pNFS/flexfiles: Ensure we have enough buffer for layoutreturn

The flexfiles client can piggyback both layout errors and layoutstats
as part of the layoutreturn. Both these payloads can get large, with
20 layout error entries taking up about 1.2K, and 4 layoutstats entries
taking up another 1K.
This patch allows a maximum payload of 4k by allocating a full page.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c
index 49954442173dc938f441a24d46539bd25f3d1267..9e111d07f66747b200051955d9c21997187d4002 100644 (file)
--- a/fs/nfs/flexfilelayout/flexfilelayout.c
+++ b/fs/nfs/flexfilelayout/flexfilelayout.c
@@ -2049,16 +2049,28 @@ ff_layout_encode_layoutreturn(struct xdr_stream *xdr,
 {
        const struct nfs4_layoutreturn_args *args = voidargs;
        struct nfs4_flexfile_layoutreturn_args *ff_args = ff_opaque->data;
+       struct xdr_buf tmp_buf = {
+               .head = {
+                       [0] = {
+                               .iov_base = page_address(ff_args->pages[0]),
+                       },
+               },
+               .buflen = PAGE_SIZE,
+       };
+       struct xdr_stream tmp_xdr;
        __be32 *start;
 
        dprintk("%s: Begin\n", __func__);
-       start = xdr_reserve_space(xdr, 4);
-       BUG_ON(!start);
 
-       ff_layout_encode_ioerr(xdr, args, ff_args);
-       ff_layout_encode_iostats_array(xdr, args, ff_args);
+       xdr_init_encode(&tmp_xdr, &tmp_buf, NULL);
+
+       ff_layout_encode_ioerr(&tmp_xdr, args, ff_args);
+       ff_layout_encode_iostats_array(&tmp_xdr, args, ff_args);
+
+       start = xdr_reserve_space(xdr, 4);
+       *start = cpu_to_be32(tmp_buf.len);
+       xdr_write_pages(xdr, ff_args->pages, 0, tmp_buf.len);
 
-       *start = cpu_to_be32((xdr->p - start - 1) * 4);
        dprintk("%s: Return\n", __func__);
 }
 
@@ -2075,6 +2087,7 @@ ff_layout_free_layoutreturn(struct nfs4_xdr_opaque_data *args)
        ff_layout_free_ds_ioerr(&ff_args->errors);
        ff_layout_free_iostats_array(ff_args->devinfo, ff_args->num_dev);
 
+       put_page(ff_args->pages[0]);
        kfree(ff_args);
 }
 
@@ -2091,7 +2104,10 @@ ff_layout_prepare_layoutreturn(struct nfs4_layoutreturn_args *args)
 
        ff_args = kmalloc(sizeof(*ff_args), GFP_KERNEL);
        if (!ff_args)
-               return -ENOMEM;
+               goto out_nomem;
+       ff_args->pages[0] = alloc_page(GFP_KERNEL);
+       if (!ff_args->pages[0])
+               goto out_nomem_free;
 
        INIT_LIST_HEAD(&ff_args->errors);
        ff_args->num_errors = ff_layout_fetch_ds_ioerr(args->layout,
@@ -2106,6 +2122,10 @@ ff_layout_prepare_layoutreturn(struct nfs4_layoutreturn_args *args)
        args->ld_private->ops = &layoutreturn_ops;
        args->ld_private->data = ff_args;
        return 0;
+out_nomem_free:
+       kfree(ff_args);
+out_nomem:
+       return -ENOMEM;
 }
 
 static int

diff --git a/fs/nfs/flexfilelayout/flexfilelayout.h b/fs/nfs/flexfilelayout/flexfilelayout.h
index 7223c4ea8cdedfafae1dddef9476508d948d7d60..f4f39b0ab09b25170ed1f9f9a9a961ecadb9a5d2 100644 (file)
--- a/fs/nfs/flexfilelayout/flexfilelayout.h
+++ b/fs/nfs/flexfilelayout/flexfilelayout.h
@@ -113,6 +113,7 @@ struct nfs4_flexfile_layoutreturn_args {
        struct nfs42_layoutstat_devinfo devinfo[FF_LAYOUTSTATS_MAXDEV];
        unsigned int num_errors;
        unsigned int num_dev;
+       struct page *pages[1];
 };
 
 static inline struct nfs4_flexfile_layout *