NFS: Reduce inode->i_lock contention in nfs_lock_and_join_requests() (b5bab9bf) · Commits · 戴 / test

fs/nfs/write.c

+22 −18

Original line number	Diff line number	Diff line
		@@ -372,15 +372,14 @@ nfs_page_group_clear_bits(struct nfs_page *req)
		* @head - head request of page group, must be holding head lock
		* @req - request that couldn't lock and needs to wait on the req bit lock
		*
		* NOTE: this must be called holding page_group bit lock and inode spin lock
		* and BOTH will be released before returning.
		* NOTE: this must be called holding page_group bit lock
		* which will be released before returning.
		*
		* returns 0 on success, < 0 on error.
		*/
		static int
		nfs_unroll_locks_and_wait(struct inode inode, struct nfs_page head,
		struct nfs_page *req)
		__releases(&inode->i_lock)
		{
		struct nfs_page *tmp;
		int ret;
		@@ -395,7 +394,6 @@ nfs_unroll_locks_and_wait(struct inode inode, struct nfs_page head,
		kref_get(&req->wb_kref);

		nfs_page_group_unlock(head);
		spin_unlock(&inode->i_lock);

		/* release ref from nfs_page_find_head_request_locked */
		nfs_unlock_and_release_request(head);
		@@ -491,8 +489,9 @@ nfs_lock_and_join_requests(struct page *page)
		int ret;

		try_again:
		if (!(PagePrivate(page) \|\| PageSwapCache(page)))
		return NULL;
		spin_lock(&inode->i_lock);

		/*
		* A reference is taken only on the head request which acts as a
		* reference to the whole page group - the group will not be destroyed
		@@ -514,16 +513,12 @@ try_again:
		return ERR_PTR(ret);
		goto try_again;
		}

		/* holding inode lock, so always make a non-blocking call to try the
		* page group lock */
		ret = nfs_page_group_lock(head, true);
		if (ret < 0) {
		spin_unlock(&inode->i_lock);

		nfs_page_group_lock_wait(head);
		ret = nfs_page_group_lock(head, false);
		if (ret < 0) {
		nfs_unlock_and_release_request(head);
		goto try_again;
		return ERR_PTR(ret);
		}

		/* lock each request in the page group */
		@@ -531,8 +526,10 @@ try_again:
		for (subreq = head->wb_this_page; subreq != head;
		subreq = subreq->wb_this_page) {
		if (!nfs_lock_request(subreq)) {
		/* releases page group bit lock and
		* inode spin lock and all references */
		/*
		* releases page group bit lock and
		* page locks and all references
		*/
		ret = nfs_unroll_locks_and_wait(inode, head,
		subreq);

		@@ -580,7 +577,9 @@ try_again:
		if (test_and_clear_bit(PG_REMOVE, &head->wb_flags)) {
		set_bit(PG_INODE_REF, &head->wb_flags);
		kref_get(&head->wb_kref);
		spin_lock(&inode->i_lock);
		NFS_I(inode)->nrequests++;
		spin_unlock(&inode->i_lock);
		}

		/*
		@@ -590,11 +589,14 @@ try_again:

		nfs_page_group_unlock(head);

		/* drop lock to clean uprequests on destroy list */
		spin_unlock(&inode->i_lock);

		nfs_destroy_unlinked_subrequests(destroy_list, head, inode);

		/* Did we lose a race with nfs_inode_remove_request()? */
		if (!(PagePrivate(page) \|\| PageSwapCache(page))) {
		nfs_unlock_and_release_request(head);
		return NULL;
		}

		/* still holds ref on head from nfs_page_find_head_request_locked
		* and still has lock on head from lock loop */
		return head;
		@@ -968,7 +970,7 @@ nfs_clear_page_commit(struct page *page)
		WB_RECLAIMABLE);
		}

		/* Called holding inode (/cinfo) lock */
		/* Called holding the request lock on @req */
		static void
		nfs_clear_request_commit(struct nfs_page *req)
		{
		@@ -977,9 +979,11 @@ nfs_clear_request_commit(struct nfs_page *req)
		struct nfs_commit_info cinfo;

		nfs_init_cinfo_from_inode(&cinfo, inode);
		spin_lock(&inode->i_lock);
		if (!pnfs_clear_request_commit(req, &cinfo)) {
		nfs_request_remove_commit_list(req, &cinfo);
		}
		spin_unlock(&inode->i_lock);
		nfs_clear_page_commit(req->wb_page);
		}
		}

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