Commit d6f5b0aa authored by Frederic Weisbecker's avatar Frederic Weisbecker
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kill-the-bkl/reiserfs: factorize the locking in reiserfs_write_end() 



reiserfs_write_end() is a hot path in reiserfs.
We have two wasteful write lock lock/release inside that can be gathered
without changing the code logic.

This patch factorizes them out in a single protected section, reducing the
number of contentions inside.

[ Impact: reduce lock contention in a reiserfs hotpath ]

Cc: Jeff Mahoney <jeffm@suse.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent 09eb47a7

fs/reiserfs/inode.c

+15 −10
Original line number Diff line number Diff line
@@ -2681,6 +2681,8 @@ static int reiserfs_write_end(struct file *file, struct address_space *mapping, 
	int update_sd = 0;

	struct reiserfs_transaction_handle *th;

	unsigned start;

	int lock_depth = 0;

	bool locked = false;



	if ((unsigned long)fsdata & AOP_FLAG_CONT_EXPAND)

		pos ++;
@@ -2707,9 +2709,11 @@ static int reiserfs_write_end(struct file *file, struct address_space *mapping, 
	 ** to do the i_size updates here.

	 */

	pos += copied;



	if (pos > inode->i_size) {

		struct reiserfs_transaction_handle myth;

		reiserfs_write_lock(inode->i_sb);

		lock_depth = reiserfs_write_lock_once(inode->i_sb);

		locked = true;

		/* If the file have grown beyond the border where it

		   can have a tail, unmark it as needing a tail

		   packing */
@@ -2720,10 +2724,9 @@ static int reiserfs_write_end(struct file *file, struct address_space *mapping, 
			REISERFS_I(inode)->i_flags &= ~i_pack_on_close_mask;



		ret = journal_begin(&myth, inode->i_sb, 1);

		if (ret) {

			reiserfs_write_unlock(inode->i_sb);

		if (ret)

			goto journal_error;

		}



		reiserfs_update_inode_transaction(inode);

		inode->i_size = pos;

		/*
@@ -2735,34 +2738,36 @@ static int reiserfs_write_end(struct file *file, struct address_space *mapping, 
		reiserfs_update_sd(&myth, inode);

		update_sd = 1;

		ret = journal_end(&myth, inode->i_sb, 1);

		reiserfs_write_unlock(inode->i_sb);

		if (ret)

			goto journal_error;

	}

	if (th) {

		reiserfs_write_lock(inode->i_sb);

		if (!locked) {

			lock_depth = reiserfs_write_lock_once(inode->i_sb);

			locked = true;

		}

		if (!update_sd)

			mark_inode_dirty(inode);

		ret = reiserfs_end_persistent_transaction(th);

		reiserfs_write_unlock(inode->i_sb);

		if (ret)

			goto out;

	}



      out:

	if (locked)

		reiserfs_write_unlock_once(inode->i_sb, lock_depth);

	unlock_page(page);

	page_cache_release(page);

	return ret == 0 ? copied : ret;



      journal_error:

	reiserfs_write_unlock_once(inode->i_sb, lock_depth);

	locked = false;

	if (th) {

		reiserfs_write_lock(inode->i_sb);

		if (!update_sd)

			reiserfs_update_sd(th, inode);

		ret = reiserfs_end_persistent_transaction(th);

		reiserfs_write_unlock(inode->i_sb);

	}



	goto out;

}

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