nfsd: Only set PF_LESS_THROTTLE when really needed. (8658452e) · Commits · 戴 / test

PF_LESS_THROTTLE has a very specific use case: to avoid deadlocks and live-locks while writing to the page cache in a loop-back NFS mount situation. It therefore makes sense to *only* set PF_LESS_THROTTLE in this situation. We now know when a request came from the local-host so it could be a loop-back mount. We already know when we are handling write requests, and when we are doing anything else. So combine those two to allow nfsd to still be throttled (like any other process) in every situation except when it is known to be problematic. Signed-off-by:

NeilBrown <neilb@suse.de> Signed-off-by:

J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfssvc.c

+0 −6

Original line number	Diff line number	Diff line
		@@ -591,12 +591,6 @@ nfsd(void *vrqstp)
		nfsdstats.th_cnt++;
		mutex_unlock(&nfsd_mutex);

		/*
		* We want less throttling in balance_dirty_pages() so that nfs to
		* localhost doesn't cause nfsd to lock up due to all the client's
		* dirty pages.
		*/
		current->flags \|= PF_LESS_THROTTLE;
		set_freezable();

		/*

fs/nfsd/vfs.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -908,6 +908,16 @@ nfsd_vfs_write(struct svc_rqst rqstp, struct svc_fh fhp, struct file *file,
		int stable = *stablep;
		int use_wgather;
		loff_t pos = offset;
		unsigned int pflags = current->flags;

		if (rqstp->rq_local)
		/*
		* We want less throttling in balance_dirty_pages()
		* and shrink_inactive_list() so that nfs to
		* localhost doesn't cause nfsd to lock up due to all
		* the client's dirty pages or its congested queue.
		*/
		current->flags \|= PF_LESS_THROTTLE;

		dentry = file->f_path.dentry;
		inode = dentry->d_inode;
		@@ -941,6 +951,8 @@ out_nfserr:
		err = 0;
		else
		err = nfserrno(host_err);
		if (rqstp->rq_local)
		tsk_restore_flags(current, pflags, PF_LESS_THROTTLE);
		return err;
		}

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