From: Darrick J. Wong <djwong@kernel.org>
Date: Thu, 22 Feb 2024 20:30:54 +0000 (-0800)
Subject: xfs: create a sparse load xfarray function
X-Git-Tag: v6.9-rc1~129^2~23^2~4
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=5a3ab5849583217090e29299c7bee88b827c12d8;p=thirdparty%2Fkernel%2Flinux.git

xfs: create a sparse load xfarray function

Create a new method to load an xfarray element from the xfile, but with
a twist.  If we've never stored to the array index, zero the caller's
buffer.  This will facilitate RMWs updates of records in a sparse array
without fuss, since the sparse xfarray convention is that uninitialized
array elements default to zeroes.

This is a separate patch to reduce the size of the upcoming quotacheck
patch.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---

diff --git a/fs/xfs/scrub/xfarray.h b/fs/xfs/scrub/xfarray.h
index ec643cc9fc143..acb2f94c56c13 100644
--- a/fs/xfs/scrub/xfarray.h
+++ b/fs/xfs/scrub/xfarray.h
@@ -45,6 +45,25 @@ int xfarray_store(struct xfarray *array, xfarray_idx_t idx, const void *ptr);
 int xfarray_store_anywhere(struct xfarray *array, const void *ptr);
 bool xfarray_element_is_null(struct xfarray *array, const void *ptr);
 
+/*
+ * Load an array element, but zero the buffer if there's no data because we
+ * haven't stored to that array element yet.
+ */
+static inline int
+xfarray_load_sparse(
+	struct xfarray	*array,
+	uint64_t	idx,
+	void		*rec)
+{
+	int		error = xfarray_load(array, idx, rec);
+
+	if (error == -ENODATA) {
+		memset(rec, 0, array->obj_size);
+		return 0;
+	}
+	return error;
+}
+
 /* Append an element to the array. */
 static inline int xfarray_append(struct xfarray *array, const void *ptr)
 {