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From: Matthew Wilcox <willy@infradead.org>
To: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: Matthew Wilcox <willy@infradead.org>, Jan Kara <jack@suse.cz>,
	Jeff Layton <jlayton@redhat.com>,
	Lukas Czerner <lczerner@redhat.com>,
	Ross Zwisler <ross.zwisler@linux.intel.com>,
	Christoph Hellwig <hch@lst.de>,
	Goldwyn Rodrigues <rgoldwyn@suse.com>,
	Nicholas Piggin <npiggin@gmail.com>,
	Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>,
	linux-nilfs@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>,
	Chao Yu <yuchao0@huawei.com>,
	linux-f2fs-devel@lists.sourceforge.net
Subject: [PATCH v14 16/74] xarray: Step through an XArray
Date: Sat, 16 Jun 2018 18:59:54 -0700	[thread overview]
Message-ID: <20180617020052.4759-17-willy@infradead.org> (raw)
In-Reply-To: <20180617020052.4759-1-willy@infradead.org>

The xas_next and xas_prev functions move the xas index by one position,
and adjust the rest of the iterator state to match it.  This is more
efficient than calling xas_set() as it keeps the iterator at the leaves
of the tree instead of walking the iterator from the root each time.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/xarray.h |  67 +++++++++++++++++++++++++
 lib/test_xarray.c      | 109 +++++++++++++++++++++++++++++++++++++++++
 lib/xarray.c           |  74 ++++++++++++++++++++++++++++
 3 files changed, 250 insertions(+)

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index fa36a0670988..921d41034d7d 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -719,6 +719,12 @@ static inline bool xas_not_node(struct xa_node *node)
 	return ((unsigned long)node & 3) || !node;
 }
 
+/* True if the node represents RESTART or an error */
+static inline bool xas_frozen(struct xa_node *node)
+{
+	return (unsigned long)node & 2;
+}
+
 /* True if the node represents head-of-tree, RESTART or BOUNDS */
 static inline bool xas_top(struct xa_node *node)
 {
@@ -977,6 +983,67 @@ enum {
 	for (entry = xas_find_tagged(xas, max, tag); entry; \
 	     entry = xas_next_tagged(xas, max, tag))
 
+void *__xas_next(struct xa_state *);
+void *__xas_prev(struct xa_state *);
+
+/**
+ * xas_prev() - Move iterator to previous index.
+ * @xas: XArray operation state.
+ *
+ * If the @xas was in an error state, it will remain in an error state
+ * and this function will return %NULL.  If the @xas has never been walked,
+ * it will have the effect of calling xas_load().  Otherwise one will be
+ * subtracted from the index and the state will be walked to the correct
+ * location in the array for the next operation.
+ *
+ * If the iterator was referencing index 0, this function wraps
+ * around to %ULONG_MAX.
+ *
+ * Return: The entry at the new index.  This may be %NULL or an internal
+ * entry.
+ */
+static inline void *xas_prev(struct xa_state *xas)
+{
+	struct xa_node *node = xas->xa_node;
+
+	if (unlikely(xas_not_node(node) || node->shift ||
+				xas->xa_offset == 0))
+		return __xas_prev(xas);
+
+	xas->xa_index--;
+	xas->xa_offset--;
+	return xa_entry(xas->xa, node, xas->xa_offset);
+}
+
+/**
+ * xas_next() - Move state to next index.
+ * @xas: XArray operation state.
+ *
+ * If the @xas was in an error state, it will remain in an error state
+ * and this function will return %NULL.  If the @xas has never been walked,
+ * it will have the effect of calling xas_load().  Otherwise one will be
+ * added to the index and the state will be walked to the correct
+ * location in the array for the next operation.
+ *
+ * If the iterator was referencing index %ULONG_MAX, this function wraps
+ * around to 0.
+ *
+ * Return: The entry at the new index.  This may be %NULL or an internal
+ * entry.
+ */
+static inline void *xas_next(struct xa_state *xas)
+{
+	struct xa_node *node = xas->xa_node;
+
+	if (unlikely(xas_not_node(node) || node->shift ||
+				xas->xa_offset == XA_CHUNK_MASK))
+		return __xas_next(xas);
+
+	xas->xa_index++;
+	xas->xa_offset++;
+	return xa_entry(xas->xa, node, xas->xa_offset);
+}
+
 /* Internal functions, mostly shared between radix-tree.c, xarray.c and idr.c */
 void xas_destroy(struct xa_state *);
 
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index a6a3705165ca..e74ade12c663 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -384,6 +384,114 @@ static void check_find(struct xarray *xa)
 	check_multi_find(xa);
 }
 
+static void check_move_small(struct xarray *xa, unsigned long idx)
+{
+	XA_STATE(xas, xa, 0);
+	unsigned long i;
+
+	xa_store_value(xa, 0, GFP_KERNEL);
+	xa_store_value(xa, idx, GFP_KERNEL);
+
+	for (i = 0; i < idx * 4; i++) {
+		void *entry = xas_next(&xas);
+		if (i <= idx)
+			XA_BUG_ON(xa, xas.xa_node == XAS_RESTART);
+		XA_BUG_ON(xa, xas.xa_index != i);
+		if (i == 0 || i == idx)
+			XA_BUG_ON(xa, entry != xa_mk_value(i));
+		else
+			XA_BUG_ON(xa, entry != NULL);
+	}
+	xas_next(&xas);
+	XA_BUG_ON(xa, xas.xa_index != i);
+
+	do {
+		void *entry = xas_prev(&xas);
+		i--;
+		if (i <= idx)
+			XA_BUG_ON(xa, xas.xa_node == XAS_RESTART);
+		XA_BUG_ON(xa, xas.xa_index != i);
+		if (i == 0 || i == idx)
+			XA_BUG_ON(xa, entry != xa_mk_value(i));
+		else
+			XA_BUG_ON(xa, entry != NULL);
+	} while (i > 0);
+
+	xas_set(&xas, ULONG_MAX);
+	XA_BUG_ON(xa, xas_next(&xas) != NULL);
+	XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
+	XA_BUG_ON(xa, xas_next(&xas) != xa_mk_value(0));
+	XA_BUG_ON(xa, xas.xa_index != 0);
+	XA_BUG_ON(xa, xas_prev(&xas) != NULL);
+	XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
+
+	xa_erase_value(xa, 0);
+	xa_erase_value(xa, idx);
+	XA_BUG_ON(xa, !xa_empty(xa));
+}
+
+static void check_move(struct xarray *xa)
+{
+	XA_STATE(xas, xa, (1 << 16) - 1);
+	unsigned long i;
+
+	for (i = 0; i < (1 << 16); i++)
+		XA_BUG_ON(xa, xa_store_value(xa, i, GFP_KERNEL) != NULL);
+
+	do {
+		void *entry = xas_prev(&xas);
+		i--;
+		XA_BUG_ON(xa, entry != xa_mk_value(i));
+		XA_BUG_ON(xa, i != xas.xa_index);
+	} while (i != 0);
+
+	XA_BUG_ON(xa, xas_prev(&xas) != NULL);
+	XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
+
+	do {
+		void *entry = xas_next(&xas);
+		XA_BUG_ON(xa, entry != xa_mk_value(i));
+		XA_BUG_ON(xa, i != xas.xa_index);
+		i++;
+	} while (i < (1 << 16));
+
+	for (i = (1 << 8); i < (1 << 15); i++)
+		xa_erase_value(xa, i);
+
+	i = xas.xa_index;
+
+	do {
+		void *entry = xas_prev(&xas);
+		i--;
+		if ((i < (1 << 8)) || (i >= (1 << 15)))
+			XA_BUG_ON(xa, entry != xa_mk_value(i));
+		else
+			XA_BUG_ON(xa, entry != NULL);
+		XA_BUG_ON(xa, i != xas.xa_index);
+	} while (i != 0);
+
+	XA_BUG_ON(xa, xas_prev(&xas) != NULL);
+	XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
+
+	do {
+		void *entry = xas_next(&xas);
+		if ((i < (1 << 8)) || (i >= (1 << 15)))
+			XA_BUG_ON(xa, entry != xa_mk_value(i));
+		else
+			XA_BUG_ON(xa, entry != NULL);
+		XA_BUG_ON(xa, i != xas.xa_index);
+		i++;
+	} while (i < (1 << 16));
+
+	xa_destroy(xa);
+
+	for (i = 0; i < 16; i++)
+		check_move_small(xa, 1UL << i);
+
+	for (i = 2; i < 16; i++)
+		check_move_small(xa, (1UL << i) - 1);
+}
+
 static int xarray_checks(void)
 {
 	DEFINE_XARRAY(array);
@@ -397,6 +505,7 @@ static int xarray_checks(void)
 	check_cmpxchg(&array);
 	check_multi_store(&array);
 	check_find(&array);
+	check_move(&array);
 
 	printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
 	return (tests_run != tests_passed) ? 0 : -EINVAL;
diff --git a/lib/xarray.c b/lib/xarray.c
index e90ba76404ae..ab1b6786711e 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -863,6 +863,80 @@ void xas_pause(struct xa_state *xas)
 }
 EXPORT_SYMBOL_GPL(xas_pause);
 
+/*
+ * __xas_prev() - Find the previous entry in the XArray.
+ * @xas: XArray operation state.
+ *
+ * Helper function for xas_prev() which handles all the complex cases
+ * out of line.
+ */
+void *__xas_prev(struct xa_state *xas)
+{
+	void *entry;
+
+	if (!xas_frozen(xas->xa_node))
+		xas->xa_index--;
+	if (xas_not_node(xas->xa_node))
+		return xas_load(xas);
+
+	if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
+		xas->xa_offset--;
+
+	while (xas->xa_offset == 255) {
+		xas->xa_offset = xas->xa_node->offset - 1;
+		xas->xa_node = xa_parent(xas->xa, xas->xa_node);
+		if (!xas->xa_node)
+			return set_bounds(xas);
+	}
+
+	for (;;) {
+		entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+		if (!xa_is_node(entry))
+			return entry;
+
+		xas->xa_node = xa_to_node(entry);
+		xas_set_offset(xas);
+	}
+}
+EXPORT_SYMBOL_GPL(__xas_prev);
+
+/*
+ * __xas_next() - Find the next entry in the XArray.
+ * @xas: XArray operation state.
+ *
+ * Helper function for xas_next() which handles all the complex cases
+ * out of line.
+ */
+void *__xas_next(struct xa_state *xas)
+{
+	void *entry;
+
+	if (!xas_frozen(xas->xa_node))
+		xas->xa_index++;
+	if (xas_not_node(xas->xa_node))
+		return xas_load(xas);
+
+	if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
+		xas->xa_offset++;
+
+	while (xas->xa_offset == XA_CHUNK_SIZE) {
+		xas->xa_offset = xas->xa_node->offset + 1;
+		xas->xa_node = xa_parent(xas->xa, xas->xa_node);
+		if (!xas->xa_node)
+			return set_bounds(xas);
+	}
+
+	for (;;) {
+		entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+		if (!xa_is_node(entry))
+			return entry;
+
+		xas->xa_node = xa_to_node(entry);
+		xas_set_offset(xas);
+	}
+}
+EXPORT_SYMBOL_GPL(__xas_next);
+
 /**
  * xas_find() - Find the next present entry in the XArray.
  * @xas: XArray operation state.
-- 
2.17.1

  parent reply	other threads:[~2018-06-17  1:59 UTC|newest]

Thread overview: 90+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 01/74] Update email address Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 02/74] radix tree test suite: Enable ubsan Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 03/74] dax: Fix use of zero page Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 04/74] xarray: Replace exceptional entries Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 05/74] xarray: Change definition of sibling entries Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 06/74] xarray: Add definition of struct xarray Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 07/74] xarray: Define struct xa_node Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 08/74] xarray: Add documentation Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 09/74] xarray: Add XArray load operation Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 10/74] xarray: Add XArray tags Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 11/74] xarray: Add XArray unconditional store operations Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 12/74] xarray: Add XArray conditional " Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 13/74] xarray: Add XArray iterators Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 14/74] xarray: Extract entries from an XArray Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 15/74] xarray: Destroy " Matthew Wilcox
2018-06-17  1:59 ` Matthew Wilcox [this message]
2018-06-17  1:59 ` [PATCH v14 17/74] xarray: Add xas_for_each_conflict Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 18/74] xarray: Add xas_create_range Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 19/74] xarray: Add MAINTAINERS entry Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 20/74] page cache: Rearrange address_space Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 21/74] page cache: Convert hole search to XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 22/74] page cache: Add and replace pages using the XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 23/74] page cache: Convert page deletion to XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 24/74] page cache: Convert find_get_entry " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 25/74] page cache: Convert find_get_entries " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 26/74] page cache: Convert find_get_pages_range " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 27/74] page cache: Convert find_get_pages_contig " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 28/74] page cache; Convert find_get_pages_range_tag " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 29/74] page cache: Convert find_get_entries_tag " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 30/74] page cache: Convert filemap_map_pages " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 31/74] radix tree test suite: Convert regression1 " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 32/74] page cache: Convert delete_batch " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 33/74] page cache: Remove stray radix comment Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 34/74] page cache: Convert filemap_range_has_page to XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 35/74] mm: Convert page-writeback " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 36/74] mm: Convert workingset " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 37/74] mm: Convert truncate " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 38/74] mm: Convert add_to_swap_cache " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 39/74] mm: Convert delete_from_swap_cache " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 40/74] mm: Convert __do_page_cache_readahead " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 41/74] mm: Convert page migration " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 42/74] mm: Convert huge_memory " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 43/74] mm: Convert collapse_shmem " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 44/74] mm: Convert khugepaged_scan_shmem " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 45/74] mm: Convert is_page_cache_freeable " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 46/74] pagevec: Use xa_tag_t Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 47/74] shmem: Convert shmem_radix_tree_replace to XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 48/74] shmem: Convert shmem_confirm_swap " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 49/74] shmem: Convert find_swap_entry " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 50/74] shmem: Convert shmem_add_to_page_cache " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 51/74] shmem: Convert shmem_alloc_hugepage " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 52/74] shmem: Convert shmem_free_swap " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 53/74] shmem: Convert shmem_partial_swap_usage " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 54/74] memfd: Convert memfd_wait_for_pins " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 55/74] memfd: Convert memfd_tag_pins " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 56/74] shmem: Comment fixups Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 57/74] btrfs: Convert page cache to XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 58/74] fs: Convert buffer " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 59/74] fs: Convert writeback " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 60/74] nilfs2: Convert " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 61/74] f2fs: " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 62/74] dax: Rename some functions Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 63/74] dax: Hash on XArray instead of mapping Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 64/74] dax: Convert dax_insert_pfn_mkwrite to XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 65/74] dax: Convert dax_layout_busy_page " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 66/74] dax: Convert __dax_invalidate_entry " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 67/74] dax: Convert dax writeback " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 68/74] dax: Convert dax_lock_page " Matthew Wilcox
2018-06-29 17:30   ` Ross Zwisler
2018-07-06 11:54     ` [PATCH] fs/dax: remove unused function Anders Roxell
2018-07-06 13:04     ` [PATCH v14 68/74] dax: Convert dax_lock_page to XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 69/74] dax: Convert page fault handlers " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 70/74] page cache: Finish XArray conversion Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 71/74] radix tree: Remove radix_tree_update_node_t Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 72/74] radix tree: Remove split/join code Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 73/74] radix tree: Remove radix_tree_maybe_preload_order Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 74/74] radix tree: Remove radix_tree_clear_tags Matthew Wilcox
2018-06-19  3:12 ` [PATCH v14 00/74] Convert page cache to XArray Ross Zwisler
2018-06-19  9:22   ` Matthew Wilcox
2018-06-19 16:40     ` Ross Zwisler
2018-06-19 17:16       ` Matthew Wilcox
2018-06-27 11:05         ` Matthew Wilcox
2018-06-27 19:44           ` Ross Zwisler
2018-06-28  8:39             ` Matthew Wilcox
2018-06-28 16:30               ` Ross Zwisler
2018-07-25 21:03             ` Matthew Wilcox
2018-07-25 21:12               ` Ross Zwisler
2018-07-27 17:20               ` Ross Zwisler
2018-07-30 15:43                 ` Matthew Wilcox

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