[PATCH 3/6] mm: migrate: Move migrate_page_lock_buffers()

Jan Kara
2018-12-11T17:21:51Z

buffer_migrate_page() is the only caller of migrate_page_lock_buffers()
move it close to it and also drop the now unused stub for !CONFIG_BLOCK.

Signed-off-by: Jan Kara <jack@suse.cz>
---
mm/migrate.c | 92 +++++++++++++++++++++++++++---------------------------------
1 file changed, 42 insertions(+), 50 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index d58a8ecf275e..f8df1ad6e7cf 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -378,56 +378,6 @@ void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd)
}
#endif

-#ifdef CONFIG_BLOCK
-/* Returns true if all buffers are successfully locked */
-static bool buffer_migrate_lock_buffers(struct buffer_head *head,
- enum migrate_mode mode)
-{
- struct buffer_head *bh = head;
-
- /* Simple case, sync compaction */
- if (mode != MIGRATE_ASYNC) {
- do {
- get_bh(bh);
- lock_buffer(bh);
- bh = bh->b_this_page;
-
- } while (bh != head);
-
- return true;
- }
-
- /* async case, we cannot block on lock_buffer so use trylock_buffer */
- do {
- get_bh(bh);
- if (!trylock_buffer(bh)) {
- /*
- * We failed to lock the buffer and cannot stall in
- * async migration. Release the taken locks
- */
- struct buffer_head *failed_bh = bh;
- put_bh(failed_bh);
- bh = head;
- while (bh != failed_bh) {
- unlock_buffer(bh);
- put_bh(bh);
- bh = bh->b_this_page;
- }
- return false;
- }
-
- bh = bh->b_this_page;
- } while (bh != head);
- return true;
-}
-#else
-static inline bool buffer_migrate_lock_buffers(struct buffer_head *head,
- enum migrate_mode mode)
-{
- return true;
-}
-#endif /* CONFIG_BLOCK */
-
static int expected_page_refs(struct page *page)
{
int expected_count = 1;
@@ -755,6 +705,48 @@ int migrate_page(struct address_space *mapping,
EXPORT_SYMBOL(migrate_page);

#ifdef CONFIG_BLOCK
+/* Returns true if all buffers are successfully locked */
+static bool buffer_migrate_lock_buffers(struct buffer_head *head,
+ enum migrate_mode mode)
+{
+ struct buffer_head *bh = head;
+
+ /* Simple case, sync compaction */
+ if (mode != MIGRATE_ASYNC) {
+ do {
+ get_bh(bh);
+ lock_buffer(bh);
+ bh = bh->b_this_page;
+
+ } while (bh != head);
+
+ return true;
+ }
+
+ /* async case, we cannot block on lock_buffer so use trylock_buffer */
+ do {
+ get_bh(bh);
+ if (!trylock_buffer(bh)) {
+ /*
+ * We failed to lock the buffer and cannot stall in
+ * async migration. Release the taken locks
+ */
+ struct buffer_head *failed_bh = bh;
+ put_bh(failed_bh);
+ bh = head;
+ while (bh != failed_bh) {
+ unlock_buffer(bh);
+ put_bh(bh);
+ bh = bh->b_this_page;
+ }
+ return false;
+ }
+
+ bh = bh->b_this_page;
+ } while (bh != head);
+ return true;
+}
+
/*
* Migration function for pages with buffers. This function can only be used
* if the underlying filesystem guarantees that no other references to "page"
--
2.16.4