@@ -981,6 +981,37 @@ void inode_io_list_del(struct inode *inode)
}
/*
+ * mark an inode as under writeback on the sb
+ */
+void sb_mark_inode_writeback(struct inode *inode)
+{
+ struct super_block *sb = inode->i_sb;
+ unsigned long flags;
+
+ if (list_empty(&inode->i_wb_list)) {
+ spin_lock_irqsave(&sb->s_inode_wblist_lock, flags);
+ if (list_empty(&inode->i_wb_list))
+ list_add_tail(&inode->i_wb_list, &sb->s_inodes_wb);
+ spin_unlock_irqrestore(&sb->s_inode_wblist_lock, flags);
+ }
+}
+
+/*
+ * clear an inode as under writeback on the sb
+ */
+void sb_clear_inode_writeback(struct inode *inode)
+{
+ struct super_block *sb = inode->i_sb;
+ unsigned long flags;
+
+ if (!list_empty(&inode->i_wb_list)) {
+ spin_lock_irqsave(&sb->s_inode_wblist_lock, flags);
+ list_del_init(&inode->i_wb_list);
+ spin_unlock_irqrestore(&sb->s_inode_wblist_lock, flags);
+ }
+}
+
+/*
* Redirty an inode: set its when-it-was dirtied timestamp and move it to the
* furthest end of its superblock's dirty-inode list.
*
@@ -2154,7 +2185,7 @@ EXPORT_SYMBOL(__mark_inode_dirty);
*/
static void wait_sb_inodes(struct super_block *sb)
{
- struct inode *inode, *old_inode = NULL;
+ LIST_HEAD(sync_list);
/*
* We need to be protected against the filesystem going from
@@ -2163,38 +2194,60 @@ static void wait_sb_inodes(struct super_block *sb)
WARN_ON(!rwsem_is_locked(&sb->s_umount));
mutex_lock(&sb->s_sync_lock);
- spin_lock(&sb->s_inode_list_lock);
/*
- * Data integrity sync. Must wait for all pages under writeback,
- * because there may have been pages dirtied before our sync
- * call, but which had writeout started before we write it out.
- * In which case, the inode may not be on the dirty list, but
- * we still have to wait for that writeout.
+ * Splice the writeback list onto a temporary list to avoid waiting on
+ * inodes that have started writeback after this point.
+ *
+ * Use rcu_read_lock() to keep the inodes around until we have a
+ * reference. s_inode_wblist_lock protects sb->s_inodes_wb as well as
+ * the local list because inodes can be dropped from either by writeback
+ * completion.
+ */
+ rcu_read_lock();
+ spin_lock_irq(&sb->s_inode_wblist_lock);
+ list_splice_init(&sb->s_inodes_wb, &sync_list);
+
+ /*
+ * Data integrity sync. Must wait for all pages under writeback, because
+ * there may have been pages dirtied before our sync call, but which had
+ * writeout started before we write it out. In which case, the inode
+ * may not be on the dirty list, but we still have to wait for that
+ * writeout.
*/
- list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+ while (!list_empty(&sync_list)) {
+ struct inode *inode = list_first_entry(&sync_list, struct inode,
+ i_wb_list);
struct address_space *mapping = inode->i_mapping;
+ /*
+ * Move each inode back to the wb list before we drop the lock
+ * to preserve consistency between i_wb_list and the mapping
+ * writeback tag. Writeback completion is responsible to remove
+ * the inode from either list once the writeback tag is cleared.
+ */
+ list_move_tail(&inode->i_wb_list, &sb->s_inodes_wb);
+
+ /*
+ * The mapping can appear untagged while still on-list since we
+ * do not have the mapping lock. Skip it here, wb completion
+ * will remove it.
+ */
+ if (!mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK))
+ continue;
+
+ spin_unlock_irq(&sb->s_inode_wblist_lock);
+
spin_lock(&inode->i_lock);
- if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
- (mapping->nrpages == 0)) {
+ if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) {
spin_unlock(&inode->i_lock);
+
+ spin_lock_irq(&sb->s_inode_wblist_lock);
continue;
}
__iget(inode);
spin_unlock(&inode->i_lock);
- spin_unlock(&sb->s_inode_list_lock);
-
- /*
- * We hold a reference to 'inode' so it couldn't have been
- * removed from s_inodes list while we dropped the
- * s_inode_list_lock. We cannot iput the inode now as we can
- * be holding the last reference and we cannot iput it under
- * s_inode_list_lock. So we keep the reference and iput it
- * later.
- */
- iput(old_inode);
- old_inode = inode;
+ rcu_read_unlock();
/*
* We keep the error status of individual mapping so that
@@ -2205,10 +2258,13 @@ static void wait_sb_inodes(struct super_block *sb)
cond_resched();
- spin_lock(&sb->s_inode_list_lock);
+ iput(inode);
+
+ rcu_read_lock();
+ spin_lock_irq(&sb->s_inode_wblist_lock);
}
- spin_unlock(&sb->s_inode_list_lock);
- iput(old_inode);
+ spin_unlock_irq(&sb->s_inode_wblist_lock);
+ rcu_read_unlock();
mutex_unlock(&sb->s_sync_lock);
}
@@ -365,6 +365,7 @@ void inode_init_once(struct inode *inode)
INIT_HLIST_NODE(&inode->i_hash);
INIT_LIST_HEAD(&inode->i_devices);
INIT_LIST_HEAD(&inode->i_io_list);
+ INIT_LIST_HEAD(&inode->i_wb_list);
INIT_LIST_HEAD(&inode->i_lru);
address_space_init_once(&inode->i_data);
i_size_ordered_init(inode);
@@ -507,6 +508,7 @@ void clear_inode(struct inode *inode)
BUG_ON(!list_empty(&inode->i_data.private_list));
BUG_ON(!(inode->i_state & I_FREEING));
BUG_ON(inode->i_state & I_CLEAR);
+ BUG_ON(!list_empty(&inode->i_wb_list));
/* don't need i_lock here, no concurrent mods to i_state */
inode->i_state = I_FREEING | I_CLEAR;
}
@@ -206,6 +206,8 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags)
mutex_init(&s->s_sync_lock);
INIT_LIST_HEAD(&s->s_inodes);
spin_lock_init(&s->s_inode_list_lock);
+ INIT_LIST_HEAD(&s->s_inodes_wb);
+ spin_lock_init(&s->s_inode_wblist_lock);
if (list_lru_init_memcg(&s->s_dentry_lru))
goto fail;
@@ -665,6 +665,7 @@ struct inode {
#endif
struct list_head i_lru; /* inode LRU list */
struct list_head i_sb_list;
+ struct list_head i_wb_list; /* backing dev writeback list */
union {
struct hlist_head i_dentry;
struct rcu_head i_rcu;
@@ -1448,6 +1449,9 @@ struct super_block {
/* s_inode_list_lock protects s_inodes */
spinlock_t s_inode_list_lock ____cacheline_aligned_in_smp;
struct list_head s_inodes; /* all inodes */
+
+ spinlock_t s_inode_wblist_lock;
+ struct list_head s_inodes_wb; /* writeback inodes */
};
extern struct timespec current_fs_time(struct super_block *sb);
@@ -384,4 +384,7 @@ void tag_pages_for_writeback(struct address_space *mapping,
void account_page_redirty(struct page *page);
+void sb_mark_inode_writeback(struct inode *inode);
+void sb_clear_inode_writeback(struct inode *inode);
+
#endif /* WRITEBACK_H */
@@ -2747,6 +2747,11 @@ int test_clear_page_writeback(struct page *page)
__wb_writeout_inc(wb);
}
}
+
+ if (mapping->host && !mapping_tagged(mapping,
+ PAGECACHE_TAG_WRITEBACK))
+ sb_clear_inode_writeback(mapping->host);
+
spin_unlock_irqrestore(&mapping->tree_lock, flags);
} else {
ret = TestClearPageWriteback(page);
@@ -2774,11 +2779,24 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
spin_lock_irqsave(&mapping->tree_lock, flags);
ret = TestSetPageWriteback(page);
if (!ret) {
+ bool on_wblist;
+
+ on_wblist = mapping_tagged(mapping,
+ PAGECACHE_TAG_WRITEBACK);
+
radix_tree_tag_set(&mapping->page_tree,
page_index(page),
PAGECACHE_TAG_WRITEBACK);
if (bdi_cap_account_writeback(bdi))
__inc_wb_stat(inode_to_wb(inode), WB_WRITEBACK);
+
+ /*
+ * We can come through here when swapping anonymous
+ * pages, so we don't necessarily have an inode to track
+ * for sync.
+ */
+ if (mapping->host && !on_wblist)
+ sb_mark_inode_writeback(mapping->host);
}
if (!PageDirty(page))
radix_tree_tag_clear(&mapping->page_tree,