NFS: create and destroy inode's layout cache

At the start of the io paths, try to grab the relevant layout
information.  This will initiate the inode's layout cache, but
stubs ensure the cache stays empty.

Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Dean Hildebrand <dhildebz@umich.edu>
Signed-off-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: Tao Guo <guotao@nrchpc.ac.cn>
Signed-off-by: Ricardo Labiaga <ricardo.labiaga@netapp.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index 61531f338576..4ed1b48c71b1 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -34,6 +34,11 @@
 
 #define LAYOUT_NFSV4_1_MODULE_PREFIX "nfs-layouttype4"
 
+enum {
+        NFS_LAYOUT_RO_FAILED = 0,       /* get ro layout failed stop trying */
+        NFS_LAYOUT_RW_FAILED,           /* get rw layout failed stop trying */
+};
+
 /* Per-layout driver specific registration structure */
 struct pnfs_layoutdriver_type {
         struct list_head pnfs_tblid;
@@ -44,14 +49,48 @@ struct pnfs_layoutdriver_type {
         int (*uninitialize_mountpoint) (struct nfs_server *);
 };
 
+struct pnfs_layout_hdr {
+        unsigned long           refcount;
+        unsigned long           state;
+        struct inode            *inode;
+};
+
 extern int pnfs_register_layoutdriver(struct pnfs_layoutdriver_type *);
 extern void pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *);
 
+struct pnfs_layout_segment *
+pnfs_update_layout(struct inode *ino, struct nfs_open_context *ctx,
+                   enum pnfs_iomode access_type);
 void set_pnfs_layoutdriver(struct nfs_server *, u32 id);
 void unset_pnfs_layoutdriver(struct nfs_server *);
+void pnfs_destroy_layout(struct nfs_inode *);
+
+
+static inline int lo_fail_bit(u32 iomode)
+{
+        return iomode == IOMODE_RW ?
+                         NFS_LAYOUT_RW_FAILED : NFS_LAYOUT_RO_FAILED;
+}
+
+/* Return true if a layout driver is being used for this mountpoint */
+static inline int pnfs_enabled_sb(struct nfs_server *nfss)
+{
+        return nfss->pnfs_curr_ld != NULL;
+}
 
 #else  /* CONFIG_NFS_V4_1 */
 
+static inline void pnfs_destroy_layout(struct nfs_inode *nfsi)
+{
+}
+
+static inline struct pnfs_layout_segment *
+pnfs_update_layout(struct inode *ino, struct nfs_open_context *ctx,
+                   enum pnfs_iomode access_type)
+{
+        return NULL;
+}
+
 static inline void set_pnfs_layoutdriver(struct nfs_server *s, u32 id)
 {
 }