ceph: simplify ceph_buffer interface

We never allocate the ceph_buffer and buffer separtely, so use a single
constructor.

Disallow put on NULL buffer; make the caller check.
Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/buffer.c

@@ -2,23 +2,38 @@
 #include "ceph_debug.h"
 #include "buffer.h"
 
-struct ceph_buffer *ceph_buffer_new(gfp_t gfp)
+struct ceph_buffer *ceph_buffer_new(size_t len, gfp_t gfp)
 {
 	struct ceph_buffer *b;
 
 	b = kmalloc(sizeof(*b), gfp);
 	if (!b)
 		return NULL;
+
+	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);
+		if (!b->vec.iov_base) {
+			kfree(b);
+			return NULL;
+		}
+		b->is_vmalloc = true;
+	}
+
 	kref_init(&b->kref);
-	b->vec.iov_base = NULL;
-	b->vec.iov_len = 0;
-	b->alloc_len = 0;
+	b->alloc_len = len;
+	b->vec.iov_len = len;
+	dout("buffer_new %p\n", b);
 	return b;
 }
 
 void ceph_buffer_release(struct kref *kref)
 {
 	struct ceph_buffer *b = container_of(kref, struct ceph_buffer, kref);
+
+	dout("buffer_release %p\n", b);
 	if (b->vec.iov_base) {
 		if (b->is_vmalloc)
 			vfree(b->vec.iov_base);

fs/ceph/buffer.h

@@ -20,8 +20,8 @@ struct ceph_buffer {
 	bool is_vmalloc;
 };
 
-struct ceph_buffer *ceph_buffer_new(gfp_t gfp);
-int ceph_buffer_alloc(struct ceph_buffer *b, int len, gfp_t gfp);
+extern struct ceph_buffer *ceph_buffer_new(size_t len, gfp_t gfp);
+extern void ceph_buffer_release(struct kref *kref);
 
 static inline struct ceph_buffer *ceph_buffer_get(struct ceph_buffer *b)
 {
@@ -29,23 +29,9 @@ static inline struct ceph_buffer *ceph_buffer_get(struct ceph_buffer *b)
 	return b;
 }
 
-void ceph_buffer_release(struct kref *kref);
-
 static inline void ceph_buffer_put(struct ceph_buffer *b)
 {
-	if (b)
 	kref_put(&b->kref, ceph_buffer_release);
 }
 
-static inline struct ceph_buffer *ceph_buffer_new_alloc(int len, gfp_t gfp)
-{
-	struct ceph_buffer *b = ceph_buffer_new(gfp);
-
-	if (b && ceph_buffer_alloc(b, len, gfp) < 0) {
-		ceph_buffer_put(b);
-		b = NULL;
-	}
-	return b;
-}
-
 #endif

fs/ceph/inode.c

@@ -383,7 +383,9 @@ void ceph_destroy_inode(struct inode *inode)
 	}
 
 	__ceph_destroy_xattrs(ci);
+	if (ci->i_xattrs.blob)
 		ceph_buffer_put(ci->i_xattrs.blob);
+	if (ci->i_xattrs.prealloc_blob)
 		ceph_buffer_put(ci->i_xattrs.prealloc_blob);
 
 	kmem_cache_free(ceph_inode_cachep, ci);
@@ -526,7 +528,7 @@ static int fill_inode(struct inode *inode,
 	 * bytes are the xattr count).
 	 */
 	if (iinfo->xattr_len > 4) {
-		xattr_blob = ceph_buffer_new_alloc(iinfo->xattr_len, GFP_NOFS);
+		xattr_blob = ceph_buffer_new(iinfo->xattr_len, GFP_NOFS);
 		if (!xattr_blob)
 			pr_err("fill_inode ENOMEM xattr blob %d bytes\n",
 			       iinfo->xattr_len);
@@ -715,6 +717,7 @@ static int fill_inode(struct inode *inode,
 	err = 0;
 
 out:
+	if (xattr_blob)
 		ceph_buffer_put(xattr_blob);
 	return err;
 }

fs/ceph/messenger.c

@@ -2047,7 +2047,7 @@ int ceph_alloc_middle(struct ceph_connection *con, struct ceph_msg *msg)
 	BUG_ON(!middle_len);
 	BUG_ON(msg->middle);
 
-	msg->middle = ceph_buffer_new_alloc(middle_len, GFP_NOFS);
+	msg->middle = ceph_buffer_new(middle_len, GFP_NOFS);
 	if (!msg->middle)
 		return -ENOMEM;
 	return 0;

fs/ceph/xattr.c

@@ -482,6 +482,7 @@ void __ceph_build_xattrs_blob(struct ceph_inode_info *ci)
 		ci->i_xattrs.prealloc_blob->vec.iov_len =
 			dest - ci->i_xattrs.prealloc_blob->vec.iov_base;
 
+		if (ci->i_xattrs.blob)
 			ceph_buffer_put(ci->i_xattrs.blob);
 		ci->i_xattrs.blob = ci->i_xattrs.prealloc_blob;
 		ci->i_xattrs.prealloc_blob = NULL;
@@ -745,10 +746,11 @@ int ceph_setxattr(struct dentry *dentry, const char *name,
 
 		spin_unlock(&inode->i_lock);
 		dout(" preaallocating new blob size=%d\n", required_blob_size);
-		blob = ceph_buffer_new_alloc(required_blob_size, GFP_NOFS);
+		blob = ceph_buffer_new(required_blob_size, GFP_NOFS);
 		if (!blob)
 			goto out;
 		spin_lock(&inode->i_lock);
+		if (ci->i_xattrs.prealloc_blob)
 			ceph_buffer_put(ci->i_xattrs.prealloc_blob);
 		ci->i_xattrs.prealloc_blob = blob;
 		goto retry;