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Date: Mon, 11 Jun 2018 07:05:43 -0700
From: Matthew Wilcox <willy@...radead.org>
To: linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Matthew Wilcox <mawilcox@...rosoft.com>, Jan Kara <jack@...e.cz>,
Jeff Layton <jlayton@...hat.com>,
Lukas Czerner <lczerner@...hat.com>,
Ross Zwisler <ross.zwisler@...ux.intel.com>,
Christoph Hellwig <hch@....de>,
Goldwyn Rodrigues <rgoldwyn@...e.com>,
Nicholas Piggin <npiggin@...il.com>,
Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>,
linux-nilfs@...r.kernel.org, Jaegeuk Kim <jaegeuk@...nel.org>,
Chao Yu <yuchao0@...wei.com>,
linux-f2fs-devel@...ts.sourceforge.net
Subject: [PATCH v13 16/72] xarray: Add xas_for_each_conflict
From: Matthew Wilcox <mawilcox@...rosoft.com>
This iterator iterates over each entry that is stored in the index or
indices specified by the xa_state. This is intended for use for a
conditional store of a multiindex entry, or to allow entries which are
about to be removed from the xarray to be disposed of properly.
Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
---
include/linux/xarray.h | 17 +++++++
lib/xarray.c | 61 +++++++++++++++++++++++++
tools/testing/radix-tree/xarray-test.c | 63 ++++++++++++++++++++++++++
3 files changed, 141 insertions(+)
diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index dd941454bb5b..6a61aab11038 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -750,6 +750,7 @@ static inline bool xas_retry(struct xa_state *xas, const void *entry)
void *xas_load(struct xa_state *);
void *xas_store(struct xa_state *, void *entry);
void *xas_find(struct xa_state *, unsigned long max);
+void *xas_next_conflict(struct xa_state *);
bool xas_get_tag(const struct xa_state *, xa_tag_t);
void xas_set_tag(const struct xa_state *, xa_tag_t);
@@ -964,6 +965,22 @@ enum {
for (entry = xas_find_tagged(xas, max, tag); entry; \
entry = xas_next_tagged(xas, max, tag))
+/**
+ * xas_for_each_conflict() - Iterate over a range of an XArray.
+ * @xas: XArray operation state.
+ * @entry: Entry retrieved from the array.
+ *
+ * The loop body will be executed for each entry in the XArray that lies
+ * within the range specified by @xas. If the loop completes successfully,
+ * any entries that lie in this range will be replaced by @entry. The caller
+ * may break out of the loop; if they do so, the contents of the XArray will
+ * be unchanged. The operation may fail due to an out of memory condition.
+ * The caller may also call xa_set_err() to exit the loop while setting an
+ * error to record the reason.
+ */
+#define xas_for_each_conflict(xas, entry) \
+ while ((entry = xas_next_conflict(xas)))
+
void *__xas_next(struct xa_state *);
void *__xas_prev(struct xa_state *);
diff --git a/lib/xarray.c b/lib/xarray.c
index 3b2c2f2240bf..d76db0ff17cf 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1100,6 +1100,67 @@ void *xas_find_tagged(struct xa_state *xas, unsigned long max, xa_tag_t tag)
}
EXPORT_SYMBOL_GPL(xas_find_tagged);
+/**
+ * xas_next_conflict() - Step for xas_for_each_conflict().
+ * @xas: XArray operation state.
+ *
+ * This function does the work for xas_for_each_conflict().
+ *
+ * Context: Any context. Expects xa_lock to be held.
+ * Return: The next entry in the range covered by @xas or %NULL.
+ */
+void *xas_next_conflict(struct xa_state *xas)
+{
+ void *curr;
+
+ if (xas_error(xas))
+ return NULL;
+
+ if (!xas->xa_node)
+ return NULL;
+
+ if (xas_top(xas->xa_node)) {
+ curr = xas_start(xas);
+ if (!curr)
+ return NULL;
+ while (xa_is_node(curr)) {
+ struct xa_node *node = xa_to_node(curr);
+ curr = xas_descend(xas, node);
+ }
+ if (curr)
+ return curr;
+ }
+
+ if (xas->xa_node->shift > xas->xa_shift)
+ return NULL;
+
+ for (;;) {
+ if (xas->xa_node->shift == xas->xa_shift) {
+ if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
+ break;
+ } else if (xas->xa_offset == XA_CHUNK_MASK) {
+ xas->xa_offset = xas->xa_node->offset;
+ xas->xa_node = xas->xa_node->parent;
+ if (!xas->xa_node)
+ break;
+ continue;
+ }
+ curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
+ if (xa_is_sibling(curr))
+ continue;
+ while (xa_is_node(curr)) {
+ xas->xa_node = xa_to_node(curr);
+ xas->xa_offset = 0;
+ curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
+ }
+ if (curr)
+ return curr;
+ }
+ xas->xa_offset -= xas->xa_sibs;
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(xas_next_conflict);
+
/**
* xa_init_flags() - Initialise an empty XArray with flags.
* @xa: XArray.
diff --git a/tools/testing/radix-tree/xarray-test.c b/tools/testing/radix-tree/xarray-test.c
index eeafbf8c948c..296ace77c4f4 100644
--- a/tools/testing/radix-tree/xarray-test.c
+++ b/tools/testing/radix-tree/xarray-test.c
@@ -315,6 +315,68 @@ void check_multi_store(struct xarray *xa)
BUG_ON(!xa_empty(xa));
}
+void __check_store_iter(struct xarray *xa, unsigned long start,
+ unsigned int order, unsigned int present)
+{
+ XA_STATE_ORDER(xas, xa, start, order);
+ void *entry;
+ unsigned int count = 0;
+
+retry:
+ xas_for_each_conflict(&xas, entry) {
+ BUG_ON(!xa_is_value(entry));
+ BUG_ON(entry < xa_mk_value(start));
+ BUG_ON(entry > xa_mk_value(start + (1UL << order) - 1));
+ count++;
+ }
+ xas_store(&xas, xa_mk_value(start));
+ if (xas_nomem(&xas, GFP_KERNEL)) {
+ count = 0;
+ goto retry;
+ }
+ BUG_ON(xas_error(&xas));
+ BUG_ON(count != present);
+ BUG_ON(xa_load(xa, start) != xa_mk_value(start));
+ BUG_ON(xa_load(xa, start + (1UL << order) - 1) != xa_mk_value(start));
+ xa_store(xa, start, NULL, 0);
+}
+
+void check_store_iter(struct xarray *xa)
+{
+ unsigned int i, j;
+
+ for (i = 0; i < 20; i++) {
+ unsigned int min = 1 << i;
+ unsigned int max = (2 << i) - 1;
+ __check_store_iter(xa, 0, i, 0);
+ BUG_ON(!xa_empty(xa));
+ __check_store_iter(xa, min, i, 0);
+ BUG_ON(!xa_empty(xa));
+
+ xa_store(xa, min, xa_mk_value(min), GFP_KERNEL);
+ __check_store_iter(xa, min, i, 1);
+ BUG_ON(!xa_empty(xa));
+ xa_store(xa, max, xa_mk_value(max), GFP_KERNEL);
+ __check_store_iter(xa, min, i, 1);
+ BUG_ON(!xa_empty(xa));
+
+ for (j = 0; j < min; j++)
+ xa_store(xa, j, xa_mk_value(j), GFP_KERNEL);
+ __check_store_iter(xa, 0, i, min);
+ BUG_ON(!xa_empty(xa));
+ for (j = 0; j < min; j++)
+ xa_store(xa, min + j, xa_mk_value(min + j), GFP_KERNEL);
+ __check_store_iter(xa, min, i, min);
+ BUG_ON(!xa_empty(xa));
+ }
+ xa_store(xa, 63, xa_mk_value(63), GFP_KERNEL);
+ xa_store(xa, 65, xa_mk_value(65), GFP_KERNEL);
+ __check_store_iter(xa, 64, 2, 1);
+ BUG_ON(xa_load(xa, 63) != xa_mk_value(63));
+ xa_store(xa, 63, NULL, 0);
+ BUG_ON(!xa_empty(xa));
+}
+
void check_multi_find(struct xarray *xa)
{
unsigned long index;
@@ -537,6 +599,7 @@ void xarray_checks(void)
check_cmpxchg(&array);
check_multi_store(&array);
item_kill_tree(&array);
+ check_store_iter(&array);
check_find(&array);
check_xas_delete(&array);
--
2.17.1
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