[PATCH 2/3] fs: move drop_pagecache_sb() for others to use

[Shiyang Ruan <ruansy.fnst@fujitsu.com>]

xfs_notify_failure requires a method to invalidate all mappings.
drop_pagecache_sb() can do this but it is a static function and only
build with CONFIG_SYSCTL.  Now, move it to super.c and make it available
for others.

Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
---
 fs/drop_caches.c   | 33 ---------------------------------
 fs/super.c         | 34 ++++++++++++++++++++++++++++++++++
 include/linux/fs.h |  1 +
 3 files changed, 35 insertions(+), 33 deletions(-)

diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index e619c31b6bd9..5c8406076f9b 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -3,7 +3,6 @@
  * Implement the manual drop-all-pagecache function
  */
 
-#include <linux/pagemap.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/fs.h>
@@ -15,38 +14,6 @@
 /* A global variable is a bit ugly, but it keeps the code simple */
 int sysctl_drop_caches;
 
-static void drop_pagecache_sb(struct super_block *sb, void *unused)
-{
-	struct inode *inode, *toput_inode = NULL;
-
-	spin_lock(&sb->s_inode_list_lock);
-	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
-		spin_lock(&inode->i_lock);
-		/*
-		 * We must skip inodes in unusual state. We may also skip
-		 * inodes without pages but we deliberately won't in case
-		 * we need to reschedule to avoid softlockups.
-		 */
-		if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
-		    (mapping_empty(inode->i_mapping) && !need_resched())) {
-			spin_unlock(&inode->i_lock);
-			continue;
-		}
-		__iget(inode);
-		spin_unlock(&inode->i_lock);
-		spin_unlock(&sb->s_inode_list_lock);
-
-		invalidate_mapping_pages(inode->i_mapping, 0, -1);
-		iput(toput_inode);
-		toput_inode = inode;
-
-		cond_resched();
-		spin_lock(&sb->s_inode_list_lock);
-	}
-	spin_unlock(&sb->s_inode_list_lock);
-	iput(toput_inode);
-}
-
 int drop_caches_sysctl_handler(struct ctl_table *table, int write,
 		void *buffer, size_t *length, loff_t *ppos)
 {
diff --git a/fs/super.c b/fs/super.c
index 734ed584a946..bdf53dbe834c 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -36,6 +36,7 @@
 #include <linux/lockdep.h>
 #include <linux/user_namespace.h>
 #include <linux/fs_context.h>
+#include <linux/pagemap.h>
 #include <uapi/linux/mount.h>
 #include "internal.h"
 
@@ -677,6 +678,39 @@ void drop_super_exclusive(struct super_block *sb)
 }
 EXPORT_SYMBOL(drop_super_exclusive);
 
+void drop_pagecache_sb(struct super_block *sb, void *unused)
+{
+	struct inode *inode, *toput_inode = NULL;
+
+	spin_lock(&sb->s_inode_list_lock);
+	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+		spin_lock(&inode->i_lock);
+		/*
+		 * We must skip inodes in unusual state. We may also skip
+		 * inodes without pages but we deliberately won't in case
+		 * we need to reschedule to avoid softlockups.
+		 */
+		if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
+		    (mapping_empty(inode->i_mapping) && !need_resched())) {
+			spin_unlock(&inode->i_lock);
+			continue;
+		}
+		__iget(inode);
+		spin_unlock(&inode->i_lock);
+		spin_unlock(&sb->s_inode_list_lock);
+
+		invalidate_mapping_pages(inode->i_mapping, 0, -1);
+		iput(toput_inode);
+		toput_inode = inode;
+
+		cond_resched();
+		spin_lock(&sb->s_inode_list_lock);
+	}
+	spin_unlock(&sb->s_inode_list_lock);
+	iput(toput_inode);
+}
+EXPORT_SYMBOL(drop_pagecache_sb);
+
 static void __iterate_supers(void (*f)(struct super_block *))
 {
 	struct super_block *sb, *p = NULL;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9eced4cc286e..5ded28c0d2c9 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3292,6 +3292,7 @@ extern struct super_block *get_super(struct block_device *);
 extern struct super_block *get_active_super(struct block_device *bdev);
 extern void drop_super(struct super_block *sb);
 extern void drop_super_exclusive(struct super_block *sb);
+void drop_pagecache_sb(struct super_block *sb, void *unused);
 extern void iterate_supers(void (*)(struct super_block *, void *), void *);
 extern void iterate_supers_type(struct file_system_type *,
 			        void (*)(struct super_block *, void *), void *);
-- 
2.37.2