pNFS: Fix a deadlock between read resends and layoutreturn

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>
Cc: stable@vger.kernel.org # v4.0+

diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c
index 98ace127bf861e723647019a0c8ad856f5ee0391..a5c38889e7ae7fb5584ca366972bdc8c3ea2688b 100644 (file)
--- 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 259ef85f435aa7f9e0b0e4d06d3ce24a9e7a3ad3..206d560c74f4a3d9ea16e367299b2760ced3a547 100644 (file)
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -2286,6 +2286,10 @@ 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);