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authorNeilBrown <neilb@suse.de>2014-09-24 01:28:32 (GMT)
committerTrond Myklebust <trond.myklebust@primarydata.com>2014-09-25 12:25:47 (GMT)
commit1aff52562939485e503936e17934be077ffaea53 (patch)
tree16dba0b5ce0005389ea045e29f69c6b65d133e32 /fs/nfs
parent353db7966288a2f18da22438aeec2b4862c0b241 (diff)
downloadlinux-1aff52562939485e503936e17934be077ffaea53.tar.xz
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 <neilb@suse.de> Acked-by: Jeff Layton <jlayton@primarydata.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Diffstat (limited to 'fs/nfs')
-rw-r--r--fs/nfs/file.c14
1 files changed, 6 insertions, 8 deletions
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 24832d0..6920127c 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);