Often when I'm debugging ENOSPC related issues I have to resort to
printing the entire ENOSPC state with trace_printk() in different spots.
This gets pretty annoying, so add a trace state that does this for us.
Then add a trace point at the end of preemptive flushing so you can see
the state of the space_info when we decide to exit preemptive flushing.
This helped me figure out we weren't kicking in the preemptive flushing
soon enough.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Since we have normal ticketed flushing and preemptive flushing, adjust
the tracepoint so that we know the source of the flushing action to make
it easier to debug problems.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Starting preemptive flushing at 50% of available free space is a good
start, but some workloads are particularly abusive and can quickly
overwhelm the preemptive flushing code and drive us into using tickets.
Handle this by clamping down on our threshold for starting and
continuing to run preemptive flushing. This is particularly important
for our overcommit case, as we can really drive the file system into
overages and then it's more difficult to pull it back as we start to
actually fill up the file system.
The clamping is essentially 2^CLAMP, but we start at 1 so whatever we
calculate for overcommit is the baseline.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
A lot of this was added all in one go with no explanation, and is a bit
unwieldy and confusing. Simplify the logic to start preemptive flushing
if we've reserved more than half of our available free space.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently btrfs_calc_reclaim_metadata_size does two things, it returns
the space currently required for flushing by the tickets, and if there
are no tickets it calculates a value for the preemptive flushing.
However for the normal ticketed flushing we really only care about the
space required for tickets. We will accidentally come in and flush one
time, but as soon as we see there are no tickets we bail out of our
flushing.
Fix this by making btrfs_calc_reclaim_metadata_size really only tell us
what is required for flushing if we have people waiting on space. Then
move the preemptive flushing logic into need_preemptive_reclaim(). We
ignore btrfs_calc_reclaim_metadata_size() in need_preemptive_reclaim()
because if we are in this path then we made our reservation and there
are not pending tickets currently, so we do not need to check it, simply
do the fuzzy logic to check if we're getting low on space.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we're flushing space for tickets then we have
space_info->reclaim_size set and we do not need to do background
reclaim.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
All of our normal flushing is asynchronous reclaim, so this helper is
poorly named. This is more checking if we need to preemptively flush
space, so rename it to need_preemptive_reclaim.
Also switch it to bool and make it plain static as followup patches will
move more code here.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently if we ever have to flush space because we do not have enough
we allocate a ticket and attach it to the space_info, and then
systematically flush things in the filesystem that hold space
reservations until our space is reclaimed.
However this has a latency cost, we must go to sleep and wait for the
flushing to make progress before we are woken up and allowed to continue
doing our work.
In order to address that we used to kick off the async worker to flush
space preemptively, so that we could be reclaiming space hopefully
before any tasks needed to stop and wait for space to reclaim.
When I introduced the ticketed ENOSPC stuff this broke slightly in the
fact that we were using tickets to indicate if we were done flushing.
No tickets, no more flushing. However this meant that we essentially
never preemptively flushed. This caused a write performance regression
that Nikolay noticed in an unrelated patch that removed the committing
of the transaction during btrfs_end_transaction.
The behavior that happened pre that patch was btrfs_end_transaction()
would see that we were low on space, and it would commit the
transaction. This was bad because in this particular case you could end
up with thousands and thousands of transactions being committed during
the 5 minute reproducer. With the patch to remove this behavior we got
much more sane transaction commits, but we ended up slower because we
would write for a while, flush, write for a while, flush again.
To address this we need to reinstate a preemptive flushing mechanism.
However it is distinctly different from our ticketing flushing in that
it doesn't have tickets to base it's decisions on. Instead of bolting
this logic into our existing flushing work, add another worker to handle
this preemptive flushing. Here we will attempt to be slightly
intelligent about the things that we flushing, attempting to balance
between whichever pool is taking up the most space.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Solely for preemptive flushing, we want to be able to force the
transaction commit without any of the ambiguity of
may_commit_transaction(). This is because may_commit_transaction()
checks tickets and such, and in preemptive flushing we already know
it'll be helpful, so use this to keep the code nice and clean and
straightforward.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ add comment ]
Signed-off-by: David Sterba <dsterba@suse.com>
We track dio_bytes because the shrink delalloc code needs to know if we
have more DIO in flight than we have normal buffered IO. The reason for
this is because we can't "flush" DIO, we have to just wait on the
ordered extents to finish.
However this is true of all ordered extents. If we have more ordered
space outstanding than dirty pages we should be waiting on ordered
extents. We already are ok on this front technically, because we always
do a FLUSH_DELALLOC_WAIT loop, but I want to use the ordered counter in
the preemptive flushing code as well, so change this to count all
ordered bytes instead of just DIO ordered bytes.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
While debugging a ENOSPC related performance problem I needed to see the
time difference between start and end of a reserve ticket, so add a
trace point to report when we handle a reserve ticket.
I opted to spit out start_ns itself without calculating the difference
because there could be a gap between enabling the tracepoint and setting
start_ns. Doing it this way allows us to filter on 0 start_ns so we
don't get bogus entries, and we can easily calculate the time difference
with bpftrace or something else.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
I got a automated message from somebody who runs clang against our
kernels and it's because I used the wrong enum type for what I passed
into flush_space, caught by -Wenum-conversion. Change the argument to
be explicitly the enum we're expecting to make everything consistent.
Maybe eventually gcc will catch errors like this.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_compare_trees and changed_cb use a void *ctx parameter instead of
struct send_ctx *sctx but when used in changed_cb it is immediately
cast to `struct send_ctx *sctx = ctx;`.
changed_cb is only ever called from btrfs_compare_trees and full_send_tree:
- full_send_tree already passes a struct send_ctx *sctx
- btrfs_compare_trees is only called by send_subvol with a struct send_ctx *sctx
- void *ctx in btrfs_compare_trees is only used to be passed to changed_cb
So casting to/from void *ctx seems unnecessary and directly using
struct send_ctx *sctx instead provides better type-safety.
The original reason for using void *ctx in the first place seems to have
been dropped with 1b51d6fce4 ("btrfs: send: remove indirect callback
parameter for changed_cb").
Signed-off-by: Roman Anasal <roman.anasal@bdsu.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We love running delayed refs in commit_cowonly_roots, but it is a bit
excessive. I was seeing cases of running 3 or 4 refs a few times in a
row during this time. Instead simply:
- update all of the roots first
- then run delayed refs
- then handle the empty block groups case
- and then if we have any more dirty roots do the whole thing again
This allows us to be much more efficient with our delayed ref running,
as we can batch a few more operations at once.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This was added in commit 361048f586 ("Btrfs: fix full backref problem
when inserting shared block reference") to address a problem where we
hit the following BUG_ON() in alloc_reserved_tree_block
if (node->type == BTRFS_SHARED_BLOCK_REF_KEY) {
BUG_ON(!(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
However this BUG_ON() is bogus, and was removed by previous commit:
btrfs: remove bogus BUG_ON in alloc_reserved_tree_block
We no longer need to run delayed refs because of this, and can remove
this flushing here.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The fix 361048f586 ("Btrfs: fix full backref problem when inserting
shared block reference") added a delayed ref flushing at subvolume
creation time in order to avoid hitting this particular BUG_ON().
Before this fix, we were tripping the BUG_ON() by
1. Modify snapshot A, which creates blocks with a normal reference for
snapshot A, as A is the owner of these blocks. We now have delayed
refs for these blocks.
2. Create a snapshot of A named B, which pushes references for the
children blocks of the root node for the new root B, thus creating
more delayed refs for newly allocated blocks.
3. A is modified, and because the metadata blocks can now be shared, it
must push FULL_BACKREF references to the children of any block that A
COWs down it's path to its target key.
4. Delayed refs are run. Because these are newly allocated blocks, we
have ->must_insert_reserved reserved set on the delayed ref head, we
call into alloc_reserved_tree_block() to add the extent item, and
then add our ref. At the time of this fix, we were ordering
FULL_BACKREF delayed ref operations first, so we'd go to add this
reference and then BUG_ON() because we didn't have the FULL_BACKREF
flag set.
The patch fixed this problem by making sure we ran the delayed refs
before we had the chance to modify A. This meant that any *new* blocks
would have had their extent items created _before_ we would ever
actually COW down and generate FULL_BACKREF entries. Thus the problem
went away.
However this BUG_ON() is actually completely bogus. The existence of a
full backref doesn't necessarily mean that FULL_BACKREF must be set on
that block, it must only be set on the actual parent itself. Consider
the example provided above. If we COW down one path from A, any nodes
are going to have a FULL_BACKREF ref pushed down to _all_ of their
children, but not all of the children are going to have FULL_BACKREF
set. It is completely valid to have an extent item with normal and full
backrefs without FULL_BACKREF actually set on the block itself.
As a final note, I have been testing with the patch (applied after this
one)
btrfs: stop running all delayed refs during snapshot
which removed this flushing. My test was a torture test which did a lot
of operations while snapshotting and deleting snapshots as well as
relocation, and I never tripped this BUG_ON(). This is actually because
at the time of 361048f586, we ordered SHARED keys _before_ normal
references, and thus they would get run first. However currently they
are ordered _after_ normal references, so we'd do the initial creation
without having a shared reference, and thus not hit this BUG_ON(), which
explains why I didn't start hitting this problem during my testing with
my other patch applied.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The commit d672633545 ("btrfs: qgroup: Make snapshot accounting work
with new extent-oriented qgroup.") added a flush of the delayed refs
during snapshot creation in order to get the qgroup accounting properly.
However this code has changed and been moved to it's own helper that is
skipped if qgroups are turned off. Move the flushing to the helper, as
we do not need it when qgroups are turned off.
Also add a comment explaining why it exists, and why it doesn't actually
save us. This will be helpful later when we try to fix qgroup
accounting properly.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We try to pre-flush the delayed refs when committing, because we want to
do as little work as possible in the critical section of the transaction
commit.
However doing this twice can lead to very long transaction commit delays
as other threads are allowed to continue to generate more delayed refs,
which potentially delays the commit by multiple minutes in very extreme
cases.
So simply stick to one pre-flush, and then continue the rest of the
transaction commit.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Previously our delayed ref running used the total number of items as the
items to run. However we changed that to number of heads to run with
the delayed_refs_rsv, as generally we want to run all of the operations
for one bytenr.
But with btrfs_run_delayed_refs(trans, 0) we set our count to 2x the
number of items that we have. This is generally fine, but if we have
some operation generation loads of delayed refs while we're doing this
pre-flushing in the transaction commit, we'll just spin forever doing
delayed refs.
Fix this to simply pick the number of delayed refs we currently have,
that way we do not end up doing a lot of extra work that's being
generated in other threads.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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>
While running some stress tests I started getting hung task messages.
This is because the delete unused block groups code has to take the
delete_unused_bgs_mutex to do it's work, which is taken by balance to
make sure we don't delete block groups while we're balancing.
The problem is that balance can take a while, and so we were getting
hung task warnings. We don't need to block and run these things, and
the cleaner is needed to do other work, so trylock on this mutex and
just bail if we can't acquire it right away.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
While testing my error handling patches, I added a error injection site
at btrfs_inc_extent_ref, to validate the error handling I added was
doing the correct thing. However I hit a pretty ugly corruption while
doing this check, with the following error injection stack trace:
btrfs_inc_extent_ref
btrfs_copy_root
create_reloc_root
btrfs_init_reloc_root
btrfs_record_root_in_trans
btrfs_start_transaction
btrfs_update_inode
btrfs_update_time
touch_atime
file_accessed
btrfs_file_mmap
This is because we do not catch the error from btrfs_inc_extent_ref,
which in practice would be ENOMEM, which means we lose the extent
references for a root that has already been allocated and inserted,
which is the problem. Fix this by aborting the transaction if we fail
to do the reference modification.
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
A weird KASAN problem that Zygo reported could have been easily caught
if we checked for basic things in our backref freeing code. We have two
methods of freeing a backref node
- btrfs_backref_free_node: this just is kfree() essentially.
- btrfs_backref_drop_node: this actually unlinks the node and cleans up
everything and then calls btrfs_backref_free_node().
We should mostly be using btrfs_backref_drop_node(), to make sure the
node is properly unlinked from the backref cache, and only use
btrfs_backref_free_node() when we know the node isn't actually linked to
the backref cache. We made a mistake here and thus got the KASAN splat.
Make this style of issue easier to find by adding some ASSERT()'s to
btrfs_backref_free_node() and adjusting our deletion stuff to properly
init the list so we can rely on list_empty() checks working properly.
BUG: KASAN: use-after-free in btrfs_backref_cleanup_node+0x18a/0x420
Read of size 8 at addr ffff888112402950 by task btrfs/28836
CPU: 0 PID: 28836 Comm: btrfs Tainted: G W 5.10.0-e35f27394290-for-next+ #23
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
dump_stack+0xbc/0xf9
? btrfs_backref_cleanup_node+0x18a/0x420
print_address_description.constprop.8+0x21/0x210
? record_print_text.cold.34+0x11/0x11
? btrfs_backref_cleanup_node+0x18a/0x420
? btrfs_backref_cleanup_node+0x18a/0x420
kasan_report.cold.10+0x20/0x37
? btrfs_backref_cleanup_node+0x18a/0x420
__asan_load8+0x69/0x90
btrfs_backref_cleanup_node+0x18a/0x420
btrfs_backref_release_cache+0x83/0x1b0
relocate_block_group+0x394/0x780
? merge_reloc_roots+0x4a0/0x4a0
btrfs_relocate_block_group+0x26e/0x4c0
btrfs_relocate_chunk+0x52/0x120
btrfs_balance+0xe2e/0x1900
? check_flags.part.50+0x6c/0x1e0
? btrfs_relocate_chunk+0x120/0x120
? kmem_cache_alloc_trace+0xa06/0xcb0
? _copy_from_user+0x83/0xc0
btrfs_ioctl_balance+0x3a7/0x460
btrfs_ioctl+0x24c8/0x4360
? __kasan_check_read+0x11/0x20
? check_chain_key+0x1f4/0x2f0
? __asan_loadN+0xf/0x20
? btrfs_ioctl_get_supported_features+0x30/0x30
? kvm_sched_clock_read+0x18/0x30
? check_chain_key+0x1f4/0x2f0
? lock_downgrade+0x3f0/0x3f0
? handle_mm_fault+0xad6/0x2150
? do_vfs_ioctl+0xfc/0x9d0
? ioctl_file_clone+0xe0/0xe0
? check_flags.part.50+0x6c/0x1e0
? check_flags.part.50+0x6c/0x1e0
? check_flags+0x26/0x30
? lock_is_held_type+0xc3/0xf0
? syscall_enter_from_user_mode+0x1b/0x60
? do_syscall_64+0x13/0x80
? rcu_read_lock_sched_held+0xa1/0xd0
? __kasan_check_read+0x11/0x20
? __fget_light+0xae/0x110
__x64_sys_ioctl+0xc3/0x100
do_syscall_64+0x37/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f4c4bdfe427
RSP: 002b:00007fff33ee6df8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fff33ee6e98 RCX: 00007f4c4bdfe427
RDX: 00007fff33ee6e98 RSI: 00000000c4009420 RDI: 0000000000000003
RBP: 0000000000000003 R08: 0000000000000003 R09: 0000000000000078
R10: fffffffffffff59d R11: 0000000000000202 R12: 0000000000000001
R13: 0000000000000000 R14: 00007fff33ee8a34 R15: 0000000000000001
Allocated by task 28836:
kasan_save_stack+0x21/0x50
__kasan_kmalloc.constprop.18+0xbe/0xd0
kasan_kmalloc+0x9/0x10
kmem_cache_alloc_trace+0x410/0xcb0
btrfs_backref_alloc_node+0x46/0xf0
btrfs_backref_add_tree_node+0x60d/0x11d0
build_backref_tree+0xc5/0x700
relocate_tree_blocks+0x2be/0xb90
relocate_block_group+0x2eb/0x780
btrfs_relocate_block_group+0x26e/0x4c0
btrfs_relocate_chunk+0x52/0x120
btrfs_balance+0xe2e/0x1900
btrfs_ioctl_balance+0x3a7/0x460
btrfs_ioctl+0x24c8/0x4360
__x64_sys_ioctl+0xc3/0x100
do_syscall_64+0x37/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Freed by task 28836:
kasan_save_stack+0x21/0x50
kasan_set_track+0x20/0x30
kasan_set_free_info+0x1f/0x30
__kasan_slab_free+0xf3/0x140
kasan_slab_free+0xe/0x10
kfree+0xde/0x200
btrfs_backref_error_cleanup+0x452/0x530
build_backref_tree+0x1a5/0x700
relocate_tree_blocks+0x2be/0xb90
relocate_block_group+0x2eb/0x780
btrfs_relocate_block_group+0x26e/0x4c0
btrfs_relocate_chunk+0x52/0x120
btrfs_balance+0xe2e/0x1900
btrfs_ioctl_balance+0x3a7/0x460
btrfs_ioctl+0x24c8/0x4360
__x64_sys_ioctl+0xc3/0x100
do_syscall_64+0x37/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
The buggy address belongs to the object at ffff888112402900
which belongs to the cache kmalloc-128 of size 128
The buggy address is located 80 bytes inside of
128-byte region [ffff888112402900, ffff888112402980)
The buggy address belongs to the page:
page:0000000028b1cd08 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888131c810c0 pfn:0x112402
flags: 0x17ffe0000000200(slab)
raw: 017ffe0000000200 ffffea000424f308 ffffea0007d572c8 ffff888100040440
raw: ffff888131c810c0 ffff888112402000 0000000100000009 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff888112402800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888112402880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888112402900: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888112402980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888112402a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
Link: https://lore.kernel.org/linux-btrfs/20201208194607.GI31381@hungrycats.org/
CC: stable@vger.kernel.org # 5.10+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The backref code is looking for a reloc_root that corresponds to the
given fs root. However any number of things could have gone wrong while
initializing that reloc_root, like ENOMEM while trying to allocate the
root itself, or EIO while trying to write the root item. This would
result in no corresponding reloc_root being in the reloc root cache, and
thus would return NULL when we do the find_reloc_root() call.
Because of this we do not want to WARN_ON(). This presumably was meant
to catch developer errors, cases where we messed up adding the reloc
root. However we can easily hit this case with error injection, and
thus should not do a WARN_ON().
CC: stable@vger.kernel.org # 5.10+
Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
While doing error injection testing with my relocation patches I hit the
following assert:
assertion failed: list_empty(&block_group->dirty_list), in fs/btrfs/block-group.c:3356
------------[ cut here ]------------
kernel BUG at fs/btrfs/ctree.h:3357!
invalid opcode: 0000 [#1] SMP NOPTI
CPU: 0 PID: 24351 Comm: umount Tainted: G W 5.10.0-rc3+ #193
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
RIP: 0010:assertfail.constprop.0+0x18/0x1a
RSP: 0018:ffffa09b019c7e00 EFLAGS: 00010282
RAX: 0000000000000056 RBX: ffff8f6492c18000 RCX: 0000000000000000
RDX: ffff8f64fbc27c60 RSI: ffff8f64fbc19050 RDI: ffff8f64fbc19050
RBP: ffff8f6483bbdc00 R08: 0000000000000000 R09: 0000000000000000
R10: ffffa09b019c7c38 R11: ffffffff85d70928 R12: ffff8f6492c18100
R13: ffff8f6492c18148 R14: ffff8f6483bbdd70 R15: dead000000000100
FS: 00007fbfda4cdc40(0000) GS:ffff8f64fbc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbfda666fd0 CR3: 000000013cf66002 CR4: 0000000000370ef0
Call Trace:
btrfs_free_block_groups.cold+0x55/0x55
close_ctree+0x2c5/0x306
? fsnotify_destroy_marks+0x14/0x100
generic_shutdown_super+0x6c/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20
deactivate_locked_super+0x36/0xa0
cleanup_mnt+0x12d/0x190
task_work_run+0x5c/0xa0
exit_to_user_mode_prepare+0x1b1/0x1d0
syscall_exit_to_user_mode+0x54/0x280
entry_SYSCALL_64_after_hwframe+0x44/0xa9
This happened because I injected an error in btrfs_cow_block() while
running the dirty block groups. When we run the dirty block groups, we
splice the list onto a local list to process. However if an error
occurs, we only cleanup the transactions dirty block group list, not any
pending block groups we have on our locally spliced list.
In fact if we fail to allocate a path in this function we'll also fail
to clean up the splice list.
Fix this by splicing the list back onto the transaction dirty block
group list so that the block groups are cleaned up. Then add a 'out'
label and have the error conditions jump to out so that the errors are
handled properly. This also has the side-effect of fixing a problem
where we would clear 'ret' on error because we unconditionally ran
btrfs_run_delayed_refs().
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When recovering a relocation, if we run into a reloc root that has 0
refs we simply add it to the reloc_control->reloc_roots list, and then
clean it up later. The problem with this is __del_reloc_root() doesn't
do anything if the root isn't in the radix tree, which in this case it
won't be because we never call __add_reloc_root() on the reloc_root.
This exit condition simply isn't correct really. During normal
operation we can remove ourselves from the rb tree and then we're meant
to clean up later at merge_reloc_roots() time, and this happens
correctly. During recovery we're depending on free_reloc_roots() to
drop our references, but we're short-circuiting.
Fix this by continuing to check if we're on the list and dropping
ourselves from the reloc_control root list and dropping our reference
appropriately. Change the corresponding BUG_ON() to an ASSERT() that
does the correct thing if we aren't in the rb tree.
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Comment for processed extent end of range has an unnecessary "in",
remove it.
Signed-off-by: Nigel Christian <nigel.l.christian@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
My recent patch set "A variety of lock contention fixes", found here
https://lore.kernel.org/linux-btrfs/cover.1608319304.git.josef@toxicpanda.com/
(Tracked in https://github.com/btrfs/linux/issues/86)
that reduce lock contention on the extent root by running delayed refs
less often resulted in a regression in generic/371. This test
fallocate()'s the fs until it's full, deletes all the files, and then
tries to fallocate() until full again.
Before these patches we would run all of the delayed refs during
flushing, and then would commit the transaction because we had plenty of
pinned space to recover in order to allocate. However my patches made
it so we weren't running the delayed refs as aggressively, which meant
that we appeared to have less pinned space when we were deciding to
commit the transaction.
We use the space_info->total_bytes_pinned to approximate how much space
we have pinned. It's approximate because if we remove a reference to an
extent we may free it, but there may be more references to it than we
know of at that point, but we account it as pinned at the creation time,
and then it's properly accounted when the delayed ref runs.
The way we account for pinned space is if the
delayed_ref_head->total_ref_mod is < 0, because that is clearly a
freeing option. However there is another case, and that is where
->total_ref_mod == 0 && ->must_insert_reserved == 1.
When we allocate a new extent, we have ->total_ref_mod == 1 and we have
->must_insert_reserved == 1. This is used to indicate that it is a
brand new extent and will need to have its extent entry added before we
modify any references on the delayed ref head. But if we subsequently
remove that extent reference, our ->total_ref_mod will be 0, and that
space will be pinned and freed. Accounting for this case properly
allows for generic/371 to pass with my delayed refs patches applied.
It's important to note that this problem exists without the referenced
patches, it just was uncovered by them.
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>
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>
Now that the btrfs' codebase is clean of almost all W=1 warnings let's
enable those checks unconditionally for the entire fs/btrfs/ and its
subdirectories to catch potential errors during development.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add some comments ]
Signed-off-by: David Sterba <dsterba@suse.com>
These constants are really used internally by zstd and including
linux/zstd.h into users results in the following warnings:
In file included from fs/btrfs/zstd.c:19:
./include/linux/zstd.h:798:21: warning: ‘ZSTD_skippableHeaderSize’ defined but not used [-Wunused-const-variable=]
798 | static const size_t ZSTD_skippableHeaderSize = 8;
| ^~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/zstd.h:796:21: warning: ‘ZSTD_frameHeaderSize_max’ defined but not used [-Wunused-const-variable=]
796 | static const size_t ZSTD_frameHeaderSize_max = ZSTD_FRAMEHEADERSIZE_MAX;
| ^~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/zstd.h:795:21: warning: ‘ZSTD_frameHeaderSize_min’ defined but not used [-Wunused-const-variable=]
795 | static const size_t ZSTD_frameHeaderSize_min = ZSTD_FRAMEHEADERSIZE_MIN;
| ^~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/zstd.h:794:21: warning: ‘ZSTD_frameHeaderSize_prefix’ defined but not used [-Wunused-const-variable=]
794 | static const size_t ZSTD_frameHeaderSize_prefix = 5;
So fix those warnings by turning the constants into defines.
Reviewed-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This fixes warning:
fs/btrfs/zoned.c:491:6: warning: variable ‘zone_size’ set but not used [-Wunused-but-set-variable]
491 | u64 zone_size;
which got introduced in 12659251ca ("btrfs: implement log-structured
superblock for ZONED mode"). We'll enable the warning by default and
want clean build until the relevant zoned patches land.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This makes the file W=1 clean and fixes the following warnings:
fs/btrfs/extent_io.c:414: warning: Function parameter or member 'tree' not described in '__etree_search'
fs/btrfs/extent_io.c:414: warning: Function parameter or member 'offset' not described in '__etree_search'
fs/btrfs/extent_io.c:414: warning: Function parameter or member 'next_ret' not described in '__etree_search'
fs/btrfs/extent_io.c:414: warning: Function parameter or member 'prev_ret' not described in '__etree_search'
fs/btrfs/extent_io.c:414: warning: Function parameter or member 'p_ret' not described in '__etree_search'
fs/btrfs/extent_io.c:414: warning: Function parameter or member 'parent_ret' not described in '__etree_search'
fs/btrfs/extent_io.c:1607: warning: Function parameter or member 'tree' not described in 'find_contiguous_extent_bit'
fs/btrfs/extent_io.c:1607: warning: Function parameter or member 'start' not described in 'find_contiguous_extent_bit'
fs/btrfs/extent_io.c:1607: warning: Function parameter or member 'start_ret' not described in 'find_contiguous_extent_bit'
fs/btrfs/extent_io.c:1607: warning: Function parameter or member 'end_ret' not described in 'find_contiguous_extent_bit'
fs/btrfs/extent_io.c:1607: warning: Function parameter or member 'bits' not described in 'find_contiguous_extent_bit'
fs/btrfs/extent_io.c:1644: warning: Function parameter or member 'tree' not described in 'find_first_clear_extent_bit'
fs/btrfs/extent_io.c:1644: warning: Function parameter or member 'start' not described in 'find_first_clear_extent_bit'
fs/btrfs/extent_io.c:1644: warning: Function parameter or member 'start_ret' not described in 'find_first_clear_extent_bit'
fs/btrfs/extent_io.c:1644: warning: Function parameter or member 'end_ret' not described in 'find_first_clear_extent_bit'
fs/btrfs/extent_io.c:1644: warning: Function parameter or member 'bits' not described in 'find_first_clear_extent_bit'
fs/btrfs/extent_io.c:4187: warning: Function parameter or member 'epd' not described in 'extent_write_cache_pages'
fs/btrfs/extent_io.c:4187: warning: Excess function parameter 'data' description in 'extent_write_cache_pages'
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
With these fixes space-info.c is clear for W=1 warnings, namely the
following ones are fixed:
fs/btrfs/space-info.c:575: warning: Function parameter or member 'fs_info' not described in 'may_commit_transaction'
fs/btrfs/space-info.c:575: warning: Function parameter or member 'space_info' not described in 'may_commit_transaction'
fs/btrfs/space-info.c:1231: warning: Function parameter or member 'fs_info' not described in 'handle_reserve_ticket'
fs/btrfs/space-info.c:1231: warning: Function parameter or member 'space_info' not described in 'handle_reserve_ticket'
fs/btrfs/space-info.c:1231: warning: Function parameter or member 'ticket' not described in 'handle_reserve_ticket'
fs/btrfs/space-info.c:1231: warning: Function parameter or member 'flush' not described in 'handle_reserve_ticket'
fs/btrfs/space-info.c:1315: warning: Function parameter or member 'fs_info' not described in '__reserve_bytes'
fs/btrfs/space-info.c:1315: warning: Function parameter or member 'space_info' not described in '__reserve_bytes'
fs/btrfs/space-info.c:1315: warning: Function parameter or member 'orig_bytes' not described in '__reserve_bytes'
fs/btrfs/space-info.c:1315: warning: Function parameter or member 'flush' not described in '__reserve_bytes'
fs/btrfs/space-info.c:1427: warning: Function parameter or member 'root' not described in 'btrfs_reserve_metadata_bytes'
fs/btrfs/space-info.c:1427: warning: Function parameter or member 'block_rsv' not described in 'btrfs_reserve_metadata_bytes'
fs/btrfs/space-info.c:1427: warning: Function parameter or member 'orig_bytes' not described in 'btrfs_reserve_metadata_bytes'
fs/btrfs/space-info.c:1427: warning: Function parameter or member 'flush' not described in 'btrfs_reserve_metadata_bytes'
fs/btrfs/space-info.c:1462: warning: Function parameter or member 'fs_info' not described in 'btrfs_reserve_data_bytes'
fs/btrfs/space-info.c:1462: warning: Function parameter or member 'bytes' not described in 'btrfs_reserve_data_bytes'
fs/btrfs/space-info.c:1462: warning: Function parameter or member 'flush' not described in 'btrfs_reserve_data_bytes'
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Fixes following warnings:
fs/btrfs/delalloc-space.c:205: warning: Function parameter or member 'inode' not described in 'btrfs_inode_rsv_release'
fs/btrfs/delalloc-space.c:205: warning: Function parameter or member 'qgroup_free' not described in 'btrfs_inode_rsv_release'
fs/btrfs/delalloc-space.c:472: warning: Function parameter or member 'reserved' not described in 'btrfs_delalloc_release_space'
fs/btrfs/delalloc-space.c:472: warning: Function parameter or member 'qgroup_free' not described in 'btrfs_delalloc_release_space'
fs/btrfs/delalloc-space.c:472: warning: Excess function parameter 'release_bytes' description in 'btrfs_delalloc_release_space'
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Fixes fs/btrfs/inode.c:3101: warning: Function parameter or member 'fs_info' not described in 'btrfs_wait_on_delayed_iputs'
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Fixes fs/btrfs/block-group.c:1570: warning: Function parameter or member 'fs_info' not described in 'btrfs_rmap_block'
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Fixes fs/btrfs/discard.c:203: warning: Function parameter or member 'now' not described in 'peek_discard_list'
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Fixes following W=1 warnings:
fs/btrfs/free-space-cache.c:1317: warning: Function parameter or member 'root' not described in '__btrfs_write_out_cache'
fs/btrfs/free-space-cache.c:1317: warning: Function parameter or member 'inode' not described in '__btrfs_write_out_cache'
fs/btrfs/free-space-cache.c:1317: warning: Function parameter or member 'ctl' not described in '__btrfs_write_out_cache'
fs/btrfs/free-space-cache.c:1317: warning: Function parameter or member 'block_group' not described in '__btrfs_write_out_cache'
fs/btrfs/free-space-cache.c:1317: warning: Function parameter or member 'io_ctl' not described in '__btrfs_write_out_cache'
fs/btrfs/free-space-cache.c:1317: warning: Function parameter or member 'trans' not described in '__btrfs_write_out_cache'
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This fixes the following warnings:
fs/btrfs/delayed-ref.c:80: warning: Function parameter or member 'fs_info' not described in 'btrfs_delayed_refs_rsv_release'
fs/btrfs/delayed-ref.c:80: warning: Function parameter or member 'nr' not described in 'btrfs_delayed_refs_rsv_release'
fs/btrfs/delayed-ref.c:128: warning: Function parameter or member 'fs_info' not described in 'btrfs_migrate_to_delayed_refs_rsv'
fs/btrfs/delayed-ref.c:128: warning: Function parameter or member 'src' not described in 'btrfs_migrate_to_delayed_refs_rsv'
fs/btrfs/delayed-ref.c:128: warning: Function parameter or member 'num_bytes' not described in 'btrfs_migrate_to_delayed_refs_rsv'
fs/btrfs/delayed-ref.c:174: warning: Function parameter or member 'fs_info' not described in 'btrfs_delayed_refs_rsv_refill'
fs/btrfs/delayed-ref.c:174: warning: Function parameter or member 'flush' not described in 'btrfs_delayed_refs_rsv_refill'
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This fixes following W=1 warnings:
fs/btrfs/file-item.c:27: warning: Cannot understand * @inode: the inode we want to update the disk_i_size for
on line 27 - I thought it was a doc line
fs/btrfs/file-item.c:65: warning: Cannot understand * @inode - the inode we're modifying
on line 65 - I thought it was a doc line
fs/btrfs/file-item.c:91: warning: Cannot understand * @inode - the inode we're modifying
on line 91 - I thought it was a doc line
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This fixes the following compiler warnings:
fs/btrfs/extent_map.c:601: warning: Function parameter or member 'fs_info' not described in 'btrfs_add_extent_mapping'
fs/btrfs/extent_map.c:601: warning: Function parameter or member 'em_tree' not described in 'btrfs_add_extent_mapping'
fs/btrfs/extent_map.c:601: warning: Function parameter or member 'em_in' not described in 'btrfs_add_extent_mapping'
fs/btrfs/extent_map.c:601: warning: Function parameter or member 'start' not described in 'btrfs_add_extent_mapping'
fs/btrfs/extent_map.c:601: warning: Function parameter or member 'len' not described in 'btrfs_add_extent_mapping'
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Fixes fs/btrfs/extent_map.c:399: warning: Function parameter or member
'modified' not described in 'add_extent_mapping'
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
There is a long existing bug in the last parameter of
btrfs_add_ordered_extent(), in commit 771ed689d2 ("Btrfs: Optimize
compressed writeback and reads") back to 2008.
In that ancient commit btrfs_add_ordered_extent() expects the @type
parameter to be one of the following:
- BTRFS_ORDERED_REGULAR
- BTRFS_ORDERED_NOCOW
- BTRFS_ORDERED_PREALLOC
- BTRFS_ORDERED_COMPRESSED
But we pass 0 in cow_file_range(), which means BTRFS_ORDERED_IO_DONE.
Ironically extra check in __btrfs_add_ordered_extent() won't set the bit
if we see (type == IO_DONE || type == IO_COMPLETE), and avoid any
obvious bug.
But this still leads to regular COW ordered extent having no bit to
indicate its type in various trace events, rendering REGULAR bit
useless.
[FIX]
Change the following aspects to avoid such problem:
- Reorder btrfs_ordered_extent::flags
Now the type bits go first (REGULAR/NOCOW/PREALLCO/COMPRESSED), then
DIRECT bit, finally extra status bits like IO_DONE/COMPLETE/IOERR.
- Add extra ASSERT() for btrfs_add_ordered_extent_*()
- Remove @type parameter for btrfs_add_ordered_extent_compress()
As the only valid @type here is BTRFS_ORDERED_COMPRESSED.
- Remove the unnecessary special check for IO_DONE/COMPLETE in
__btrfs_add_ordered_extent()
This is just to make the code work, with extra ASSERT(), there are
limited values can be passed in.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
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>
Fix below warnings reported by coccicheck:
./fs/btrfs/raid56.c:237:2-8: WARNING: NULL check before some freeing
functions is not needed.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Yang Li <abaci-bugfix@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Zygo reported the following panic when testing my error handling patches
for relocation:
kernel BUG at fs/btrfs/backref.c:2545!
invalid opcode: 0000 [#1] SMP KASAN PTI CPU: 3 PID: 8472 Comm: btrfs Tainted: G W 14
Hardware name: QEMU Standard PC (i440FX + PIIX,
Call Trace:
btrfs_backref_error_cleanup+0x4df/0x530
build_backref_tree+0x1a5/0x700
? _raw_spin_unlock+0x22/0x30
? release_extent_buffer+0x225/0x280
? free_extent_buffer.part.52+0xd7/0x140
relocate_tree_blocks+0x2a6/0xb60
? kasan_unpoison_shadow+0x35/0x50
? do_relocation+0xc10/0xc10
? kasan_kmalloc+0x9/0x10
? kmem_cache_alloc_trace+0x6a3/0xcb0
? free_extent_buffer.part.52+0xd7/0x140
? rb_insert_color+0x342/0x360
? add_tree_block.isra.36+0x236/0x2b0
relocate_block_group+0x2eb/0x780
? merge_reloc_roots+0x470/0x470
btrfs_relocate_block_group+0x26e/0x4c0
btrfs_relocate_chunk+0x52/0x120
btrfs_balance+0xe2e/0x18f0
? pvclock_clocksource_read+0xeb/0x190
? btrfs_relocate_chunk+0x120/0x120
? lock_contended+0x620/0x6e0
? do_raw_spin_lock+0x1e0/0x1e0
? do_raw_spin_unlock+0xa8/0x140
btrfs_ioctl_balance+0x1f9/0x460
btrfs_ioctl+0x24c8/0x4380
? __kasan_check_read+0x11/0x20
? check_chain_key+0x1f4/0x2f0
? __asan_loadN+0xf/0x20
? btrfs_ioctl_get_supported_features+0x30/0x30
? kvm_sched_clock_read+0x18/0x30
? check_chain_key+0x1f4/0x2f0
? lock_downgrade+0x3f0/0x3f0
? handle_mm_fault+0xad6/0x2150
? do_vfs_ioctl+0xfc/0x9d0
? ioctl_file_clone+0xe0/0xe0
? check_flags.part.50+0x6c/0x1e0
? check_flags.part.50+0x6c/0x1e0
? check_flags+0x26/0x30
? lock_is_held_type+0xc3/0xf0
? syscall_enter_from_user_mode+0x1b/0x60
? do_syscall_64+0x13/0x80
? rcu_read_lock_sched_held+0xa1/0xd0
? __kasan_check_read+0x11/0x20
? __fget_light+0xae/0x110
__x64_sys_ioctl+0xc3/0x100
do_syscall_64+0x37/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
This occurs because of this check
if (RB_EMPTY_NODE(&upper->rb_node))
BUG_ON(!list_empty(&node->upper));
As we are dropping the backref node, if we discover that our upper node
in the edge we just cleaned up isn't linked into the cache that we are
now done with this node, thus the BUG_ON().
However this is an erroneous assumption, as we will look up all the
references for a node first, and then process the pending edges. All of
the 'upper' nodes in our pending edges won't be in the cache's rb_tree
yet, because they haven't been processed. We could very well have many
edges still left to cleanup on this node.
The fact is we simply do not need this check, we can just process all of
the edges only for this node, because below this check we do the
following
if (list_empty(&upper->lower)) {
list_add_tail(&upper->lower, &cache->leaves);
upper->lowest = 1;
}
If the upper node truly isn't used yet, then we add it to the
cache->leaves list to be cleaned up later. If it is still used then the
last child node that has it linked into its node will add it to the
leaves list and then it will be cleaned up.
Fix this problem by dropping this logic altogether. With this fix I no
longer see the panic when testing with error injection in the backref
code.
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
While testing the error paths in relocation, I hit the following lockdep
splat:
======================================================
WARNING: possible circular locking dependency detected
5.10.0-rc3+ #206 Not tainted
------------------------------------------------------
btrfs-balance/1571 is trying to acquire lock:
ffff8cdbcc8f77d0 (&head_ref->mutex){+.+.}-{3:3}, at: btrfs_lookup_extent_info+0x156/0x3b0
but task is already holding lock:
ffff8cdbc54adbf8 (btrfs-tree-00){++++}-{3:3}, at: __btrfs_tree_lock+0x27/0x100
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (btrfs-tree-00){++++}-{3:3}:
down_write_nested+0x43/0x80
__btrfs_tree_lock+0x27/0x100
btrfs_search_slot+0x248/0x890
relocate_tree_blocks+0x490/0x650
relocate_block_group+0x1ba/0x5d0
kretprobe_trampoline+0x0/0x50
-> #1 (btrfs-csum-01){++++}-{3:3}:
down_read_nested+0x43/0x130
__btrfs_tree_read_lock+0x27/0x100
btrfs_read_lock_root_node+0x31/0x40
btrfs_search_slot+0x5ab/0x890
btrfs_del_csums+0x10b/0x3c0
__btrfs_free_extent+0x49d/0x8e0
__btrfs_run_delayed_refs+0x283/0x11f0
btrfs_run_delayed_refs+0x86/0x220
btrfs_start_dirty_block_groups+0x2ba/0x520
kretprobe_trampoline+0x0/0x50
-> #0 (&head_ref->mutex){+.+.}-{3:3}:
__lock_acquire+0x1167/0x2150
lock_acquire+0x116/0x3e0
__mutex_lock+0x7e/0x7b0
btrfs_lookup_extent_info+0x156/0x3b0
walk_down_proc+0x1c3/0x280
walk_down_tree+0x64/0xe0
btrfs_drop_subtree+0x182/0x260
do_relocation+0x52e/0x660
relocate_tree_blocks+0x2ae/0x650
relocate_block_group+0x1ba/0x5d0
kretprobe_trampoline+0x0/0x50
other info that might help us debug this:
Chain exists of:
&head_ref->mutex --> btrfs-csum-01 --> btrfs-tree-00
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(btrfs-tree-00);
lock(btrfs-csum-01);
lock(btrfs-tree-00);
lock(&head_ref->mutex);
*** DEADLOCK ***
5 locks held by btrfs-balance/1571:
#0: ffff8cdb89749ff8 (&fs_info->delete_unused_bgs_mutex){+.+.}-{3:3}, at: btrfs_balance+0x563/0xf40
#1: ffff8cdb89748838 (&fs_info->cleaner_mutex){+.+.}-{3:3}, at: btrfs_relocate_block_group+0x156/0x300
#2: ffff8cdbc2c16650 (sb_internal#2){.+.+}-{0:0}, at: start_transaction+0x413/0x5c0
#3: ffff8cdbc135f538 (btrfs-treloc-01){+.+.}-{3:3}, at: __btrfs_tree_lock+0x27/0x100
#4: ffff8cdbc54adbf8 (btrfs-tree-00){++++}-{3:3}, at: __btrfs_tree_lock+0x27/0x100
stack backtrace:
CPU: 1 PID: 1571 Comm: btrfs-balance Not tainted 5.10.0-rc3+ #206
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
Call Trace:
dump_stack+0x8b/0xb0
check_noncircular+0xcf/0xf0
? trace_call_bpf+0x139/0x260
__lock_acquire+0x1167/0x2150
lock_acquire+0x116/0x3e0
? btrfs_lookup_extent_info+0x156/0x3b0
__mutex_lock+0x7e/0x7b0
? btrfs_lookup_extent_info+0x156/0x3b0
? btrfs_lookup_extent_info+0x156/0x3b0
? release_extent_buffer+0x124/0x170
? _raw_spin_unlock+0x1f/0x30
? release_extent_buffer+0x124/0x170
btrfs_lookup_extent_info+0x156/0x3b0
walk_down_proc+0x1c3/0x280
walk_down_tree+0x64/0xe0
btrfs_drop_subtree+0x182/0x260
do_relocation+0x52e/0x660
relocate_tree_blocks+0x2ae/0x650
? add_tree_block+0x149/0x1b0
relocate_block_group+0x1ba/0x5d0
elfcorehdr_read+0x40/0x40
? elfcorehdr_read+0x40/0x40
? btrfs_balance+0x796/0xf40
? __kthread_parkme+0x66/0x90
? btrfs_balance+0xf40/0xf40
? balance_kthread+0x37/0x50
? kthread+0x137/0x150
? __kthread_bind_mask+0x60/0x60
? ret_from_fork+0x1f/0x30
As you can see this is bogus, we never take another tree's lock under
the csum lock. This happens because sometimes we have to read tree
blocks from disk without knowing which root they belong to during
relocation. We defaulted to an owner of 0, which translates to an fs
tree. This is fine as all fs trees have the same class, but obviously
isn't fine if the block belongs to a COW only tree.
Thankfully COW only trees only have their owners root as a reference to
them, and since we already look up the extent information during
relocation, go ahead and check and see if this block might belong to a
COW only tree, and if so save the owner in the tree_block struct. This
allows us to read_tree_block with the proper owner, which gets rid of
this lockdep splat.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This patch will extract the code to grab an extent buffer from a page
into a helper, grab_extent_buffer_from_page().
This reduces one indent level, and provides the work place for later
expansion for subapge support.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.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 original comment is from the initial merge, which has several
problems:
- No holes check any more
- No inline decision is made
Update the out-of-date comment with more correct one.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
