The patch titled
Subject: mm: use radix_tree_iter_retry()
has been added to the -mm tree. Its filename is
mm-use-radix_tree_iter_retry.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-use-radix_tree_iter_retry.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-use-radix_tree_iter_retry.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Subject: 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.
Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 53 +++++++++++++++----------------------------------
mm/shmem.c | 18 +++++++++++-----
2 files changed, 29 insertions(+), 42 deletions(-)
diff -puN mm/filemap.c~mm-use-radix_tree_iter_retry mm/filemap.c
--- a/mm/filemap.c~mm-use-radix_tree_iter_retry
+++ a/mm/filemap.c
@@ -1245,7 +1245,6 @@ unsigned find_get_entries(struct address
return 0;
rcu_read_lock();
-restart:
radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
struct page *page;
repeat:
@@ -1253,8 +1252,10 @@ repeat:
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
@@ -1307,7 +1308,6 @@ unsigned find_get_pages(struct address_s
return 0;
rcu_read_lock();
-restart:
radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
struct page *page;
repeat:
@@ -1317,13 +1317,8 @@ repeat:
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,
@@ -1374,7 +1369,6 @@ unsigned find_get_pages_contig(struct ad
return 0;
rcu_read_lock();
-restart:
radix_tree_for_each_contig(slot, &mapping->page_tree, &iter, index) {
struct page *page;
repeat:
@@ -1385,12 +1379,8 @@ repeat:
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,
@@ -1450,7 +1440,6 @@ unsigned find_get_pages_tag(struct addre
return 0;
rcu_read_lock();
-restart:
radix_tree_for_each_tagged(slot, &mapping->page_tree,
&iter, *index, tag) {
struct page *page;
@@ -1461,12 +1450,8 @@ repeat:
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.
@@ -1529,7 +1514,6 @@ unsigned find_get_entries_tag(struct add
return 0;
rcu_read_lock();
-restart:
radix_tree_for_each_tagged(slot, &mapping->page_tree,
&iter, start, tag) {
struct page *page;
@@ -1539,12 +1523,8 @@ repeat:
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;
}
/*
@@ -2160,10 +2140,11 @@ repeat:
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))
diff -puN mm/shmem.c~mm-use-radix_tree_iter_retry mm/shmem.c
--- a/mm/shmem.c~mm-use-radix_tree_iter_retry
+++ a/mm/shmem.c
@@ -388,8 +388,10 @@ restart:
* don't need to reset the counter, nor do we risk infinite
* restarts.
*/
- if (radix_tree_deref_retry(page))
- goto restart;
+ if (radix_tree_deref_retry(page)) {
+ slot = radix_tree_iter_retry(&iter);
+ continue;
+ }
if (radix_tree_exceptional_entry(page))
swapped++;
@@ -1951,8 +1953,10 @@ restart:
radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
page = radix_tree_deref_slot(slot);
if (!page || 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;
+ }
} else if (page_count(page) - page_mapcount(page) > 1) {
spin_lock_irq(&mapping->tree_lock);
radix_tree_tag_set(&mapping->page_tree, iter.index,
@@ -2006,8 +2010,10 @@ restart:
page = radix_tree_deref_slot(slot);
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;
+ }
page = NULL;
}
_
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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