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[MINOR PROBLEM]
When a running dev-replace hits some error for the target device (devid
0), there will be a DEV_STATS with error records created at the next
transaction commit.
Unfortunately that item will never to be deleted.
This means at the next dev-replace, if the replace is interrupted, then
at the next mount, the target device will suddenly inherit the old error
records from that DEV_STATS item, which can give some false alerts on
that device.
This shouldn't affect end users that much, as it requires all the
following conditions to be met, which is pretty rare:
- The initial dev-replace hits some error on the target device
E.g. write errors, but those errors itself is already a big problem
for a running replace.
This is required to create the DEV_STATS item in the first place.
- The next replace is interrupted
This is required to allow btrfs to read from the old records.
[CAUSE]
Btrfs just never deletes the DEV_STATS after a replace is finished.
[FIX]
Remove the DEV_STATS item for devid 0 after the replace is finished.
This is not going to completely fix the error, as we still have other
error paths, e.g. by somehow the fs flips RO and can not start a new
transaction for the DEV_STATS item removal.
But those corner cases will be addressed by later patches which provide
a more generic fix to DEV_STATS related problems.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Currently btrfs_writepages() just accumulates as large bio as possible
(within writeback_control constraints) and then submits it. This can
however lead to significant latency in writeback IO submission (I have
observed tens of milliseconds) because the submitted bio easily has over
hundred of megabytes. Consequently this leads to IO pipeline stalls and
reduced throughput.
At the same time beyond certain size submitting so large bio provides
diminishing returns because the bio is split by the block layer
immediately anyway. So compute (estimate of) bio size beyond which we
are unlikely to improve performance and just submit the bio for
writeback once we accumulate that much to keep the IO pipeline busy.
This improves writeback throughput for sequential writes by about 15% on
the test machine I was using.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
[ Fix the handling of missing device to avoid NULL pointer dereference. ]
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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[BUG]
There is a long known bug that if metadata is using RAID1 on two disks
with unbalanced sizes, there is a very high chance to hit ENOSPC related
transaction abort.
[CAUSE]
The root cause is in the available space estimation code:
- Factor based calculation
Just use all unallocated space, divide by the profile factor
One obvious user is can_overcommit().
This can not handle the following example:
devid 1 unallocated: 1GiB
devid 2 unallocated: 50GiB
metadata type: RAID1
If using factor based estimation, we can use (1GiB + 50GiB) / 2 = 25.5GiB
free space for metadata.
Thus we can continue allocating metadata (over-commit) way beyond the
1GiB limit.
But this estimation is completely wrong, in reality we can only allocate
one single 1GiB RAID1 block group, thus if we continue over-commit, at
one time we will hit ENOSPC at some critical path and flips the fs
read-only.
[SOLUTION]
This patch will introduce per-profile available space estimation,
which can provide chunk-allocator like behavior to give a (mostly)
accurate result, with under-estimate corner cases.
There are some differences between the estimation and real chunk
allocator:
- No consideration on hole size
It's fine for most cases, as all data/metadata strips are in 1GiB size
thus there should not be any hole wasting much space.
And chunk allocator is able to use smaller stripes when there is
really no other choice.
Although in theory this means it can lead to some over-estimation, it
should not cause too much hassle in the real world.
The other benefit of such behavior is, we avoid dev-extent tree search
completely, thus the overhead is very small.
- No true balance for certain cases
If we have 3 disks RAID1, and each device has 2GiB unallocated space,
we can load balance the chunk allocation so that we can allocate 3GiB
RAID1 chunks, and that's what chunk allocator will do.
But this current estimation code is using the largest available space
to do a single allocation. Meaning the estimation will be 2GiB, thus
under estimate.
Such under estimation is fine and after the first chunk allocation, the
estimation will be updated and still give a correct 2GiB
estimation.
So this only means the estimation will be a little conservative, which
is safer for call sites like metadata over-commit check.
With that facility, for above 1GiB + 50GiB case, it will give a RAID1
estimation of 1GiB, instead of the incorrect 25.5GiB.
Or for a more complex example:
devid 1 unallocated: 1T
devid 2 unallocated: 1T
devid 3 unallocated: 10T
We will get an array of:
RAID10: 2T
RAID1: 2T
RAID1C3: 1T
RAID1C4: 0 (not enough devices)
DUP: 6T
RAID0: 3T
SINGLE: 12T
RAID5: 2T
RAID6: 1T
[IMPLEMENTATION]
And for the each profile , we go chunk allocator level calculation:
The pseudo code looks like:
clear_virtual_used_space_of_all_rw_devices();
do {
/*
* The same as chunk allocator, despite used space,
* we also take virtual used space into consideration.
*/
sort_device_with_virtual_free_space();
/*
* Unlike chunk allocator, we don't need to bother hole/stripe
* size, so we use the smallest device to make sure we can
* allocated as many stripes as regular chunk allocator
*/
stripe_size = device_with_smallest_free->avail_space;
stripe_size = min(stripe_size, to_alloc / ndevs);
/*
* Allocate a virtual chunk, allocated virtual chunk will
* increase virtual used space, allow next iteration to
* properly emulate chunk allocator behavior.
*/
ret = alloc_virtual_chunk(stripe_size, &allocated_size);
if (ret == 0)
avail += allocated_size;
} while (ret == 0)
This minimal available space based calculation is not perfect, but the
important part is, the estimation is never exceeding the real available
space.
This patch just introduces the infrastructure, no hooks are executed
yet.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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I ran into another sort of trivial bug in v1 of the patch and concluded
that these functions really ought to be unit tested.
These two functions form the core of searching the chunk allocation
pending extent bitmap and have relatively easily definable semantics, so
unit testing them can help ensure the correctness of chunk allocation.
I also made a minor unrelated fix in volumes.h to properly forward
declare btrfs_space_info. Because of the order of the includes in the
new test, this was actually hitting a latent build warning.
Note:
This is an early example for me of a commit authored in part by an AI
agent, so I wanted to more clear about what I did. I defined a
trivial test and explained the set of tests I wanted to the agent and it
produced the large set of test cases seen here. I then checked each test
case to make sure it matched the description and simplified the
constants and numbers until they looked reasonable to me. I then checked
the looping logic to make sure it made sense to the original spirit of
the trivial test. Finally, carefully combed over all the lines it wrote
to loop over the tests it generated to make sure they followed our code
style guide.
Assisted-by: Claude:claude-opus-4-5
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
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btrfs_discard_extent() can be called either when an extent is removed
or from walking the free-space tree. With a remapped block group these
two things are no longer equivalent: the extent's addresses are
remapped, while the free-space tree exclusively uses underlying
addresses.
Add a do_remap parameter to btrfs_discard_extent() and
btrfs_map_discard(), saying whether or not the address needs to be run
through the remap tree first.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Handle the case where we free an extent from a block group that has the
REMAPPED flag set. Because the remap tree is orthogonal to the extent
tree, for data this may be within any number of identity remaps or
actual remaps. If we're freeing a metadata node, this will be wholly
inside one or the other.
btrfs_remove_extent_from_remap_tree() searches the remap tree for the
remaps that cover the range in question, then calls
remove_range_from_remap_tree() for each one, to punch a hole in the
remap and adjust the free-space tree.
For an identity remap, remove_range_from_remap_tree() will adjust the
block group's `identity_remap_count` if this changes. If it reaches
zero we mark the block group as fully remapped.
For an identity remap, remove_range_from_remap_tree() will adjust the
block group's `identity_remap_count` if this changes. If it reaches
zero we mark the block group as fully remapped.
Fully remapped block groups have their chunk stripes removed and their
device extents freed, which makes the disk space available again to the
chunk allocator. This happens asynchronously: in the cleaner thread for
sync discard and nodiscard, and (in a later patch) in the discard worker
for async discard.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Add a new METADATA_REMAP chunk type, which is a metadata chunk that holds the
remap tree.
This is needed for bootstrapping purposes: the remap tree can't itself
be remapped, and must be relocated the existing way, by COWing every
leaf. The remap tree can't go in the SYSTEM chunk as space there is
limited, because a copy of the chunk item gets placed in the superblock.
The changes in fs/btrfs/volumes.h are because we're adding a new block
group type bit after the profile bits, and so can no longer rely on the
const_ilog2 trick.
The sizing to 32MB per chunk, matching the SYSTEM chunk, is an estimate
here, we can adjust it later if it proves to be too big or too small.
This works out to be ~500,000 remap items, which for a 4KB block size
covers ~2GB of remapped data in the worst case and ~500TB in the best case.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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There are two main causes of holes inside btrfs_device:
- The single bytes member of last_flush_error
Not only it's a single byte member, but we never really care about the
exact error number.
- The @devt member
Which is placed between two u64 members.
Shrink the size of btrfs_device by:
- Use a single bit flag for flush error
Use BTRFS_DEV_STATE_FLUSH_FAILED so that we no longer need that
dedicated member.
- Move @devt to the hole after dev_stat_values[]
This reduces the size of btrfs_device from 528 to exact 512 bytes for
x86_64.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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The offload csum mode was introduced to allow developers to compare the
performance of generating checksum for data writes at different timings:
- During btrfs_submit_chunk()
This is the most common one, if any of the following condition is met
we go this path:
* The csum is fast
For now it's CRC32C and xxhash.
* It's a synchronous write
* Zoned
- Delay the checksum generation to a workqueue
However since commit dd57c78aec39 ("btrfs: introduce
btrfs_bio::async_csum") we no longer need to bother any of them.
As if it's an experimental build, async checksum generation at the
background will be faster anyway.
And if not an experimental build, we won't even have the offload csum
mode support.
Considering the async csum will be the new default, let's remove the
offload csum mode code.
There will be no impact to end users, and offload csum mode is still
under experimental features.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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[BUG]
There is a bug report where after a dev-replace, the replace source
device with devid 4 is properly erased (dump tree shows it's the old
devid 4), but the target device is still using devid 0.
When the user tries to mount the fs degraded, the mount failed with the
following errors:
BTRFS: device fsid 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9 devid 5 transid 1394395 /dev/sda (8:0) scanned by btrfs (261)
BTRFS: device fsid 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9 devid 6 transid 1394395 /dev/sde (8:64) scanned by btrfs (261)
BTRFS: device fsid 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9 devid 0 transid 1394395 /dev/sdd (8:48) scanned by btrfs (261)
BTRFS: device fsid 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9 devid 3 transid 1394395 /dev/sdf (8:80) scanned by btrfs (261)
BTRFS info (device sdd): first mount of filesystem 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9
BTRFS info (device sdd): using crc32c (crc32c-intel) checksum algorithm
BTRFS warning (device sdd): devid 4 uuid 01e2081c-9c2a-4071-b9f4-e1b27e571ff5 is missing
BTRFS info (device sdd): bdev <missing disk> errs: wr 84994544, rd 15567, flush 65872, corrupt 0, gen 0
BTRFS info (device sdd): bdev /dev/sdd errs: wr 71489901, rd 0, flush 30001, corrupt 0, gen 0
BTRFS error (device sdd): replace without active item, run 'device scan --forget' on the target device
BTRFS error (device sdd): failed to init dev_replace: -117
BTRFS error (device sdd): open_ctree failed: -117
[CAUSE]
The devid 0 didn't get its devid updated is its own problem, here I'm
only focusing on the mount failure itself.
The mount is not caused by the missing device, as the fs has RAID1C3 for
metadata and RAID10 for data, thus is completely able to tolerate one
missing device.
The device tree shows the dev-replace has properly finished:
item 7 key (0 DEV_REPLACE 0) itemoff 15931 itemsize 72
src devid -1 cursor left 11091821199360 cursor right 11091821199360 mode ALWAYS
state FINISHED write errors 0 uncorrectable read errors 0
^^^^^^^^
And the chunk tree shows there is no devid 0:
leaf 37980736602112 items 23 free space 12548 generation 1394388 owner CHUNK_TREE
leaf 37980736602112 flags 0x1(WRITTEN) backref revision 1
fs uuid 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9
chunk uuid d074c661-6311-4570-b59f-a5c83fd37f8e
item 0 key (DEV_ITEMS DEV_ITEM 3) itemoff 16185 itemsize 98
devid 3 total_bytes 20000588955648 bytes_used 8282877984768
io_align 4096 io_width 4096 sector_size 4096 type 0
generation 0 start_offset 0 dev_group 0
seek_speed 0 bandwidth 0
uuid 0d596b69-fb0d-4031-b4af-a301d0868b8b
fsid 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9
...
Which shows the first device is devid 3.
But there is indeed /dev/sdd with devid 0:
superblock: bytenr=65536, device=/dev/sdd
---------------------------------------------------------
csum_type 0 (crc32c)
csum_size 4
csum 0xd4bed87e [match]
bytenr 65536
flags 0x1
( WRITTEN )
magic _BHRfS_M [match]
fsid 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9
...
uuid_tree_generation 1394388
dev_item.uuid ee6532ad-5442-45f7-87fb-7703e29ed934
dev_item.fsid 84a1ed4a-365c-45c3-a9ee-a7df525dc3c9 [match]
dev_item.type 0
dev_item.total_bytes 20000588955648
dev_item.bytes_used 8292541661184
dev_item.io_align 0
dev_item.io_width 0
dev_item.sector_size 0
dev_item.devid 0 <<<
So this means device scan will register sdd as devid 0 into the fs, then
during btrfs_init_dev_replace(), we located the replace progress item,
found the previous replace is finished, but we still need to check if
the dev-replace target device (devid 0) exists.
If that device exists, we error out showing that error message.
But to be honest the end user may not really remember which device is
the replace target device, thus not sure what to do in the next step.
[ENHANCEMENT]
To make the error more obvious, and tell the end user which devices
should be unregistered:
- Introduce BTRFS_DEV_STATE_ITEM_FOUND flag
During device item read from the chunk tree, set the flag for each
found device item.
- Verify there is no device without the above flag during mount
Even missing device should have that flag set.
If we found a device without that flag set, it means it's an
unexpected one and should be rejected.
- More detailed error message on what to do next
This will show all unexpected devices and tell the end user to use
'btrfs dev scan --forget' to forget them or remove them before mount.
There is an example dmesg where a device of a valid filesystem is modified to
have devid 0, then try degraded mount:
BTRFS info (device dm-6): first mount of filesystem 7c873869-844c-4b39-bd75-a96148bf4656
BTRFS info (device dm-6): using crc32c checksum algorithm
BTRFS warning (device dm-6): devid 3 uuid b4a9f35b-db42-4ac4-b55a-cbf81d3b9683 is missing
BTRFS error (device dm-6): devid 0 path /dev/mapper/test-scratch3 is registered but not found in chunk tree
BTRFS error (device dm-6): please remove above devices or use 'btrfs device scan --forget <dev>' to unregister them before mount
BTRFS error (device dm-6): open_ctree failed: -117
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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const_ilog2() was a workaround of some sparse issue, which has never
appeared in the C functions. Replace it with ilog2().
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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For the ->remove_bdev() callback, btrfs will:
- Mark the target device as missing
- Go degraded if the fs can afford it
- Return error other wise
Thus falls back to the shutdown callback
For the ->shutdown callback, btrfs will:
- Set the SHUTDOWN flag
Which will reject all new incoming operations, and make all writeback
to fail.
The behavior is the same as the NOLOGFLUSH behavior.
To support the lookup from bdev to a btrfs_device,
btrfs_dev_lookup_args is enhanced to have a new @devt member.
If set, we should be able to use that @devt member to uniquely locating a
btrfs device.
I know the shutdown can be a little overkilled, if one has a RAID1
metadata and RAID0 data, in that case one can still read data with 50%
chance to got some good data.
But a filesystem returning -EIO for half of the time is not really
considered usable.
Further it can also be as bad as the only device went missing for a single
device btrfs.
So here we go safe other than sorry when handling missing device.
And the remove_bdev callback will be hidden behind experimental features
for now, the reasons are:
- There are not enough btrfs specific bdev removal test cases
The existing test cases are all removing the only device, thus only
exercises the ->shutdown() behavior.
- Not yet determined what's the expected behavior
Although the current auto-degrade behavior is no worse than the old
behavior, it may not always be what the end users want.
Before there is a concrete interface, better hide the new feature
from end users.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <asj@kernel.org>
Tested-by: Anand Jain <asj@kernel.org>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Annual typo fixing pass. Strangely codespell found only about 30% of
what is in this patch, the rest was done manually using text
spellchecker with a custom dictionary of acceptable terms.
Reviewed-by: Neal Gompa <neal@gompa.dev>
Signed-off-by: David Sterba <dsterba@suse.com>
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When BTRFS is doing automatic block-group reclaim, it is spamming the
kernel log messages a lot.
Add a 'verbose' parameter to btrfs_relocate_chunk() and
btrfs_relocate_block_group() to control the verbosity of these log
message. This way the old behaviour of printing log messages on a
user-space initiated balance operation can be kept while excessive log
spamming due to auto reclaim is mitigated.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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The only use for device name has been removed so we can kill the RCU
string API.
Reviewed-by: Daniel Vacek <neelx@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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The RCU protected string is only used for a device name, and RCU is used
so we can print the name and eventually synchronize against the rare
device rename in device_list_add().
We don't need the whole API just for that. Open code all the helpers and
access to the string itself.
Notable change is in device_list_add() when the device name is changed,
which is the only place that can actually happen at the same time as
message prints using the device name under RCU read lock.
Previously there was kfree_rcu() which used the embedded rcu_head to
delay freeing the object depending on the RCU mechanism. Now there's
kfree_rcu_mightsleep() which does not need the rcu_head and waits for
the grace period.
Sleeping is safe in this context and as this is a rare event it won't
interfere with the rest as it's holding the device_list_mutex.
Straightforward changes:
- rcu_string_strdup -> kstrdup
- rcu_str_deref -> rcu_dereference
- drop ->str from safe contexts and use rcu_dereference_raw() so it does
not trigger RCU validators
Historical notes:
Introduced in 606686eeac45 ("Btrfs: use rcu to protect device->name")
with a vague reference of the potential problem described in
https://lore.kernel.org/all/20120531155304.GF11775@ZenIV.linux.org.uk/ .
The RCU protection looks like the easiest and most lightweight way of
protecting the rare event of device rename racing device_list_add()
with a random printk() that uses the device name.
Alternatives: a spin lock would require to protect the printk
anyway, a fixed buffer for the name would be eventually wrong in case
the new name is overwritten when being printed, an array switching
pointers and cleaning them up eventually resembles RCU too much.
The cleanups up to this patch should hide special case of RCU to the
minimum that only the name needs rcu_dereference(), which can be further
cleaned up to use btrfs_dev_name().
Reviewed-by: Daniel Vacek <neelx@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Currently we always call btrfs_open_devices() before creating the
super block.
It's fine for now because:
- No blk_holder_ops is provided
- btrfs_fs_type is used as a holder
This means no matter who wins the device opening race, the holder will be
the same thus not affecting the later sget_fc() race.
And since no blk_holder_ops is provided, no bdev operation is depending on
the holder.
But this will no longer be true if we want to implement a proper
blk_holder_ops using fs_holder_ops.
This means we will need a proper super block as the bdev holder.
To prepare for such change:
- Add btrfs_fs_devices::holding member
This will prevent btrfs_free_stale_devices() and btrfs_close_device()
from deleting the fs_devices when there is another process trying to
mount the fs.
Along with the new member, here come the two helpers,
btrfs_fs_devices_inc_holding() and btrfs_fs_devices_dec_holding().
This will allow us to hold fs_devices without opening it.
This is needed because we cannot hold uuid_mutex while calling
sget_fc(), this will reverse the lock sequence with s_umount, causing
a lockdep warning.
- Delay btrfs_open_devices() until a super block is returned
This means we have to hold the initial fs_devices first, then unlock
uuid_mutex, call sget_fc(), then re-lock uuid_mutex, and decrease the
holding number.
For new super block case, we continue to btrfs_open_devices() with
uuid_mutex hold.
For existing super block case, we can unlock uuid_mutex and continue.
Although this means a more complex error handling path, as if we
didn't call btrfs_open_devices() (either got an existing sb, or
sget_fc() failed), we cannot let btrfs_put_fs_info() cleanup the
fs_devices, as it can be freed at any time after we decrease the hold
on fs_devices and unlock uuid_mutex.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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btrfs_scan_one_device() opens the block device only to read the super
block. Instead of passing a blk_mode_t argument to sometimes open
it for writing, just hard code BLK_OPEN_READ as it will never write
to the device or hand the block_device out to someone else.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Another batch of pointer parameter constifications. This is for clarity
and minor addition to type safety. There are no observable effects in the
assembly code and .ko measured on release config.
Signed-off-by: David Sterba <dsterba@suse.com>
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Add struct btrfs_space_info parameter to btrfs_make_block_group(), its
related functions and related struct. Passed space_info will have a new
block group.
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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We have two functions to read a super block from a block device:
- btrfs_read_dev_one_super()
Exported from disk-io.c
- btrfs_read_disk_super()
Local to volumes.c
And they have some minor differences:
- btrfs_read_dev_one_super() uses @copy_num
Meanwhile btrfs_read_disk_super() relies on the physical and expected
bytenr passed from the caller.
The parameter list of btrfs_read_dev_one_super() is more user
friendly.
- btrfs_read_disk_super() makes sure the label is NUL terminated
We do not need two different functions doing the same job, so merge the
behavior into btrfs_read_disk_super() by:
- Remove btrfs_read_dev_one_super()
- Export btrfs_read_disk_super()
The name pairs with btrfs_release_disk_super() perfectly.
- Change the parameter list of btrfs_read_disk_super() to mimic
btrfs_read_dev_one_super()
All existing callers are calculating the physical address and expect
bytenr before calling btrfs_read_disk_super() already.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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We have only two chunk allocation policies right now and the
switch/cases don't handle an unknown one properly. The error is in the
impossible category (the policy is stored only in memory), we don't have
to BUG(), falling back to regular policy should be safe.
Signed-off-by: David Sterba <dsterba@suse.com>
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First added (but not effectively used) in 02c372e1f016e5 ("btrfs: add
support for inserting raid stripe extents"). The structure is
initialized to zeros so the only use in btrfs_insert_one_raid_extent()
u64 length = bioc->stripes[i].length;
struct btrfs_raid_stride *raid_stride = &stripe_extent->strides[i];
if (length == 0)
length = bioc->size;
the 'if' always happens.
Last use in 4016358e852861 ("btrfs: remove unused variable length in
btrfs_insert_one_raid_extent()") was an obvious cleanup. It seems to be
safe to remove, raid-stripe-tree works without using it since 6.6.
This was found by tool https://github.com/jirislaby/clang-struct .
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Pass over all header files and add missing forward declarations,
includes or fix include types.
Signed-off-by: David Sterba <dsterba@suse.com>
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Add read policy that will force all reads to go to the given device
(specified by devid) on the RAID1 profiles.
This will be used for testing, e.g. to read from stale device. Users may
find other use cases.
Can be set in sysfs, the value format is "devid:<devid>" to the file
/sys/fs/btrfs/FSID/read_policy
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Add round-robin read policy that balances reads over available devices
(all RAID1 block group profiles). Switch to the next devices is done
after a number of blocks is read, which is 256K by default and is
configurable in sysfs.
The format is "round-robin:<min-contig-read>" and can be set in file
/sys/fs/btrfs/FSID/read_policy
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Track number of read blocks in the whole filesystem. The counter is
initialized when devices are opened. The counter is increased at
btrfs_submit_dev_bio() if the stats tracking is enabled (depends on the
read policy). Stats tracking is disabled by default and is enabled
through fs_devices::collect_fs_stats when required.
The code is not under the EXPERIMENTAL define, as stats can be expanded
to include write counts and other performance counters, with the user
interface independent of its internal use.
This is an in-memory-only feature, not related to the dev error stats.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Cache the decision if a particular I/O needs to update RAID stripe tree
entries in struct btrfs_io_context.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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btrfs_is_parity_mirror() has been unused since commit 4886ff7b50f6
("btrfs: introduce a new helper to submit write bio for repair").
Remove it as the code was refactored and we don't need the helper
anymore.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Add first stash of very basic self tests for the RAID stripe-tree.
More test cases will follow exercising the tree.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Currently CONFIG_BTRFS_EXPERIMENTAL is not only for the extra debugging
output, but also for experimental features.
This is not ideal to distinguish planned but not yet stable features
from those purely designed for debugging.
This patch splits the following features into CONFIG_BTRFS_EXPERIMENTAL:
- Extent map shrinker
This seems to be the first one to exit experimental.
- Extent tree v2
This seems to be the last one to graduate from experimental.
- Raid stripe tree
- Csum offload mode
- Send protocol v3
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Per Qu Wenruo in case we have a very large disk, e.g. 8TiB device,
mostly empty although we will do the split according to our super block
locations, the last super block ends at 256G, we can submit a huge
discard for the range [256G, 8T), causing a large delay.
Split the space left to discard based on BTRFS_MAX_DISCARD_CHUNK_SIZE in
preparation of introduction of cancellation points to trim. The value
of the chunk size is arbitrary, it can be higher or derived from actual
device capabilities but we can't easily read that using
bio_discard_limit().
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219180
Link: https://bugzilla.suse.com/show_bug.cgi?id=1229737
CC: stable@vger.kernel.org # 5.15+
Signed-off-by: Luca Stefani <luca.stefani.ge1@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Rename 'btrfs_io_stripe::is_scrub' to 'rst_search_commit_root'. While
'is_scrub' describes the state of the io_stripe (it is a stripe submitted
by scrub) it does not describe the purpose, namely looking at the commit
root when searching RAID stripe-tree entries.
Renaming the stripe to rst_search_commit_root describes this purpose.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Qu Wenruo <wqu@suse.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>
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Functions btrfs_uuid_scan_kthread() and btrfs_create_uuid_tree() are for
UUID tree rescan and creation, it's not suitable for volumes.[ch].
Move them to uuid-tree.[ch] instead.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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We can add const to many parameters, this is for clarity and minor
addition to safety. There are some minor effects, in the assembly
code and .ko measured on release config. This patch does not cover all
possible conversions.
Signed-off-by: David Sterba <dsterba@suse.com>
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error state
Currently the error status of super block write is tracked in page/folio
status bit Error. For that we need to keep the reference for the whole
duration of write and wait.
Count the number of superblock writeback errors in the btrfs_device.
That means we don't need the folio to stay around until it's waited for,
and can avoid the extra call to folio_get/put.
Also remove a mention of PageError in a comment as it's the last mention
of the page Error state.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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There are no more users of btrfs_clone_chunk_map(), the last one (and
only one ever) was removed in commit 1ec17ef59168 ("btrfs: zoned: fix
use-after-free in do_zone_finish()"). So remove btrfs_clone_chunk_map().
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>
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git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs updates from David Sterba:
"Mostly stabilization, refactoring and cleanup changes. There rest are
minor performance optimizations due to caching or lock contention
reduction and a few notable fixes.
Performance improvements:
- minor speedup in logging when repeatedly allocated structure is
preallocated only once, improves latency and decreases lock
contention
- minor throughput increase (+6%), reduced lock contention after
clearing delayed allocation bits, applies to several common
workload types
- skip full quota rescan if a new relation is added in the same
transaction
Fixes:
- zstd fix for inline compressed file in subpage mode, updated
version from the 6.8 time
- proper qgroup inheritance ioctl parameter validation
- more fiemap followup fixes after reduced locking done in 6.8:
- fix race when detecting delalloc ranges
Core changes:
- more debugging code:
- added assertions for a very rare crash in raid56 calculation
- tree-checker dumps page state to give more insights into
possible reference counting issues
- add checksum calculation offloading sysfs knob, for now enabled
under DEBUG only to determine a good heuristic for deciding the
offload or synchronous, depends on various factors (block group
profile, device speed) and is not as clear as initially thought
(checksum type)
- error handling improvements, added assertions
- more page to folio conversion (defrag, truncate), cached size and
shift
- preparation for more fine grained locking of sectors in subpage
mode
- cleanups and refactoring:
- include cleanups, forward declarations
- pointer-to-structure helpers
- redundant argument removals
- removed unused code
- slab cache updates, last use of SLAB_MEM_SPREAD removed"
* tag 'for-6.9-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (114 commits)
btrfs: reuse cloned extent buffer during fiemap to avoid re-allocations
btrfs: fix race when detecting delalloc ranges during fiemap
btrfs: fix off-by-one chunk length calculation at contains_pending_extent()
btrfs: qgroup: allow quick inherit if snapshot is created and added to the same parent
btrfs: qgroup: validate btrfs_qgroup_inherit parameter
btrfs: include device major and minor numbers in the device scan notice
btrfs: mark btrfs_put_caching_control() static
btrfs: remove SLAB_MEM_SPREAD flag use
btrfs: qgroup: always free reserved space for extent records
btrfs: tree-checker: dump the page status if hit something wrong
btrfs: compression: remove dead comments in btrfs_compress_heuristic()
btrfs: subpage: make writer lock utilize bitmap
btrfs: subpage: make reader lock utilize bitmap
btrfs: unexport btrfs_subpage_start_writer() and btrfs_subpage_end_and_test_writer()
btrfs: pass a valid extent map cache pointer to __get_extent_map()
btrfs: merge btrfs_del_delalloc_inode() helpers
btrfs: pass btrfs_device to btrfs_scratch_superblocks()
btrfs: handle transaction commit errors in flush_reservations()
btrfs: use KMEM_CACHE() to create btrfs_free_space cache
btrfs: use KMEM_CACHE() to create delayed ref caches
...
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Replace the two parameters bdev and name by one that can be used to get
them both.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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We disable offloading checksum to workqueues and do it synchronously when
the checksum algorithm is fast. However, as reported in the link below,
RAID0 with multiple devices may suffer from the sync checksum, because
"fast checksum" is still not fast enough to catch up with RAID0 writing.
We don't have an effective way to determine whether to offload or not,
for now add a sysfs knob so this can be debugged. This is intentionally
under CONFIG_BTRFS_DEBUG so ti's not exposed to users as it may be
removed in the future agin.
Introduce fs_devices->offload_csum_mode, so that a btrfs developer can
change the behavior by writing to /sys/fs/btrfs/<uuid>/offload_csum. The
default is "auto" which is the same as the previous behavior. Or, you
can set "on" or "off" (or "y" or "n" whatever kstrtobool() accepts) to
always/never offload checksum.
More benchmark need to be collected with this knob to implement a proper
criteria to enable/disable checksum offloading.
Link: https://lore.kernel.org/linux-btrfs/20230731152223.4EFB.409509F4@e16-tech.com/
Link: https://lore.kernel.org/linux-btrfs/p3vo3g7pqn664mhmdhlotu5dzcna6vjtcoc2hb2lsgo2fwct7k@xzaxclba5tae/
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Do a cleanup in the rest of the headers:
- add forward declarations for types referenced by pointers
- add includes when types need them
This fixes potential compilation problems if the headers are reordered
or the missing includes are not provided indirectly.
Signed-off-by: David Sterba <dsterba@suse.com>
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Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-19-adbd023e19cc@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Signed-off-by: David Sterba <dsterba@suse.com>
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Currently we abuse the extent_map structure for two purposes:
1) To actually represent extents for inodes;
2) To represent chunk mappings.
This is odd and has several disadvantages:
1) To create a chunk map, we need to do two memory allocations: one for
an extent_map structure and another one for a map_lookup structure, so
more potential for an allocation failure and more complicated code to
manage and link two structures;
2) For a chunk map we actually only use 3 fields (24 bytes) of the
respective extent map structure: the 'start' field to have the logical
start address of the chunk, the 'len' field to have the chunk's size,
and the 'orig_block_len' field to contain the chunk's stripe size.
Besides wasting a memory, it's also odd and not intuitive at all to
have the stripe size in a field named 'orig_block_len'.
We are also using 'block_len' of the extent_map structure to contain
the chunk size, so we have 2 fields for the same value, 'len' and
'block_len', which is pointless;
3) When an extent map is associated to a chunk mapping, we set the bit
EXTENT_FLAG_FS_MAPPING on its flags and then make its member named
'map_lookup' point to the associated map_lookup structure. This means
that for an extent map associated to an inode extent, we are not using
this 'map_lookup' pointer, so wasting 8 bytes (on a 64 bits platform);
4) Extent maps associated to a chunk mapping are never merged or split so
it's pointless to use the existing extent map infrastructure.
So add a dedicated data structure named 'btrfs_chunk_map' to represent
chunk mappings, this is basically the existing map_lookup structure with
some extra fields:
1) 'start' to contain the chunk logical address;
2) 'chunk_len' to contain the chunk's length;
3) 'stripe_size' for the stripe size;
4) 'rb_node' for insertion into a rb tree;
5) 'refs' for reference counting.
This way we do a single memory allocation for chunk mappings and we don't
waste memory for them with unused/unnecessary fields from an extent_map.
We also save 8 bytes from the extent_map structure by removing the
'map_lookup' pointer, so the size of struct extent_map is reduced from
144 bytes down to 136 bytes, and we can now have 30 extents map per 4K
page instead of 28.
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>
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git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs updates from David Sterba:
"New features:
- raid-stripe-tree
New tree for logical file extent mapping where the physical mapping
may not match on multiple devices. This is now used in zoned mode
to implement RAID0/RAID1* profiles, but can be used in non-zoned
mode as well. The support for RAID56 is in development and will
eventually fix the problems with the current implementation. This
is a backward incompatible feature and has to be enabled at mkfs
time.
- simple quota accounting (squota)
A simplified mode of qgroup that accounts all space on the initial
extent owners (a subvolume), the snapshots are then cheap to create
and delete. The deletion of snapshots in fully accounting qgroups
is a known CPU/IO performance bottleneck.
The squota is not suitable for the general use case but works well
for containers where the original subvolume exists for the whole
time. This is a backward incompatible feature as it needs extending
some structures, but can be enabled on an existing filesystem.
- temporary filesystem fsid (temp_fsid)
The fsid identifies a filesystem and is hard coded in the
structures, which disallows mounting the same fsid found on
different devices.
For a single device filesystem this is not strictly necessary, a
new temporary fsid can be generated on mount e.g. after a device is
cloned. This will be used by Steam Deck for root partition A/B
testing, or can be used for VM root images.
Other user visible changes:
- filesystems with partially finished metadata_uuid conversion cannot
be mounted anymore and the uuid fixup has to be done by btrfs-progs
(btrfstune).
Performance improvements:
- reduce reservations for checksum deletions (with enabled free space
tree by factor of 4), on a sample workload on file with many
extents the deletion time decreased by 12%
- make extent state merges more efficient during insertions, reduce
rb-tree iterations (run time of critical functions reduced by 5%)
Core changes:
- the integrity check functionality has been removed, this was a
debugging feature and removal does not affect other integrity
checks like checksums or tree-checker
- space reservation changes:
- more efficient delayed ref reservations, this avoids building up
too much work or overusing or exhausting the global block
reserve in some situations
- move delayed refs reservation to the transaction start time,
this prevents some ENOSPC corner cases related to exhaustion of
global reserve
- improvements in reducing excessive reservations for block group
items
- adjust overcommit logic in near full situations, account for one
more chunk to eventually allocate metadata chunk, this is mostly
relevant for small filesystems (<10GiB)
- single device filesystems are scanned but not registered (except
seed devices), this allows temp_fsid to work
- qgroup iterations do not need GFP_ATOMIC allocations anymore
- cleanups, refactoring, reduced data structure size, function
parameter simplifications, error handling fixes"
* tag 'for-6.7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (156 commits)
btrfs: open code timespec64 in struct btrfs_inode
btrfs: remove redundant log root tree index assignment during log sync
btrfs: remove redundant initialization of variable dirty in btrfs_update_time()
btrfs: sysfs: show temp_fsid feature
btrfs: disable the device add feature for temp-fsid
btrfs: disable the seed feature for temp-fsid
btrfs: update comment for temp-fsid, fsid, and metadata_uuid
btrfs: remove pointless empty log context list check when syncing log
btrfs: update comment for struct btrfs_inode::lock
btrfs: remove pointless barrier from btrfs_sync_file()
btrfs: add and use helpers for reading and writing last_trans_committed
btrfs: add and use helpers for reading and writing fs_info->generation
btrfs: add and use helpers for reading and writing log_transid
btrfs: add and use helpers for reading and writing last_log_commit
btrfs: support cloned-device mount capability
btrfs: add helper function find_fsid_by_disk
btrfs: stop reserving excessive space for block group item insertions
btrfs: stop reserving excessive space for block group item updates
btrfs: reorder btrfs_inode to fill gaps
btrfs: open code btrfs_ordered_inode_tree in btrfs_inode
...
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Convert btrfs to use bdev_open_by_path() and pass the handle around. We
also drop the holder from struct btrfs_device as it is now not needed
anymore.
CC: David Sterba <dsterba@suse.com>
CC: linux-btrfs@vger.kernel.org
Acked-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230927093442.25915-20-jack@suse.cz
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Update the comment to explain the relationship between temp_fsid, fsid,
and metadata_uuid.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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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.
Example:
$ fallocate -l 300m ./disk1.img
$ mkfs.btrfs -f ./disk1.img
$ cp ./disk1.img ./disk2.img
$ cp ./disk1.img ./disk3.img
$ mount -o loop ./disk1.img /btrfs
$ mount -o ./disk2.img /btrfs1
$ mount -o ./disk3.img /btrfs2
$ 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>
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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>
|
