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nfsd: Only set PF_LESS_THROTTLE when really needed. 

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>
This commit is contained in:
NeilBrown 2014-05-12 11:22:47 +10:00 committed by J. Bruce Fields
parent ef11ce2487
commit 8658452e4a
2 changed files with 12 additions and 6 deletions
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6
fs/nfsd/nfssvc.c
View File

@ -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();
/*

12
fs/nfsd/vfs.c
View File

@ -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;
}