From: Darrick J. Wong <djwong@xxxxxxxxxx>
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.
Christoph requested this as a separate patch to reduce the size
of the upcoming quotacheck patch.
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
fs/xfs/scrub/xfarray.h | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
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)
{
