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Diffstat (limited to 'fs/nfs/pnfs.c')
-rw-r--r--fs/nfs/pnfs.c140
1 files changed, 140 insertions, 0 deletions
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index cf795625610e..c0cd954855b9 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -166,3 +166,143 @@ pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
spin_unlock(&pnfs_spinlock);
}
EXPORT_SYMBOL_GPL(pnfs_unregister_layoutdriver);
+
+static void
+get_layout_hdr_locked(struct pnfs_layout_hdr *lo)
+{
+ assert_spin_locked(&lo->inode->i_lock);
+ lo->refcount++;
+}
+
+static void
+put_layout_hdr_locked(struct pnfs_layout_hdr *lo)
+{
+ assert_spin_locked(&lo->inode->i_lock);
+ BUG_ON(lo->refcount == 0);
+
+ lo->refcount--;
+ if (!lo->refcount) {
+ dprintk("%s: freeing layout cache %p\n", __func__, lo);
+ NFS_I(lo->inode)->layout = NULL;
+ kfree(lo);
+ }
+}
+
+void
+pnfs_destroy_layout(struct nfs_inode *nfsi)
+{
+ struct pnfs_layout_hdr *lo;
+
+ spin_lock(&nfsi->vfs_inode.i_lock);
+ lo = nfsi->layout;
+ if (lo) {
+ /* Matched by refcount set to 1 in alloc_init_layout_hdr */
+ put_layout_hdr_locked(lo);
+ }
+ spin_unlock(&nfsi->vfs_inode.i_lock);
+}
+
+/* STUB - pretend LAYOUTGET to server failed */
+static struct pnfs_layout_segment *
+send_layoutget(struct pnfs_layout_hdr *lo,
+ struct nfs_open_context *ctx,
+ u32 iomode)
+{
+ struct inode *ino = lo->inode;
+
+ set_bit(lo_fail_bit(iomode), &lo->state);
+ spin_lock(&ino->i_lock);
+ put_layout_hdr_locked(lo);
+ spin_unlock(&ino->i_lock);
+ return NULL;
+}
+
+static struct pnfs_layout_hdr *
+alloc_init_layout_hdr(struct inode *ino)
+{
+ struct pnfs_layout_hdr *lo;
+
+ lo = kzalloc(sizeof(struct pnfs_layout_hdr), GFP_KERNEL);
+ if (!lo)
+ return NULL;
+ lo->refcount = 1;
+ lo->inode = ino;
+ return lo;
+}
+
+static struct pnfs_layout_hdr *
+pnfs_find_alloc_layout(struct inode *ino)
+{
+ struct nfs_inode *nfsi = NFS_I(ino);
+ struct pnfs_layout_hdr *new = NULL;
+
+ dprintk("%s Begin ino=%p layout=%p\n", __func__, ino, nfsi->layout);
+
+ assert_spin_locked(&ino->i_lock);
+ if (nfsi->layout)
+ return nfsi->layout;
+
+ spin_unlock(&ino->i_lock);
+ new = alloc_init_layout_hdr(ino);
+ spin_lock(&ino->i_lock);
+
+ if (likely(nfsi->layout == NULL)) /* Won the race? */
+ nfsi->layout = new;
+ else
+ kfree(new);
+ return nfsi->layout;
+}
+
+/* STUB - LAYOUTGET never succeeds, so cache is empty */
+static struct pnfs_layout_segment *
+pnfs_has_layout(struct pnfs_layout_hdr *lo, u32 iomode)
+{
+ return NULL;
+}
+
+/*
+ * Layout segment is retreived from the server if not cached.
+ * The appropriate layout segment is referenced and returned to the caller.
+ */
+struct pnfs_layout_segment *
+pnfs_update_layout(struct inode *ino,
+ struct nfs_open_context *ctx,
+ enum pnfs_iomode iomode)
+{
+ struct nfs_inode *nfsi = NFS_I(ino);
+ struct pnfs_layout_hdr *lo;
+ struct pnfs_layout_segment *lseg = NULL;
+
+ if (!pnfs_enabled_sb(NFS_SERVER(ino)))
+ return NULL;
+ spin_lock(&ino->i_lock);
+ lo = pnfs_find_alloc_layout(ino);
+ if (lo == NULL) {
+ dprintk("%s ERROR: can't get pnfs_layout_hdr\n", __func__);
+ goto out_unlock;
+ }
+
+ /* Check to see if the layout for the given range already exists */
+ lseg = pnfs_has_layout(lo, iomode);
+ if (lseg) {
+ dprintk("%s: Using cached lseg %p for iomode %d)\n",
+ __func__, lseg, iomode);
+ goto out_unlock;
+ }
+
+ /* if LAYOUTGET already failed once we don't try again */
+ if (test_bit(lo_fail_bit(iomode), &nfsi->layout->state))
+ goto out_unlock;
+
+ get_layout_hdr_locked(lo);
+ spin_unlock(&ino->i_lock);
+
+ lseg = send_layoutget(lo, ctx, iomode);
+out:
+ dprintk("%s end, state 0x%lx lseg %p\n", __func__,
+ nfsi->layout->state, lseg);
+ return lseg;
+out_unlock:
+ spin_unlock(&ino->i_lock);
+ goto out;
+}