mm: use radix_tree_iter_retry()
Instead of a 'goto restart', we can now use radix_tree_iter_retry() to
restart from our current position. This will make a difference when
there are more ways to happen across an indirect pointer. And it
eliminates some confusing gotos.
[vbabka@suse.cz: remove now-obsolete-and-misleading comment]
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/filemap.c b/mm/filemap.c
index 084ad0f..7c00f10 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1255,7 +1255,6 @@
return 0;
rcu_read_lock();
-restart:
radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
struct page *page;
repeat:
@@ -1263,8 +1262,10 @@
if (unlikely(!page))
continue;
if (radix_tree_exception(page)) {
- if (radix_tree_deref_retry(page))
- goto restart;
+ if (radix_tree_deref_retry(page)) {
+ slot = radix_tree_iter_retry(&iter);
+ continue;
+ }
/*
* A shadow entry of a recently evicted page, a swap
* entry from shmem/tmpfs or a DAX entry. Return it
@@ -1317,7 +1318,6 @@
return 0;
rcu_read_lock();
-restart:
radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
struct page *page;
repeat:
@@ -1327,13 +1327,8 @@
if (radix_tree_exception(page)) {
if (radix_tree_deref_retry(page)) {
- /*
- * Transient condition which can only trigger
- * when entry at index 0 moves out of or back
- * to root: none yet gotten, safe to restart.
- */
- WARN_ON(iter.index);
- goto restart;
+ slot = radix_tree_iter_retry(&iter);
+ continue;
}
/*
* A shadow entry of a recently evicted page,
@@ -1384,7 +1379,6 @@
return 0;
rcu_read_lock();
-restart:
radix_tree_for_each_contig(slot, &mapping->page_tree, &iter, index) {
struct page *page;
repeat:
@@ -1395,12 +1389,8 @@
if (radix_tree_exception(page)) {
if (radix_tree_deref_retry(page)) {
- /*
- * Transient condition which can only trigger
- * when entry at index 0 moves out of or back
- * to root: none yet gotten, safe to restart.
- */
- goto restart;
+ slot = radix_tree_iter_retry(&iter);
+ continue;
}
/*
* A shadow entry of a recently evicted page,
@@ -1460,7 +1450,6 @@
return 0;
rcu_read_lock();
-restart:
radix_tree_for_each_tagged(slot, &mapping->page_tree,
&iter, *index, tag) {
struct page *page;
@@ -1471,12 +1460,8 @@
if (radix_tree_exception(page)) {
if (radix_tree_deref_retry(page)) {
- /*
- * Transient condition which can only trigger
- * when entry at index 0 moves out of or back
- * to root: none yet gotten, safe to restart.
- */
- goto restart;
+ slot = radix_tree_iter_retry(&iter);
+ continue;
}
/*
* A shadow entry of a recently evicted page.
@@ -1539,7 +1524,6 @@
return 0;
rcu_read_lock();
-restart:
radix_tree_for_each_tagged(slot, &mapping->page_tree,
&iter, start, tag) {
struct page *page;
@@ -1549,12 +1533,8 @@
continue;
if (radix_tree_exception(page)) {
if (radix_tree_deref_retry(page)) {
- /*
- * Transient condition which can only trigger
- * when entry at index 0 moves out of or back
- * to root: none yet gotten, safe to restart.
- */
- goto restart;
+ slot = radix_tree_iter_retry(&iter);
+ continue;
}
/*
@@ -2171,10 +2151,11 @@
if (unlikely(!page))
goto next;
if (radix_tree_exception(page)) {
- if (radix_tree_deref_retry(page))
- break;
- else
- goto next;
+ if (radix_tree_deref_retry(page)) {
+ slot = radix_tree_iter_retry(&iter);
+ continue;
+ }
+ goto next;
}
if (!page_cache_get_speculative(page))