Commit eb3fabde authored by Mike Snitzer's avatar Mike Snitzer Committed by Anna Schumaker
Browse files

pnfs/flexfiles: retry getting layout segment for reads 



If ff_layout_pg_get_read()'s attempt to get a layout segment results
in -EAGAIN have ff_layout_pg_init_read() retry it after sleeping.

If "softerr" mount is used, use 'io_maxretrans' to limit the number of
attempts to get a layout segment.

This fixes a long-standing issue of O_DIRECT reads failing with
-EAGAIN (11) when using flexfiles Client Side Mirroring (CSM).

Cc: stable@vger.kernel.org
Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
Signed-off-by: default avatarAnna Schumaker <anna.schumaker@oracle.com>
parent 0b96c75d

fs/nfs/flexfilelayout/flexfilelayout.c

+21 −6
Original line number Diff line number Diff line
@@ -848,6 +848,9 @@ ff_layout_pg_init_read(struct nfs_pageio_descriptor *pgio, 
	struct nfs4_pnfs_ds *ds;

	u32 ds_idx;



	if (NFS_SERVER(pgio->pg_inode)->flags &

			(NFS_MOUNT_SOFT|NFS_MOUNT_SOFTERR))

		pgio->pg_maxretrans = io_maxretrans;

retry:

	pnfs_generic_pg_check_layout(pgio, req);

	/* Use full layout for now */
@@ -861,6 +864,8 @@ ff_layout_pg_init_read(struct nfs_pageio_descriptor *pgio, 
		if (!pgio->pg_lseg)

			goto out_nolseg;

	}

	/* Reset wb_nio, since getting layout segment was successful */

	req->wb_nio = 0;



	ds = ff_layout_get_ds_for_read(pgio, &ds_idx);

	if (!ds) {
@@ -877,14 +882,24 @@ ff_layout_pg_init_read(struct nfs_pageio_descriptor *pgio, 
	pgm->pg_bsize = mirror->mirror_ds->ds_versions[0].rsize;



	pgio->pg_mirror_idx = ds_idx;



	if (NFS_SERVER(pgio->pg_inode)->flags &

			(NFS_MOUNT_SOFT|NFS_MOUNT_SOFTERR))

		pgio->pg_maxretrans = io_maxretrans;

	return;

out_nolseg:

	if (pgio->pg_error < 0)

	if (pgio->pg_error < 0) {

		if (pgio->pg_error != -EAGAIN)

			return;

		/* Retry getting layout segment if lower layer returned -EAGAIN */

		if (pgio->pg_maxretrans && req->wb_nio++ > pgio->pg_maxretrans) {

			if (NFS_SERVER(pgio->pg_inode)->flags & NFS_MOUNT_SOFTERR)

				pgio->pg_error = -ETIMEDOUT;

			else

				pgio->pg_error = -EIO;

			return;

		}

		pgio->pg_error = 0;

		/* Sleep for 1 second before retrying */

		ssleep(1);

		goto retry;

	}

out_mds:

	trace_pnfs_mds_fallback_pg_init_read(pgio->pg_inode,

			0, NFS4_MAX_UINT64, IOMODE_READ,