kernel/linux.git/fs/btrfs/locking.c, branch v6.12.80

btrfs: change root->root_key.objectid to btrfs_root_id()

2024-05-07T19:31:06+00:00

A comment from Filipe on one of my previous cleanups brought my attention to a new helper we have for getting the root id of a root, which makes it easier to read in the code. The changes where made with the following Coccinelle semantic patch: // @@ expression E,E1; @@ ( E->root_key.objectid = E1 | - E->root_key.objectid + btrfs_root_id(E) ) // Reviewed-by: Filipe Manana Signed-off-by: Josef Bacik Reviewed-by: David Sterba [ minor style fixups ] Signed-off-by: David Sterba

btrfs: avoid pointless wake ups of drew lock readers

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

When unlocking a write lock on a drew lock, at btrfs_drew_write_unlock(), it's pointless to wake up tasks waiting to acquire a read lock if we didn't decrement the 'writers' counter down to 0, since a read lock can only be acquired when the counter reaches a value of 0. Doing so is harmless from a functional point of view, but it's not efficient due to unnecessarily waking up tasks just for them to sleep again on the waitqueue. So change this to wake up readers only if we decremented the 'writers' counter to 0. Signed-off-by: Filipe Manana 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: change BUG_ON to assertion when verifying lockdep class setup

2024-03-04T15:24:48+00:00

The BUG_ON in btrfs_set_buffer_lockdep_class() is a sanity check of the level which is verified in callers, e.g. when initializing an extent buffer or reading from an eb header. Change it to an assertion as this would not happen unless things are really bad and would fail elsewhere too. Reviewed-by: Josef Bacik Reviewed-by: Anand Jain Signed-off-by: David Sterba

btrfs: remove unused included headers

2024-03-04T15:24:46+00:00

With help of neovim, LSP and clangd we can identify header files that are not actually needed to be included in the .c files. This is focused only on removal (with minor fixups), further cleanups are possible but will require doing the header files properly with forward declarations, minimized includes and include-what-you-use care. Reviewed-by: Josef Bacik Signed-off-by: David Sterba

btrfs: add raid stripe tree definitions

2023-10-12T14:44:09+00:00

Add definitions for the raid stripe tree. This tree will hold information about the on-disk layout of the stripes in a RAID set. Each stripe extent has a 1:1 relationship with an on-disk extent item and is doing the logical to per-drive physical address translation for the extent item in question. Signed-off-by: Johannes Thumshirn Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: move extent_buffer::lock_owner to debug section

2023-10-12T14:44:05+00:00

The lock_owner is used for a rare corruption case and we haven't seen any reports in years. Move it to the debugging section of eb. To close the holes also move log_index so the final layout looks like: struct extent_buffer { u64 start; /* 0 8 */ long unsigned int len; /* 8 8 */ long unsigned int bflags; /* 16 8 */ struct btrfs_fs_info * fs_info; /* 24 8 */ spinlock_t refs_lock; /* 32 4 */ atomic_t refs; /* 36 4 */ int read_mirror; /* 40 4 */ s8 log_index; /* 44 1 */ /* XXX 3 bytes hole, try to pack */ struct callback_head callback_head __attribute__((__aligned__(8))); /* 48 16 */ /* --- cacheline 1 boundary (64 bytes) --- */ struct rw_semaphore lock; /* 64 40 */ struct page * pages[16]; /* 104 128 */ /* size: 232, cachelines: 4, members: 11 */ /* sum members: 229, holes: 1, sum holes: 3 */ /* forced alignments: 1, forced holes: 1, sum forced holes: 3 */ /* last cacheline: 40 bytes */ } __attribute__((__aligned__(8))); This saves 8 bytes in total and still keeps the lock on a separate cacheline. Reviewed-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: reformat remaining kdoc style comments

2023-10-12T14:44:04+00:00

Function name in the comment does not bring much value to code not exposed as API and we don't stick to the kdoc format anymore. Update formatting of parameter descriptions. Reviewed-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: include trace header in where necessary

2023-10-12T14:44:03+00:00

If we no longer include the tracepoints from ctree.h we fail to compile because we have the dependency in some of the header files and source files. Add the include where we have these dependencies to allow us to remove the include from ctree.h. Reviewed-by: Johannes Thumshirn Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba