Commit ee39b432 authored by David Sterba's avatar David Sterba
Browse files

btrfs: remove unlikely from data-dependent branches and slow paths 



There are the branch hints that obviously depend on the data being
processed, the CPU predictor will do better job according to the actual
load. It also does not make sense to use the hints in slow paths that do
a lot of other operations like locking, waiting or IO.

Signed-off-by: default avatarDavid Sterba <dsterba@suse.cz>
parent 5d99a998

fs/btrfs/extent-tree.c

+2 −2
Original line number Diff line number Diff line
@@ -9694,7 +9694,7 @@ void btrfs_end_nocow_write(struct btrfs_root *root) 


int btrfs_start_nocow_write(struct btrfs_root *root)

{

	if (unlikely(atomic_read(&root->will_be_snapshoted)))

	if (atomic_read(&root->will_be_snapshoted))

		return 0;



	percpu_counter_inc(&root->subv_writers->counter);
@@ -9702,7 +9702,7 @@ int btrfs_start_nocow_write(struct btrfs_root *root) 
	 * Make sure counter is updated before we check for snapshot creation.

	 */

	smp_mb();

	if (unlikely(atomic_read(&root->will_be_snapshoted))) {

	if (atomic_read(&root->will_be_snapshoted)) {

		btrfs_end_nocow_write(root);

		return 0;

	}

fs/btrfs/file.c

+2 −2
Original line number Diff line number Diff line
@@ -452,7 +452,7 @@ static noinline int btrfs_copy_from_user(loff_t pos, int num_pages, 
		if (unlikely(copied == 0))

			break;



		if (unlikely(copied < PAGE_CACHE_SIZE - offset)) {

		if (copied < PAGE_CACHE_SIZE - offset) {

			offset += copied;

		} else {

			pg++;
@@ -1792,7 +1792,7 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb, 
	if (sync)

		atomic_inc(&BTRFS_I(inode)->sync_writers);



	if (unlikely(file->f_flags & O_DIRECT)) {

	if (file->f_flags & O_DIRECT) {

		num_written = __btrfs_direct_write(iocb, from, pos);

	} else {

		num_written = __btrfs_buffered_write(file, from, pos);

fs/btrfs/inode.c

+4 −4
Original line number Diff line number Diff line
@@ -7802,9 +7802,9 @@ static int btrfs_submit_direct_hook(int rw, struct btrfs_dio_private *dip, 
	atomic_inc(&dip->pending_bios);



	while (bvec <= (orig_bio->bi_io_vec + orig_bio->bi_vcnt - 1)) {

		if (unlikely(map_length < submit_len + bvec->bv_len ||

		if (map_length < submit_len + bvec->bv_len ||

		    bio_add_page(bio, bvec->bv_page, bvec->bv_len,

				 bvec->bv_offset) < bvec->bv_len)) {

				 bvec->bv_offset) < bvec->bv_len) {

			/*

			 * inc the count before we submit the bio so

			 * we know the end IO handler won't happen before
@@ -8017,8 +8017,8 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb, 
		ret = btrfs_delalloc_reserve_space(inode, count);

		if (ret)

			goto out;

	} else if (unlikely(test_bit(BTRFS_INODE_READDIO_NEED_LOCK,

				     &BTRFS_I(inode)->runtime_flags))) {

	} else if (test_bit(BTRFS_INODE_READDIO_NEED_LOCK,

				     &BTRFS_I(inode)->runtime_flags)) {

		inode_dio_done(inode);

		flags = DIO_LOCKING | DIO_SKIP_HOLES;

		wakeup = false;

fs/btrfs/ioctl.c

+1 −1
Original line number Diff line number Diff line
@@ -3167,7 +3167,7 @@ static void clone_update_extent_map(struct inode *inode, 
					em->start + em->len - 1, 0);

	}



	if (unlikely(ret))

	if (ret)

		set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,

			&BTRFS_I(inode)->runtime_flags);

}

fs/btrfs/transaction.c

+1 −1
Original line number Diff line number Diff line
@@ -418,7 +418,7 @@ start_transaction(struct btrfs_root *root, u64 num_items, unsigned int type, 
		/*

		 * Do the reservation for the relocation root creation

		 */

		if (unlikely(need_reserve_reloc_root(root))) {

		if (need_reserve_reloc_root(root)) {

			num_bytes += root->nodesize;

			reloc_reserved = true;

		}

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