4.4-stable review patch. If anyone has any objections, please let me know.
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From: Scott Mayhew smayhew@redhat.com
commit ba4a76f703ab7eb72941fdaac848502073d6e9ee upstream.
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 dwysocha@redhat.com):
stap -v -g -e 'probe module("nfs_layout_nfsv41_files").function("nfs4_fl_prepare_ds").return { $return=NULL; exit(); }'
Suggested-by: Trond Myklebust trond.myklebust@primarydata.com Signed-off-by: Scott Mayhew smayhew@redhat.com Fixes: 1ca018d28d ("pNFS: Fix a memory leak when attempted pnfs fails") Signed-off-by: Trond Myklebust trond.myklebust@primarydata.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/nfs/pnfs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/fs/nfs/pnfs.c +++ b/fs/nfs/pnfs.c @@ -1943,7 +1943,7 @@ pnfs_write_through_mds(struct nfs_pageio nfs_pageio_reset_write_mds(desc); mirror->pg_recoalesce = 1; } - hdr->release(hdr); + hdr->completion_ops->completion(hdr); }
static enum pnfs_try_status @@ -2058,7 +2058,7 @@ pnfs_read_through_mds(struct nfs_pageio_ nfs_pageio_reset_read_mds(desc); mirror->pg_recoalesce = 1; } - hdr->release(hdr); + hdr->completion_ops->completion(hdr); }
/*