From 1aff52562939485e503936e17934be077ffaea53 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Wed, 24 Sep 2014 11:28:32 +1000 Subject: NFS/SUNRPC: Remove other deadlock-avoidance mechanisms in nfs_release_page() Now that nfs_release_page() doesn't block indefinitely, other deadlock avoidance mechanisms aren't needed. - it doesn't hurt for kswapd to block occasionally. If it doesn't want to block it would clear __GFP_WAIT. The current_is_kswapd() was only added to avoid deadlocks and we have a new approach for that. - memory allocation in the SUNRPC layer can very rarely try to ->releasepage() a page it is trying to handle. The deadlock is removed as nfs_release_page() doesn't block indefinitely. So we don't need to set PF_FSTRANS for sunrpc network operations any more. Signed-off-by: NeilBrown Acked-by: Jeff Layton Signed-off-by: Trond Myklebust --- fs/nfs/file.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) (limited to 'fs/nfs/file.c') diff --git a/fs/nfs/file.c b/fs/nfs/file.c index 24832d040eb8..6920127c5eb7 100644 --- a/fs/nfs/file.c +++ b/fs/nfs/file.c @@ -476,20 +476,18 @@ static int nfs_release_page(struct page *page, gfp_t gfp) dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page); /* Always try to initiate a 'commit' if relevant, but only - * wait for it if __GFP_WAIT is set and the calling process is - * allowed to block. Even then, only wait 1 second and only - * if the 'bdi' is not congested. + * wait for it if __GFP_WAIT is set. Even then, only wait 1 + * second and only if the 'bdi' is not congested. * Waiting indefinitely can cause deadlocks when the NFS - * server is on this machine, and there is no particular need - * to wait extensively here. A short wait has the benefit - * that someone else can worry about the freezer. + * server is on this machine, when a new TCP connection is + * needed and in other rare cases. There is no particular + * need to wait extensively here. A short wait has the + * benefit that someone else can worry about the freezer. */ if (mapping) { struct nfs_server *nfss = NFS_SERVER(mapping->host); nfs_commit_inode(mapping->host, 0); if ((gfp & __GFP_WAIT) && - !current_is_kswapd() && - !(current->flags & PF_FSTRANS) && !bdi_write_congested(&nfss->backing_dev_info)) { wait_on_page_bit_killable_timeout(page, PG_private, HZ); -- cgit v1.2.3