Return-Path: From: Scott Mayhew To: trond.myklebust@primarydata.com, anna.schumaker@netapp.com Cc: bcodding@redhat.com, dwysocha@redhat.com, fsorenso@redhat.com, linux-nfs@vger.kernel.org Subject: [PATCH v2] nfs/pnfs: fix nfs_direct_req ref leak when i/o falls back to the mds Date: Fri, 15 Dec 2017 16:12:32 -0500 Message-Id: <20171215211232.18942-1-smayhew@redhat.com> In-Reply-To: <20171213182220.lrfbvkaj65fg6abk@tonberry.usersys.redhat.com> References: <20171213182220.lrfbvkaj65fg6abk@tonberry.usersys.redhat.com> List-ID: Currently when falling back to doing I/O through the MDS (via pnfs_{read|write}_through_mds), the client frees the nfs_pgio_header without releasing the reference taken on the dreq via pnfs_generic_pg_{read|write}pages -> nfs_pgheader_init -> nfs_direct_pgio_init. It then takes another reference on the dreq via nfs_generic_pg_pgios -> nfs_pgheader_init -> nfs_direct_pgio_init and as a result the requester will become stuck in inode_dio_wait. Once that happens, other processes accessing the inode will become stuck as well. Ensure that pnfs_read_through_mds() and pnfs_write_through_mds() clean up correctly by calling hdr->completion_ops->completion() instead of calling hdr->release() directly. This can be reproduced (sometimes) by performing "storage failover takeover" commands on NetApp filer while doing direct I/O from a client. This can also be reproduced using SystemTap to simulate a failure while doing direct I/O from a client (from Dave Wysochanski ): stap -v -g -e 'probe module("nfs_layout_nfsv41_files").function("nfs4_fl_prepare_ds").return { $return=NULL; exit(); }' Suggested-by: Trond Myklebust Signed-off-by: Scott Mayhew --- fs/nfs/pnfs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c index d602fe9..eb098cc 100644 --- a/fs/nfs/pnfs.c +++ b/fs/nfs/pnfs.c @@ -2255,7 +2255,7 @@ pnfs_write_through_mds(struct nfs_pageio_descriptor *desc, nfs_pageio_reset_write_mds(desc); mirror->pg_recoalesce = 1; } - hdr->release(hdr); + hdr->completion_ops->completion(hdr); } static enum pnfs_try_status @@ -2378,7 +2378,7 @@ pnfs_read_through_mds(struct nfs_pageio_descriptor *desc, nfs_pageio_reset_read_mds(desc); mirror->pg_recoalesce = 1; } - hdr->release(hdr); + hdr->completion_ops->completion(hdr); } /* -- 2.9.5