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pnfs/flexfiles: retry getting layout segment for reads

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commit eb3fabde15bccdf34f1c9b35a83aa4c0dacbb4ca upstream.

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: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mike Snitzer 2025-01-16 20:05:39 -05:00 committed by Greg Kroah-Hartman
parent 805bf50521
commit f8e05df84b
1 changed files with 21 additions and 6 deletions
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25
fs/nfs/flexfilelayout/flexfilelayout.c
View File

@ -839,6 +839,9 @@ 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:
ff_layout_pg_check_layout(pgio, req);
/* Use full layout for now */
@ -852,6 +855,8 @@ retry:
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) {
@ -868,14 +873,24 @@ retry:
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,