pNFS: Fix a deadlock between read resends and layoutreturn

commit 54e4a0dfa25d9365c4e80a639e80d9213eb6edbe upstream.

We must not call nfs_pageio_init_read() on a new nfs_pageio_descriptor
while holding a reference to a layout segment, as that can deadlock
pnfs_update_layout().

Fixes: d67ae825a59d6 ("pnfs/flexfiles: Add the FlexFile Layout Driver")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 8 insertions, 0 deletions

diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c
index 98ace127bf86..a5c38889e7ae 100644
--- a/fs/nfs/flexfilelayout/flexfilelayout.c
+++ b/fs/nfs/flexfilelayout/flexfilelayout.c
@@ -28,6 +28,9 @@
 
 static struct group_info        *ff_zero_group;
 
+static void ff_layout_read_record_layoutstats_done(struct rpc_task *task,
+                struct nfs_pgio_header *hdr);
+
 static struct pnfs_layout_hdr *
 ff_layout_alloc_layout_hdr(struct inode *inode, gfp_t gfp_flags)
 {
@@ -1293,6 +1296,7 @@ static int ff_layout_read_done_cb(struct rpc_task *task,
                                         hdr->pgio_mirror_idx + 1,
                                         &hdr->pgio_mirror_idx))
                         goto out_eagain;
+                ff_layout_read_record_layoutstats_done(task, hdr);
                 pnfs_read_resend_pnfs(hdr);
                 return task->tk_status;
         case -NFS4ERR_RESET_TO_MDS:
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index a106f709c1a7..31b107e196fd 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -2293,6 +2293,10 @@ void pnfs_read_resend_pnfs(struct nfs_pgio_header *hdr)
         struct nfs_pageio_descriptor pgio;
 
         if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
+                /* Prevent deadlocks with layoutreturn! */
+                pnfs_put_lseg(hdr->lseg);
+                hdr->lseg = NULL;
+
                 nfs_pageio_init_read(&pgio, hdr->inode, false,
                                         hdr->completion_ops);
                 hdr->task.tk_status = nfs_pageio_resend(&pgio, hdr);