When discard=async was introduced there were also sysfs knobs and stats
for debugging and tuning, hidden under CONFIG_BTRFS_DEBUG. The defaults
have been set and so far seem to satisfy all users on a range of
workloads. As there are not only tunables (like iops or kbps) but also
stats tracking amount of discardable bytes, that should be available
when the async discard is on (otherwise it's not).
The stats are moved from the per-fs debug directory, so it's under
/sys/fs/btrfs/FSID/discard
- discard_bitmap_bytes - amount of discarded bytes from data tracked as
bitmaps
- discard_extent_bytes - dtto but as extents
- discard_bytes_saved -
- discardable_bytes - amount of bytes that can be discarded
- discardable_extents - number of extents to be discarded
- iops_limit - tunable limit of number of discard IOs to be issued
- kbps_limit - tunable limit of kilobytes per second issued as discard IO
- max_discard_size - tunable limit for size of one IO discard request
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Preserve the fs-verity status of a btrfs file across send/recv.
There is no facility for installing the Merkle tree contents directly on
the receiving filesystem, so we package up the parameters used to enable
verity found in the verity descriptor. This gives the receive side
enough information to properly enable verity again. Note that this means
that receive will have to re-compute the whole Merkle tree, similar to
how compression worked before encoded_write.
Since the file becomes read-only after verity is enabled, it is
important that verity is added to the send stream after any file writes.
Therefore, when we process a verity item, merely note that it happened,
then actually create the command in the send stream during
'finish_inode_if_needed'.
This also creates V3 of the send stream format, without any format
changes besides adding the new commands and attributes.
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_insert_file_extent() is only ever used to insert holes, so rename
it and remove the redundant parameters.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This wait event is very similar to the pending ordered wait event in the
sense that it occurs in a different context than the condition signaling
for the event. The signaling occurs in btrfs_remove_ordered_extent()
while the wait event is implemented in btrfs_start_ordered_extent() in
fs/btrfs/ordered-data.c
However, in this case a thread must not acquire the lockdep map for the
ordered extents wait event when the ordered extent is related to a free
space inode. That is because lockdep creates dependencies between locks
acquired both in execution paths related to normal inodes and paths
related to free space inodes, thus leading to false positives.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Ioannis Angelakopoulos <iangelak@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In contrast to the num_writers and num_extwriters wait events, the
condition for the pending ordered wait event is signaled in a different
context from the wait event itself. The condition signaling occurs in
btrfs_remove_ordered_extent() in fs/btrfs/ordered-data.c while the wait
event is implemented in btrfs_commit_transaction() in
fs/btrfs/transaction.c
Thus the thread signaling the condition has to acquire the lockdep map
as a reader at the start of btrfs_remove_ordered_extent() and release it
after it has signaled the condition. In this case some dependencies
might be left out due to the placement of the annotation, but it is
better than no annotation at all.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Ioannis Angelakopoulos <iangelak@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add lockdep annotations for the transaction states that have wait
events;
1) TRANS_STATE_COMMIT_START
2) TRANS_STATE_UNBLOCKED
3) TRANS_STATE_SUPER_COMMITTED
4) TRANS_STATE_COMPLETED
The new macros introduced here to annotate the transaction states wait
events have the same effect as the generic lockdep annotation macros.
With the exception of the lockdep annotation for TRANS_STATE_COMMIT_START
the transaction thread has to acquire the lockdep maps for the
transaction states as reader after the lockdep map for num_writers is
released so that lockdep does not complain.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Ioannis Angelakopoulos <iangelak@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Similarly to the num_writers wait event in fs/btrfs/transaction.c add a
lockdep annotation for the num_extwriters wait event.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Ioannis Angelakopoulos <iangelak@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Annotate the num_writers wait event in fs/btrfs/transaction.c with
lockdep in order to catch deadlocks involving this wait event.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Ioannis Angelakopoulos <iangelak@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Introduce four macros that are used to annotate wait events in btrfs code
with lockdep;
1) the btrfs_lockdep_init_map
2) the btrfs_lockdep_acquire,
3) the btrfs_lockdep_release
4) the btrfs_might_wait_for_event macros.
The btrfs_lockdep_init_map macro is used to initialize a lockdep map.
The btrfs_lockdep_<acquire,release> macros are used by threads to take
the lockdep map as readers (shared lock) and release it, respectively.
The btrfs_might_wait_for_event macro is used by threads to take the
lockdep map as writers (exclusive lock) and release it.
In general, the lockdep annotation for wait events work as follows:
The condition for a wait event can be modified and signaled at the same
time by multiple threads. These threads hold the lockdep map as readers
when they enter a context in which blocking would prevent signaling the
condition. Frequently, this occurs when a thread violates a condition
(lockdep map acquire), before restoring it and signaling it at a later
point (lockdep map release).
The threads that block on the wait event take the lockdep map as writers
(exclusive lock). These threads have to block until all the threads that
hold the lockdep map as readers signal the condition for the wait event
and release the lockdep map.
The lockdep annotation is used to warn about potential deadlock scenarios
that involve the threads that modify and signal the wait event condition
and threads that block on the wait event. A simple example is illustrated
below:
Without lockdep:
TA TB
cond = false
lock(A)
wait_event(w, cond)
unlock(A)
lock(A)
cond = true
signal(w)
unlock(A)
With lockdep:
TA TB
rwsem_acquire_read(lockdep_map)
cond = false
lock(A)
rwsem_acquire(lockdep_map)
rwsem_release(lockdep_map)
wait_event(w, cond)
unlock(A)
lock(A)
cond = true
signal(w)
unlock(A)
rwsem_release(lockdep_map)
In the second case, with the lockdep annotation, lockdep would warn about
an ABBA deadlock, while the first case would just deadlock at some point.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Ioannis Angelakopoulos <iangelak@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The commit 2ce543f478 ("btrfs: zoned: wait until zone is finished when
allocation didn't progress") implemented a zone finish waiting mechanism
to the write path of zoned mode. However, using
wait_var_event()/wake_up_all() on fs_info->zone_finish_wait is wrong and
wait_var_event() just hangs because no one ever wakes it up once it goes
into sleep.
Instead, we can simply use wait_on_bit_io() and clear_and_wake_up_bit()
on fs_info->flags with a proper barrier installed.
Fixes: 2ce543f478 ("btrfs: zoned: wait until zone is finished when allocation didn't progress")
CC: stable@vger.kernel.org # 5.16+
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When testing space_cache v2 on a large set of machines, we encountered a
few symptoms:
1. "unable to add free space :-17" (EEXIST) errors.
2. Missing free space info items, sometimes caught with a "missing free
space info for X" error.
3. Double-accounted space: ranges that were allocated in the extent tree
and also marked as free in the free space tree, ranges that were
marked as allocated twice in the extent tree, or ranges that were
marked as free twice in the free space tree. If the latter made it
onto disk, the next reboot would hit the BUG_ON() in
add_new_free_space().
4. On some hosts with no on-disk corruption or error messages, the
in-memory space cache (dumped with drgn) disagreed with the free
space tree.
All of these symptoms have the same underlying cause: a race between
caching the free space for a block group and returning free space to the
in-memory space cache for pinned extents causes us to double-add a free
range to the space cache. This race exists when free space is cached
from the free space tree (space_cache=v2) or the extent tree
(nospace_cache, or space_cache=v1 if the cache needs to be regenerated).
struct btrfs_block_group::last_byte_to_unpin and struct
btrfs_block_group::progress are supposed to protect against this race,
but commit d0c2f4fa55 ("btrfs: make concurrent fsyncs wait less when
waiting for a transaction commit") subtly broke this by allowing
multiple transactions to be unpinning extents at the same time.
Specifically, the race is as follows:
1. An extent is deleted from an uncached block group in transaction A.
2. btrfs_commit_transaction() is called for transaction A.
3. btrfs_run_delayed_refs() -> __btrfs_free_extent() runs the delayed
ref for the deleted extent.
4. __btrfs_free_extent() -> do_free_extent_accounting() ->
add_to_free_space_tree() adds the deleted extent back to the free
space tree.
5. do_free_extent_accounting() -> btrfs_update_block_group() ->
btrfs_cache_block_group() queues up the block group to get cached.
block_group->progress is set to block_group->start.
6. btrfs_commit_transaction() for transaction A calls
switch_commit_roots(). It sets block_group->last_byte_to_unpin to
block_group->progress, which is block_group->start because the block
group hasn't been cached yet.
7. The caching thread gets to our block group. Since the commit roots
were already switched, load_free_space_tree() sees the deleted extent
as free and adds it to the space cache. It finishes caching and sets
block_group->progress to U64_MAX.
8. btrfs_commit_transaction() advances transaction A to
TRANS_STATE_SUPER_COMMITTED.
9. fsync calls btrfs_commit_transaction() for transaction B. Since
transaction A is already in TRANS_STATE_SUPER_COMMITTED and the
commit is for fsync, it advances.
10. btrfs_commit_transaction() for transaction B calls
switch_commit_roots(). This time, the block group has already been
cached, so it sets block_group->last_byte_to_unpin to U64_MAX.
11. btrfs_commit_transaction() for transaction A calls
btrfs_finish_extent_commit(), which calls unpin_extent_range() for
the deleted extent. It sees last_byte_to_unpin set to U64_MAX (by
transaction B!), so it adds the deleted extent to the space cache
again!
This explains all of our symptoms above:
* If the sequence of events is exactly as described above, when the free
space is re-added in step 11, it will fail with EEXIST.
* If another thread reallocates the deleted extent in between steps 7
and 11, then step 11 will silently re-add that space to the space
cache as free even though it is actually allocated. Then, if that
space is allocated *again*, the free space tree will be corrupted
(namely, the wrong item will be deleted).
* If we don't catch this free space tree corruption, it will continue
to get worse as extents are deleted and reallocated.
The v1 space_cache is synchronously loaded when an extent is deleted
(btrfs_update_block_group() with alloc=0 calls btrfs_cache_block_group()
with load_cache_only=1), so it is not normally affected by this bug.
However, as noted above, if we fail to load the space cache, we will
fall back to caching from the extent tree and may hit this bug.
The easiest fix for this race is to also make caching from the free
space tree or extent tree synchronous. Josef tested this and found no
performance regressions.
A few extra changes fall out of this change. Namely, this fix does the
following, with step 2 being the crucial fix:
1. Factor btrfs_caching_ctl_wait_done() out of
btrfs_wait_block_group_cache_done() to allow waiting on a caching_ctl
that we already hold a reference to.
2. Change the call in btrfs_cache_block_group() of
btrfs_wait_space_cache_v1_finished() to
btrfs_caching_ctl_wait_done(), which makes us wait regardless of the
space_cache option.
3. Delete the now unused btrfs_wait_space_cache_v1_finished() and
space_cache_v1_done().
4. Change btrfs_cache_block_group()'s `int load_cache_only` parameter to
`bool wait` to more accurately describe its new meaning.
5. Change a few callers which had a separate call to
btrfs_wait_block_group_cache_done() to use wait = true instead.
6. Make btrfs_wait_block_group_cache_done() static now that it's not
used outside of block-group.c anymore.
Fixes: d0c2f4fa55 ("btrfs: make concurrent fsyncs wait less when waiting for a transaction commit")
CC: stable@vger.kernel.org # 5.12+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have been hitting the following lockdep splat with btrfs/187 recently
WARNING: possible circular locking dependency detected
5.19.0-rc8+ #775 Not tainted
------------------------------------------------------
btrfs/752500 is trying to acquire lock:
ffff97e1875a97b8 (btrfs-treloc-02#2){+.+.}-{3:3}, at: __btrfs_tree_lock+0x24/0x110
but task is already holding lock:
ffff97e1875a9278 (btrfs-tree-01/1){+.+.}-{3:3}, at: __btrfs_tree_lock+0x24/0x110
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (btrfs-tree-01/1){+.+.}-{3:3}:
down_write_nested+0x41/0x80
__btrfs_tree_lock+0x24/0x110
btrfs_init_new_buffer+0x7d/0x2c0
btrfs_alloc_tree_block+0x120/0x3b0
__btrfs_cow_block+0x136/0x600
btrfs_cow_block+0x10b/0x230
btrfs_search_slot+0x53b/0xb70
btrfs_lookup_inode+0x2a/0xa0
__btrfs_update_delayed_inode+0x5f/0x280
btrfs_async_run_delayed_root+0x24c/0x290
btrfs_work_helper+0xf2/0x3e0
process_one_work+0x271/0x590
worker_thread+0x52/0x3b0
kthread+0xf0/0x120
ret_from_fork+0x1f/0x30
-> #1 (btrfs-tree-01){++++}-{3:3}:
down_write_nested+0x41/0x80
__btrfs_tree_lock+0x24/0x110
btrfs_search_slot+0x3c3/0xb70
do_relocation+0x10c/0x6b0
relocate_tree_blocks+0x317/0x6d0
relocate_block_group+0x1f1/0x560
btrfs_relocate_block_group+0x23e/0x400
btrfs_relocate_chunk+0x4c/0x140
btrfs_balance+0x755/0xe40
btrfs_ioctl+0x1ea2/0x2c90
__x64_sys_ioctl+0x88/0xc0
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
-> #0 (btrfs-treloc-02#2){+.+.}-{3:3}:
__lock_acquire+0x1122/0x1e10
lock_acquire+0xc2/0x2d0
down_write_nested+0x41/0x80
__btrfs_tree_lock+0x24/0x110
btrfs_lock_root_node+0x31/0x50
btrfs_search_slot+0x1cb/0xb70
replace_path+0x541/0x9f0
merge_reloc_root+0x1d6/0x610
merge_reloc_roots+0xe2/0x260
relocate_block_group+0x2c8/0x560
btrfs_relocate_block_group+0x23e/0x400
btrfs_relocate_chunk+0x4c/0x140
btrfs_balance+0x755/0xe40
btrfs_ioctl+0x1ea2/0x2c90
__x64_sys_ioctl+0x88/0xc0
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
other info that might help us debug this:
Chain exists of:
btrfs-treloc-02#2 --> btrfs-tree-01 --> btrfs-tree-01/1
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(btrfs-tree-01/1);
lock(btrfs-tree-01);
lock(btrfs-tree-01/1);
lock(btrfs-treloc-02#2);
*** DEADLOCK ***
7 locks held by btrfs/752500:
#0: ffff97e292fdf460 (sb_writers#12){.+.+}-{0:0}, at: btrfs_ioctl+0x208/0x2c90
#1: ffff97e284c02050 (&fs_info->reclaim_bgs_lock){+.+.}-{3:3}, at: btrfs_balance+0x55f/0xe40
#2: ffff97e284c00878 (&fs_info->cleaner_mutex){+.+.}-{3:3}, at: btrfs_relocate_block_group+0x236/0x400
#3: ffff97e292fdf650 (sb_internal#2){.+.+}-{0:0}, at: merge_reloc_root+0xef/0x610
#4: ffff97e284c02378 (btrfs_trans_num_writers){++++}-{0:0}, at: join_transaction+0x1a8/0x5a0
#5: ffff97e284c023a0 (btrfs_trans_num_extwriters){++++}-{0:0}, at: join_transaction+0x1a8/0x5a0
#6: ffff97e1875a9278 (btrfs-tree-01/1){+.+.}-{3:3}, at: __btrfs_tree_lock+0x24/0x110
stack backtrace:
CPU: 1 PID: 752500 Comm: btrfs Not tainted 5.19.0-rc8+ #775
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
Call Trace:
dump_stack_lvl+0x56/0x73
check_noncircular+0xd6/0x100
? lock_is_held_type+0xe2/0x140
__lock_acquire+0x1122/0x1e10
lock_acquire+0xc2/0x2d0
? __btrfs_tree_lock+0x24/0x110
down_write_nested+0x41/0x80
? __btrfs_tree_lock+0x24/0x110
__btrfs_tree_lock+0x24/0x110
btrfs_lock_root_node+0x31/0x50
btrfs_search_slot+0x1cb/0xb70
? lock_release+0x137/0x2d0
? _raw_spin_unlock+0x29/0x50
? release_extent_buffer+0x128/0x180
replace_path+0x541/0x9f0
merge_reloc_root+0x1d6/0x610
merge_reloc_roots+0xe2/0x260
relocate_block_group+0x2c8/0x560
btrfs_relocate_block_group+0x23e/0x400
btrfs_relocate_chunk+0x4c/0x140
btrfs_balance+0x755/0xe40
btrfs_ioctl+0x1ea2/0x2c90
? lock_is_held_type+0xe2/0x140
? lock_is_held_type+0xe2/0x140
? __x64_sys_ioctl+0x88/0xc0
__x64_sys_ioctl+0x88/0xc0
do_syscall_64+0x38/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
This isn't necessarily new, it's just tricky to hit in practice. There
are two competing things going on here. With relocation we create a
snapshot of every fs tree with a reloc tree. Any extent buffers that
get initialized here are initialized with the reloc root lockdep key.
However since it is a snapshot, any blocks that are currently in cache
that originally belonged to the fs tree will have the normal tree
lockdep key set. This creates the lock dependency of
reloc tree -> normal tree
for the extent buffer locking during the first phase of the relocation
as we walk down the reloc root to relocate blocks.
However this is problematic because the final phase of the relocation is
merging the reloc root into the original fs root. This involves
searching down to any keys that exist in the original fs root and then
swapping the relocated block and the original fs root block. We have to
search down to the fs root first, and then go search the reloc root for
the block we need to replace. This creates the dependency of
normal tree -> reloc tree
which is why lockdep complains.
Additionally even if we were to fix this particular mismatch with a
different nesting for the merge case, we're still slotting in a block
that has a owner of the reloc root objectid into a normal tree, so that
block will have its lockdep key set to the tree reloc root, and create a
lockdep splat later on when we wander into that block from the fs root.
Unfortunately the only solution here is to make sure we do not set the
lockdep key to the reloc tree lockdep key normally, and then reset any
blocks we wander into from the reloc root when we're doing the merged.
This solves the problem of having mixed tree reloc keys intermixed with
normal tree keys, and then allows us to make sure in the merge case we
maintain the lock order of
normal tree -> reloc tree
We handle this by setting a bit on the reloc root when we do the search
for the block we want to relocate, and any block we search into or COW
at that point gets set to the reloc tree key. This works correctly
because we only ever COW down to the parent node, so we aren't resetting
the key for the block we're linking into the fs root.
With this patch we no longer have the lockdep splat in btrfs/187.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently the checksum of compressed extents is verified based on the
compressed data and the lower btrfs_bio, but the actual repair process
is driven by end_bio_extent_readpage on the upper btrfs_bio for the
decompressed data.
This has a bunch of issues, including not being able to properly
communicate the failed mirror up in case that the I/O submission got
preempted, a general loss of if an error was an I/O error or a checksum
verification failure, but most importantly that this design causes
btrfs_clean_io_failure to eventually write back the uncompressed good
data onto the disk sectors that are supposed to contain compressed data.
Fix this by moving the repair to the lower btrfs_bio. To do so, a fair
amount of code has to be reshuffled:
a) the lower btrfs_bio now needs a valid csum pointer. The easiest way
to achieve that is to pass NULL btrfs_lookup_bio_sums and just use
the btrfs_bio management of csums. For a compressed_bio that is
split into multiple btrfs_bios this means additional memory
allocations, but the code becomes a lot more regular.
b) checksum verification now runs directly on the lower btrfs_bio instead
of the compressed_bio. This actually nicely simplifies the end I/O
processing.
c) btrfs_repair_one_sector can't just look up the logical address for
the file offset any more, as there is no corresponding relative
offsets that apply to the file offset and the logic address for
compressed extents. Instead require that the saved bvec_iter in the
btrfs_bio is filled out for all read bios and use that, which again
removes a fair amount of code.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>
Derive the value of start from the btrfs_bio now that ->file_offset is
always valid. Also export and rename the function so it's available
outside of inode.c as we'll need that soon.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When the allocated position doesn't progress, we cannot submit IOs to
finish a block group, but there should be ongoing IOs that will finish a
block group. So, in that case, we wait for a zone to be finished and retry
the allocation after that.
Introduce a new flag BTRFS_FS_NEED_ZONE_FINISH for fs_info->flags to
indicate we need a zone finish to have proceeded. The flag is set when the
allocator detected it cannot activate a new block group. And, it is cleared
once a zone is finished.
CC: stable@vger.kernel.org # 5.16+
Fixes: afba2bc036 ("btrfs: zoned: implement active zone tracking")
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If count_max_extents() uses BTRFS_MAX_EXTENT_SIZE to calculate the number
of extents needed, btrfs release the metadata reservation too much on its
way to write out the data.
Now that BTRFS_MAX_EXTENT_SIZE is replaced with fs_info->max_extent_size,
convert count_max_extents() to use it instead, and fix the calculation of
the metadata reservation.
CC: stable@vger.kernel.org # 5.12+
Fixes: d8e3fb106f ("btrfs: zoned: use ZONE_APPEND write for zoned mode")
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
On zoned filesystem, data write out is limited by max_zone_append_size,
and a large ordered extent is split according the size of a bio. OTOH,
the number of extents to be written is calculated using
BTRFS_MAX_EXTENT_SIZE, and that estimated number is used to reserve the
metadata bytes to update and/or create the metadata items.
The metadata reservation is done at e.g, btrfs_buffered_write() and then
released according to the estimation changes. Thus, if the number of extent
increases massively, the reserved metadata can run out.
The increase of the number of extents easily occurs on zoned filesystem
if BTRFS_MAX_EXTENT_SIZE > max_zone_append_size. And, it causes the
following warning on a small RAM environment with disabling metadata
over-commit (in the following patch).
[75721.498492] ------------[ cut here ]------------
[75721.505624] BTRFS: block rsv 1 returned -28
[75721.512230] WARNING: CPU: 24 PID: 2327559 at fs/btrfs/block-rsv.c:537 btrfs_use_block_rsv+0x560/0x760 [btrfs]
[75721.581854] CPU: 24 PID: 2327559 Comm: kworker/u64:10 Kdump: loaded Tainted: G W 5.18.0-rc2-BTRFS-ZNS+ #109
[75721.597200] Hardware name: Supermicro Super Server/H12SSL-NT, BIOS 2.0 02/22/2021
[75721.607310] Workqueue: btrfs-endio-write btrfs_work_helper [btrfs]
[75721.616209] RIP: 0010:btrfs_use_block_rsv+0x560/0x760 [btrfs]
[75721.646649] RSP: 0018:ffffc9000fbdf3e0 EFLAGS: 00010286
[75721.654126] RAX: 0000000000000000 RBX: 0000000000004000 RCX: 0000000000000000
[75721.663524] RDX: 0000000000000004 RSI: 0000000000000008 RDI: fffff52001f7be6e
[75721.672921] RBP: ffffc9000fbdf420 R08: 0000000000000001 R09: ffff889f8d1fc6c7
[75721.682493] R10: ffffed13f1a3f8d8 R11: 0000000000000001 R12: ffff88980a3c0e28
[75721.692284] R13: ffff889b66590000 R14: ffff88980a3c0e40 R15: ffff88980a3c0e8a
[75721.701878] FS: 0000000000000000(0000) GS:ffff889f8d000000(0000) knlGS:0000000000000000
[75721.712601] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[75721.720726] CR2: 000055d12e05c018 CR3: 0000800193594000 CR4: 0000000000350ee0
[75721.730499] Call Trace:
[75721.735166] <TASK>
[75721.739886] btrfs_alloc_tree_block+0x1e1/0x1100 [btrfs]
[75721.747545] ? btrfs_alloc_logged_file_extent+0x550/0x550 [btrfs]
[75721.756145] ? btrfs_get_32+0xea/0x2d0 [btrfs]
[75721.762852] ? btrfs_get_32+0xea/0x2d0 [btrfs]
[75721.769520] ? push_leaf_left+0x420/0x620 [btrfs]
[75721.776431] ? memcpy+0x4e/0x60
[75721.781931] split_leaf+0x433/0x12d0 [btrfs]
[75721.788392] ? btrfs_get_token_32+0x580/0x580 [btrfs]
[75721.795636] ? push_for_double_split.isra.0+0x420/0x420 [btrfs]
[75721.803759] ? leaf_space_used+0x15d/0x1a0 [btrfs]
[75721.811156] btrfs_search_slot+0x1bc3/0x2790 [btrfs]
[75721.818300] ? lock_downgrade+0x7c0/0x7c0
[75721.824411] ? free_extent_buffer.part.0+0x107/0x200 [btrfs]
[75721.832456] ? split_leaf+0x12d0/0x12d0 [btrfs]
[75721.839149] ? free_extent_buffer.part.0+0x14f/0x200 [btrfs]
[75721.846945] ? free_extent_buffer+0x13/0x20 [btrfs]
[75721.853960] ? btrfs_release_path+0x4b/0x190 [btrfs]
[75721.861429] btrfs_csum_file_blocks+0x85c/0x1500 [btrfs]
[75721.869313] ? rcu_read_lock_sched_held+0x16/0x80
[75721.876085] ? lock_release+0x552/0xf80
[75721.881957] ? btrfs_del_csums+0x8c0/0x8c0 [btrfs]
[75721.888886] ? __kasan_check_write+0x14/0x20
[75721.895152] ? do_raw_read_unlock+0x44/0x80
[75721.901323] ? _raw_write_lock_irq+0x60/0x80
[75721.907983] ? btrfs_global_root+0xb9/0xe0 [btrfs]
[75721.915166] ? btrfs_csum_root+0x12b/0x180 [btrfs]
[75721.921918] ? btrfs_get_global_root+0x820/0x820 [btrfs]
[75721.929166] ? _raw_write_unlock+0x23/0x40
[75721.935116] ? unpin_extent_cache+0x1e3/0x390 [btrfs]
[75721.942041] btrfs_finish_ordered_io.isra.0+0xa0c/0x1dc0 [btrfs]
[75721.949906] ? try_to_wake_up+0x30/0x14a0
[75721.955700] ? btrfs_unlink_subvol+0xda0/0xda0 [btrfs]
[75721.962661] ? rcu_read_lock_sched_held+0x16/0x80
[75721.969111] ? lock_acquire+0x41b/0x4c0
[75721.974982] finish_ordered_fn+0x15/0x20 [btrfs]
[75721.981639] btrfs_work_helper+0x1af/0xa80 [btrfs]
[75721.988184] ? _raw_spin_unlock_irq+0x28/0x50
[75721.994643] process_one_work+0x815/0x1460
[75722.000444] ? pwq_dec_nr_in_flight+0x250/0x250
[75722.006643] ? do_raw_spin_trylock+0xbb/0x190
[75722.013086] worker_thread+0x59a/0xeb0
[75722.018511] kthread+0x2ac/0x360
[75722.023428] ? process_one_work+0x1460/0x1460
[75722.029431] ? kthread_complete_and_exit+0x30/0x30
[75722.036044] ret_from_fork+0x22/0x30
[75722.041255] </TASK>
[75722.045047] irq event stamp: 0
[75722.049703] hardirqs last enabled at (0): [<0000000000000000>] 0x0
[75722.057610] hardirqs last disabled at (0): [<ffffffff8118a94a>] copy_process+0x1c1a/0x66b0
[75722.067533] softirqs last enabled at (0): [<ffffffff8118a989>] copy_process+0x1c59/0x66b0
[75722.077423] softirqs last disabled at (0): [<0000000000000000>] 0x0
[75722.085335] ---[ end trace 0000000000000000 ]---
To fix the estimation, we need to introduce fs_info->max_extent_size to
replace BTRFS_MAX_EXTENT_SIZE, which allow setting the different size for
regular vs zoned filesystem.
Set fs_info->max_extent_size to BTRFS_MAX_EXTENT_SIZE by default. On zoned
filesystem, it is set to fs_info->max_zone_append_size.
CC: stable@vger.kernel.org # 5.12+
Fixes: d8e3fb106f ("btrfs: zoned: use ZONE_APPEND write for zoned mode")
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>
This patch is basically a revert of commit 5a80d1c6a2 ("btrfs: zoned:
remove max_zone_append_size logic"), but without unnecessary ASSERT and
check. The max_zone_append_size will be used as a hint to estimate the
number of extents to cover delalloc/writeback region in the later commits.
The size of a ZONE APPEND bio is also limited by queue_max_segments(), so
this commit considers it to calculate max_zone_append_size. Technically, a
bio can be larger than queue_max_segments() * PAGE_SIZE if the pages are
contiguous. But, it is safe to consider "queue_max_segments() * PAGE_SIZE"
as an upper limit of an extent size to calculate the number of extents
needed to write data.
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>
Track several stats about transaction commit, to be later exported via
sysfs:
- number of commits so far
- duration of the last commit in ns
- maximum commit duration seen so far in ns
- total duration for all commits so far in ns
The update of the commit stats occurs after the commit thread has gone
through all the logic that checks if there is another thread committing
at the same time. This means that we only account for actual commit work
in the commit stats we report and not the time the thread spends waiting
until it is ready to do the commit work.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Ioannis Angelakopoulos <iangelak@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There's a reserved space on each device of size 1MiB that can be used by
bootloaders or to avoid accidental overwrite. Use a symbolic constant
with the explaining comment instead of hard coding the value and
multiple comments.
Note: since btrfs-progs v4.1, mkfs.btrfs will reserve the first 1MiB for
the primary super block (at offset 64KiB), until then the range could
have been used by mistake. Kernel has been always respecting the 1MiB
range for writes.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
The bits are passed to all extent state helpers for no apparent reason,
the value only read and never updated so remove the indirection and pass
it directly. Also unify the type to u32 where needed.
Signed-off-by: David Sterba <dsterba@suse.com>
When using "btrfs inspect-internal dump-super" to inspect an fs with
dirty log, it always shows the log_root_transid as 0:
log_root 30474240
log_root_transid 0 <<<
log_root_level 0
It turns out that, btrfs_super_block::log_root_transid is never really
utilized (even no read for it).
This can date back to the introduction of btrfs into upstream kernel.
In fact, when reading log tree root, we always use
btrfs_super_block::generation + 1 as the expected generation.
So here we're completely safe to mark this member deprecated.
In theory we can easily reuse this member for other purposes, but to be
extra safe, here we follow the leafsize way, by adding "__unused_" for
log_root_transid.
And we can safely remove the accessors, since there is no such callers
from the very beginning.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
All reads bio that go through btrfs_map_bio need to be completed in
user context. And read I/Os are the most common and timing critical
in almost any file system workloads.
Embed a work_struct into struct btrfs_bio and use it to complete all
read bios submitted through btrfs_map, using the REQ_META flag to decide
which workqueue they are placed on.
This removes the need for a separate 128 byte allocation (typically
rounded up to 192 bytes by slab) for all reads with a size increase
of 24 bytes for struct btrfs_bio. Future patches will reorganize
struct btrfs_bio to make use of this extra space for writes as well.
(All sizes are based a on typical 64-bit non-debug build)
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>
Compressed write bio completion is the only user of btrfs_bio_wq_end_io
for writes, and the use of btrfs_bio_wq_end_io is a little suboptimal
here as we only real need user context for the final completion of a
compressed_bio structure, and not every single bio completion.
Add a work_struct to struct compressed_bio instead and use that to call
finish_compressed_bio_write. This allows to remove all handling of
write bios in the btrfs_bio_wq_end_io infrastructure.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of attaching an extra allocation an indirect call to each
low-level bio issued by the RAID code, add a work_struct to struct
btrfs_raid_bio and only defer the per-rbio completion action. The
per-bio action for all the I/Os are trivial and can be safely done
from interrupt context.
As a nice side effect this also allows sharing the boilerplate code
for the per-bio completions
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>
Split btrfs_submit_data_bio into one helper for reads and one for writes.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now that all of the pieces are in place, we can use the ENCODED_WRITE
command to send compressed extents when appropriate.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add a helper to find the csum for a byte offset into the csum buffer.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>
Although we have several data csum verification code, we never have a
function really just to verify checksum for one sector.
Function check_data_csum() do extra work for error reporting, thus it
requires a lot of extra things like file offset, bio_offset etc.
Function btrfs_verify_data_csum() is even worse, it will utilize page
checked flag, which means it can not be utilized for direct IO pages.
Here we introduce a new helper, btrfs_check_sector_csum(), which really
only accept a sector in page, and expected checksum pointer.
We use this function to implement check_data_csum(), and export it for
incoming patch.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
[hch: keep passing the csum array as an arguments, as the callers want
to print it, rename per request]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This reverts commit 253bf57555.
Revert the xarray conversion, there's a problem with potential
sleep-inside-spinlock [1] when calling xa_insert that triggers GFP_NOFS
allocation. The radix tree used the preloading mechanism to avoid
sleeping but this is not available in xarray.
Conversion from spin lock to mutex is possible but at time of rc6 is
riskier than a clean revert.
[1] https://lore.kernel.org/linux-btrfs/cover.1657097693.git.fdmanana@suse.com/
Reported-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This reverts commit 8ee922689d.
Revert the xarray conversion, there's a problem with potential
sleep-inside-spinlock [1] when calling xa_insert that triggers GFP_NOFS
allocation. The radix tree used the preloading mechanism to avoid
sleeping but this is not available in xarray.
Conversion from spin lock to mutex is possible but at time of rc6 is
riskier than a clean revert.
[1] https://lore.kernel.org/linux-btrfs/cover.1657097693.git.fdmanana@suse.com/
Reported-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This reverts commit 48b36a602a.
Revert the xarray conversion, there's a problem with potential
sleep-inside-spinlock [1] when calling xa_insert that triggers GFP_NOFS
allocation. The radix tree used the preloading mechanism to avoid
sleeping but this is not available in xarray.
Conversion from spin lock to mutex is possible but at time of rc6 is
riskier than a clean revert.
[1] https://lore.kernel.org/linux-btrfs/cover.1657097693.git.fdmanana@suse.com/
Reported-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When replacing file extents, called during fallocate, hole punching,
clone and deduplication, we may not be able to replace/drop all the
target file extent items with a single transaction handle. We may get
-ENOSPC while doing it, in which case we release the transaction handle,
balance the dirty pages of the btree inode, flush delayed items and get
a new transaction handle to operate on what's left of the target range.
By dropping and replacing file extent items we have effectively modified
the inode, so we should bump its iversion and update its mtime/ctime
before we update the inode item. This is because if the transaction
we used for partially modifying the inode gets committed by someone after
we release it and before we finish the rest of the range, a power failure
happens, then after mounting the filesystem our inode has an outdated
iversion and mtime/ctime, corresponding to the values it had before we
changed it.
So add the missing iversion and mtime/ctime updates.
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The btrfs_dio_private structure is only used in inode.c, so move the
definition there.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add a wrapper around iomap_dio_rw that keeps the direct I/O internals
isolated in inode.c.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Several functions take parameter bio_flags that was simplified to just
compress type, unify it and change the type accordingly.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The parameter has been added in 2009 in the infamous monster commit
5d4f98a28c ("Btrfs: Mixed back reference (FORWARD ROLLING FORMAT
CHANGE)") but not used ever since. We can sink it and allow further
simplifications.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
… rename it to simply fs_roots and adjust all usages of this object to use
the XArray API, because it is notionally easier to use and understand, as
it provides array semantics, and also takes care of locking for us,
further simplifying the code.
Also do some refactoring, esp. where the API change requires largely
rewriting some functions, anyway.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Gabriel Niebler <gniebler@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
… named 'extent_buffers'. Also adjust all usages of this object to use
the XArray API, which greatly simplifies the code as it takes care of
locking and is generally easier to use and understand, providing
notionally simpler array semantics.
Also perform some light refactoring.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Gabriel Niebler <gniebler@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
… in the btrfs_root struct and adjust all usages of this object to use
the XArray API, because it is notionally easier to use and understand,
as it provides array semantics, and also takes care of locking for us,
further simplifying the code.
Also use the opportunity to do some light refactoring.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Gabriel Niebler <gniebler@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
rmw_workers doesn't need ordered execution or thread disabling threshold
(as the thresh parameter is less than DFT_THRESHOLD).
Just switch to the normal workqueues that use a lot less resources,
especially in the work_struct vs btrfs_work structures.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
All three scrub workqueues don't need ordered execution or thread
disabling threshold (as the thresh parameter is less than DFT_THRESHOLD).
Just switch to the normal workqueues that use a lot less resources,
especially in the work_struct vs btrfs_work structures.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Just let the one caller that wants optional WQ_HIGHPRI handling allocate
a separate btrfs_workqueue for that. This allows to rename struct
__btrfs_workqueue to btrfs_workqueue, remove a pointer indirection and
separate allocation for all btrfs_workqueue users and generally simplify
the code.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Both btrfs_repair_one_sector and submit_bio_one as the direct caller of
one of the instances ignore errors as they expect the methods themselves
to call ->bi_end_io on error. Remove the unused and dangerous return
value.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Keep btrfs_readpage next to btrfs_do_readpage and the other address
space operations. This allows to keep submit_one_bio and
struct btrfs_bio_ctrl file local in extent_io.c.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently we use a spin lock to protect the red black tree that we use to
track block groups. Most accesses to that tree are actually read only and
for large filesystems, with thousands of block groups, it actually has
a bad impact on performance, as concurrent read only searches on the tree
are serialized.
Read only searches on the tree are very frequent and done when:
1) Pinning and unpinning extents, as we need to lookup the respective
block group from the tree;
2) Freeing the last reference of a tree block, regardless if we pin the
underlying extent or add it back to free space cache/tree;
3) During NOCOW writes, both buffered IO and direct IO, we need to check
if the block group that contains an extent is read only or not and to
increment the number of NOCOW writers in the block group. For those
operations we need to search for the block group in the tree.
Similarly, after creating the ordered extent for the NOCOW write, we
need to decrement the number of NOCOW writers from the same block
group, which requires searching for it in the tree;
4) Decreasing the number of extent reservations in a block group;
5) When allocating extents and freeing reserved extents;
6) Adding and removing free space to the free space tree;
7) When releasing delalloc bytes during ordered extent completion;
8) When relocating a block group;
9) During fitrim, to iterate over the block groups;
10) etc;
Write accesses to the tree, to add or remove block groups, are much less
frequent as they happen only when allocating a new block group or when
deleting a block group.
We also use the same spin lock to protect the list of currently caching
block groups. Additions to this list are made when we need to cache a
block group, because we don't have a free space cache for it (or we have
but it's invalid), and removals from this list are done when caching of
the block group's free space finishes. These cases are also not very
common, but when they happen, they happen only once when the filesystem
is mounted.
So switch the lock that protects the tree of block groups from a spinning
lock to a read/write lock.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We keep track of the start offset of the block group with the lowest start
offset at fs_info->first_logical_byte. This requires explicitly updating
that field every time we add, delete or lookup a block group to/from the
red black tree at fs_info->block_group_cache_tree.
Since the block group with the lowest start address happens to always be
the one that is the leftmost node of the tree, we can use a red black tree
that caches the left most node. Then when we need the start address of
that block group, we can just quickly get the leftmost node in the tree
and extract the start offset of that node's block group. This avoids the
need to explicitly keep track of that address in the dedicated member
fs_info->first_logical_byte, and it also allows the next patch in the
series to switch the lock that protects the red black tree from a spin
lock to a read/write lock - without this change it would be tricky
because block group searches also update fs_info->first_logical_byte.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Reading a value from a different member of a union is not just a great
way to obfuscate code, but also creates an aliasing violation. Switch
btrfs_is_zoned to look at ->zone_size and remove the union.
Note: union was to simplify the detection of zoned filesystem but now
this is wrapped behind btrfs_is_zoned so we can drop the union.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add note ]
Signed-off-by: David Sterba <dsterba@suse.com>
When doing a NOWAIT direct IO write, if we can NOCOW then it means we can
proceed with the non-blocking, NOWAIT path. However reserving the metadata
space and qgroup meta space can often result in blocking - flushing
delalloc, wait for ordered extents to complete, trigger transaction
commits, etc, going against the semantics of a NOWAIT write.
So make the NOWAIT write path to try to reserve all the metadata it needs
without resulting in a blocking behaviour - if we get -ENOSPC or -EDQUOT
then return -EAGAIN to make the caller fallback to a blocking direct IO
write.
This is part of a patchset comprised of the following patches:
btrfs: avoid blocking on page locks with nowait dio on compressed range
btrfs: avoid blocking nowait dio when locking file range
btrfs: avoid double nocow check when doing nowait dio writes
btrfs: stop allocating a path when checking if cross reference exists
btrfs: free path at can_nocow_extent() before checking for checksum items
btrfs: release path earlier at can_nocow_extent()
btrfs: avoid blocking when allocating context for nowait dio read/write
btrfs: avoid blocking on space revervation when doing nowait dio writes
The following test was run before and after applying this patchset:
$ cat io-uring-nodatacow-test.sh
#!/bin/bash
DEV=/dev/sdc
MNT=/mnt/sdc
MOUNT_OPTIONS="-o ssd -o nodatacow"
MKFS_OPTIONS="-R free-space-tree -O no-holes"
NUM_JOBS=4
FILE_SIZE=8G
RUN_TIME=300
cat <<EOF > /tmp/fio-job.ini
[io_uring_rw]
rw=randrw
fsync=0
fallocate=posix
group_reporting=1
direct=1
ioengine=io_uring
iodepth=64
bssplit=4k/20:8k/20:16k/20:32k/10:64k/10:128k/5:256k/5:512k/5:1m/5
filesize=$FILE_SIZE
runtime=$RUN_TIME
time_based
filename=foobar
directory=$MNT
numjobs=$NUM_JOBS
thread
EOF
echo performance | \
tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
umount $MNT &> /dev/null
mkfs.btrfs -f $MKFS_OPTIONS $DEV &> /dev/null
mount $MOUNT_OPTIONS $DEV $MNT
fio /tmp/fio-job.ini
umount $MNT
The test was run a 12 cores box with 64G of ram, using a non-debug kernel
config (Debian's default config) and a spinning disk.
Result before the patchset:
READ: bw=407MiB/s (427MB/s), 407MiB/s-407MiB/s (427MB/s-427MB/s), io=119GiB (128GB), run=300175-300175msec
WRITE: bw=407MiB/s (427MB/s), 407MiB/s-407MiB/s (427MB/s-427MB/s), io=119GiB (128GB), run=300175-300175msec
Result after the patchset:
READ: bw=436MiB/s (457MB/s), 436MiB/s-436MiB/s (457MB/s-457MB/s), io=128GiB (137GB), run=300044-300044msec
WRITE: bw=435MiB/s (456MB/s), 435MiB/s-435MiB/s (456MB/s-456MB/s), io=128GiB (137GB), run=300044-300044msec
That's about +7.2% throughput for reads and +6.9% for writes.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
