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Commit 1403390d authored by Trond Myklebust's avatar Trond Myklebust
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NFS: Reduce lock contention in nfs_try_to_update_request() 



Micro-optimisation to move the lockless check into the for(;;) loop.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent 82749dd4

fs/nfs/write.c

+3 −5
Original line number Diff line number Diff line
@@ -1097,13 +1097,12 @@ static struct nfs_page *nfs_try_to_update_request(struct inode *inode, 
	unsigned int end;

	int error;



	if (!PagePrivate(page))

		return NULL;



	end = offset + bytes;

	spin_lock(&inode->i_lock);



	for (;;) {

		if (!(PagePrivate(page) || PageSwapCache(page)))

			return NULL;

		spin_lock(&inode->i_lock);

		req = nfs_page_find_head_request_locked(NFS_I(inode), page);

		if (req == NULL)

			goto out_unlock;
@@ -1132,7 +1131,6 @@ static struct nfs_page *nfs_try_to_update_request(struct inode *inode, 
		nfs_release_request(req);

		if (error != 0)

			goto out_err;

		spin_lock(&inode->i_lock);

	}



	/* Okay, the request matches. Update the region */