NFSv4.1 Fix gdia_maxcount calculation to fit in ca_maxresponsesize

The GETDEVICEINFO gdia_maxcount represents all of the data being returned
within the GETDEVICEINFO4resok structure and includes the XDR overhead.

The CREATE_SESSION ca_maxresponsesize is the maximum reply and includes the RPC
headers (including security flavor credentials and verifiers).

Split out the struct pnfs_device field maxcount which is the gdia_maxcount
from the pglen field which is the reply (the total) buffer length.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

4 files changed, 11 insertions, 2 deletions

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 91e59a39fc08..4bd53f4e0fd2 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -255,6 +255,7 @@ extern int nfs4_decode_dirent(struct xdr_stream *,
 #ifdef CONFIG_NFS_V4_1
 extern const u32 nfs41_maxread_overhead;
 extern const u32 nfs41_maxwrite_overhead;
+extern const u32 nfs41_maxgetdevinfo_overhead;
 #endif
 
 /* nfs4proc.c */
diff --git a/fs/nfs/nfs4filelayoutdev.c b/fs/nfs/nfs4filelayoutdev.c
index 0493dbd129c5..95604f64cab8 100644
--- a/fs/nfs/nfs4filelayoutdev.c
+++ b/fs/nfs/nfs4filelayoutdev.c
@@ -711,6 +711,7 @@ filelayout_get_device_info(struct inode *inode,
         pdev->pgbase = 0;
         pdev->pglen = max_resp_sz;
         pdev->mincount = 0;
+        pdev->maxcount = max_resp_sz - nfs41_maxgetdevinfo_overhead;
 
         rc = nfs4_proc_getdeviceinfo(server, pdev, cred);
         dprintk("%s getdevice info returns %d\n", __func__, rc);
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 4be8d135ed61..27cc76d88f9a 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -853,6 +853,12 @@ const u32 nfs41_maxread_overhead = ((RPC_MAX_HEADER_WITH_AUTH +
                                      decode_sequence_maxsz +
                                      decode_putfh_maxsz) *
                                     XDR_UNIT);
+
+const u32 nfs41_maxgetdevinfo_overhead = ((RPC_MAX_REPHEADER_WITH_AUTH +
+                                           compound_decode_hdr_maxsz +
+                                           decode_sequence_maxsz) *
+                                          XDR_UNIT);
+EXPORT_SYMBOL_GPL(nfs41_maxgetdevinfo_overhead);
 #endif /* CONFIG_NFS_V4_1 */
 
 static const umode_t nfs_type2fmt[] = {
@@ -1889,7 +1895,7 @@ encode_getdeviceinfo(struct xdr_stream *xdr,
         p = xdr_encode_opaque_fixed(p, args->pdev->dev_id.data,
                                     NFS4_DEVICEID4_SIZE);
         *p++ = cpu_to_be32(args->pdev->layout_type);
-        *p++ = cpu_to_be32(args->pdev->pglen);          /* gdia_maxcount */
+        *p++ = cpu_to_be32(args->pdev->maxcount);       /* gdia_maxcount */
         *p++ = cpu_to_be32(0);                          /* bitmap length 0 */
 }
 
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index 1441dff9b0e7..a4f41810a7f4 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -149,9 +149,10 @@ struct pnfs_device {
         struct nfs4_deviceid dev_id;
         unsigned int  layout_type;
         unsigned int  mincount;
+        unsigned int  maxcount; /* gdia_maxcount */
         struct page **pages;
         unsigned int  pgbase;
-        unsigned int  pglen;
+        unsigned int  pglen;    /* reply buffer length */
 };
 
 #define NFS4_PNFS_GETDEVLIST_MAXNUM 16