dquot: cleanup space allocation / freeing routines

Get rid of the alloc_space, free_space, reserve_space, claim_space and
release_rsv dquot operations - they are always called from the filesystem
and if a filesystem really needs their own (which none currently does)
it can just call into it's own routine directly.

Move shared logic into the common __dquot_alloc_space,
dquot_claim_space_nodirty and __dquot_free_space low-level methods,
and rationalize the wrappers around it to move as much as possible
code into the common block for CONFIG_QUOTA vs not.  Also rename
all these helpers to be named dquot_* instead of vfs_dq_*.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
index 7f8d2e5..1d081f0 100644
--- a/fs/ext2/balloc.c
+++ b/fs/ext2/balloc.c
@@ -570,7 +570,7 @@
 error_return:
 	brelse(bitmap_bh);
 	release_blocks(sb, freed);
-	vfs_dq_free_block(inode, freed);
+	dquot_free_block(inode, freed);
 }
 
 /**
@@ -1236,6 +1236,7 @@
 	unsigned short windowsz = 0;
 	unsigned long ngroups;
 	unsigned long num = *count;
+	int ret;
 
 	*errp = -ENOSPC;
 	sb = inode->i_sb;
@@ -1247,8 +1248,9 @@
 	/*
 	 * Check quota for allocation of this block.
 	 */
-	if (vfs_dq_alloc_block(inode, num)) {
-		*errp = -EDQUOT;
+	ret = dquot_alloc_block(inode, num);
+	if (ret) {
+		*errp = ret;
 		return 0;
 	}
 
@@ -1409,7 +1411,7 @@
 
 	*errp = 0;
 	brelse(bitmap_bh);
-	vfs_dq_free_block(inode, *count-num);
+	dquot_free_block(inode, *count-num);
 	*count = num;
 	return ret_block;
 
@@ -1420,7 +1422,7 @@
 	 * Undo the block allocation
 	 */
 	if (!performed_allocation)
-		vfs_dq_free_block(inode, *count);
+		dquot_free_block(inode, *count);
 	brelse(bitmap_bh);
 	return 0;
 }
diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index 904f006..e44dc92 100644
--- a/fs/ext2/xattr.c
+++ b/fs/ext2/xattr.c
@@ -644,8 +644,8 @@
 				   the inode.  */
 				ea_bdebug(new_bh, "reusing block");
 
-				error = -EDQUOT;
-				if (vfs_dq_alloc_block(inode, 1)) {
+				error = dquot_alloc_block(inode, 1);
+				if (error) {
 					unlock_buffer(new_bh);
 					goto cleanup;
 				}
@@ -702,7 +702,7 @@
 		 * as if nothing happened and cleanup the unused block */
 		if (error && error != -ENOSPC) {
 			if (new_bh && new_bh != old_bh)
-				vfs_dq_free_block(inode, 1);
+				dquot_free_block(inode, 1);
 			goto cleanup;
 		}
 	} else
@@ -734,7 +734,7 @@
 			le32_add_cpu(&HDR(old_bh)->h_refcount, -1);
 			if (ce)
 				mb_cache_entry_release(ce);
-			vfs_dq_free_block(inode, 1);
+			dquot_free_block(inode, 1);
 			mark_buffer_dirty(old_bh);
 			ea_bdebug(old_bh, "refcount now=%d",
 				le32_to_cpu(HDR(old_bh)->h_refcount));
@@ -797,7 +797,7 @@
 		mark_buffer_dirty(bh);
 		if (IS_SYNC(inode))
 			sync_dirty_buffer(bh);
-		vfs_dq_free_block(inode, 1);
+		dquot_free_block(inode, 1);
 	}
 	EXT2_I(inode)->i_file_acl = 0;