Boris Burkov [Mon, 14 Jul 2025 23:44:28 +0000 (16:44 -0700)]
btrfs: fix ssd_spread overallocation
If the ssd_spread mount option is enabled, then we run the so called
clustered allocator for data block groups. In practice, this results in
creating a btrfs_free_cluster which caches a block_group and borrows its
free extents for allocation.
Since the introduction of allocation size classes in 6.1, there has been
a bug in the interaction between that feature and ssd_spread.
find_free_extent() has a number of nested loops. The loop going over the
allocation stages, stored in ffe_ctl->loop and managed by
find_free_extent_update_loop(), the loop over the raid levels, and the
loop over all the block_groups in a space_info. The size class feature
relies on the block_group loop to ensure it gets a chance to see a
block_group of a given size class. However, the clustered allocator
uses the cached cluster block_group and breaks that loop. Each call to
do_allocation() will really just go back to the same cached block_group.
Normally, this is OK, as the allocation either succeeds and we don't
want to loop any more or it fails, and we clear the cluster and return
its space to the block_group.
But with size classes, the allocation can succeed, then later fail,
outside of do_allocation() due to size class mismatch. That latter
failure is not properly handled due to the highly complex multi loop
logic. The result is a painful loop where we continue to allocate the
same num_bytes from the cluster in a tight loop until it fails and
releases the cluster and lets us try a new block_group. But by then, we
have skipped great swaths of the available block_groups and are likely
to fail to allocate, looping the outer loop. In pathological cases like
the reproducer below, the cached block_group is often the very last one,
in which case we don't perform this tight bg loop but instead rip
through the ffe stages to LOOP_CHUNK_ALLOC and allocate a chunk, which
is now the last one, and we enter the tight inner loop until an
allocation failure. Then allocation succeeds on the final block_group
and if the next allocation is a size mismatch, the exact same thing
happens again.
Triggering this is as easy as mounting with -o ssd_spread and then
running:
if you do the two writes + sync in a loop, you can force btrfs to spin
an excessive amount on semi-successful clustered allocations, before
ultimately failing and advancing to the stage where we force a chunk
allocation. This results in 2G of data allocated per iteration, despite
only using ~20M of data. By using a small size classed extent, the inner
loop takes longer and we can spin for longer.
The simplest, shortest term fix to unbreak this is to make the clustered
allocator size_class aware in the dumbest way, where it fails on size
class mismatch. This may hinder the operation of the clustered
allocator, but better hindered than completely broken and terribly
overallocating.
Further re-design improvements are also in the works.
Fixes: 52bb7a2166af ("btrfs: introduce size class to block group allocator") CC: stable@vger.kernel.org # 6.1+ Reported-by: David Sterba <dsterba@suse.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Naohiro Aota [Sun, 29 Jun 2025 14:07:42 +0000 (23:07 +0900)]
btrfs: zoned: do not remove unwritten non-data block group
There are some reports of "unable to find chunk map for logical 2147483648
length 16384" error message appears in dmesg. This means some IOs are
occurring after a block group is removed.
When a metadata tree node is cleaned on a zoned setup, we keep that node
still dirty and write it out not to create a write hole. However, this can
make a block group's used bytes == 0 while there is a dirty region left.
Such an unused block group is moved into the unused_bg list and processed
for removal. When the removal succeeds, the block group is removed from the
transaction->dirty_bgs list, so the unused dirty nodes in the block group
are not sent at the transaction commit time. It will be written at some
later time e.g, sync or umount, and causes "unable to find chunk map"
errors.
This can happen relatively easy on SMR whose zone size is 256MB. However,
calling do_zone_finish() on such block group returns -EAGAIN and keep that
block group intact, which is why the issue is hidden until now.
Fixes: afba2bc036b0 ("btrfs: zoned: implement active zone tracking") CC: stable@vger.kernel.org # 6.1+ Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 11 Jul 2025 08:46:16 +0000 (09:46 +0100)]
btrfs: remove btrfs_clear_extent_bits()
It's just a simple wrapper around btrfs_clear_extent_bit() that passes a
NULL for its last argument (a cached extent state record), plus there is
not counter part - we have a btrfs_set_extent_bit() but we do not have a
btrfs_set_extent_bits() (plural version). So just remove it and make all
callers use btrfs_clear_extent_bit() directly.
Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.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, 11 Jul 2025 08:23:09 +0000 (09:23 +0100)]
btrfs: use cached state when falling back from NOCoW write to CoW write
We have a cached extent state record from the previous extent locking so
we can use when setting the EXTENT_NORESERVE in the range, allowing the
operation to be faster if the extent io tree is relatively large.
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 [Tue, 8 Jul 2025 15:32:33 +0000 (16:32 +0100)]
btrfs: set EXTENT_NORESERVE before range unlock in btrfs_truncate_block()
Set the EXTENT_NORESERVE bit in the io tree before unlocking the range so
that we can use the cached state and speedup the operation, since the
unlock operation releases the cached state.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: don't print relocation messages from auto reclaim
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>
Remove the log message before reclaiming a chunk in
btrfs_reclaim_bgs_work(). Especially with automatic block-group
reclaiming these messages spam the kernel log.
Note there is also a tracepoint for the same condition to ease debugging.
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>
Filipe Manana [Wed, 9 Jul 2025 15:34:20 +0000 (16:34 +0100)]
btrfs: make btrfs_check_nocow_lock() check more than one extent
Currently btrfs_check_nocow_lock() stops at the first extent it finds and
that extent may be smaller than the target range we want to NOCOW into.
But we can have multiple consecutive extents which we can NOCOW into, so
by stopping at the first one we find we just make the caller do more work
by splitting the write into multiple ones, or in the case of mmap writes
with large folios we fail with -ENOSPC in case the folio's range is
covered by more than one extent (the fallback to NOCOW for mmap writes in
case there's no available data space to reserve/allocate was recently
added by the patch "btrfs: fix -ENOSPC mmap write failure on NOCOW
files/extents").
Improve on this by checking for multiple consecutive extents.
Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Wed, 9 Jul 2025 15:26:13 +0000 (16:26 +0100)]
btrfs: assert we can NOCOW the range in btrfs_truncate_block()
We call btrfs_check_nocow_lock() to see if we can NOCOW a block sized
range but we don't check later if we can NOCOW the whole range.
It's unexpected to be able to NOCOW a range smaller than blocksize, so
add an assertion to check the NOCOW range matches the blocksize.
Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Wed, 9 Jul 2025 14:03:54 +0000 (15:03 +0100)]
btrfs: update function comment for btrfs_check_nocow_lock()
The documentation for the @nowait parameter is missing, so add it.
The @nowait parameter was added in commit 80f9d24130e4 ("btrfs: make
btrfs_check_nocow_lock nowait compatible"), which forgot to update the
function comment.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 8 Jul 2025 15:28:44 +0000 (16:28 +0100)]
btrfs: use btrfs_inode local variable at btrfs_page_mkwrite()
Most of the time we want to use the btrfs_inode, so change the local inode
variable to be a btrfs_inode instead of a VFS inode, reducing verbosity
by eliminating a lot of BTRFS_I() calls.
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 [Tue, 8 Jul 2025 15:01:19 +0000 (16:01 +0100)]
btrfs: fix -ENOSPC mmap write failure on NOCOW files/extents
If we attempt a mmap write into a NOCOW file or a prealloc extent when
there is no more available data space (or unallocated space to allocate a
new data block group) and we can do a NOCOW write (there are no reflinks
for the target extent or snapshots), we always fail due to -ENOSPC, unlike
for the regular buffered write and direct IO paths where we check that we
can do a NOCOW write in case we can't reserve data space.
touch $MNT/foobar
# Make it a NOCOW file.
chattr +C $MNT/foobar
# Add initial data to file.
xfs_io -c "pwrite -S 0xab 0 1M" $MNT/foobar
# Fill all the remaining data space and unallocated space with data.
dd if=/dev/zero of=$MNT/filler bs=4K &> /dev/null
# Overwrite the file with a mmap write. Should succeed.
xfs_io -c "mmap -w 0 1M" \
-c "mwrite -S 0xcd 0 1M" \
-c "munmap" \
$MNT/foobar
# Unmount, mount again and verify the new data was persisted.
umount $MNT
mount $DEV $MNT
od -A d -t x1 $MNT/foobar
umount $MNT
Running this:
$ ./test.sh
(...)
wrote 1048576/1048576 bytes at offset 0
1 MiB, 256 ops; 0.0008 sec (1.188 GiB/sec and 311435.5231 ops/sec)
./test.sh: line 24: 234865 Bus error xfs_io -c "mmap -w 0 1M" -c "mwrite -S 0xcd 0 1M" -c "munmap" $MNT/foobar 0000000 ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab
* 1048576
Fix this by not failing in case we can't allocate data space and we can
NOCOW into the target extent - reserving only metadata space in this case.
After this change the test passes:
$ ./test.sh
(...)
wrote 1048576/1048576 bytes at offset 0
1 MiB, 256 ops; 0.0007 sec (1.262 GiB/sec and 330749.3540 ops/sec) 0000000 cd cd cd cd cd cd cd cd cd cd cd cd cd cd cd cd
* 1048576
A test case for fstests will be added soon.
Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Tue, 1 Jul 2025 17:23:54 +0000 (19:23 +0200)]
btrfs: accessors: factor out split memcpy with two sources
The case of a reading the bytes from 2 folios needs two memcpy()s, the
compiler does not emit calls but two inline loops.
Factoring out the code makes some improvement (stack, code) and in the
future will provide an optimized implementation as well. (The analogical
version with two destinations is not done as it increases stack usage
but can be done if needed.)
The address of the second folio is reordered before the first memcpy,
which leads to an optimization reusing the vmemmap_base and
page_offset_base (implementing folio_address()).
David Sterba [Tue, 1 Jul 2025 17:23:53 +0000 (19:23 +0200)]
btrfs: accessors: set target address at initialization
The target address for the read/write can be simplified as it's the same
expression for the first folio. This improves the generated code as the
folio address does not have to be cached on stack.
David Sterba [Tue, 1 Jul 2025 17:23:52 +0000 (19:23 +0200)]
btrfs: accessors: compile-time fast path for u16
Reading/writing 2 bytes (u16) may need 2 folios to be written to, each
time it's just one byte so using memcpy for that is an overkill.
Add a branch for the split case so that memcpy is now used for u32 and
u64. Another side effect is that the u16 types now don't need additional
stack space, everything fits to registers.
David Sterba [Tue, 1 Jul 2025 17:23:51 +0000 (19:23 +0200)]
btrfs: accessors: compile-time fast path for u8
Reading/writing 1 byte (u8) is a special case compared to the others as
it's always contained in the folio we find, so the split memcpy will
never be needed. Turn it to a compile-time check that the memcpy part
can be optimized out.
David Sterba [Tue, 1 Jul 2025 17:23:50 +0000 (19:23 +0200)]
btrfs: accessors: inline eb bounds check and factor out the error report
There's a check in each set/get helper if the requested range is within
extent buffer bounds, and if it's not then report it. This was in an
ASSERT statement so with CONFIG_BTRFS_ASSERT this crashes right away, on
other configs this is only reported but reading out of the bounds is
done anyway. There are currently no known reports of this particular
condition failing.
There are some drawbacks though. The behaviour dependence on the
assertions being compiled in or not and a less visible effect of
inlining report_setget_bounds() into each helper.
As the bounds check is expected to succeed almost always it's ok to
inline it but make the report a function and move it out of the helper
completely (__cold puts it to a different section). This also skips
reading/writing the requested range in case it fails.
David Sterba [Tue, 1 Jul 2025 17:23:49 +0000 (19:23 +0200)]
btrfs: accessors: use type sizeof constants directly
Now unit_size is used only once, so use it directly in 'part'
calculation. Don't cache sizeof(type) in a variable. While this is a
compile-time constant, forcing the type 'int' generates worse code as it
leads to additional conversion from 32 to 64 bit type on x86_64.
The sizeof() is used only a few times and it does not make the code that
harder to read, so use it directly and let the compiler utilize the
immediate constants in the context it needs. The .ko code size slightly
increases (+50) but further patches will reduce that again.
Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Tue, 1 Jul 2025 17:23:48 +0000 (19:23 +0200)]
btrfs: accessors: simplify folio bounds checks
As we can a have non-contiguous range in the eb->folios, any item can be
straddling two folios and we need to check if it can be read in one go
or in two parts. For that there's a check which is not implemented in
the simplest way:
this can be simplified and reusing existing run-time or compile-time
constants.
Add likely() annotation for this expression as this is the fast path and
compiler sometimes reorders that after the followup block with the
memcpy (observed in practice with other simplifications).
David Sterba [Wed, 25 Jun 2025 13:37:19 +0000 (15:37 +0200)]
btrfs: open code RCU for device name
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>
Daniel Vacek [Fri, 4 Jul 2025 16:07:02 +0000 (18:07 +0200)]
btrfs: index buffer_tree using node size
So far we've been deriving the buffer tree index using the sector size.
But each extent buffer covers multiple sectors. This makes the buffer
tree rather sparse.
For example the typical and quite common configuration uses sector size
of 4KiB and node size of 16KiB. In this case it means the buffer tree is
using up to the maximum of 25% of it's slots. Or in other words at least
75% of the tree slots are wasted as never used.
We can score significant memory savings on the required tree nodes by
indexing the tree using the node size instead. As a result far less
slots are wasted and the tree can now use up to all 100% of it's slots
this way.
Note: This works even with unaligned tree blocks as we can still get
unique index by doing eb->start >> nodesize_shift.
Getting some stats from running fio write test, there is a bit of
variance. The values presented in the table below are medians from 5
test runs. The numbers are:
- # of allocated ebs in the tree
- # of leaf tree nodes
- highest index in the tree (radix tree width)):
ebs / leaves / Index | bare for-next | with fix
---------------------+--------------------+-------------------
post mount | 16 / 11 / 10e5c | 16 / 10 / 4240
post test | 5810 / 891 / 11cfc | 4420 / 252 / 473a
post rm | 574 / 300 / 10ef0 | 540 / 163 / 46e9
In this case (10GiB filesystem) the height of the tree is still 3 levels
but the 4x width reduction is clearly visible as expected. But since the
tree is more dense we can see the 54-72% reduction of leaf nodes. That's
very close to ideal with this test. It means the tree is getting really
dense with this kind of workload.
Also, the fio results show no performance change.
Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Daniel Vacek <neelx@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Wed, 26 Feb 2025 16:18:25 +0000 (16:18 +0000)]
btrfs: send: directly return strcmp() result when comparing recorded refs
There's no point in converting the return values from strcmp() as all we
need is that it returns a negative value if the first argument is less
than the second, a positive value if it's greater and 0 if equal. We do
not have a need for -1 instead of any other negative value and no need
for 1 instead of any other positive value - that's all that rb_find()
needs and no where else we need specific negative and positive values.
So remove the intermediate local variable and checks and return directly
the result from strcmp().
This also reduces the module's text size.
Before:
$ size fs/btrfs/btrfs.ko
text data bss dec hex filename 1888116 161347 16136 2065599 1f84bf fs/btrfs/btrfs.ko
After:
$ size fs/btrfs/btrfs.ko
text data bss dec hex filename 1888052 161347 16136 2065535 1f847f fs/btrfs/btrfs.ko
Reviewed-by: Boris Burkov <boris@bur.io> 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 [Tue, 1 Jul 2025 21:45:47 +0000 (22:45 +0100)]
btrfs: set search_commit_root to false in iterate_inodes_from_logical()
There's no point in checking at iterate_inodes_from_logical() if the path
has search_commit_root set, the only caller never sets search_commit_root
to true and it doesn't make sense for it ever to be true for the current
use case (logical_to_ino ioctl). So stop checking for that and since the
only caller allocates the path just for it to be used by
iterate_inodes_from_logical(), move the path allocation into that function.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 1 Jul 2025 22:01:56 +0000 (23:01 +0100)]
btrfs: reduce size of struct tree_mod_elem
Several members are used for specific types of tree mod log operations so
they can be placed in a union in order to reduce the structure's size.
This reduces the structure size from 112 bytes to 88 bytes on x86_64,
so we can now use the kmalloc-96 slab instead of the kmalloc-128 slab.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 1 Jul 2025 21:20:19 +0000 (22:20 +0100)]
btrfs: avoid logging tree mod log elements for irrelevant extent buffers
We are logging tree mod log operations for extent buffers from any tree
but we only need to log for the extent tree and subvolume tree, since
the tree mod log is used to get a consistent view, within a transaction,
of extents and their backrefs. So it's pointless to log operations for
trees such as the csum tree, free space tree, root tree, chunk tree,
log trees, data relocation tree, etc, as these trees are not used for
backref walking and all tree mod log users are about backref walking.
So skip extent buffers that don't belong neither to the extent nor to
subvolume trees. This avoids unnecessary memory allocations and having a
larger tree mod log rbtree with nodes that are never needed.
Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Boris Burkov [Thu, 5 Jun 2025 00:46:58 +0000 (17:46 -0700)]
btrfs: use readahead_expand() on compressed extents
We recently received a report of poor performance doing sequential
buffered reads of a file with compressed extents. With bs=128k, a naive
sequential dd ran as fast on a compressed file as on an uncompressed
(1.2GB/s on my reproducing system) while with bs<32k, this performance
tanked down to ~300MB/s.
The cause of this slowness is overhead to do with looking up extent_maps
to enable readahead pre-caching on compressed extents
(add_ra_bio_pages()), as well as some overhead in the generic VFS
readahead code we hit more in the slow case. Notably, the main
difference between the two read sizes is that in the large sized request
case, we call btrfs_readahead() relatively rarely while in the smaller
request we call it for every compressed extent. So the fast case stays
in the btrfs readahead loop:
while ((folio = readahead_folio(rac)) != NULL)
btrfs_do_readpage(folio, &em_cached, &bio_ctrl, &prev_em_start);
where the slower one breaks out of that loop every time. This results in
calling add_ra_bio_pages a lot, doing lots of extent_map lookups,
extent_map locking, etc.
This happens because although add_ra_bio_pages() does add the
appropriate un-compressed file pages to the cache, it does not
communicate back to the ractl in any way. To solve this, we should be
using readahead_expand() to signal to readahead to expand the readahead
window.
This change passes the readahead_control into the btrfs_bio_ctrl and in
the case of compressed reads sets the expansion to the size of the
extent_map we already looked up anyway. It skips the subpage case as
that one already doesn't do add_ra_bio_pages().
With this change, whether we use bs=4k or bs=128k, btrfs expands the
readahead window up to the largest compressed extent we have seen so far
(in the trivial example: 128k) and the call stacks of the two modes look
identical. Notably, we barely call add_ra_bio_pages at all. And the
performance becomes identical as well. So this change certainly "fixes"
this performance problem.
Of course, it does seem to beg a few questions:
1. Will this waste too much page cache with a too large ra window?
2. Will this somehow cause bugs prevented by the more thoughtful
checking in add_ra_bio_pages?
3. Should we delete add_ra_bio_pages?
My stabs at some answers:
1. Hard to say. See attempts at generic performance testing below. Is
there a "readahead_shrink" we should be using? Should we expand more
slowly, by half the remaining em size each time?
2. I don't think so. Since the new behavior is indistinguishable from
reading the file with a larger read size passed in, I don't see why
one would be safe but not the other.
3. Probably! I tested that and it was fine in fstests, and it seems like
the pages would get re-used just as well in the readahead case.
However, it is possible some reads that use page cache but not
btrfs_readahead() could suffer. I will investigate this further as a
follow up.
I tested the performance implications of this change in 3 ways (using
compress-force=zstd:3 for compression):
Directly test the affected workload of small sequential reads on a
compressed file (improved from ~250MB/s to ~1.2GB/s)
==========for-next==========
dd /mnt/lol/non-cmpr 4k 1048576+0 records in 1048576+0 records out 4294967296 bytes (4.3 GB, 4.0 GiB) copied, 6.02983 s, 712 MB/s
dd /mnt/lol/non-cmpr 128k
32768+0 records in
32768+0 records out 4294967296 bytes (4.3 GB, 4.0 GiB) copied, 5.92403 s, 725 MB/s
dd /mnt/lol/cmpr 4k 1048576+0 records in 1048576+0 records out 4294967296 bytes (4.3 GB, 4.0 GiB) copied, 17.8832 s, 240 MB/s
dd /mnt/lol/cmpr 128k
32768+0 records in
32768+0 records out 4294967296 bytes (4.3 GB, 4.0 GiB) copied, 3.71001 s, 1.2 GB/s
==========ra-expand==========
dd /mnt/lol/non-cmpr 4k 1048576+0 records in 1048576+0 records out 4294967296 bytes (4.3 GB, 4.0 GiB) copied, 6.09001 s, 705 MB/s
dd /mnt/lol/non-cmpr 128k
32768+0 records in
32768+0 records out 4294967296 bytes (4.3 GB, 4.0 GiB) copied, 6.07664 s, 707 MB/s
dd /mnt/lol/cmpr 4k 1048576+0 records in 1048576+0 records out 4294967296 bytes (4.3 GB, 4.0 GiB) copied, 3.79531 s, 1.1 GB/s
dd /mnt/lol/cmpr 128k
32768+0 records in
32768+0 records out 4294967296 bytes (4.3 GB, 4.0 GiB) copied, 3.69533 s, 1.2 GB/s
Built the linux kernel from clean (no change)
Ran fsperf. Mostly neutral results with some improvements and
regressions here and there.
[TEST FAILURE WITH EXPERIMENTAL FEATURES]
When running test case generic/508, the test case will fail with the new
btrfs shutdown support:
generic/508 - output mismatch (see /home/adam/xfstests/results//generic/508.out.bad)
--- tests/generic/508.out 2022-05-11 11:25:30.806666664 +0930
+++ /home/adam/xfstests/results//generic/508.out.bad 2025-07-02 14:53:22.401824212 +0930
@@ -1,2 +1,6 @@
QA output created by 508
Silence is golden
+Before:
+After : stat.btime = Thu Jan 1 09:30:00 1970
+Before:
+After : stat.btime = Wed Jul 2 14:53:22 2025
...
(Run 'diff -u /home/adam/xfstests/tests/generic/508.out /home/adam/xfstests/results//generic/508.out.bad' to see the entire diff)
Ran: generic/508
Failures: generic/508
Failed 1 of 1 tests
Please note that the test case requires shutdown support, thus the test
case will be skipped using the current upstream kernel, as it doesn't
have shutdown ioctl support.
[CAUSE]
The direct cause the 0 time stamp in the log tree:
Filipe Manana [Tue, 1 Jul 2025 14:25:14 +0000 (15:25 +0100)]
btrfs: qgroup: use btrfs_qgroup_enabled() in ioctls
We have a publicly exported btrfs_qgroup_enabled() and an ioctl.c private
qgroup_enabled() helper. Both of these test if qgroups are enabled, the
first check if the flag BTRFS_FS_QUOTA_ENABLED is set in fs_info->flags
while the second checks if fs_info->quota_root is not NULL while holding
the mutex fs_info->qgroup_ioctl_lock.
We can get away with the private ioctl.c:qgroup_enabled(), as all entry
points into the qgroup code check if fs_info->quota_root is NULL or not
while holding the mutex fs_info->qgroup_ioctl_lock, and returning the
error -ENOTCONN in case it's NULL.
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>
When quotas are disabled qgroup ioctls are supposed to return -ENOTCONN,
but the qgroup create ioctl stopped doing that when it races with a quota
disable operation, returning 0 instead. This change of behaviour happened
in commit 6ed05643ddb1 ("btrfs: create qgroup earlier in snapshot
creation").
The issue happens as follows:
1) Task A enters btrfs_ioctl_qgroup_create(), qgroups are enabled and so
qgroup_enabled() returns true since fs_info->quota_root is not NULL;
2) Task B enters btrfs_ioctl_quota_ctl() -> btrfs_quota_disable() and
disables qgroups, so now fs_info->quota_root is NULL;
3) Task A enters btrfs_create_qgroup() and calls btrfs_qgroup_mode(),
which returns BTRFS_QGROUP_MODE_DISABLED since quotas are disabled,
and then btrfs_create_qgroup() returns 0 to the caller, which makes
the ioctl return 0 instead of -ENOTCONN.
The check for fs_info->quota_root and returning -ENOTCONN if it's NULL
is made only after the call btrfs_qgroup_mode().
Fix this by moving the check for disabled quotas with btrfs_qgroup_mode()
into transaction.c:create_pending_snapshot(), so that we don't abort the
transaction if btrfs_create_qgroup() returns -ENOTCONN and quotas are
disabled.
Fixes: 6ed05643ddb1 ("btrfs: create qgroup earlier in snapshot creation") CC: stable@vger.kernel.org # 6.12+ 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 [Tue, 1 Jul 2025 10:39:44 +0000 (11:39 +0100)]
btrfs: qgroup: set quota enabled bit if quota disable fails flushing reservations
Before waiting for the rescan worker to finish and flushing reservations,
we clear the BTRFS_FS_QUOTA_ENABLED flag from fs_info. If we fail flushing
reservations we leave with the flag not set which is not correct since
quotas are still enabled - we must set back the flag on error paths, such
as when we fail to start a transaction, except for error paths that abort
a transaction. The reservation flushing happens very early before we do
any operation that actually disables quotas and before we start a
transaction, so set back BTRFS_FS_QUOTA_ENABLED if it fails.
Fixes: af0e2aab3b70 ("btrfs: qgroup: flush reservations during quota disable") CC: stable@vger.kernel.org # 6.12+ 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>
[FLAG EXCLUSION]
Commit ead622674df5 ("btrfs: Do not restrict writes to btrfs devices")
removes the BLK_OPEN_RESTRICT_WRITES flag when opening the devices
during mount. This was an exception at the time as it depended on other
patches.
[REASON TO EXCLUDE THAT FLAG]
Btrfs needs to call btrfs_scan_one_device() to determine the fsid, no
matter if we're mounting a new fs or an existing one.
But if a fs is already mounted and the BLK_OPEN_RESTRICT_WRITES is
honored, meaning no other write open is allowed for the block device.
Then we want to mount a subvolume of the mounted fs to another mount
point, we will call btrfs_scan_one_device() again, but it will fail due
to the BLK_OPEN_RESTRICT_WRITES flag (no more write open allowed),
causing only one mount point for the fs.
Thus at that time, we had to exclude the BLK_OPEN_RESTRICT_WRITES to
allow multiple mount points for one fs.
[WHY IT'S SAFE NOW]
The root problem is, we do not need to nor should use BLK_OPEN_WRITE for
btrfs_scan_one_device().
That function is only to read out the super block, no write at all, and
BLK_OPEN_WRITE is only going to cause problems for such usage.
The root problem has been fixed by patch "btrfs: always open the device
read-only in btrfs_scan_one_device", so btrfs_scan_one_device() will
always work no matter if the device is opened with
BLK_OPEN_RESTRICT_WRITES.
[ENHANCEMENT]
Just remove the btrfs_open_mode(), as the only call site can be replaced
with regular sb_open_mode().
Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Thu, 19 Jun 2025 07:18:44 +0000 (16:48 +0930)]
btrfs: use fs_holder_ops for all opened devices
Since we have btrfs_fs_info::sb (struct super_block) as our block device
holder, we can safely use fs_holder_ops for all of our block devices.
This enables freezing/thawing the filesystem from the underlying block
devices.
This may enhance hibernation/suspend support since previously
freezing/thawing a block device managed by btrfs won't do anything btrfs
specific, but only syncing the block device.
Thus before this change, freezing the underlying block devices won't
prevent future writes into the filesystem, thus may cause problems for
hibernation/suspend when btrfs is involved.
Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: use the super_block as holder when mounting file systems
The file system type is not a very useful holder as it doesn't allow us
to go back to the actual file system instance. Pass the super_block
instead which is useful when passed back to the file system driver.
This matches what is done for all other block device based file systems,
and allows us to remove btrfs_fs_info::bdev_holder completely.
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Mon, 16 Jun 2025 22:11:14 +0000 (07:41 +0930)]
btrfs: delay btrfs_open_devices() until super block is created
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>
Although btrfs is not yet implementing blk_holder_ops, there is a
requirement for proper blk_holder_ops:
- blkdev_put() must not be called under sb->s_umount
The blkdev_put()/bdev_fput() must not be called under sb->s_umount to
avoid lock order reversal with disk->open_mutex.
This is for the proper blk_holder_ops callbacks.
Currently we're fine because we call regular fput() which defers the
blk holder reclaiming.
To prepare for the future of blk_holder_ops, move the
btrfs_close_devices() calls into btrfs_free_fs_info().
That will be called from kill_sb() callbacks, which is also called for
error handing during mount failures, or there is already an existing
super block.
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Sun, 15 Jun 2025 22:44:25 +0000 (08:14 +0930)]
btrfs: add assertions to make super block creation more clear
When calling sget_fc(), there are 3 different situations:
a) Critical error
No super block created.
b) A new super block is created
The fc->s_fs_info is transferred to the super block, and fc->s_fs_info
is reset to NULL.
In this case sb->s_root should still be NULL, and needs to be properly
initialized later by btrfs_fill_super().
c) An existing super block is returned
The fc->s_fs_info is untouched, and anything related to that fs_info
should be properly cleaned up.
This is not obvious even with the extra comments at sget_fc().
Enhance the situation by:
- Add comments for case b) and c)
Especially for case c), the fs_info and fs_devices cleanup happens at
different timing, thus needs extra explanation.
- Move the comments closer to case b) and case c)
Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Thu, 12 Jun 2025 05:44:35 +0000 (15:14 +0930)]
btrfs: get rid of re-entering of btrfs_get_tree()
[EXISTING PROBLEM]
Currently btrfs mount is split into two parts:
- btrfs_get_tree_subvol()
Which sets up the very basic fs_info, and eventually calls
mount_subvol() to mount the target subvolume.
- btrfs_get_tree_super()
This is the part doing super block allocation and if there is no
existing super block, do the real open_ctree() to open the fs.
However currently we're doing this in a complex re-entering way:
In our case, super_wake() can be skipped, as after
btrfs_get_tree_subvol() finishes, vfs_get_tree() will call super_wake()
on the super block we got anyway.
The same applies to security_sb_set_mnt_opts(), as long as we do not
free the security from our original fc in btrfs_get_tree_subvol(), the
first vfs_get_tree() call will handle the security correctly.
So here we only need to:
- Replace vfs_get_tree() call with btrfs_get_tree_super()
- Keep the existing fc->security for vfs_get_tree() to handle the
security
This will remove the re-entering behavior and make thing much easier to
follow.
Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: always open the device read-only in btrfs_scan_one_device()
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>
btrfs: don't skip accounting in early ENOTTY return in btrfs_uring_encoded_read()
btrfs_uring_encoded_read() returns early with -ENOTTY if the uring_cmd
is issued with IO_URING_F_COMPAT but the kernel doesn't support compat
syscalls. However, this early return bypasses the syscall accounting.
Go to out_acct instead to ensure the syscall is counted.
Fixes: 34310c442e17 ("btrfs: add io_uring command for encoded reads (ENCODED_READ ioctl)") CC: stable@vger.kernel.org # 6.15+ Signed-off-by: Caleb Sander Mateos <csander@purestorage.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Thu, 26 Jun 2025 14:30:10 +0000 (16:30 +0200)]
btrfs: pass dentry to btrfs_mksubvol() and btrfs_mksnapshot()
There's no reason to pass 'struct path' to btrfs_mksubvol(), though it's
been like the since the first commit 76dda93c6ae2c1 ("Btrfs: add
snapshot/subvolume destroy ioctl"). We only use the dentry so we should
pass it directly.
Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Thu, 26 Jun 2025 14:30:09 +0000 (16:30 +0200)]
btrfs: use struct qstr for subvolume ioctl helpers
We pass name and length of subvolumes separately to the related
functions, while this can be a struct qstr which is otherwise used for
dentry interfaces.
Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
Brahmajit Das [Fri, 20 Jun 2025 16:49:57 +0000 (22:19 +0530)]
btrfs: replace strcpy() with strscpy()
strcpy() is discouraged from use due to lack of bounds checking.
Replaces it with strscpy(), the recommended alternative for null
terminated strings, to follow best practices.
There are instances where strscpy() cannot be used such as where both
the source and destination are character pointers. In that instance we
can use sysfs_emit().
Link: https://github.com/KSPP/linux/issues/88 Suggested-by: Anthony Iliopoulos <ailiop@suse.com> Signed-off-by: Brahmajit Das <bdas@suse.de> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Fri, 27 Jun 2025 14:03:53 +0000 (16:03 +0200)]
btrfs: accessors: delete token versions of set/get helpers
Once upon a time there was a need to cache address of extent buffer
pages, as it was a costly operation (map_private_extent_buffer(), cfed81a04eb555 ("Btrfs: add the ability to cache a pointer into the
eb")). This was not even due to use of HIGHMEM, this had been removed
before that due to possible locking issues (a65917156e3459 ("Btrfs:
stop using highmem for extent_buffers")).
Over time the amount of work in the set/get helpers got reduced and
became quite straightforward bounds checking with an unaligned
read/write, commit db3756c879773c ("btrfs: remove unused
map_private_extent_buffer").
The actual caching of the page_address()/folio_address() in the token
was more work for very little gain. This depended on subsequent access
into the same page/folio, otherwise the cached pointer had to be
updated.
For metadata-heavy operations this showed up in the 'perf top' profile
where the btrfs_get_token_32() calls were at the top, on my testing
machine consuming about 2-3%. The other generic 32/64 bit helpers also
appeared in the profile with similar fraction.
After removing use of the token helpers we can remove them completely,
this leads to reduction of btrfs.ko by 6.7KiB on release config.
text data bss dec hex filename 1463289 115665 16088 1595042 1856a2 pre/btrfs.ko 1456601 115665 16088 1588354 183c82 post/btrfs.ko
DELTA: -6688
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Fri, 27 Jun 2025 14:03:52 +0000 (16:03 +0200)]
btrfs: tree-log: don't use token set/get accessors in fill_inode_item()
The token versions of set/get accessors will be removed, use the normal
helpers.
There's additional overhead of the token helpers that update the cached
address in case it moves to another page/folio. The normal versions
don't need to do that.
Note this is similar to fill_inode_item() in inode.c but with slight
differences. The two functions could be deduplicated eventually.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Fri, 27 Jun 2025 14:03:51 +0000 (16:03 +0200)]
btrfs: don't use token set/get accessors in inode.c:fill_inode_item()
The token versions of set/get accessors will be removed, use the normal
helpers.
There's additional overhead of the token helpers that update the cached
address in case it moves to another page/folio. The normal versions
don't need to do that.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Fri, 27 Jun 2025 14:03:50 +0000 (16:03 +0200)]
btrfs: don't use token set/get accessors for btrfs_item members
The token versions of set/get accessors will be removed, use the normal
helpers. The btrfs_item members use that interface the most but there
are no real benefits anymore.
This reduces stack consumption on x86_64 release config:
Filipe Manana [Mon, 30 Jun 2025 12:30:44 +0000 (13:30 +0100)]
btrfs: qgroup: remove no longer used fs_info->qgroup_ulist
It's not used anymore after commit 091344508249 ("btrfs: qgroup: use
qgroup_iterator in qgroup_convert_meta()"), so remove it.
Reviewed-by: Boris Burkov <boris@bur.io> 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 [Mon, 30 Jun 2025 12:19:20 +0000 (13:19 +0100)]
btrfs: qgroup: fix race between quota disable and quota rescan ioctl
There's a race between a task disabling quotas and another running the
rescan ioctl that can result in a use-after-free of qgroup records from
the fs_info->qgroup_tree rbtree.
This happens as follows:
1) Task A enters btrfs_ioctl_quota_rescan() -> btrfs_qgroup_rescan();
2) Task B enters btrfs_quota_disable() and calls
btrfs_qgroup_wait_for_completion(), which does nothing because at that
point fs_info->qgroup_rescan_running is false (it wasn't set yet by
task A);
3) Task B calls btrfs_free_qgroup_config() which starts freeing qgroups
from fs_info->qgroup_tree without taking the lock fs_info->qgroup_lock;
4) Task A enters qgroup_rescan_zero_tracking() which starts iterating
the fs_info->qgroup_tree tree while holding fs_info->qgroup_lock,
but task B is freeing qgroup records from that tree without holding
the lock, resulting in a use-after-free.
Fix this by taking fs_info->qgroup_lock at btrfs_free_qgroup_config().
Also at btrfs_qgroup_rescan() don't start the rescan worker if quotas
were already disabled.
Filipe Manana [Mon, 30 Jun 2025 09:50:46 +0000 (10:50 +0100)]
btrfs: clear dirty status from extent buffer on error at insert_new_root()
If we failed to insert the tree mod log operation, we are not removing the
dirty status from the allocated and dirtied extent buffer before we free
it. Removing the dirty status is needed for several reasons such as to
adjust the fs_info->dirty_metadata_bytes counter and remove the dirty
status from the respective folios. So add the missing call to
btrfs_clear_buffer_dirty().
Fixes: f61aa7ba08ab ("btrfs: do not BUG_ON() on tree mod log failure at insert_new_root()") CC: stable@vger.kernel.org # 6.6+ Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
btrfs: change dump_block_groups() in btrfs_dump_space_info() from int to bool
btrfs_dump_space_info()'s parameter dump_block_groups is used as a boolean
although it is defined as an integer.
Change it from int to bool.
Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Daniel Vacek <neelx@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>
David Sterba [Fri, 27 Jun 2025 11:01:17 +0000 (13:01 +0200)]
btrfs: use pgoff_t for page index variables
Any conversion of offsets in the logical or the physical mapping space
of the pages is done by a shift and the target type should be pgoff_t
(type of struct page::index). Fix the locations where it's still
unsigned long.
George Hu [Sat, 28 Jun 2025 05:21:30 +0000 (13:21 +0800)]
btrfs: replace nested usage of min & max with clamp in btrfs_compress_set_level()
Refactor the btrfs_compress_set_level() function by replacing the
nested usage of min() and max() macro with clamp() to simplify the
code and improve readability.
Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: George Hu <integral@archlinux.org> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Dmitry Antipov [Fri, 27 Jun 2025 08:51:17 +0000 (11:51 +0300)]
btrfs: send: avoid extra calls to strlen() in gen_unique_name()
Since 'snprintf()' returns the number of characters which would
be emitted and output truncation is handled by 'ASSERT()', it
should be safe to use that return value instead of the subsequent
calls to 'strlen()' in 'gen_unique_name()'.
This also reduces the module's text size.
Before:
$ size fs/btrfs/btrfs.ko
text data bss dec hex filename 1897006 161571 16136 2074713 1fa859 fs/btrfs/btrfs.ko
After:
$ size fs/btrfs/btrfs.ko
text data bss dec hex filename 1896848 161571 16136 2074555 1fa7bb fs/btrfs/btrfs.ko
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru> Reviewed-by: Filipe Manana <fdmanana@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 [Thu, 26 Jun 2025 15:57:02 +0000 (16:57 +0100)]
btrfs: qgroup: avoid memory allocation if qgroups are not enabled
At btrfs_qgroup_inherit() we allocate a qgroup record even if qgroups are
not enabled, which is unnecessary overhead and can result in subvolume
creation to fail with -ENOMEM, as create_subvol() calls this function.
Improve on this by making btrfs_qgroup_inherit() check if qgroups are
enabled earlier and return if they are not, avoiding the unnecessary
memory allocation and taking some locks.
Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.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 [Wed, 25 Jun 2025 15:16:05 +0000 (16:16 +0100)]
btrfs: qgroup: remove pointless error check for add_qgroup_rb() call
The add_qgroup_rb() function never returns an error pointer anymore since
commit 8d54518b5e52 ("btrfs: qgroup: pre-allocate btrfs_qgroup to reduce
GFP_ATOMIC usage"), so checking for an error pointer result at
btrfs_quota_enable() is pointless.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> 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 [Mon, 23 Jun 2025 12:15:58 +0000 (13:15 +0100)]
btrfs: split btrfs_is_fstree() into multiple if statements for readability
Instead of a single if statement with multiple conditions, split it into
several if statements testing only one condition at a time and return true
or false immediately after. This makes it more immediate to reason.
The module's text size also slightly decreases, at least with gcc 14.2.0
on x86_64.
Before:
$ size fs/btrfs/btrfs.ko
text data bss dec hex filename 1897138 161583 16136 2074857 1fa8e9 fs/btrfs/btrfs.ko
After:
$ size fs/btrfs/btrfs.ko
text data bss dec hex filename 1896976 161583 16136 2074695 1fa847 fs/btrfs/btrfs.ko
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> 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 [Mon, 23 Jun 2025 12:13:23 +0000 (13:13 +0100)]
btrfs: add btrfs prefix to is_fstree() and make it return bool
This is an exported function and therefore it should have a 'btrfs_'
prefix, to make it clear it's btrfs specific, avoid future name collisions
with code outside btrfs, and make its naming consistent with most other
btrfs exported functions.
So add a 'btrfs_' prefix to it and make it return bool instead of int,
since all we need is to return true or false.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> 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 [Mon, 23 Jun 2025 11:54:40 +0000 (12:54 +0100)]
btrfs: split inode extref processing from __add_inode_ref() into a helper
The __add_inode_ref() function is quite big and with too much nesting, so
move the code that processes inode extrefs into a helper function, to make
the function easier to read and reduce the level of indentation too.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> 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 [Mon, 23 Jun 2025 10:22:48 +0000 (11:22 +0100)]
btrfs: split inode ref processing from __add_inode_ref() into a helper
The __add_inode_ref() function is quite big and with too much nesting, so
move the code that processes inode refs into a helper function, to make
the function easier to read and reduce the level of indentation too.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> 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, 20 Jun 2025 15:58:48 +0000 (16:58 +0100)]
btrfs: use btrfs inodes in btrfs_rmdir() to avoid so much usage of BTRFS_I()
Almost everywhere we want to use a btrfs inode and therefore we have a
lot of calls to BTRFS_I(), making the code more verbose. Instead use btrfs
inode local variables to avoid so much use of BTRFS_I().
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> 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, 20 Jun 2025 15:50:31 +0000 (16:50 +0100)]
btrfs: use inode already stored in local variable at btrfs_rmdir()
There's no need to call d_inode(dentry) when calling btrfs_unlink_inode()
since we have already stored that in a local inode variable. So just use
the local variable to make the code less verbose.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> 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>
David Sterba [Fri, 20 Jun 2025 16:06:45 +0000 (18:06 +0200)]
btrfs: use our message helpers instead of pr_err/pr_warn/pr_info
Our message helpers accept NULL for the fs_info in the context that does
not provide and print the common header of the message. The use of pr_*
helpers is only for special reasons, like module loading, device
scanning or multi-line output (print-tree).
Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Sun YangKai [Thu, 12 Jun 2025 08:32:23 +0000 (16:32 +0800)]
btrfs: remove partial support for lowest level from btrfs_search_forward()
Commit 323ac95bce44 ("Btrfs: don't read leaf blocks containing only
checksums during truncate") changed the condition from `level == 0` to
`level == path->lowest_level`, while its original purpose was just to do
some leaf node handling (calling btrfs_item_key_to_cpu()) and skip some
code that doesn't fit leaf nodes.
After changing the condition, the code path:
1. Also handles the non-leaf nodes when path->lowest_level is nonzero,
which is wrong. However btrfs_search_forward() is never called with a
nonzero path->lowest_level, which makes this bug not found before.
2. Makes the later if block with the same condition, which was originally
used to handle non-leaf node (calling btrfs_node_key_to_cpu()) when
lowest_level is not zero, dead code.
Since btrfs_search_forward() is never called for a path with a
lowest_level different from zero, just completely remove the partial
support for a non-zero lowest_level, simplifying a bit the code, and
assert that lowest_level is zero at the start of the function.
Suggested-by: Qu Wenruo <wqu@suse.com> Fixes: 323ac95bce44 ("Btrfs: don't read leaf blocks containing only checksums during truncate") Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Sun YangKai <sunk67188@gmail.com> Signed-off-by: David Sterba <dsterba@suse.com>
Sun YangKai [Sat, 14 Jun 2025 03:39:06 +0000 (11:39 +0800)]
btrfs: remove unused parameters from btrfs_lookup_inode_extref()
The function btrfs_lookup_inode_extref(` no longer requires transaction
handle, insert length, or COW flag, as the only caller now performs a
read-only lookup using trans == NULL, ins_len == 0 and cow == 0.
This function was introduced in the early days where extref feature was
introduced by commit f186373fef00 ("btrfs: extended inode refs").
Then some cleanup was done in commit 33b98f227111 ("btrfs: cleanup:
removed unused 'btrfs_get_inode_ref_index'"), which removed the only
caller passing trans and other COW specific options.
Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Sun YangKai <sunk67188@gmail.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Thu, 12 Jun 2025 16:19:05 +0000 (17:19 +0100)]
btrfs: cache if we are using free space bitmaps for a block group
Every time we add free space to the free space tree or we remove free
space from the free space tree, we do a lookup for the block group's free
space info item in the free space tree. This takes time, navigating the
btree and we may block either on IO when reading extent buffers from disk
or on extent buffer lock contention due to concurrency.
Instead of doing this lookup every time, cache the result in the block
structure and use it after the first lookup. This adds two boolean members
to the block group structure but doesn't increase the structure's size.
The following script that runs fs_mark was used to measure the time spent
on run_delayed_tree_ref(), since down that call chain we have calls to
add and remove free space to/from the free space tree (calls to
btrfs_add_to_free_space_tree() and btrfs_remove_from_free_space_tree()):
OPTS="-S 0 -L 5 -n $FILES -s 0 -t $THREADS -k"
for ((i = 1; i <= $THREADS; i++)); do
OPTS="$OPTS -d $MNT/d$i"
done
fs_mark $OPTS
umount $MNT
This is a heavy metadata test as it's exercising only file creation, so a
lot of allocations of metadata extents, creating delayed refs for adding
new metadata extents and dropping existing ones due to COW. The results
of the times it took to execute run_delayed_tree_ref(), in nanoseconds,
are the following.
Approximate improvement in the first four buckets is about 20%.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 17:10:24 +0000 (18:10 +0100)]
btrfs: add and use helper to determine if using bitmaps in free space tree
When adding and removing free space to the free space tree, we need to
lookup the respective block group's free info item in the free space tree,
check its flags for the BTRFS_FREE_SPACE_USING_BITMAPS bit and then
release the path.
Move these steps into a helper function and use it in both sites.
This will also help avoiding duplicate code in a subsequent change.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 22:11:14 +0000 (23:11 +0100)]
btrfs: use fs_info from local variable in btrfs_convert_free_space_to_extents()
There's no need to dereference the block group to extract fs_info as we
have already stored fs_info in a local variable. So use the local variable
instead.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 22:04:45 +0000 (23:04 +0100)]
btrfs: avoid double slot decrement at btrfs_convert_free_space_to_extents()
There's no need to subtract 1 from path->slots[0] and then decrement the
slot, we can reduce the generated assembly code by decrementing the slot
and then use it.
Module size before:
$ size fs/btrfs/btrfs.ko
text data bss dec hex filename 1846220 162998 16136 2025354 1ee78a fs/btrfs/btrfs.ko
Module size after:
$ size fs/btrfs/btrfs.ko
text data bss dec hex filename 1846204 162998 16136 2025338 1ee77a fs/btrfs/btrfs.ko
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 16:58:04 +0000 (17:58 +0100)]
btrfs: turn remove argument of modify_free_space_bitmap() to boolean
The argument is used as a boolean, so switch its type from int to bool.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 16:48:28 +0000 (17:48 +0100)]
btrfs: rename free_space_set_bits() and make it less confusing
The free_space_set_bits() is used both to set a range of bits or to clear
range of bits, depending on the 'bit' argument value. So the name is very
misleading since it's not used only to set bits. Furthermore the 'bit'
argument is an integer when a boolean is all that is needed plus its name
is singular, which gives the idea the function operates on a single bit
and not on a range of bits.
So rename the function to free_space_modify_bits(), rename the 'bit'
argument to 'set_bits' and turn the argument to bool instead of int.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 16:05:12 +0000 (17:05 +0100)]
btrfs: add btrfs prefix to free space tree exported functions
A few of the free space tree exported functions have a 'btrfs_' prefix in
their name, but most don't. Not only is this inconsistent, the preferred
style is to have such a prefix, to avoid potential collisions in the
future with other kernel code and offer a somewhat better readibility by
making it obvious in calls sites that we are calling btrfs specific code.
So add the 'btrfs_' prefix to all free space tree functions that are
missing it.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 12:06:39 +0000 (13:06 +0100)]
btrfs: remove pointless out label from load_free_space_extents()
All we do under the label is to return, so there's no point in having it,
just return directly whenever we get an error.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 12:04:59 +0000 (13:04 +0100)]
btrfs: remove pointless out label from load_free_space_bitmaps()
All we do under the label is to return, so there's no point in having it,
just return directly whenever we get an error.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 12:00:44 +0000 (13:00 +0100)]
btrfs: remove pointless out label from add_free_space_extent()
All we do under the label is to return, so there's no point in having it,
just return directly whenever we get an error.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 11:56:47 +0000 (12:56 +0100)]
btrfs: remove pointless out label from remove_free_space_extent()
All we do under the label is to return, so there's no point in having it,
just return directly whenever we get an error.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 11:54:53 +0000 (12:54 +0100)]
btrfs: remove pointless out label from modify_free_space_bitmap()
All we do under the label is to return, so there's no point in having it,
just return directly whenever we get an error.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 11:44:11 +0000 (12:44 +0100)]
btrfs: make free_space_test_bit() return a boolean instead
The function returns the result of another function that returns a boolean
(extent_buffer_test_bit()), and all the callers need is a boolean an not
an integer. So change its return type from int to bool, and modify the
callers to store results in booleans instead of integers, which also makes
them simpler.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 11:25:48 +0000 (12:25 +0100)]
btrfs: make extent_buffer_test_bit() return a boolean instead
All the callers want is to determine if a bit is set and all of them call
the function and do a double negation (!!) on its result to get a boolean.
So change it to return a boolean and simplify callers.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 11:18:26 +0000 (12:18 +0100)]
btrfs: remove pointless out label from update_free_space_extent_count()
Just return directly, we don't need the label since all we do under it is
to return.
Reviewed-by: Boris Burkov <boris@bur.io> 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, 11 Jun 2025 11:06:57 +0000 (12:06 +0100)]
btrfs: remove pointless out label from add_new_free_space_info()
We can just return directly if btrfs_insert_empty_item() fails, there is
no need to release the path before returning, as all callers (or upper
in the call chain) will free the path if they get an error from the call
to add_new_free_space_info(), which is also a common pattern everywhere
in btrfs. Finally there's no need to set 'ret' to 0 if the call to
btrfs_insert_empty_item() didn't fail, since 'ret' is already 0.
Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Tue, 10 Jun 2025 16:30:09 +0000 (18:30 +0200)]
btrfs: tree-log: add and rename extent bits for dirty_log_pages tree
The dirty_log_pages tree is used for tree logging and marks extents
based on log_transid. The bits could be renamed to resemble the
LOG1/LOG2 naming used for the BTRFS_FS_LOG1_ERR bits.
David Sterba [Tue, 10 Jun 2025 12:17:53 +0000 (14:17 +0200)]
btrfs: add helper folio_end()
There are several cases of folio_pos + folio_size, add a convenience
helper for that. This is a local helper and not proposed as folio API
because it does not seem to be heavily used elsewhere:
A quick grep (folio_size + folio_end) in fs/ shows
David Sterba [Tue, 10 Jun 2025 12:17:51 +0000 (14:17 +0200)]
btrfs: rename variables for locked range in defrag_prepare_one_folio()
In preparation to use a helper for folio_pos + folio_size, rename the
variables for the locked range so they don't use the 'folio_' prefix. As
the locking ranges take inclusive end of the range (hence the "-1") this
would be confusing as the folio helpers typically use exclusive end of
the range.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Tue, 10 Jun 2025 12:17:48 +0000 (14:17 +0200)]
btrfs: simplify range end calculations in truncate_block_zero_beyond_eof()
The way zero_end is calculated and used does a -1 and +1 that
effectively cancel out, so this can be simplified. This is also
preparatory patch for using a helper for folio_pos + folio_size with the
semantics of exclusive end of the range.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Sat, 7 Jun 2025 18:55:41 +0000 (19:55 +0100)]
btrfs: check BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE at __add_block_group_free_space()
Every caller of __add_block_group_free_space() is checking if the flag
BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE is set before calling it. This is
duplicate code and it's prone to some mistake in case we add more callers
in the future. So move the check for that flag into the start of
__add_block_group_free_space(), and, as a consequence, the path allocation
from add_block_group_free_space() is moved into
__add_block_group_free_space(), to preserve the behaviour of allocating
a path only if the flag BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE is set.
Reviewed-by: Boris Burkov <boris@bur.io> 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
