Filipe Manana [Wed, 4 Oct 2023 10:38:50 +0000 (11:38 +0100)]
btrfs: add and use helpers for reading and writing fs_info->generation
Currently the generation field of struct btrfs_fs_info is always modified
while holding fs_info->trans_lock locked. Most readers will access this
field without taking that lock but while holding a transaction handle,
which is safe to do due to the transaction life cycle.
However there are other readers that are neither holding the lock nor
holding a transaction handle open:
1) When reading an inode from disk, at btrfs_read_locked_inode();
2) When reading the generation to expose it to sysfs, at
btrfs_generation_show();
3) Early in the fsync path, at skip_inode_logging();
4) When creating a hole at btrfs_cont_expand(), during write paths,
truncate and reflinking;
5) In the fs_info ioctl (btrfs_ioctl_fs_info());
6) While mounting the filesystem, in the open_ctree() path. In these
cases it's safe to directly read fs_info->generation as no one
can concurrently start a transaction and update fs_info->generation.
In case of the fsync path, races here should be harmless, and in the worst
case they may cause a fsync to log an inode when it's not really needed,
so nothing bad from a functional perspective. In the other cases it's not
so clear if functional problems may arise, though in case 1 rare things
like a load/store tearing [1] may cause the BTRFS_INODE_NEEDS_FULL_SYNC
flag not being set on an inode and therefore result in incorrect logging
later on in case a fsync call is made.
To avoid data race warnings from tools like KCSAN and other issues such
as load and store tearing (amongst others, see [1]), create helpers to
access the generation field of struct btrfs_fs_info using READ_ONCE() and
WRITE_ONCE(), and use these helpers where needed.
[1] https://lwn.net/Articles/793253/
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Wed, 4 Oct 2023 10:38:49 +0000 (11:38 +0100)]
btrfs: add and use helpers for reading and writing log_transid
Currently the log_transid field of a root is always modified while holding
the root's log_mutex locked. Most readers of a root's log_transid are also
holding the root's log_mutex locked, however there is one exception which
is btrfs_set_inode_last_trans() where we don't take the lock to avoid
blocking several operations if log syncing is happening in parallel.
Any races here should be harmless, and in the worst case they may cause a
fsync to log an inode when it's not really needed, so nothing bad from a
functional perspective.
To avoid data race warnings from tools like KCSAN and other issues such
as load and store tearing (amongst others, see [1]), create helpers to
access the log_transid field of a root using READ_ONCE() and WRITE_ONCE(),
and use these helpers where needed.
[1] https://lwn.net/Articles/793253/
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Wed, 4 Oct 2023 10:38:48 +0000 (11:38 +0100)]
btrfs: add and use helpers for reading and writing last_log_commit
Currently, the last_log_commit of a root can be accessed concurrently
without any lock protection. Readers can be calling btrfs_inode_in_log()
early in a fsync call, which reads a root's last_log_commit, while a
writer can change the last_log_commit while a log tree if being synced,
at btrfs_sync_log(). Any races here should be harmless, and in the worst
case they may cause a fsync to log an inode when it's not really needed,
so nothing bad from a functional perspective.
To avoid data race warnings from tools like KCSAN and other issues such
as load and store tearing (amongst others, see [1]), create helpers to
access the last_log_commit field of a root using READ_ONCE() and
WRITE_ONCE(), and use these helpers everywhere.
[1] https://lwn.net/Articles/793253/
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Guilherme's previous work [1] aimed at the mounting of cloned devices
using a superblock flag SINGLE_DEV during mkfs.
[1] https://lore.kernel.org/linux-btrfs/20230831001544.3379273-1-gpiccoli@igalia.com/
Building upon this work, here is in memory only approach. As it mounts
we determine if the same fsid is already mounted if then we generate a
random temp fsid which shall be used the mount, in memory only not
written to the disk. We distinguish devices by devt.
$ btrfs fi show -m
Label: none uuid: 4a212b48-1bec-46a5-938a-783c8c1f0b02
Total devices 1 FS bytes used 144.00KiB
devid 1 size 300.00MiB used 88.00MiB path /dev/loop0
Label: none uuid: adabf2fe-5515-4ad0-95b4-7b1609218c16
Total devices 1 FS bytes used 144.00KiB
devid 1 size 300.00MiB used 88.00MiB path /dev/loop1
Label: none uuid: 1d77d0df-7d92-439e-adbd-20b9b86fdedb
Total devices 1 FS bytes used 144.00KiB
devid 1 size 300.00MiB used 88.00MiB path /dev/loop2
Co-developed-by: Guilherme G. Piccoli <gpiccoli@igalia.com> Signed-off-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Thu, 28 Sep 2023 10:12:50 +0000 (11:12 +0100)]
btrfs: stop reserving excessive space for block group item insertions
Space for block group item insertions, necessary after allocating a new
block group, is reserved in the delayed refs block reserve. Currently we
do this by incrementing the transaction handle's delayed_ref_updates
counter and then calling btrfs_update_delayed_refs_rsv(), which will
increase the size of the delayed refs block reserve by an amount that
corresponds to the same amount we use for delayed refs, given by
btrfs_calc_delayed_ref_bytes().
That is an excessive amount because it corresponds to the amount of space
needed to insert one item in a btree (btrfs_calc_insert_metadata_size())
times 2 when the free space tree feature is enabled. All we need is an
amount as given by btrfs_calc_insert_metadata_size(), since we only need to
insert a block group item in the extent tree (or block group tree if this
feature is enabled). By using btrfs_calc_insert_metadata_size() we will
need to reserve 2 times less space when using the free space tree, putting
less pressure on space reservation.
So use helpers to reserve and release space for block group item
insertions that use btrfs_calc_insert_metadata_size() for calculation of
the space.
Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Thu, 28 Sep 2023 10:12:49 +0000 (11:12 +0100)]
btrfs: stop reserving excessive space for block group item updates
Space for block group item updates, necessary after allocating or
deallocating an extent from a block group, is reserved in the delayed
refs block reserve. Currently we do this by incrementing the transaction
handle's delayed_ref_updates counter and then calling
btrfs_update_delayed_refs_rsv(), which will increase the size of the
delayed refs block reserve by an amount that corresponds to the same
amount we use for delayed refs, given by btrfs_calc_delayed_ref_bytes().
That is an excessive amount because it corresponds to the amount of space
needed to insert one item in a btree (btrfs_calc_insert_metadata_size())
times 2 when the free space tree feature is enabled. All we need is an
amount as given by btrfs_calc_metadata_size(), since we only need to
update an existing block group item in the extent tree (or block group
tree if this feature is enabled). By using btrfs_calc_metadata_size() we
will need to reserve 4 times less space when using the free space tree
and 2 times less space when not using it, putting less pressure on space
reservation.
So use helpers to reserve and release space for block group item updates
that use btrfs_calc_metadata_size() for calculation of the space.
Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Wed, 27 Sep 2023 19:04:32 +0000 (21:04 +0200)]
btrfs: reorder btrfs_inode to fill gaps
Previous commit created a hole in struct btrfs_inode, we can move
outstanding_extents there. This reduces size by 8 bytes from 1120 to
1112 on a release config.
As you can see we've gotten ourselves quite full with metadata, with all
of the disk being allocated for data.
On smaller file systems there's not a lot of time before we get full, so
our overcommit behavior bites us here. Generally speaking data
reservations result in chunk allocations as we assume reservation ==
actual use for data. This means at any point we could end up with a
chunk allocation for data, and if we're very close to full we could do
this before we have a chance to figure out that we need another metadata
chunk.
Address this by adjusting the overcommit logic. Simply put we need to
take away 1 chunk from the available chunk space in case of a data
reservation. This will allow us to stop overcommitting before we
potentially lose this space to a data allocation. With this fix in
place we properly allocate a metadata chunk before we're completely
full, allowing for enough slack space in metadata.
Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Wed, 27 Sep 2023 17:47:00 +0000 (13:47 -0400)]
btrfs: increase ->free_chunk_space in btrfs_grow_device
My overcommit patch exposed a bug with btrfs/177 [1]. The problem here is
that when we grow the device we're not adding to ->free_chunk_space, so
subsequent allocations can cause ->free_chunk_space to wrap, which
causes problems in can_overcommit because we add this to ->total_bytes,
which causes the counter to wrap and gives us an unexpected ENOSPC.
Fix this by properly updating ->free_chunk_space with the new available
space in btrfs_grow_device.
Josef Bacik [Wed, 27 Sep 2023 17:46:59 +0000 (13:46 -0400)]
btrfs: fix ->free_chunk_space math in btrfs_shrink_device
There are two bugs in how we adjust ->free_chunk_space in
btrfs_shrink_device. First we're removing the entire diff between
new_size and old_size from ->free_chunk_space. This only works if we're
reducing the free area, which we could potentially not be. So adjust
the math to only subtract the diff in the free space from
->free_chunk_space.
Additionally in the error case we're unconditionally adding the diff
back into ->free_chunk_space, which we need to only do if this device is
writeable.
Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 22 Sep 2023 10:39:09 +0000 (11:39 +0100)]
btrfs: make sure we cache next state in find_first_extent_bit()
Currently, at find_first_extent_bit(), when we are given a cached extent
state that happens to have its end offset match the desired range start,
we find the next extent state using that cached state, with next_state()
calls, and then return it.
We then try to cache that next state by calling cache_state_if_flags(),
but that will not cache the state because we haven't reset *cached_state
to NULL, so we end up with the cached_state unchanged, and if the caller
is iterating over extent states in the io tree, its next call to
find_first_extent_bit() will not use the current cached state as its end
offset does not match the minimum start range offset, therefore the cached
state is reset and we have to search the rbtree to find the next suitable
extent state record.
So fix this by resetting the cached state to NULL (and dropping our ref
on it) when we have a suitable cached state and we found a next state by
using next_state() starting from the cached state. This makes use cases
of calling find_first_extent_bit() to go over all ranges in the io tree
to do a single rbtree full search, only on the first call, and the next
calls will just do next_state() (rb_next() wrapper) calls, which is more
efficient.
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 22 Sep 2023 10:39:08 +0000 (11:39 +0100)]
btrfs: use extent_io_tree_release() to empty dirty log pages
When freeing a log tree, during a transaction commit, we clear its dirty
log pages io tree by calling clear_extent_bits() using a range from 0 to
(u64)-1. This will iterate the io tree's rbtree and call rb_erase() on
each node before freeing it, which will often trigger rebalance operations
on the rbtree. A better alternative it to use extent_io_tree_release(),
which will not do deletions and trigger rebalances.
So use extent_io_tree_release() instead of clear_extent_bits().
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 22 Sep 2023 10:39:07 +0000 (11:39 +0100)]
btrfs: make tree iteration in extent_io_tree_release() more efficient
Currently extent_io_tree_release() is a loop that keeps getting the first
node in the io tree, using rb_first() which is a loop that gets to the
leftmost node of the rbtree, and then for each node it calls rb_erase(),
which often requires rebalancing the rbtree.
We can make this more efficient by using
rbtree_postorder_for_each_entry_safe() to free each node without having
to delete it from the rbtree and without looping to get the first node.
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 22 Sep 2023 10:39:06 +0000 (11:39 +0100)]
btrfs: collapse wait_on_state() to its caller wait_extent_bit()
The wait_on_state() function is very short and has a single caller, which
is wait_extent_bit(), so remove the function and put its code into the
caller.
Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 22 Sep 2023 10:39:05 +0000 (11:39 +0100)]
btrfs: remove redundant memory barrier from extent_io_tree_release()
The memory barrier at extent_io_tree_release() is redundant. Holding
spin_lock here is not enough to drop the barrier completely. We only
change the waitqueue of an extent state record while holding the tree
lock - see wait_on_state().
The update to waitqueue state will not become stale because there will
be an spin_unlock/spin_lock sequence between the change and waiting,
this implies a full memory barrier.
So remove the explicit smp_mb() barrier.
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com>
[ reword reasoning ] Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 22 Sep 2023 10:39:03 +0000 (11:39 +0100)]
btrfs: update stale comment at extent_io_tree_release()
There's this comment at extent_io_tree_release() that mentions io btrees,
but this function is no longer used only for io btrees. Originally it was
added as a static function named clear_btree_io_tree() at transaction.c,
in commit 663dfbb07774 ("Btrfs: deal with convert_extent_bit errors to
avoid fs corruption"), as it was used only for cleaning one of the io
trees that track dirty extent buffers, the dirty_log_pages io tree of a
a root and the dirty_pages io tree of a transaction. Later it was renamed
and exported and now it's used to cleanup other io trees such as the
allocation state io tree of a device or the csums range io tree of a log
root.
So remove that comment and replace it with one at the top of the function
that is more complete, mentioning what the function does and that it's
expected to be called only when a task is sure no one else will need to
use the tree anymore, as well as there should be no locked ranges in the
tree and therefore no waiters on its extent state records. Also add an
assertion to check that there are no locked extent state records in the
tree.
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 22 Sep 2023 10:39:02 +0000 (11:39 +0100)]
btrfs: make extent state merges more efficient during insertions
When inserting a new extent state record into an io tree that happens to
be mergeable, we currently do the following:
1) Insert the extent state record in the io tree's rbtree. This requires
going down the tree to find where to insert it, and during the
insertion we often need to balance the rbtree;
2) We then check if the previous node is mergeable, so we call rb_prev()
to find it, which requires some looping to find the previous node;
3) If the previous node is mergeable, we adjust our node to include the
range of the previous node and then delete the previous node from the
rbtree, which again may need to balance the rbtree;
4) Then we check if the next node is mergeable with the node we inserted,
so we call rb_next(), which requires some looping too. If the next node
is indeed mergeable, we expand the range of our node to include the
next node's range and then delete the next node from the rbtree, which
again may need to balance the tree.
So these are quite of lot of iterations and looping over the rbtree, and
some of the operations may need to rebalance the rb tree. This can be made
a bit more efficient by:
1) When iterating the rbtree, once we find a node that is mergeable with
the node we want to insert, we can just adjust that node's range with
the range of the node to insert - this avoids continuing iterating
over the tree and deleting a node from the rbtree;
2) If we expand the range of a mergeable node, then we find the next or
the previous node, depending on other we merged a range to the right or
to the left of the node we are currently at during the iteration. This
merging is as before, we find the next or previous node with rb_next()
or rb_prev() and if that other node is mergeable with the current one,
we adjust the range of the current node and remove the other node from
the rbtree;
3) Whenever we need to insert the new extent state record it's because
we don't have any extent state record in the rbtree which can be
merged, so we can remove the call to merge_state() after the insertion,
saving rb_next() and rb_prev() calls, which require some looping.
So update the insertion function insert_state() to have this behaviour.
Running dbench for 120 seconds and capturing the execution times of
set_extent_bit() at pin_down_extent(), resulted in the following data
(time values are in nanoseconds):
David Sterba [Fri, 14 Aug 2020 09:35:16 +0000 (11:35 +0200)]
btrfs: change test_range_bit to scan the whole range
The semantics of test_range_bit() with filled == 0 is now in it's own
helper so test_range_bit will check the whole range unconditionally.
The detection logic is flipped and assumes success by default and
catches exceptions.
David Sterba [Mon, 11 Sep 2023 23:09:23 +0000 (01:09 +0200)]
btrfs: add specific helper for range bit test exists
The existing helper test_range_bit works in two ways, checks if the whole
range contains all the bits, or stop on the first occurrence. By adding
a specific helper for the latter case, the inner loop can be simplified
and contains fewer conditionals, making it a bit faster.
There's no caller that uses the cached state pointer so this reduces the
argument count further.
Filipe Manana [Wed, 27 Sep 2023 11:09:26 +0000 (12:09 +0100)]
btrfs: rename and export __btrfs_cow_block()
Rename and export __btrfs_cow_block() as btrfs_force_cow_block(). This is
to allow to move defrag specific code out of ctree.c and into defrag.c in
one of the next patches.
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Wed, 27 Sep 2023 11:09:25 +0000 (12:09 +0100)]
btrfs: use round_down() to align block offset at btrfs_cow_block()
At btrfs_cow_block() we can use round_down() to align the extent buffer's
logical offset to the start offset of a metadata block group, instead of
the less easy to read set of bitwise operations (two plus one subtraction).
So replace the bitwise operations with a round_down() call.
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Previous commit ("btrfs: reject devices with CHANGING_FSID_V2") has
stopped the assembly of devices with the CHANGING_FSID_V2 flag in the
kernel. Such devices can be scanned but will not be registered and can't
be mounted without a manual fix by btrfstune. Remove the related logic
and now unused code.
The original motivation was to allow an interrupted partial conversion
fix itself on next mount, in case the system has to be rebooted. This is
a convenience but brings a lot of complexity the device scanning and
handling the partial states. It's hard to estimate if this was ever
needed in practice, expecting the typical use case like a manual
conversion of an unmounted filesystem where the user can verify the
success and rerun it eventually.
Signed-off-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: David Sterba <dsterba@suse.com>
[ add historical context ] Signed-off-by: David Sterba <dsterba@suse.com>
The BTRFS_SUPER_FLAG_CHANGING_FSID_V2 flag indicates a transient state
where the device in the userspace btrfstune -m|-M operation failed to
complete changing the fsid.
This flag makes the kernel to automatically determine the other
partner devices to which a given device can be associated, based on the
fsid, metadata_uuid and generation values.
btrfstune -m|M feature is especially useful in virtual cloud setups, where
compute instances (disk images) are quickly copied, fsid changed, and
launched. Given numerous disk images with the same metadata_uuid but
different fsid, there's no clear way a device can be correctly assembled
with the proper partners when the CHANGING_FSID_V2 flag is set. So, the
disk could be assembled incorrectly, as in the example below:
Before this patch:
Consider the following two filesystems:
/dev/loop[2-3] are raw copies of /dev/loop[0-1] and the btrsftune -m
operation fails.
In this scenario, as the /dev/loop0's fsid change is interrupted, and the
CHANGING_FSID_V2 flag is set as shown below.
It is normal that some devices aren't instantly discovered during
system boot or iSCSI discovery. The controlled scan below demonstrates
this.
$ btrfs device scan --forget
$ btrfs device scan /dev/loop0
Scanning for btrfs filesystems on '/dev/loop0'
$ mount /dev/loop3 /btrfs
$ btrfs filesystem show -m
Label: none uuid: 7d4b4b93-2b27-4432-b4e4-4be1fbccbd45
Total devices 2 FS bytes used 144.00KiB
devid 1 size 300.00MiB used 48.00MiB path /dev/loop0
devid 2 size 300.00MiB used 40.00MiB path /dev/loop3
/dev/loop0 and /dev/loop3 are incorrectly partnered.
This kernel patch removes functions and code connected to the
CHANGING_FSID_V2 flag.
With this patch, now devices with the CHANGING_FSID_V2 flag are rejected.
And its partner will fail to mount with the extra -o degraded option.
The check is removed from open_ctree(), devices are rejected during
scanning which in turn fails the mount.
Signed-off-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Fri, 22 Sep 2023 11:07:29 +0000 (13:07 +0200)]
btrfs: relocation: constify parameters where possible
Lots of the functions in relocation.c don't change pointer parameters
but lack the annotations. Add them and reformat according to current
coding style if needed.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 22 Sep 2023 10:37:56 +0000 (11:37 +0100)]
btrfs: move btrfs_defrag_root() to defrag.{c,h}
The btrfs_defrag_root() function does not really belong in the
transaction.{c,h} module and as we have a defrag.{c,h} nowadays,
move it to there instead. This also allows to stop exporting
btrfs_defrag_leaves(), so we can make it static.
Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com>
[ rename info to fs_info for consistency ] Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 22 Sep 2023 10:37:26 +0000 (11:37 +0100)]
btrfs: remove redundant root argument from fixup_inode_link_count()
The root argument for fixup_inode_link_count() always matches the root of
the given inode, so remove the root argument and get it from the inode
argument. This also applies to the helpers count_inode_extrefs() and
count_inode_refs() used by fixup_inode_link_count() - they don't need the
root argument, as it always matches the root of the inode passed to them.
Reviewed-by: Qu Wenruo <wqu@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>
Filipe Manana [Fri, 22 Sep 2023 10:37:24 +0000 (11:37 +0100)]
btrfs: remove redundant root argument from btrfs_delayed_update_inode()
The root argument for btrfs_delayed_update_inode() always matches the root
of the given inode, so remove the root argument and get it from the inode
argument.
Reviewed-by: Qu Wenruo <wqu@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>
Filipe Manana [Fri, 22 Sep 2023 10:37:23 +0000 (11:37 +0100)]
btrfs: remove redundant root argument from btrfs_update_inode_item()
The root argument for btrfs_update_inode_item() always matches the root of
the given inode, so remove the root argument and get it from the inode
argument.
Reviewed-by: Qu Wenruo <wqu@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>
Filipe Manana [Fri, 22 Sep 2023 10:37:21 +0000 (11:37 +0100)]
btrfs: remove redundant root argument from btrfs_update_inode_fallback()
The root argument for btrfs_update_inode_fallback() always matches the
root of the given inode, so remove the root argument and get it from the
inode argument.
Reviewed-by: Qu Wenruo <wqu@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>
Boris Burkov [Thu, 20 Jul 2023 19:05:28 +0000 (12:05 -0700)]
btrfs: qgroup: only set QUOTA_ENABLED when done reading qgroups
In open_ctree, we set BTRFS_FS_QUOTA_ENABLED as soon as we see a
quota_root, as opposed to after we are done setting up the qgroup
structures. In the quota_enable path, we wait until after the structures
are set up. Likewise, in disable, we clear the bit before tearing down
the structures. I feel that this organization is less surprising for the
open_ctree path.
I don't believe this fixes any actual bug, but avoids potential
confusion when using btrfs_qgroup_mode in an intermediate state where we
are enabled but haven't yet setup the qgroup status flags. It also
avoids any risk of calling a qgroup function and attempting to use the
qgroup rbtrees before they exist/are setup.
This all occurs before we do rw setup, so I believe it should be mostly
a no-op.
Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Wed, 28 Jun 2023 21:00:09 +0000 (14:00 -0700)]
btrfs: track data relocation with simple quota
Relocation data allocations are quite tricky for simple quotas. The
basic data relocation sequence is (ignoring details that aren't relevant
to this fix):
- create a fake relocation data fs root
- create a fake relocation inode in that root
- for each data extent:
- preallocate a data extent on behalf of the fake inode
- copy over the data
- for each extent
- swap the refs so that the original file extent now refers to the new
extent item
- drop the fake root, dropping its refs on the old extents, which lets
us delete them.
Done naively, this results in storing an extent item in the extent tree
whose owner_ref points at the relocation data root and a no-op squota
recording, since the reloc root is not a legit fstree. So far, that's
OK. The problem comes when you do the swap, and leave an extent item
owned by this bogus root as the real permanent extents of the file. If
the file then drops that ref, we free it and no-op account that against
the fake relocation root. Essentially, this means that relocation is
simple quota "extent laundering", since we re-own the extents into a
fake root.
Simple quotas very intentionally doesn't have a mechanism for
transferring ownership of extents, as that is exactly the complicated
thing we are trying to avoid with the new design. Further, it cannot be
correctly done in this case, since at the time you create the new
"real" refs, there is no way to know which was the original owner before
relocation unless we track it.
Therefore, it makes more sense to trick the preallocation to handle
relocation as a special case and note the proper owner ref from the
beginning. That way, we never write out an extent item without the
correct owner ref that it will eventually have.
This could be done by wiring a special root parameter all the way
through the allocation code path, but to avoid that special case
touching all the code, take advantage of the serial nature of relocation
to store the src root on the relocation root object. Then when we finish
the prealloc, if it happens to be this case, prepare the delayed ref
appropriately.
We must also add logic to handle relocating adjacent extents with
different owning roots. Those cannot be preallocated together in a
cluster as it would lose the separate ownership information.
This is obviously a smelly bit of code, but I think it is the best
solution to the problem, given the relocation implementation.
Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Thu, 22 Jun 2023 00:37:23 +0000 (17:37 -0700)]
btrfs: qgroup: track metadata relocation COW with simple quota
Relocation COWs metadata blocks in two cases for the reloc root:
- copying the subvolume root item when creating the reloc root
- copying a btree node when there is a COW during relocation
In both cases, the resulting btree node hits an abnormal code path with
respect to the owner field in its btrfs_header. It first creates the
root item for the new objectid, which populates the reloc root id, and
it at this point that delayed refs are created.
Later, it fully copies the old node into the new node (including the
original owner field) which overwrites it. This results in a simple
quotas mismatch where we run the delayed ref for the reloc root which
has no simple quota effect (reloc root is not an fstree) but when we
ultimately delete the node, the owner is the real original fstree and we
do free the space.
To work around this without tampering with the behavior of relocation,
add a parameter to btrfs_add_tree_block that lets the relocation code
path specify a different owning root than the "operating" root (in this
case, owning root is the real root and the operating root is the reloc
root). These can naturally be plumbed into delayed refs that have the
same concept.
Note that this is a double count in some sense, but a relatively natural
one, as there are really two extents, and the old one will be deleted
soon. This is consistent with how data relocation extents are accounted
by simple quotas.
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Tue, 28 Mar 2023 22:45:20 +0000 (15:45 -0700)]
btrfs: qgroup: check generation when recording simple quota delta
Simple quotas count extents only from the moment the feature is enabled.
Therefore, if we do something like:
1. create subvol S
2. write F in S
3. enable quotas
4. remove F
5. write G in S
then after 3. and 4. we would expect the simple quota usage of S to be 0
(putting aside some metadata extents that might be written) and after
5., it should be the size of G plus metadata. Therefore, we need to be
able to determine whether a particular quota delta we are processing
predates simple quota enablement.
To do this, store the transaction id when quotas were enabled. In
fs_info for immediate use and in the quota status item to make it
recoverable on mount. When we see a delta, check if the generation of
the extent item is less than that of quota enablement. If so, we should
ignore the delta from this extent.
Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Tue, 28 Mar 2023 20:55:25 +0000 (13:55 -0700)]
btrfs: qgroup: simple quota auto hierarchy for nested subvolumes
Consider the following sequence:
- enable quotas
- create subvol S id 256 at dir outer/
- create a qgroup 1/100
- add 0/256 (S's auto qgroup) to 1/100
- create subvol T id 257 at dir outer/inner/
With full qgroups, there is no relationship between 0/257 and either of
0/256 or 1/100. There is an inherit feature that the creator of inner/
can use to specify it ought to be in 1/100.
Simple quotas are targeted at container isolation, where such automatic
inheritance for not necessarily trusted/controlled nested subvol
creation would be quite helpful. Therefore, add a new default behavior
for simple quotas: when you create a nested subvol, automatically
inherit as parents any parents of the qgroup of the subvol the new inode
is going in.
In our example, 257/0 would also be under 1/100, allowing easy control
of a total quota over an arbitrary hierarchy of subvolumes.
I think this _might_ be a generally useful behavior, so it could be
interesting to put it behind a new inheritance flag that simple quotas
always use while traditional quotas let the user specify, but this is a
minimally intrusive change to start.
Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Wed, 28 Jun 2023 18:00:15 +0000 (11:00 -0700)]
btrfs: record simple quota deltas in delayed refs
At the moment that we run delayed refs, we make the final ref-count
based decision on creating/removing extent (and metadata) items.
Therefore, it is exactly the spot to hook up simple quotas.
There are a few important subtleties to the fields we must collect to
accurately track simple quotas, particularly when removing an extent.
When removing a data extent, the ref could be in any tree (due to
reflink, for example) and so we need to recover the owning root id from
the owner ref item. When removing a metadata extent, we know the owning
root from the owner field in the header when we create the delayed ref,
so we can recover it from there.
We must also be careful to handle reservations properly to not leaked
reserved space. The happy path is freeing the reservation when the
simple quota delta runs on a data extent. If that doesn't happen, due to
refs canceling out or some error, the ref head already has the
must_insert_reserved machinery to handle this, so we piggy back on that
and use it to clean up the reserved data.
Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Wed, 28 Jun 2023 17:45:29 +0000 (10:45 -0700)]
btrfs: add helper for inline owner ref lookup
Inline ref parsing is a bit tricky and relies on a decent amount of
implicit information, so I think it is beneficial to have a helper
function for reading the owner ref, if only to "document" the format,
along with the write path.
The main subtlety of note which I was missing by open-coding this was
that it is important to check whether or not inline refs are present
*at all*. i.e., if we are writing out a new extent under squotas, we
will always use a big enough item for the inline ref and have it.
However, it is possible that some random item predating squotas will not
have any inline refs. In that case, trying to read the "type" field of
the first inline ref will just be reading garbage in the form of
whatever is in the next item.
This will be used by the extent free-ing path, which looks up data
extent owners as well as a relocation path which needs to grab the owner
before relocating an extent.
Signed-off-by: Boris Burkov <boris@bur.io> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Mon, 30 Jan 2023 22:45:55 +0000 (14:45 -0800)]
btrfs: new inline ref storing owning subvol of data extents
In order to implement simple quota groups, we need to be able to
associate a data extent with the subvolume that created it. Once you
account for reflink, this information cannot be recovered without
explicitly storing it. Options for storing it are:
- a new key/item
- a new extent inline ref item
The former is backwards compatible, but wastes space, the latter is
incompat, but is efficient in space and reuses the existing inline ref
machinery, while only abusing it a tiny amount -- specifically, the new
item is not a ref, per-se.
Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Wed, 28 Jun 2023 21:03:35 +0000 (14:03 -0700)]
btrfs: track original extent owner in head_ref
Simple quotas requires tracking the original creating root of any given
extent. This gets complicated when multiple subvolumes create
overlapping/contradictory refs in the same transaction. For example,
due to modifying or deleting an extent while also snapshotting it.
To resolve this in a general way, take advantage of the fact that we are
essentially already tracking this for handling releasing reservations.
The head ref coalesces the various refs and uses must_insert_reserved to
check if it needs to create an extent/free reservation. Store the ref
that set must_insert_reserved as the owning ref on the head ref.
Note that this can result in writing an extent for the very first time
with an owner different from its only ref, but it will look the same as
if you first created it with the original owning ref, then added the
other ref, then removed the owning ref.
Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Tue, 28 Mar 2023 23:04:02 +0000 (16:04 -0700)]
btrfs: track owning root in btrfs_ref
While data extents require us to store additional inline refs to track
the original owner on free, this information is available implicitly for
metadata. It is found in the owner field of the header of the tree
block. Even if other trees refer to this block and the original ref goes
away, we will not rewrite that header field, so it will reliably give the
original owner.
In addition, there is a relocation case where a new data extent needs to
have an owning root separate from the referring root wired through
delayed refs.
To use it for recording simple quota deltas, we need to wire this root
id through from when we create the delayed ref until we fully process
it. Store it in the generic btrfs_ref struct of the delayed ref.
Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Wed, 28 Jun 2023 21:32:58 +0000 (14:32 -0700)]
btrfs: rename tree_ref and data_ref owning_root
commit 113479d5b8eb ("btrfs: rename root fields in delayed refs structs")
changed these from ref_root to owning_root. However, there are many
circumstances where that name is not really accurate and the root on the
ref struct _is_ the referring root. In general, these are not the owning
root, though it does happen in some ref merging cases involving
overwrites during snapshots and similar.
Simple quotas cares quite a bit about tracking the original owner of an
extent through delayed refs, so rename these back to free up the name
for the real owning root (which will live on the generic btrfs_ref and
the head ref)
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Tue, 28 Mar 2023 20:43:47 +0000 (13:43 -0700)]
btrfs: add helper for recording simple quota deltas
Rather than re-computing shared/exclusive ownership based on backrefs
and walking roots for implicit backrefs, simple quotas does an increment
when creating an extent and a decrement when deleting it. Add the API
for the extent item code to use to track those events.
Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Wed, 28 Jun 2023 18:00:05 +0000 (11:00 -0700)]
btrfs: create qgroup earlier in snapshot creation
Pull creating the qgroup earlier in the snapshot. This allows simple
quotas qgroups to see all the metadata writes related to the snapshot
being created and to be born with the root node accounted.
Note this has an impact on transaction commit where the qgroup creation
can do a lot of work, allocate memory and take locks. The change is done
for correctness, potential performance issues will be fixed in the
future.
Signed-off-by: Boris Burkov <boris@bur.io>
[ add note ] Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Wed, 28 Jun 2023 17:06:45 +0000 (10:06 -0700)]
btrfs: qgroup: flush reservations during quota disable
The following sequence:
enable simple quotas
do some writes
reserve space
create ordered_extent
release rsv (store rsv_bytes in OE, mark QGROUP_RESERVED bits)
disable quotas
enable simple quotas
set qgroup rsv to 0 on all subvolumes
ordered_extent finishes
create delayed ref with rsv_bytes from before
run delayed ref
record_simple_quota_delta
free rsv_bytes (0 -> -rsv_delta)
results in us reliably underflowing the subvolume's qgroup rsv counter,
because disabling/re-enabling quotas toggles reservation counters down
to 0, but does not remove other file system state which represents
successful acquisition of qgroup rsv space. Specifically metadata rsv
counters on the root object and rsv_bytes on ordered_extent objects that
have released their reservation as well as the corresponding
QGROUP_RESERVED extent bits.
Normal qgroups gets away with this, I believe because it forces more
work to happen on transaction commit, but I am not certain it is totally
safe from the ordered_extent/leaked extent bit variant. Simple quotas
hits this reliably.
The intent of the fix is to make disable take the time to clear that
external to qgroups state as well: after flipping off the quota bit on
fs_info, flush delalloc and ordered extents, clearing the extent bits
along the way. This makes it so there are no ordered extents or meta
prealloc hanging around from the first enablement period during the second.
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Tue, 16 May 2023 23:35:45 +0000 (16:35 -0700)]
btrfs: qgroup: add new quota mode for simple quotas
Add a new quota mode called "simple quotas". It can be enabled by the
existing quota enable ioctl via a new command, and sets an incompat
bit, as the implementation of simple quotas will make backwards
incompatible changes to the disk format of the extent tree.
Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Tue, 16 May 2023 23:33:55 +0000 (16:33 -0700)]
btrfs: qgroup: introduce quota mode
In preparation for introducing simple quotas, change from a binary
setting for quotas to an enum based mode. Initially, the possible modes
are disabled/full. Full quotas is normal btrfs qgroups.
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Boris Burkov <boris@bur.io> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Tue, 19 Sep 2023 16:49:23 +0000 (18:49 +0200)]
btrfs: merge ordered work callbacks in btrfs_work into one
There are two callbacks defined in btrfs_work but only two actually make
use of them, otherwise there are NULLs. We can get rid of the freeing
callback making it a special case of the normal work. This reduces the
size of btrfs_work by 8 bytes, final layout:
btrfs: add raid stripe tree to features enabled with debug config
Until the raid stripe tree code is well enough tested and feature
complete, "hide" it behind CONFIG_BTRFS_DEBUG so only people who
want to use it are actually using it.
The scrub support may still fail some tests (btrfs/060 and up) and will
be fixed, RAID5/6 is not supported.
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: tree-checker: add support for raid stripe tree
Add a tree checker support for RAID stripe tree items, verify:
- alignment
- presence of the incompat bit
- supported encoding
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: tracepoints: add events for raid stripe tree
Add trace events for raid-stripe-tree operations.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: sysfs: announce presence of raid-stripe-tree
If a filesystem with a raid-stripe-tree is mounted, show the RST feature
in sysfs, currently still under the CONFIG_BTRFS_DEBUG option.
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Decode raid-stripe-tree entries on btrfs_print_tree().
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: zoned: support RAID0/1/10 on top of raid stripe tree
When we have a raid-stripe-tree, we can do RAID0/1/10 on zoned devices
for data block groups. For metadata block groups, we don't actually
need anything special, as all metadata I/O is protected by the
btrfs_zoned_meta_io_lock() already.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
A filesystem that uses the raid stripe tree for logical to physical
address translation can't use the regular scrub path, that reads all
stripes and then checks if a sector is unused afterwards.
When using the raid stripe tree, this will result in lookup errors, as
the stripe tree doesn't know the requested logical addresses.
In case we're scrubbing a filesystem which uses the RAID stripe tree for
multi-device logical to physical address translation, perform an extra
block mapping step to get the real on-disk stripe length from the stripe
tree when scrubbing the sectors.
This prevents a double completion of the btrfs_bio caused by splitting the
underlying bio and ultimately a use-after-free.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
As each stripe extent is tied to an extent item, delete the stripe extent
once the corresponding extent item is deleted.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: add support for inserting raid stripe extents
Add support for inserting stripe extents into the raid stripe tree on
completion of every write that needs an extra logical-to-physical
translation when using RAID.
Inserting the stripe extents happens after the data I/O has completed,
this is done to
a) support zone-append and
b) rule out the possibility of a RAID-write-hole.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
If we find the raid-stripe-tree on mount, read it from disk. This is
a backward incompatible feature. The rescue=ignorebadroots mount option
will skip this tree.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Add definitions for the raid stripe tree. This tree will hold information
about the on-disk layout of the stripes in a RAID set.
Each stripe extent has a 1:1 relationship with an on-disk extent item and
is doing the logical to per-drive physical address translation for the
extent item in question.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Thu, 24 Aug 2023 06:33:36 +0000 (14:33 +0800)]
btrfs: warn on tree blocks which are not nodesize aligned
A long time ago, we had some metadata chunks which started at sector
boundary but not aligned to nodesize boundary.
This led to some older filesystems which can have tree blocks only
aligned to sectorsize, but not nodesize.
Later 'btrfs check' gained the ability to detect and warn about such tree
blocks, and kernel fixed the chunk allocation behavior, nowadays those
tree blocks should be pretty rare.
But in the future, if we want to migrate metadata to folio, we cannot
have such tree blocks, as filemap_add_folio() requires the page index to
be aligned with the folio number of pages. Such unaligned tree blocks
can lead to VM_BUG_ON().
So this patch adds extra warning for those unaligned tree blocks, as a
preparation for the future folio migration.
Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Mon, 18 Sep 2023 18:15:33 +0000 (14:15 -0400)]
btrfs: don't arbitrarily slow down delalloc if we're committing
We have a random schedule_timeout() if the current transaction is
committing, which seems to be a holdover from the original delalloc
reservation code.
Remove this, we have the proper flushing stuff, we shouldn't be hoping
for random timing things to make everything work. This just induces
latency for no reason.
CC: stable@vger.kernel.org # 5.4+ Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 15 Sep 2023 15:03:57 +0000 (16:03 +0100)]
btrfs: remove useless comment from btrfs_pin_extent_for_log_replay()
The comment on top of btrfs_pin_extent_for_log_replay() mentioning that
the function must be called within a transaction is pointless as of
commit 9fce5704542c ("btrfs: Make btrfs_pin_extent_for_log_replay take
transaction handle"), since the function now takes a transaction handle
as its first argument. So remove the comment because it's completely
useless now.
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 15 Sep 2023 15:02:56 +0000 (16:02 +0100)]
btrfs: remove stale comment from btrfs_free_extent()
A comment at btrfs_free_extent() mentions the call to btrfs_pin_extent()
unlocks the pinned mutex, however that mutex is long gone, it was removed
in 2009 by commit 04018de5d41e ("Btrfs: kill the pinned_mutex"). So just
delete the comment.
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: zoned: factor out DUP bg handling from btrfs_load_block_group_zone_info
Split the code handling a type DUP block group from
btrfs_load_block_group_zone_info to make the code more readable.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: zoned: factor out single bg handling from btrfs_load_block_group_zone_info
Split the code handling a type single block group from
btrfs_load_block_group_zone_info to make the code more readable.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: zoned: factor out per-zone logic from btrfs_load_block_group_zone_info
Split out a helper for the body of the per-zone loop in
btrfs_load_block_group_zone_info to make the function easier to read and
modify.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: zoned: introduce a zone_info struct in btrfs_load_block_group_zone_info
Add a new zone_info structure to hold per-zone information in
btrfs_load_block_group_zone_info and prepare for breaking out helpers
from it.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Wed, 13 Sep 2023 11:23:18 +0000 (12:23 +0100)]
btrfs: remove pointless loop from btrfs_update_block_group()
When an extent is allocated or freed, we call btrfs_update_block_group()
to update its block group and space info. An extent always belongs to a
single block group, it can never span multiple block groups, so the loop
we have at btrfs_update_block_group() is pointless, as it always has a
single iteration. The loop was added in the very early days, 2007, when
the block group code was added in commit 9078a3e1e4e4 ("Btrfs: start of
block group code"), but even back then it seemed pointless.
So remove the loop and assert the block group containing the start offset
of the extent also contains the whole extent.
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Tue, 12 Sep 2023 12:04:31 +0000 (13:04 +0100)]
btrfs: mark transaction id check as unlikely at btrfs_mark_buffer_dirty()
At btrfs_mark_buffer_dirty(), having a transaction id mismatch is never
expected to happen and it usually means there's a bug or some memory
corruption due to a bitflip for example. So mark the condition as unlikely
to optimize code generation as well as to make it obvious for human
readers that it is a very unexpected condition.
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Tue, 12 Sep 2023 12:04:30 +0000 (13:04 +0100)]
btrfs: use btrfs_crit at btrfs_mark_buffer_dirty()
There's no need to use WARN() at btrfs_mark_buffer_dirty() to print an
error message, as we have the fs_info pointer we can use btrfs_crit()
which prints device information and makes the message have a more uniform
format. As we are already aborting the transaction we already have a stack
trace printed as well. So replace the use of WARN() with btrfs_crit().
Also slightly reword the message to use 'logical' instead of 'block' as
it's what is used in other error/warning messages.
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Tue, 12 Sep 2023 12:04:29 +0000 (13:04 +0100)]
btrfs: abort transaction on generation mismatch when marking eb as dirty
When marking an extent buffer as dirty, at btrfs_mark_buffer_dirty(),
we check if its generation matches the running transaction and if not we
just print a warning. Such mismatch is an indicator that something really
went wrong and only printing a warning message (and stack trace) is not
enough to prevent a corruption. Allowing a transaction to commit with such
an extent buffer will trigger an error if we ever try to read it from disk
due to a generation mismatch with its parent generation.
So abort the current transaction with -EUCLEAN if we notice a generation
mismatch. For this we need to pass a transaction handle to
btrfs_mark_buffer_dirty() which is always available except in test code,
in which case we can pass NULL since it operates on dummy extent buffers
and all test roots have a single node/leaf (root node at level 0).
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: scan but don't register device on single device filesystem
After the commit 5f58d783fd78 ("btrfs: free device in btrfs_close_devices
for a single device filesystem") we unregister the device from the kernel
memory upon unmounting for a single device.
So, device registration that was performed before mounting if any is no
longer in the kernel memory.
However, in fact, note that device registration is unnecessary for a
single-device btrfs filesystem unless it's a seed device.
So for commands like 'btrfs device scan' or 'btrfs device ready' with a
non-seed single-device btrfs filesystem, they can return success just
after superblock verification and without the actual device scan. When
'device scan --forget' is called on such device no error is returned.
The seed device must remain in the kernel memory to allow the sprout
device to mount without the need to specify the seed device explicitly.
Signed-off-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Fri, 8 Sep 2023 19:05:47 +0000 (21:05 +0200)]
btrfs: rename errno identifiers to error
We sync the kernel files to userspace and the 'errno' symbol is defined
by standard library, which does not matter in kernel but the parameters
or local variables could clash. Rename them all.
Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 8 Sep 2023 17:20:38 +0000 (18:20 +0100)]
btrfs: always reserve space for delayed refs when starting transaction
When starting a transaction (or joining an existing one with
btrfs_start_transaction()), we reserve space for the number of items we
want to insert in a btree, but we don't do it for the delayed refs we
will generate while using the transaction to modify (COW) extent buffers
in a btree or allocate new extent buffers. Basically how it works:
1) When we start a transaction we reserve space for the number of items
the caller wants to be inserted/modified/deleted in a btree. This space
goes to the transaction block reserve;
2) If the delayed refs block reserve is not full, its size is greater
than the amount of its reserved space, and the flush method is
BTRFS_RESERVE_FLUSH_ALL, then we attempt to reserve more space for
it corresponding to the number of items the caller wants to
insert/modify/delete in a btree;
3) The size of the delayed refs block reserve is increased when a task
creates delayed refs after COWing an extent buffer, allocating a new
one or deleting (freeing) an extent buffer. This happens after the
the task started or joined a transaction, whenever it calls
btrfs_update_delayed_refs_rsv();
4) The delayed refs block reserve is then refilled by anyone calling
btrfs_delayed_refs_rsv_refill(), either during unlink/truncate
operations or when someone else calls btrfs_start_transaction() with
a 0 number of items and flush method BTRFS_RESERVE_FLUSH_ALL;
5) As a task COWs or allocates extent buffers, it consumes space from the
transaction block reserve. When the task releases its transaction
handle (btrfs_end_transaction()) or it attempts to commit the
transaction, it releases any remaining space in the transaction block
reserve that it did not use, as not all space may have been used (due
to pessimistic space calculation) by calling btrfs_block_rsv_release()
which will try to add that unused space to the delayed refs block
reserve (if its current size is greater than its reserved space).
That transferred space may not be enough to completely fulfill the
delayed refs block reserve.
Plus we have some tasks that will attempt do modify as many leaves
as they can before getting -ENOSPC (and then reserving more space and
retrying), such as hole punching and extent cloning which call
btrfs_replace_file_extents(). Such tasks can generate therefore a
high number of delayed refs, for both metadata and data (we can't
know in advance how many file extent items we will find in a range
and therefore how many delayed refs for dropping references on data
extents we will generate);
6) If a transaction starts its commit before the delayed refs block
reserve is refilled, for example by the transaction kthread or by
someone who called btrfs_join_transaction() before starting the
commit, then when running delayed references if we don't have enough
reserved space in the delayed refs block reserve, we will consume
space from the global block reserve.
Now this doesn't make a lot of sense because:
1) We should reserve space for delayed references when starting the
transaction, since we have no guarantees the delayed refs block
reserve will be refilled;
2) If no refill happens then we will consume from the global block reserve
when running delayed refs during the transaction commit;
3) If we have a bunch of tasks calling btrfs_start_transaction() with a
number of items greater than zero and at the time the delayed refs
reserve is full, then we don't reserve any space at
btrfs_start_transaction() for the delayed refs that will be generated
by a task, and we can therefore end up using a lot of space from the
global reserve when running the delayed refs during a transaction
commit;
4) There are also other operations that result in bumping the size of the
delayed refs reserve, such as creating and deleting block groups, as
well as the need to update a block group item because we allocated or
freed an extent from the respective block group;
5) If we have a significant gap between the delayed refs reserve's size
and its reserved space, two very bad things may happen:
1) The reserved space of the global reserve may not be enough and we
fail the transaction commit with -ENOSPC when running delayed refs;
2) If the available space in the global reserve is enough it may result
in nearly exhausting it. If the fs has no more unallocated device
space for allocating a new block group and all the available space
in existing metadata block groups is not far from the global
reserve's size before we started the transaction commit, we may end
up in a situation where after the transaction commit we have too
little available metadata space, and any future transaction commit
will fail with -ENOSPC, because although we were able to reserve
space to start the transaction, we were not able to commit it, as
running delayed refs generates some more delayed refs (to update the
extent tree for example) - this includes not even being able to
commit a transaction that was started with the goal of unlinking a
file, removing an empty data block group or doing reclaim/balance,
so there's no way to release metadata space.
In the worst case the next time we mount the filesystem we may
also fail with -ENOSPC due to failure to commit a transaction to
cleanup orphan inodes. This later case was reported and hit by
someone running a SLE (SUSE Linux Enterprise) distribution for
example - where the fs had no more unallocated space that could be
used to allocate a new metadata block group, and the available
metadata space was about 1.5M, not enough to commit a transaction
to cleanup an orphan inode (or do relocation of data block groups
that were far from being full).
So improve on this situation by always reserving space for delayed refs
when calling start_transaction(), and if the flush method is
BTRFS_RESERVE_FLUSH_ALL, also try to refill the delayed refs block
reserve if it's not full. The space reserved for the delayed refs is added
to a local block reserve that is part of the transaction handle, and when
a task updates the delayed refs block reserve size, after creating a
delayed ref, the space is transferred from that local reserve to the
global delayed refs reserve (fs_info->delayed_refs_rsv). In case the
local reserve does not have enough space, which may happen for tasks
that generate a variable and potentially large number of delayed refs
(such as the hole punching and extent cloning cases mentioned before),
we transfer any available space and then rely on the current behaviour
of hoping some other task refills the delayed refs reserve or fallback
to the global block reserve.
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 8 Sep 2023 17:20:37 +0000 (18:20 +0100)]
btrfs: stop doing excessive space reservation for csum deletion
Currently when reserving space for deleting the csum items for a data
extent, when adding or updating a delayed ref head, we determine how
many leaves of csum items we can have and then pass that number to the
helper btrfs_calc_delayed_ref_bytes(). This helper is used for calculating
space for all tree modifications we need when running delayed references,
however the amount of space it computes is excessive for deleting csum
items because:
1) It uses btrfs_calc_insert_metadata_size() which is excessive because
we only need to delete csum items from the csum tree, we don't need
to insert any items, so btrfs_calc_metadata_size() is all we need (as
it computes space needed to delete an item);
2) If the free space tree is enabled, it doubles the amount of space,
which is pointless for csum deletion since we don't need to touch the
free space tree or any other tree other than the csum tree.
So improve on this by tracking how many csum deletions we have and using
a new helper to calculate space for csum deletions (just a wrapper around
btrfs_calc_metadata_size() with a comment). This reduces the amount of
space we need to reserve for csum deletions by a factor of 4, and it helps
reduce the number of times we have to block space reservations and have
the reclaim task enter the space flushing algorithm (flush delayed items,
flush delayed refs, etc) in order to satisfy tickets.
For example this results in a total time decrease when unlinking (or
truncating) files with many extents, as we end up having to block on space
metadata reservations less often. Example test:
$ cat test.sh
#!/bin/bash
DEV=/dev/nullb0
MNT=/mnt/test
umount $DEV &> /dev/null
mkfs.btrfs -f $DEV
# Use compression to quickly create files with a lot of extents
# (each with a size of 128K).
mount -o compress=lzo $DEV $MNT
# 100G gives at least 983040 extents with a size of 128K.
xfs_io -f -c "pwrite -S 0xab -b 1M 0 120G" $MNT/foobar
# Flush all delalloc and clear all metadata from memory.
umount $MNT
mount -o compress=lzo $DEV $MNT
Filipe Manana [Fri, 8 Sep 2023 17:20:36 +0000 (18:20 +0100)]
btrfs: remove pointless initialization at btrfs_delayed_refs_rsv_release()
There's no point in initializing to 0 the local variable 'released' as
we don't use it before the next assignment to it. So remove the
initialization. This may help avoid some warnings with clang tools such
as the one reported/fixed by commit 966de47ff0c9 ("btrfs: remove redundant
initialization of variables in log_new_ancestors").
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 8 Sep 2023 17:20:35 +0000 (18:20 +0100)]
btrfs: reserve space for delayed refs on a per ref basis
Currently when reserving space for delayed refs we do it on a per ref head
basis. This is generally enough because most back refs for an extent end
up being inlined in the extent item - with the default leaf size of 16K we
can have at most 33 inline back refs (this is calculated by the macro
BTRFS_MAX_EXTENT_ITEM_SIZE()). The amount of bytes reserved for each ref
head is given by btrfs_calc_delayed_ref_bytes(), which basically
corresponds to a single path for insertion into the extent tree plus
another path for insertion into the free space tree if it's enabled.
However if we have reached the limit of inline refs or we have a mix of
inline and non-inline refs, then we will need to insert a non-inline ref
and update the existing extent item to update the total number of
references for the extent. This implies we need reserved space for two
insertion paths in the extent tree, but we only reserved for one path.
The extent item and the non-inline ref item may be located in different
leaves, or even if they are located in the same leaf, after updating the
extent item and before inserting the non-inline ref item, the extent
buffers in the btree path may have been written (due to memory pressure
for e.g.), in which case we need to COW the entire path again. In this
case since we have not reserved enough space for the delayed refs block
reserve, we will use the global block reserve.
If we are in a situation where the fs has no more unallocated space enough
to allocate a new metadata block group and available space in the existing
metadata block groups is close to the maximum size of the global block
reserve (512M), we may end up consuming too much of the free metadata
space to the point where we can't commit any future transaction because it
will fail, with -ENOSPC, during its commit when trying to allocate an
extent for some COW operation (running delayed refs generated by running
delayed refs or COWing the root tree's root node at commit_cowonly_roots()
for example). Such dramatic scenario can happen if we have many delayed
refs that require the insertion of non-inline ref items, due to too many
reflinks or snapshots. We also have situations where we use the global
block reserve because we could not in advance know that we will need
space to update some trees (block group creation for example), so this
all adds up to increase the chances of exhausting the global block reserve
and making any future transaction commit to fail with -ENOSPC and turn
the fs into RO mode, or fail the mount operation in case the mount needs
to start and commit a transaction, such as when we have orphans to cleanup
for example - such case was reported and hit by someone running a SLE
(SUSE Linux Enterprise) distribution for example - where the fs had no
more unallocated space that could be used to allocate a new metadata block
group, and the available metadata space was about 1.5M, not enough to
commit a transaction to cleanup an orphan inode (or do relocation of data
block groups that were far from being full).
So reserve space for delayed refs by individual refs and not by ref heads,
as we may need to COW multiple extent tree paths due to non-inline ref
items.
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 8 Sep 2023 17:20:34 +0000 (18:20 +0100)]
btrfs: allow to run delayed refs by bytes to be released instead of count
When running delayed references, through btrfs_run_delayed_refs(), we can
specify how many to run, run all existing delayed references and keep
running delayed references while we can find any. This is controlled with
the value of the 'count' argument, where a value of 0 means to run all
delayed references that exist by the time btrfs_run_delayed_refs() is
called, (unsigned long)-1 means to keep running delayed references while
we are able find any, and any other value to run that exact number of
delayed references.
Typically a specific value other than 0 or -1 is used when flushing space
to try to release a certain amount of bytes for a ticket. In this case
we just simply calculate how many delayed reference heads correspond to a
specific amount of bytes, with calc_delayed_refs_nr(). However that only
takes into account the space reserved for the reference heads themselves,
and does not account for the space reserved for deleting checksums from
the csum tree (see add_delayed_ref_head() and update_existing_head_ref())
in case we are going to delete a data extent. This means we may end up
running more delayed references than necessary in case we process delayed
references for deleting a data extent.
So change the logic of btrfs_run_delayed_refs() to take a bytes argument
to specify how many bytes of delayed references to run/release, using the
special values of 0 to mean all existing delayed references and U64_MAX
(or (u64)-1) to keep running delayed references while we can find any.
This prevents running more delayed references than necessary, when we have
delayed references for deleting data extents, but also makes the upcoming
changes/patches simpler and it's preparatory work for them.
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 8 Sep 2023 17:20:33 +0000 (18:20 +0100)]
btrfs: simplify check for extent item overrun at lookup_inline_extent_backref()
At lookup_inline_extent_backref() we can simplify the check for an overrun
of the extent item by making the while loop's condition to be "ptr < end"
and then check after the loop if an overrun happened ("ptr > end"). This
reduces indentation and makes the loop condition more clear. So move the
check out of the loop and change the loop condition accordingly, while
also adding the 'unlikely' tag to the check since it's not supposed to be
triggered.
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 8 Sep 2023 17:20:32 +0000 (18:20 +0100)]
btrfs: return -EUCLEAN if extent item is missing when searching inline backref
At lookup_inline_extent_backref() when trying to insert an inline backref,
if we don't find the extent item we log an error and then return -EIO.
This error code is confusing because there was actually no IO error, and
this means we have some corruption, either caused by a bug or something
like a memory bitflip for example. So change the error code from -EIO to
-EUCLEAN.
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 8 Sep 2023 17:20:31 +0000 (18:20 +0100)]
btrfs: use a single variable for return value at lookup_inline_extent_backref()
At lookup_inline_extent_backref(), instead of using a 'ret' and an 'err'
variable for tracking the return value, use a single one ('ret'). This
simplifies the code, makes it comply with most of the existing code and
it's less prone for logic errors as time has proven over and over in the
btrfs code.
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 8 Sep 2023 17:20:30 +0000 (18:20 +0100)]
btrfs: use a single variable for return value at run_delayed_extent_op()
Instead of using a 'ret' and an 'err' variable at run_delayed_extent_op()
for tracking the return value, use a single one ('ret'). This simplifies
the code, makes it comply with most of the existing code and it's less
prone for logic errors as time has proven over and over in the btrfs code.
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 8 Sep 2023 17:20:28 +0000 (18:20 +0100)]
btrfs: remove pointless 'ref_root' variable from run_delayed_data_ref()
The 'ref_root' variable, at run_delayed_data_ref(), is not really needed
as we can always use ref->root directly, plus its initialization to 0 is
completely pointless as we assign it ref->root before its first use.
So just drop that variable and use ref->root directly.
This may help avoid some warnings with clang tools such as the one
reported/fixed by commit 966de47ff0c9 ("btrfs: remove redundant
initialization of variables in log_new_ancestors").
Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
projects / thirdparty / linux.git / log
