If a task is removing the block group that currently has the highest start
offset amongst all existing block groups, there is a short time window
where it races with a concurrent block group allocation, resulting in a
transaction abort with an error code of EEXIST.
The following diagram explains the race in detail:
Task A Task B
btrfs_remove_block_group(bg offset X)
remove_extent_mapping(em offset X)
-> removes extent map X from the
tree of extent maps
(fs_info->mapping_tree), so the
next call to find_next_chunk()
will return offset X
btrfs_alloc_chunk()
find_next_chunk()
--> returns offset X
__btrfs_alloc_chunk(offset X)
btrfs_make_block_group()
btrfs_create_block_group_cache()
--> creates btrfs_block_group_cache
object with a key corresponding
to the block group item in the
extent, the key is:
(offset X, BTRFS_BLOCK_GROUP_ITEM_KEY, 1G)
--> adds the btrfs_block_group_cache object
to the list new_bgs of the transaction
handle
btrfs_end_transaction(trans handle)
__btrfs_end_transaction()
btrfs_create_pending_block_groups()
--> sees the new btrfs_block_group_cache
in the new_bgs list of the transaction
handle
--> its call to btrfs_insert_item() fails
with -EEXIST when attempting to insert
the block group item key
(offset X, BTRFS_BLOCK_GROUP_ITEM_KEY, 1G)
because task A has not removed that key yet
--> aborts the running transaction with
error -EEXIST
btrfs_del_item()
-> removes the block group's key from
the extent tree, key is
(offset X, BTRFS_BLOCK_GROUP_ITEM_KEY, 1G)
A sample transaction abort trace:
[78912.403537] ------------[ cut here ]------------
[78912.403811] BTRFS: Transaction aborted (error -17)
[78912.404082] WARNING: CPU: 2 PID: 20465 at fs/btrfs/extent-tree.c:10551 btrfs_create_pending_block_groups+0x196/0x250 [btrfs]
(...)
[78912.405642] CPU: 2 PID: 20465 Comm: btrfs Tainted: G W 5.0.0-btrfs-next-46 #1
[78912.405941] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626ccb91-prebuilt.qemu-project.org 04/01/2014
[78912.406586] RIP: 0010:btrfs_create_pending_block_groups+0x196/0x250 [btrfs]
(...)
[78912.407636] RSP: 0018:ffff9d3d4b7e3b08 EFLAGS: 00010282
[78912.407997] RAX: 0000000000000000 RBX: ffff90959a3796f0 RCX: 0000000000000006
[78912.408369] RDX: 0000000000000007 RSI: 0000000000000001 RDI: ffff909636b16860
[78912.408746] RBP: ffff909626758a58 R08: 0000000000000000 R09: 0000000000000000
[78912.409144] R10: ffff9095ff462400 R11: 0000000000000000 R12: ffff90959a379588
[78912.409521] R13: ffff909626758ab0 R14: ffff9095036c0000 R15: ffff9095299e1158
[78912.409899] FS: 00007f387f16f700(0000) GS:ffff909636b00000(0000) knlGS:0000000000000000
[78912.410285] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[78912.410673] CR2: 00007f429fc87cbc CR3: 000000014440a004 CR4: 00000000003606e0
[78912.411095] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[78912.411496] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[78912.411898] Call Trace:
[78912.412318] __btrfs_end_transaction+0x5b/0x1c0 [btrfs]
[78912.412746] btrfs_inc_block_group_ro+0xcf/0x160 [btrfs]
[78912.413179] scrub_enumerate_chunks+0x188/0x5b0 [btrfs]
[78912.413622] ? __mutex_unlock_slowpath+0x100/0x2a0
[78912.414078] btrfs_scrub_dev+0x2ef/0x720 [btrfs]
[78912.414535] ? __sb_start_write+0xd4/0x1c0
[78912.414963] ? mnt_want_write_file+0x24/0x50
[78912.415403] btrfs_ioctl+0x17fb/0x3120 [btrfs]
[78912.415832] ? lock_acquire+0xa6/0x190
[78912.416256] ? do_vfs_ioctl+0xa2/0x6f0
[78912.416685] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs]
[78912.417116] do_vfs_ioctl+0xa2/0x6f0
[78912.417534] ? __fget+0x113/0x200
[78912.417954] ksys_ioctl+0x70/0x80
[78912.418369] __x64_sys_ioctl+0x16/0x20
[78912.418812] do_syscall_64+0x60/0x1b0
[78912.419231] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[78912.419644] RIP: 0033:0x7f3880252dd7
(...)
[78912.420957] RSP: 002b:00007f387f16ed68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[78912.421426] RAX: ffffffffffffffda RBX: 000055f5becc1df0 RCX: 00007f3880252dd7
[78912.421889] RDX: 000055f5becc1df0 RSI: 00000000c400941b RDI: 0000000000000003
[78912.422354] RBP: 0000000000000000 R08: 00007f387f16f700 R09: 0000000000000000
[78912.422790] R10: 00007f387f16f700 R11: 0000000000000246 R12: 0000000000000000
[78912.423202] R13: 00007ffda49c266f R14: 0000000000000000 R15: 00007f388145e040
[78912.425505] ---[ end trace eb9bfe7c426fc4d3 ]---
Fix this by calling remove_extent_mapping(), at btrfs_remove_block_group(),
only at the very end, after removing the block group item key from the
extent tree (and removing the free space tree entry if we are using the
free space tree feature).
Fixes: 04216820fe ("Btrfs: fix race between fs trimming and block group remove/allocation")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This patch removes support for range parameters of FITRIM ioctl when
trimming unallocated space on devices. This is necessary since ranges
passed from user space are generally interpreted as logical addresses,
whereas btrfs_trim_free_extents used to interpret them as device
physical extents. This could result in counter-intuitive behavior for
users so it's best to remove that support altogether.
Additionally, the existing range support had a bug where if an offset
was passed to FITRIM which overflows u64 e.g. -1 (parsed as u64
18446744073709551615) then wrong data was fed into btrfs_issue_discard,
which in turn leads to wrap-around when aligning the passed range and
results in wrong regions being discarded which leads to data corruption.
Fixes: c2d1b3aae3 ("btrfs: Honour FITRIM range constraints during free space trim")
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit ddf30cf03f ("btrfs: extent-tree: Use btrfs_ref to refactor
add_pinned_bytes()") refactored add_pinned_bytes(), but during that
refactor, there are two callers which add the pinned bytes instead
of subtracting.
That refactor misses those two caller, causing incorrect pinned bytes
calculation and resulting unexpected ENOSPC error.
Fix it by adding a new parameter @sign to restore the original behavior.
Reported-by: kernel test robot <rong.a.chen@intel.com>
Fixes: ddf30cf03f ("btrfs: extent-tree: Use btrfs_ref to refactor add_pinned_bytes()")
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If a call to kobject_init_and_add() fails we must call kobject_put()
otherwise we leak memory.
Calling kobject_put() when kobject_init_and_add() fails drops the
refcount back to 0 and calls the ktype release method (which in turn
calls the percpu destroy and kfree).
Add call to kobject_put() in the error path of call to
kobject_init_and_add().
Cc: stable@vger.kernel.org # v4.4+
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tobin C. Harding <tobin@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
With the per-inode block reserves we started refilling the reserve based
on the calculated size of the outstanding csum bytes and extents for the
inode, including the amount we were adding with the new operation.
However, generic/224 exposed a problem with this approach. With 1000
files all writing at the same time we ended up with a bunch of bytes
being reserved but unusable.
When you write to a file we reserve space for the csum leaves for those
bytes, the number of extent items required to cover those bytes, and a
single transaction item for updating the inode at ordered extent finish
for that range of bytes. This is held until the ordered extent finishes
and we release all of the reserved space.
If a second write comes in at this point we would add a single
reservation for the new outstanding extent and however many reservations
for the csum leaves. At this point we find the delta of how much we
have reserved and how much outstanding size this is and attempt to
reserve this delta. If the first write finishes it will not release any
space, because the space it had reserved for the initial write is still
needed for the second write. However some space would have been used,
as we have added csums, extent items, and dirtied the inode. Our
reserved space would be > 0 but less than the total needed reserved
space.
This is just for a single inode, now consider generic/224. This has
1000 inodes writing in parallel to a very small file system, 1GiB. In
my testing this usually means we get about a 120MiB metadata area to
work with, more than enough to allow the writes to continue, but not
enough if all of the inodes are stuck trying to reserve the slack space
while continuing to hold their leftovers from their initial writes.
Fix this by pre-reserved _only_ for the space we are currently trying to
add. Then once that is successful modify our inodes csum count and
outstanding extents, and then add the newly reserved space to the inodes
block_rsv. This allows us to actually pass generic/224 without running
out of metadata space.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When diagnosing a slowdown of generic/224 I noticed we were not doing
anything when calling into shrink_delalloc(). This is because all
writes in 224 are O_DIRECT, not delalloc, and thus our delalloc_bytes
counter is 0, which short circuits most of the work inside of
shrink_delalloc(). However O_DIRECT writes still consume metadata
resources and generate ordered extents, which we can still wait on.
Fix this by tracking outstanding DIO write bytes, and use this as well
as the delalloc bytes counter to decide if we need to lookup and wait on
any ordered extents. If we have more DIO writes than delalloc bytes
we'll go ahead and wait on any ordered extents regardless of our flush
state as flushing delalloc is likely to not gain us anything.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ use dio instead of odirect in identifiers ]
Signed-off-by: David Sterba <dsterba@suse.com>
Since reloc tree doesn't contribute to qgroup numbers, just skip them.
This should catch the final cause of unnecessary data ref processing
when running balance of metadata with qgroups on.
The 4G data 16 snapshots test (*) should explain it pretty well:
| delayed subtree | refactor delayed ref | this patch
---------------------------------------------------------------------
relocated | 22653 | 22673 | 22744
qgroup dirty | 122792 | 48360 | 70
time | 24.494 | 11.606 | 3.944
Finally, we're at the stage where qgroup + metadata balance cost no
obvious overhead.
Test environment:
Test VM:
- vRAM 8G
- vCPU 8
- block dev vitrio-blk, 'unsafe' cache mode
- host block 850evo
Test workload:
- Copy 4G data from /usr/ to one subvolume
- Create 16 snapshots of that subvolume, and modify 3 files in each
snapshot
- Enable quota, rescan
- Time "btrfs balance start -m"
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Similar to btrfs_inc_extent_ref(), use btrfs_ref to replace the long
parameter list and the confusing @owner parameter.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Use the new btrfs_ref structure and replace parameter list to clean up
the usage of owner and level to distinguish the extent types.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Since add_pinned_bytes() only needs to know if the extent is metadata
and if it's a chunk tree extent, btrfs_ref is a perfect match for it, as
we don't need various owner/level trick to determine extent type.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
It's a perfect match for btrfs_ref_tree_mod() to use btrfs_ref, as
btrfs_ref describes a metadata/data reference update comprehensively.
Now we have one less function use confusing owner/level trick.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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>
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>
The process_func function pointer is local to __btrfs_mod_ref() and
points to either btrfs_inc_extent_ref() or btrfs_free_extent().
Open code it to make later delayed ref refactor easier, so we can
refactor btrfs_inc_extent_ref() and btrfs_free_extent() in different
patches.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
It used to be called from only two places (truncate path and releasing a
transaction handle), but commits 28bad21257 ("btrfs: fix truncate
throttling") and db2462a6ad ("btrfs: don't run delayed refs in the end
transaction logic") removed their calls to this function, so it's not used
anymore. Just remove it and all its helpers.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The member num_dirty_bgs of struct btrfs_transaction is not used anymore,
it is set and incremented but nothing reads its value anymore. Its last
read use was removed by commit 64403612b7 ("btrfs: rework
btrfs_check_space_for_delayed_refs"). So just remove that member.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of always calling the allocator to search for a free extent,
that satisfies the input criteria, switch btrfs_trim_free_extents to
using find_first_clear_extent_bit. With this change it's no longer
necessary to read the device tree in order to figure out holes in
the devices.
Now the code always searches in-memory data structure to figure out the
space range which contains the requested which should result in speed
improvements.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently unallocated chunks are always trimmed. For example
2 consecutive trims on large storage would trim freespace twice
irrespective of whether the space was actually allocated or not between
those trims.
Optimise this behavior by exploiting the newly introduced alloc_state
tree of btrfs_device. A new CHUNK_TRIMMED bit is used to mark
those unallocated chunks which have been trimmed and have not been
allocated afterwards. On chunk allocation the respective underlying devices'
physical space will have its CHUNK_TRIMMED flag cleared. This avoids
submitting discards for space which hasn't been changed since the last
time discard was issued.
This applies to the single mount period of the filesystem as the
information is not stored permanently.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This is used in more than one places so let's factor it out in ctree.h.
No functional changes.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now that these functions no longer require a handle to transaction to
inspect pending/pinned chunks the argument can be removed. At the same
time also remove any surrounding code which acquired the handle.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The pending chunks list contains chunks that are allocated in the
current transaction but haven't been created yet. The pinned chunks
list contains chunks that are being released in the current transaction.
Both describe chunks that are not reflected on disk as in use but are
unavailable just the same.
The pending chunks list is anchored by the transaction handle, which
means that we need to hold a reference to a transaction when working
with the list.
The way we use them is by iterating over both lists to perform
comparisons on the stripes they describe for each device. This is
backwards and requires that we keep a transaction handle open while
we're trimming.
This patchset adds an extent_io_tree to btrfs_device that maintains
the allocation state of the device. Extents are set dirty when
chunks are first allocated -- when the extent maps are added to the
mapping tree. They're cleared when last removed -- when the extent
maps are removed from the mapping tree. This matches the lifespan
of the pending and pinned chunks list and allows us to do trims
on unallocated space safely without pinning the transaction for what
may be a lengthy operation. We can also use this io tree to mark
which chunks have already been trimmed so we don't repeat the operation.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Up until now trimming the freespace was done irrespective of what the
arguments of the FITRIM ioctl were. For example fstrim's -o/-l arguments
will be entirely ignored. Fix it by correctly handling those paramter.
This requires breaking if the found freespace extent is after the end of
the passed range as well as completing trim after trimming
fstrim_range::len bytes.
Fixes: 499f377f49 ("btrfs: iterate over unused chunk space in FITRIM")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit db2462a6ad ("btrfs: don't run delayed refs in the end transaction
logic") removed its last use, so now it does absolutely nothing, therefore
remove it.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
qgroup_rsv_size is calculated as the product of
outstanding_extent * fs_info->nodesize. The product is calculated with
32 bit precision since both variables are defined as u32. Yet
qgroup_rsv_size expects a 64 bit result.
Avoid possible multiplication overflow by casting outstanding_extent to
u64. Such overflow would in the worst case (64K nodesize) require more
than 65536 extents, which is quite large and i'ts not likely that it
would happen in practice.
Fixes-coverity-id: 1435101
Fixes: ff6bc37eb7 ("btrfs: qgroup: Use independent and accurate per inode qgroup rsv")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Previously we only updated the drop_progress key if we were in the
DROP_REFERENCE stage of snapshot deletion. This is because the
UPDATE_BACKREF stage checks the flags of the blocks it's converting to
FULL_BACKREF, so if we go over a block we processed before it doesn't
matter, we just don't do anything.
The problem is in do_walk_down() we will go ahead and drop the roots
reference to any blocks that we know we won't need to walk into.
Given subvolume A and snapshot B. The root of B points to all of the
nodes that belong to A, so all of those nodes have a refcnt > 1. If B
did not modify those blocks it'll hit this condition in do_walk_down
if (!wc->update_ref ||
generation <= root->root_key.offset)
goto skip;
and in "goto skip" we simply do a btrfs_free_extent() for that bytenr
that we point at.
Now assume we modified some data in B, and then took a snapshot of B and
call it C. C points to all the nodes in B, making every node the root
of B points to have a refcnt > 1. This assumes the root level is 2 or
higher.
We delete snapshot B, which does the above work in do_walk_down,
free'ing our ref for nodes we share with A that we didn't modify. Now
we hit a node we _did_ modify, thus we own. We need to walk down into
this node and we set wc->stage == UPDATE_BACKREF. We walk down to level
0 which we also own because we modified data. We can't walk any further
down and thus now need to walk up and start the next part of the
deletion. Now walk_up_proc is supposed to put us back into
DROP_REFERENCE, but there's an exception to this
if (level < wc->shared_level)
goto out;
we are at level == 0, and our shared_level == 1. We skip out of this
one and go up to level 1. Since path->slots[1] < nritems we
path->slots[1]++ and break out of walk_up_tree to stop our transaction
and loop back around. Now in btrfs_drop_snapshot we have this snippet
if (wc->stage == DROP_REFERENCE) {
level = wc->level;
btrfs_node_key(path->nodes[level],
&root_item->drop_progress,
path->slots[level]);
root_item->drop_level = level;
}
our stage == UPDATE_BACKREF still, so we don't update the drop_progress
key. This is a problem because we would have done btrfs_free_extent()
for the nodes leading up to our current position. If we crash or
unmount here and go to remount we'll start over where we were before and
try to free our ref for blocks we've already freed, and thus abort()
out.
Fix this by keeping track of the last place we dropped a reference for
our block in do_walk_down. Then if wc->stage == UPDATE_BACKREF we know
we'll start over from a place we meant to, and otherwise things continue
to work as they did before.
I have a complicated reproducer for this problem, without this patch
we'll fail to fsck the fs when replaying the log writes log. With this
patch we can replay the whole log without any fsck or mount failures.
The steps to reproduce this easily are sort of tricky, I had to add a
couple of debug patches to the kernel in order to make it easy,
basically I just needed to make sure we did actually commit the
transaction every time we finished a walk_down_tree/walk_up_tree combo.
The reproducer:
1) Creates a base subvolume.
2) Creates 100k files in the subvolume.
3) Snapshots the base subvolume (snap1).
4) Touches files 5000-6000 in snap1.
5) Snapshots snap1 (snap2).
6) Deletes snap1.
I do this with dm-log-writes, and then replay to every FUA in the log
and fsck the fs.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ copy reproducer steps ]
Signed-off-by: David Sterba <dsterba@suse.com>
There's a bug in snapshot deletion where we won't update the
drop_progress key if we're in the UPDATE_BACKREF stage. This is a
problem because we could drop refs for blocks we know don't belong to
ours. If we crash or umount at the right time we could experience
messages such as the following when snapshot deletion resumes
BTRFS error (device dm-3): unable to find ref byte nr 66797568 parent 0 root 258 owner 1 offset 0
------------[ cut here ]------------
WARNING: CPU: 3 PID: 16052 at fs/btrfs/extent-tree.c:7108 __btrfs_free_extent.isra.78+0x62c/0xb30 [btrfs]
CPU: 3 PID: 16052 Comm: umount Tainted: G W OE 5.0.0-rc4+ #147
Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./890FX Deluxe5, BIOS P1.40 05/03/2011
RIP: 0010:__btrfs_free_extent.isra.78+0x62c/0xb30 [btrfs]
RSP: 0018:ffffc90005cd7b18 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff88842fade680 RSI: ffff88842fad6b18 RDI: ffff88842fad6b18
RBP: ffffc90005cd7bc8 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000001 R11: ffffffff822696b8 R12: 0000000003fb4000
R13: 0000000000000001 R14: 0000000000000102 R15: ffff88819c9d67e0
FS: 00007f08bb138fc0(0000) GS:ffff88842fac0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8f5d861ea0 CR3: 00000003e99fe000 CR4: 00000000000006e0
Call Trace:
? _raw_spin_unlock+0x27/0x40
? btrfs_merge_delayed_refs+0x356/0x3e0 [btrfs]
__btrfs_run_delayed_refs+0x75a/0x13c0 [btrfs]
? join_transaction+0x2b/0x460 [btrfs]
btrfs_run_delayed_refs+0xf3/0x1c0 [btrfs]
btrfs_commit_transaction+0x52/0xa50 [btrfs]
? start_transaction+0xa6/0x510 [btrfs]
btrfs_sync_fs+0x79/0x1c0 [btrfs]
sync_filesystem+0x70/0x90
generic_shutdown_super+0x27/0x120
kill_anon_super+0x12/0x30
btrfs_kill_super+0x16/0xa0 [btrfs]
deactivate_locked_super+0x43/0x70
deactivate_super+0x40/0x60
cleanup_mnt+0x3f/0x80
__cleanup_mnt+0x12/0x20
task_work_run+0x8b/0xc0
exit_to_usermode_loop+0xce/0xd0
do_syscall_64+0x20b/0x210
entry_SYSCALL_64_after_hwframe+0x49/0xbe
To fix this simply mark dead roots we read from disk as DEAD and then
set the walk_control->restarted flag so we know we have a restarted
deletion. From here whenever we try to drop refs for blocks we check to
verify our ref is set on them, and if it is not we skip it. Once we
find a ref that is set we unset walk_control->restarted since the tree
should be in a normal state from then on, and any problems we run into
from there are different issues. I tested this with an existing broken
fs and my reproducer that creates a broken fs and it fixed both file
systems.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[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: f64d5ca868 ("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>
There is no point in using a construct like 'if (!condition)
WARN_ON(1)'. Use WARN_ON(!condition) directly. No functional changes.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For FLUSH_LIMIT flushers we really can only allocate chunks and flush
delayed inode items, everything else is problematic. I added a bunch of
new states and it lead to weirdness in the FLUSH_LIMIT case because I
forgot about how it worked. So instead explicitly declare the states
that are ok for flushing with FLUSH_LIMIT and use that for our state
machine. Then as we add new things that are safe we can just add them
to this list.
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>
With severe fragmentation we can end up with our inode rsv size being
huge during writeout, which would cause us to need to make very large
metadata reservations.
However we may not actually need that much once writeout is complete,
because of the over-reservation for the worst case.
So instead try to make our reservation, and if we couldn't make it
re-calculate our new reservation size and try again. If our reservation
size doesn't change between tries then we know we are actually out of
space and can error. Flushing that could have been running in parallel
did not make any space.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ rename to calc_refill_bytes, update comment and changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
With the introduction of the per-inode block_rsv it became possible to
have really really large reservation requests made because of data
fragmentation. Since the ticket stuff assumed that we'd always have
relatively small reservation requests it just killed all tickets if we
were unable to satisfy the current request.
However, this is generally not the case anymore. So fix this logic to
instead see if we had a ticket that we were able to give some
reservation to, and if we were continue the flushing loop again.
Likewise we make the tickets use the space_info_add_old_bytes() method
of returning what reservation they did receive in hopes that it could
satisfy reservations down the line.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We've done this forever because of the voodoo around knowing how much
space we have. However, we have better ways of doing this now, and on
normal file systems we'll easily have a global reserve of 512MiB, and
since metadata chunks are usually 1GiB that means we'll allocate
metadata chunks more readily. Instead use the actual used amount when
determining if we need to allocate a chunk or not.
This has a side effect for mixed block group fs'es where we are no
longer allocating enough chunks for the data/metadata requirements. To
deal with this add a ALLOC_CHUNK_FORCE step to the flushing state
machine. This will only get used if we've already made a full loop
through the flushing machinery and tried committing the transaction.
If we have then we can try and force a chunk allocation since we likely
need it to make progress. This resolves issues I was seeing with
the mixed bg tests in xfstests without the new flushing state.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ merged with patch "add ALLOC_CHUNK_FORCE to the flushing code" ]
Signed-off-by: David Sterba <dsterba@suse.com>
