kernel/linux.git/fs/btrfs/locking.h, branch v6.18.22

btrfs: fix typos in comments and strings

2025-09-23T06:49:16+00:00

Annual typo fixing pass. Strangely codespell found only about 30% of what is in this patch, the rest was done manually using text spellchecker with a custom dictionary of acceptable terms. Reviewed-by: Neal Gompa Signed-off-by: David Sterba

btrfs: trivial conversion to return bool instead of int

2025-05-15T12:30:49+00:00

Old code has a lot of int for bool return values, bool is recommended and done in new code. Convert the trivial cases that do simple 0/false and 1/true. Functions comment are updated if needed. Reviewed-by: Naohiro Aota Signed-off-by: David Sterba

btrfs: add assertions and comment about path expectations to btrfs_cross_ref_exist()

2025-01-13T13:53:16+00:00

We should always call check_delayed_ref() with a path having a locked leaf from the extent tree where either the extent item is located or where it should be located in case it doesn't exist yet (when there's a pending unflushed delayed ref to do it), as we need to lock any existing delayed ref head while holding such leaf locked in order to avoid races with flushing delayed references, which could make us think an extent is not shared when it really is. So add some assertions and a comment about such expectations to btrfs_cross_ref_exist(), which is the only caller of check_delayed_ref(). Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Signed-off-by: David Sterba

btrfs: fix lockdep warnings on io_uring encoded reads

2024-11-29T15:56:38+00:00

Lockdep doesn't like the fact that btrfs_uring_read_extent() returns to userspace still holding the inode lock, even though we release it once the I/O finishes. Add calls to rwsem_release() and rwsem_acquire_read() to work round this. Reported-by: Johannes Thumshirn 34310c442e17 ("btrfs: add io_uring command for encoded reads (ENCODED_READ ioctl)") Signed-off-by: Mark Harmstone Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: remove unused btrfs_try_tree_write_lock()

2024-11-11T13:34:14+00:00

btrfs_try_tree_write_lock() has been unused since commit 50b21d7a066f ("btrfs: submit a writeback bio per extent_buffer"). Remove it as we don't need it anymore. Reviewed-by: Christoph Hellwig Reviewed-by: Qu Wenruo Signed-off-by: Dr. David Alan Gilbert Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: cleanup recursive include of the same header

2024-07-11T13:33:22+00:00

We have several headers that are including themselves, triggering clangd warnings. Such includes are caused by commit 602035d7fecf ("btrfs: add forward declarations and headers, part 2"). Just remove such unnecessary include. Reviewed-by: Filipe Manana Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: locking: rename __btrfs_tree_lock() and __btrfs_tree_read_lock()

2024-05-07T19:31:00+00:00

The __btrfs_tree_lock() and __btrfs_tree_read_lock() are using a naming with a double underscore prefix, which is specially not proper for exported functions. Remove the double underscore prefix from their name and add the "_nested" suffix. Reviewed-by: Anand Jain Reviewed-by: Johannes Thumshirn Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: locking: inline btrfs_tree_lock() and btrfs_tree_read_lock()

2024-05-07T19:31:00+00:00

The functions btrfs_tree_lock() and btrfs_tree_read_lock() are very trivial so that can be made inline and avoid call overhead, as they are very often called inside critical sections (when searching a btree for example, attempting to lock a child node/leaf while holding a lock on the parent). So make them static inline, which even reduces the size of the btrfs module a little bit. Before this change: $ size fs/btrfs/btrfs.ko text data bss dec hex filename 1718786 156276 16920 1891982 1cde8e fs/btrfs/btrfs.ko After this change: $ size fs/btrfs/btrfs.ko text data bss dec hex filename 1718650 156260 16920 1891830 1cddf6 fs/btrfs/btrfs.ko Running fs_mark also showed a tiny improvement with this script: $ cat test.sh #!/bin/bash DEV=/dev/nullb0 MNT=/mnt/nullb0 FILES=100000 THREADS=$(nproc --all) echo "performance" | \ tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor umount $DEV &> /dev/null mkfs.btrfs -f $DEV mount $DEV $MNT 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 Before this change: FSUse% Count Size Files/sec App Overhead 10 1200000 0 180894.0 10705410 16 2400000 0 228211.4 10765738 23 3600000 0 215969.6 11011072 30 4800000 0 199077.1 11145587 46 6000000 0 176624.1 11658470 After this change: FSUse% Count Size Files/sec App Overhead 10 1200000 0 185312.3 10708377 16 2400000 0 229320.4 10858013 23 3600000 0 217958.7 11006167 30 4800000 0 205122.9 11112899 46 6000000 0 178039.1 11438852 Reviewed-by: Anand Jain Reviewed-by: Johannes Thumshirn Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: add forward declarations and headers, part 2

2024-03-04T15:24:49+00:00

Do a cleanup in more headers: - add forward declarations for types referenced by pointers - add includes when types need them This fixes potential compilation problems if the headers are reordered or the missing includes are not provided indirectly. Signed-off-by: David Sterba

btrfs: do not block starts waiting on previous transaction commit

2023-09-08T12:10:49+00:00

Internally I got a report of very long stalls on normal operations like creating a new file when auto relocation was running. The reporter used the 'bpf offcputime' tracer to show that we would get stuck in start_transaction for 5 to 30 seconds, and were always being woken up by the transaction commit. Using my timing-everything script, which times how long a function takes and what percentage of that total time is taken up by its children, I saw several traces like this 1083 took 32812902424 ns 29929002926 ns 91.2110% wait_for_commit_duration 25568 ns 7.7920e-05% commit_fs_roots_duration 1007751 ns 0.00307% commit_cowonly_roots_duration 446855602 ns 1.36182% btrfs_run_delayed_refs_duration 271980 ns 0.00082% btrfs_run_delayed_items_duration 2008 ns 6.1195e-06% btrfs_apply_pending_changes_duration 9656 ns 2.9427e-05% switch_commit_roots_duration 1598 ns 4.8700e-06% btrfs_commit_device_sizes_duration 4314 ns 1.3147e-05% btrfs_free_log_root_tree_duration Here I was only tracing functions that happen where we are between START_COMMIT and UNBLOCKED in order to see what would be keeping us blocked for so long. The wait_for_commit() we do is where we wait for a previous transaction that hasn't completed it's commit. This can include all of the unpin work and other cleanups, which tends to be the longest part of our transaction commit. There is no reason we should be blocking new things from entering the transaction at this point, it just adds to random latency spikes for no reason. Fix this by adding a PREP stage. This allows us to properly deal with multiple committers coming in at the same time, we retain the behavior that the winner waits on the previous transaction and the losers all wait for this transaction commit to occur. Nothing else is blocked during the PREP stage, and then once the wait is complete we switch to COMMIT_START and all of the same behavior as before is maintained. Reviewed-by: Filipe Manana Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba