The patch titled
Subject: radix-tree,shmem: introduce radix_tree_iter_next()
has been added to the -mm tree. Its filename is
radix-treeshmem-introduce-radix_tree_iter_next.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/radix-treeshmem-introduce-radix_tree_iter_next.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/radix-treeshmem-introduce-radix_tree_iter_next.patch
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------------------------------------------------------
From: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Subject: radix-tree,shmem: introduce radix_tree_iter_next()
shmem likes to occasionally drop the lock, schedule, then reacqire the
lock and continue with the iteration from the last place it left off.
This is currently done with a pretty ugly goto. Introduce
radix_tree_iter_next() and use it throughout shmem.c.
Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/radix-tree.h | 15 +++++++++++++++
mm/shmem.c | 12 +++---------
2 files changed, 18 insertions(+), 9 deletions(-)
diff -puN include/linux/radix-tree.h~radix-treeshmem-introduce-radix_tree_iter_next include/linux/radix-tree.h
--- a/include/linux/radix-tree.h~radix-treeshmem-introduce-radix_tree_iter_next
+++ a/include/linux/radix-tree.h
@@ -403,6 +403,21 @@ void **radix_tree_iter_retry(struct radi
}
/**
+ * radix_tree_iter_next - resume iterating when the chunk may be invalid
+ * @iter: iterator state
+ *
+ * If the iterator needs to release then reacquire a lock, the chunk may
+ * have been invalidated by an insertion or deletion. Call this function
+ * to continue the iteration from the next index.
+ */
+static inline __must_check
+void **radix_tree_iter_next(struct radix_tree_iter *iter)
+{
+ iter->next_index = iter->index + 1;
+ return NULL;
+}
+
+/**
* radix_tree_chunk_size - get current chunk size
*
* @iter: pointer to radix tree iterator
diff -puN mm/shmem.c~radix-treeshmem-introduce-radix_tree_iter_next mm/shmem.c
--- a/mm/shmem.c~radix-treeshmem-introduce-radix_tree_iter_next
+++ a/mm/shmem.c
@@ -376,7 +376,6 @@ unsigned long shmem_partial_swap_usage(s
rcu_read_lock();
-restart:
radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
if (iter.index >= end)
break;
@@ -398,8 +397,7 @@ restart:
if (need_resched()) {
cond_resched_rcu();
- start = iter.index + 1;
- goto restart;
+ slot = radix_tree_iter_next(&iter);
}
}
@@ -1949,7 +1947,6 @@ static void shmem_tag_pins(struct addres
start = 0;
rcu_read_lock();
-restart:
radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
page = radix_tree_deref_slot(slot);
if (!page || radix_tree_exception(page)) {
@@ -1966,8 +1963,7 @@ restart:
if (need_resched()) {
cond_resched_rcu();
- start = iter.index + 1;
- goto restart;
+ slot = radix_tree_iter_next(&iter);
}
}
rcu_read_unlock();
@@ -2004,7 +2000,6 @@ static int shmem_wait_for_pins(struct ad
start = 0;
rcu_read_lock();
-restart:
radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter,
start, SHMEM_TAG_PINNED) {
@@ -2038,8 +2033,7 @@ restart:
continue_resched:
if (need_resched()) {
cond_resched_rcu();
- start = iter.index + 1;
- goto restart;
+ slot = radix_tree_iter_next(&iter);
}
}
rcu_read_unlock();
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxxxx are
radix-tree-fix-race-in-gang-lookup.patch
hwspinlock-fix-race-between-radix-tree-insertion-and-lookup.patch
radix-tree-add-an-explicit-include-of-bitopsh.patch
radix-tree-test-harness.patch
radix_tree-tag-all-internal-tree-nodes-as-indirect-pointers.patch
radix_tree-loop-based-on-shift-count-not-height.patch
radix_tree-add-support-for-multi-order-entries.patch
radix_tree-add-radix_tree_dump.patch
btrfs-use-radix_tree_iter_retry.patch
mm-use-radix_tree_iter_retry.patch
radix-treeshmem-introduce-radix_tree_iter_next.patch
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