
it, so each parameter assignment should be self-explaining without dirty
level/owner trick, and provides the basis for later refactoring.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: delayed-ref: Introduce better documented delayed ref structures

Current delayed ref interface has several problems:

- Longer and longer parameter lists
bytenr
num_bytes
parent
------

btrfs: delayed-ref: Introduce better documented delayed ref structures

Current delayed ref interface has several problems:

- Longer and longer parameter lists
bytenr
num_bytes
parent
---------- so far so good
ref_root
owner
offset
---------- I don't feel good now

- Different interpretation of the same parameter

Above @owner for data ref is inode number (u64),
while for tree ref, it's level (int).

They are even in different size range.
For level we only need 0 ~ 8, while for ino it's
BTRFS_FIRST_FREE_OBJECTID ~ BTRFS_LAST_FREE_OBJECTID.

And @offset doesn't even make sense for tree ref.

Such parameter reuse may look clever as an hidden union, but it
destroys code readability.

To solve both problems, we introduce a new structure, btrfs_ref to solve
them:

- Structure instead of long parameter list
This makes later expansion easier, and is better documented.

- Use btrfs_ref::type to distinguish data and tree ref

- Use proper union to store data/tree ref specific structures.

- Use separate functions to fill data/tree ref data, with a common generic
function to fill common bytenr/num_bytes members.

All parameters will find its place in btrfs_ref, and an extra member,
@real_root, inspired by ref-verify code, is newly introduced for later
qgroup code, to record which tree is triggered by this extent modification.

This patch doesn't touch any code, but provides the basis for further
refactoring.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: qgroup: Move reserved data accounting from btrfs_delayed_ref_head to btrfs_qgroup_extent_record

[BUG]
Btrfs/139 will fail with a high probability if the testing machine (VM)
has only 2G RAM.

btrfs: qgroup: Move reserved data accounting from btrfs_delayed_ref_head to btrfs_qgroup_extent_record

[BUG]
Btrfs/139 will fail with a high probability if the testing machine (VM)
has only 2G RAM.

Resulting the final write success while it should fail due to EDQUOT,
and the fs will have quota exceeding the limit by 16K.

The simplified reproducer will be: (needs a 2G ram VM)

$ mkfs.btrfs -f $dev
$ mount $dev $mnt

$ btrfs subv create $mnt/subv
$ btrfs quota enable $mnt
$ btrfs quota rescan -w $mnt
$ btrfs qgroup limit -e 1G $mnt/subv

$ for i in $(seq -w 1 8); do
xfs_io -f -c "pwrite 0 128M" $mnt/subv/file_$i > /dev/null
echo "file $i written" > /dev/kmsg
done
$ sync
$ btrfs qgroup show -pcre --raw $mnt

The last pwrite will not trigger EDQUOT and final 'qgroup show' will
show something like:

qgroupid rfer excl max_rfer max_excl parent child
-------- ---- ---- -------- -------- ------ -----
0/5 16384 16384 none none --- ---
0/256 1073758208 1073758208 none 1073741824 --- ---

And 1073758208 is larger than
> 1073741824.

[CAUSE]
It's a bug in btrfs qgroup data reserved space management.

For quota limit, we must ensure that:
reserved (data + metadata) + rfer/excl <= limit

Since rfer/excl is only updated at transaction commmit time, reserved
space needs to be taken special care.

One important part of reserved space is data, and for a new data extent
written to disk, we still need to take the reserved space until
rfer/excl numbers get updated.

Originally when an ordered extent finishes, we migrate the reserved
qgroup data space from extent_io tree to delayed ref head of the data
extent, expecting delayed ref will only be cleaned up at commit
transaction time.

However for small RAM machine, due to memory pressure dirty pages can be
flushed back to disk without committing a transaction.

The related events will be something like:

file 1 written
btrfs_finish_ordered_io: ino=258 ordered offset=0 len=54947840
btrfs_finish_ordered_io: ino=258 ordered offset=54947840 len=5636096
btrfs_finish_ordered_io: ino=258 ordered offset=61153280 len=57344
btrfs_finish_ordered_io: ino=258 ordered offset=61210624 len=8192
btrfs_finish_ordered_io: ino=258 ordered offset=60583936 len=569344
cleanup_ref_head: num_bytes=54947840
cleanup_ref_head: num_bytes=5636096
cleanup_ref_head: num_bytes=569344
cleanup_ref_head: num_bytes=57344
cleanup_ref_head: num_bytes=8192
^^^^^^^^^^^^^^^^ This will free qgroup data reserved space
file 2 written
...
file 8 written
cleanup_ref_head: num_bytes=8192
...
btrfs_commit_transaction <<< the only transaction committed during
the test

When file 2 is written, we have already freed 128M reserved qgroup data
space for ino 258. Thus later write won't trigger EDQUOT.

This allows us to write more data beyond qgroup limit.

In my 2G ram VM, it could reach about 1.2G before hitting EDQUOT.

[FIX]
By moving reserved qgroup data space from btrfs_delayed_ref_head to
btrfs_qgroup_extent_record, we can ensure that reserved qgroup data
space won't be freed half way before commit transaction, thus fix the
problem.

Fixes: f64d5ca86821 ("btrfs: delayed_ref: Add new function to record reserved space into delayed ref")
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: add btrfs_delete_ref_head helper

We do this dance in cleanup_ref_head and check_ref_cleanup, unify it
into a helper and cleanup the calling functions.

Reviewed-by: Omar Sandoval <osandov@fb.

btrfs: add btrfs_delete_ref_head helper

We do this dance in cleanup_ref_head and check_ref_cleanup, unify it
into a helper and cleanup the calling functions.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: delayed-ref: pass delayed_refs directly to btrfs_delayed_ref_lock

Since trans is only used for referring to delayed_refs, there is no need
to pass it instead of delayed_refs to btrfs_delayed_

btrfs: delayed-ref: pass delayed_refs directly to btrfs_delayed_ref_lock

Since trans is only used for referring to delayed_refs, there is no need
to pass it instead of delayed_refs to btrfs_delayed_ref_lock().

No functional change.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: delayed-ref: pass delayed_refs directly to btrfs_select_ref_head

Since trans is only used for referring to delayed_refs, there is no need
to pass it instead of delayed_refs to btrfs_select_re

btrfs: delayed-ref: pass delayed_refs directly to btrfs_select_ref_head

Since trans is only used for referring to delayed_refs, there is no need
to pass it instead of delayed_refs to btrfs_select_ref_head(). No
functional change.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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Btrfs: delayed-refs: use rb_first_cached for ref_tree

rb_first_cached() trades an extra pointer "leftmost" for doing the same
job as rb_first() but in O(1).

Functions manipulating href->ref_tree ne

Btrfs: delayed-refs: use rb_first_cached for ref_tree

rb_first_cached() trades an extra pointer "leftmost" for doing the same
job as rb_first() but in O(1).

Functions manipulating href->ref_tree need to get the first entry, this
converts href->ref_tree to use rb_first_cached().

For more details about the optimization see patch "Btrfs: delayed-refs:
use rb_first_cached for href_root".

Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

Btrfs: delayed-refs: use rb_first_cached for href_root

rb_first_cached() trades an extra pointer "leftmost" for doing the same
job as rb_first() but in O(1).

Functions manipulating href_root need t

Btrfs: delayed-refs: use rb_first_cached for href_root

rb_first_cached() trades an extra pointer "leftmost" for doing the same
job as rb_first() but in O(1).

Functions manipulating href_root need to get the first entry, this
converts href_root to use rb_first_cached().

This patch is first in the sequenct of similar updates to other rbtrees
and this is analysis of the expected behaviour and improvements.

There's a common pattern:

while (node = rb_first) {
entry = rb_entry(node)
next = rb_next(node)
rb_erase(node)
cleanup(entry)
}

rb_first needs to traverse the tree up to logN depth, rb_erase can
completely reshuffle the tree. With the caching we'll skip the traversal
in rb_first. That's a cached memory access vs looped pointer
dereference trade-off that IMHO has a clear winner.

Measurements show there's not much difference in a sample tree with
10000 nodes: 4.5s / rb_first and 4.8s / rb_first_cached. Real effects of
caching and pointer chasing are unpredictable though.

Further optimzations can be done to avoid the expensive rb_erase step.
In some cases it's ok to process the nodes in any order, so the tree can
be traversed in post-order, not rebalancing the children nodes and just
calling free. Care must be taken regarding the next node.

Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog from mail discussions ]
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: Remove fs_info from btrfs_add_delayed_data_ref

This function is always called with a valid transaction handle from
where fs_info can be referenced. No functional changes.

Signed-off-by: Niko

btrfs: Remove fs_info from btrfs_add_delayed_data_ref

This function is always called with a valid transaction handle from
where fs_info can be referenced. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: Remove fs_info from btrfs_add_delayed_tree_ref

This function is always called with a valid transaction handle from
where fs_info can be referenced. No functional changes.

Signed-off-by: Niko

btrfs: Remove fs_info from btrfs_add_delayed_tree_ref

This function is always called with a valid transaction handle from
where fs_info can be referenced. No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: Drop fs_info parameter from btrfs_merge_delayed_refs

It's provided by the transaction handle.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: Drop delayed_refs argument from btrfs_check_delayed_seq

It's used to print its pointer in a debug statement but doesn't really
bring any useful information to the error message.

Signed-off-b

btrfs: Drop delayed_refs argument from btrfs_check_delayed_seq

It's used to print its pointer in a debug statement but doesn't really
bring any useful information to the error message.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: Fix race condition between delayed refs and blockgroup removal

When the delayed refs for a head are all run, eventually
cleanup_ref_head is called which (in case of deletion) obtains a
refere

btrfs: Fix race condition between delayed refs and blockgroup removal

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: d7eae3403f46 ("Btrfs: rework delayed ref total_bytes_pinned accounting")
CC: stable@vger.kernel.org # 4.14+
Suggested-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: replace GPL boilerplate by SPDX -- headers

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

btrfs: replace GPL boilerplate by SPDX -- headers

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: David Sterba <dsterba@suse.com>

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btrfs: add more __cold annotations

The __cold functions are placed to a special section, as they're
expected to be called rarely. This could help i-cache prefetches or help
compiler to decide which

btrfs: add more __cold annotations

The __cold functions are placed to a special section, as they're
expected to be called rarely. This could help i-cache prefetches or help
compiler to decide which branches are more/less likely to be taken
without any other annotations needed.

Though we can't add more __exit annotations, it's still possible to add
__cold (that's also added with __exit). That way the following function
categories are tagged:

- printf wrappers, error messages
- exit helpers

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

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