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Commit 54e4a0df authored by Trond Myklebust's avatar Trond Myklebust
Browse files

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: d67ae825 ("pnfs/flexfiles: Add the FlexFile Layout Driver")
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org # v4.0+
parent 9a837856

fs/nfs/flexfilelayout/flexfilelayout.c

+4 −0
Original line number Diff line number Diff line
@@ -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:

fs/nfs/pnfs.c

+4 −0
Original line number Diff line number Diff line
@@ -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);