linux-kernel - [PATCH v7 23/61] xarray: Add xas_create

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Message-Id: <20180219194556.6575-24-willy@infradead.org>
Date:   Mon, 19 Feb 2018 11:45:18 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Matthew Wilcox <mawilcox@...rosoft.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org
Subject: [PATCH v7 23/61] xarray: Add xas_create_range

From: Matthew Wilcox <mawilcox@...rosoft.com>

This hopefully temporary function is useful for users who have not yet
been converted to multi-index entries.

Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
---
 include/linux/xarray.h |  2 ++
 lib/xarray.c           | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index c8a0ddc1b3df..387be18d05ba 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -744,6 +744,8 @@ void xas_init_tags(const struct xa_state *);
 bool xas_nomem(struct xa_state *, gfp_t);
 void xas_pause(struct xa_state *);
 
+void xas_create_range(struct xa_state *, unsigned long max);
+
 /**
  * xas_reload() - Refetch an entry from the xarray.
  * @xas: XArray operation state.
diff --git a/lib/xarray.c b/lib/xarray.c
index 7cf195b6e740..1d94ecc2dca3 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -612,6 +612,28 @@ void *xas_create(struct xa_state *xas)
 }
 EXPORT_SYMBOL_GPL(xas_create);
 
+/**
+ * xas_create_range() - Ensure that stores to this range will succeed
+ * @xas: XArray operation state.
+ * @max: The highest index to create a slot for.
+ *
+ * Creates all of the slots in the range between the current position of
+ * @xas and @max.  This is for the benefit of users who have not yet been
+ * converted to multi-index entries.
+ *
+ * The implementation is naive.
+ */
+void xas_create_range(struct xa_state *xas, unsigned long max)
+{
+	XA_STATE(tmp, xas->xa, xas->xa_index);
+
+	do {
+		xas_create(&tmp);
+		xas_set(&tmp, tmp.xa_index + XA_CHUNK_SIZE);
+	} while (tmp.xa_index < max);
+}
+EXPORT_SYMBOL_GPL(xas_create_range);
+
 static void store_siblings(struct xa_state *xas, void *entry, void *curr,
 				int *countp, int *valuesp)
 {
-- 
2.16.1