ceph: ref counted buffer

struct ceph_buffer is a simple ref-counted buffer.  We transparently
choose between kmalloc for small buffers and vmalloc for large ones.

This is currently used only for allocating memory for xattr data.

Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 34 insertions, 0 deletions

diff --git a/fs/ceph/buffer.c b/fs/ceph/buffer.c
new file mode 100644
index 00000000000..cf9aaccef22
--- /dev/null
+++ b/fs/ceph/buffer.c
@@ -0,0 +1,34 @@
+
+#include "ceph_debug.h"
+#include "buffer.h"
+
+struct ceph_buffer *ceph_buffer_new(gfp_t gfp)
+{
+	struct ceph_buffer *b;
+
+	b = kmalloc(sizeof(*b), gfp);
+	if (!b)
+		return NULL;
+	atomic_set(&b->nref, 1);
+	b->vec.iov_base = NULL;
+	b->vec.iov_len = 0;
+	b->alloc_len = 0;
+	return b;
+}
+
+int ceph_buffer_alloc(struct ceph_buffer *b, int len, gfp_t gfp)
+{
+	b->vec.iov_base = kmalloc(len, gfp | __GFP_NOWARN);
+	if (b->vec.iov_base) {
+		b->is_vmalloc = false;
+	} else {
+		b->vec.iov_base = __vmalloc(len, gfp, PAGE_KERNEL);
+		b->is_vmalloc = true;
+	}
+	if (!b->vec.iov_base)
+		return -ENOMEM;
+	b->alloc_len = len;
+	b->vec.iov_len = len;
+	return 0;
+}
+