4.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/nfs/flexfilelayout/flexfilelayout.c | 4 ++++
fs/nfs/pnfs.c | 4 ++++
2 files changed, 8 insertions(+)
--- 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
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:
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -2248,6 +2248,10 @@ void pnfs_read_resend_pnfs(struct nfs_pg
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);
--
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