xfs_notify_failure.c requires a method to invalidate all dax 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.  And use its second argument to choose which invalidate
method to use.

Signed-off-by: Shiyang Ruan <ruansy.f...@fujitsu.com>
---
 fs/drop_caches.c        | 35 ++-------------------------------
 fs/super.c              | 43 +++++++++++++++++++++++++++++++++++++++++
 include/linux/fs.h      |  1 +
 include/linux/pagemap.h |  1 +
 mm/truncate.c           | 20 +++++++++++++++++--
 5 files changed, 65 insertions(+), 35 deletions(-)

diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index e619c31b6bd9..4c9281885077 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -15,38 +15,6 @@
 /* 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)
 {
@@ -59,7 +27,8 @@ int drop_caches_sysctl_handler(struct ctl_table *table, int 
write,
                static int stfu;
 
                if (sysctl_drop_caches & 1) {
-                       iterate_supers(drop_pagecache_sb, NULL);
+                       iterate_supers(super_drop_pagecache,
+                                      invalidate_inode_pages);
                        count_vm_event(DROP_PAGECACHE);
                }
                if (sysctl_drop_caches & 2) {
diff --git a/fs/super.c b/fs/super.c
index 734ed584a946..7cdbf146bc31 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 +678,48 @@ void drop_super_exclusive(struct super_block *sb)
 }
 EXPORT_SYMBOL(drop_super_exclusive);
 
+/*
+ *     super_drop_pagecache - drop all page caches of a filesystem
+ *     @sb: superblock to invalidate
+ *     @arg: invalidate method, such as invalidate_inode_pages(),
+ *             invalidate_inode_pages2()
+ *
+ *     Scans the inodes of a filesystem, drop all page caches.
+ */
+void super_drop_pagecache(struct super_block *sb, void *arg)
+{
+       struct inode *inode, *toput_inode = NULL;
+       int (*invalidator)(struct address_space *) = arg;
+
+       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);
+
+               invalidator(inode->i_mapping);
+               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(super_drop_pagecache);
+
 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..0e60c494688e 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 super_drop_pagecache(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 *);
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 0178b2040ea3..8879c141b117 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -27,6 +27,7 @@ static inline void invalidate_remote_inode(struct inode 
*inode)
            S_ISLNK(inode->i_mode))
                invalidate_mapping_pages(inode->i_mapping, 0, -1);
 }
+int invalidate_inode_pages(struct address_space *mapping);
 int invalidate_inode_pages2(struct address_space *mapping);
 int invalidate_inode_pages2_range(struct address_space *mapping,
                pgoff_t start, pgoff_t end);
diff --git a/mm/truncate.c b/mm/truncate.c
index 0b0708bf935f..3016258d41e7 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -548,12 +548,13 @@ unsigned long invalidate_mapping_pagevec(struct 
address_space *mapping,
 }
 
 /**
- * invalidate_mapping_pages - Invalidate all clean, unlocked cache of one inode
+ * invalidate_mapping_pages - Invalidate range of clean, unlocked cache of one
+ *                           inode
  * @mapping: the address_space which holds the cache to invalidate
  * @start: the offset 'from' which to invalidate
  * @end: the offset 'to' which to invalidate (inclusive)
  *
- * This function removes pages that are clean, unmapped and unlocked,
+ * This function removes range of pages that are clean, unmapped and unlocked,
  * as well as shadow entries. It will not block on IO activity.
  *
  * If you want to remove all the pages of one inode, regardless of
@@ -568,6 +569,21 @@ unsigned long invalidate_mapping_pages(struct 
address_space *mapping,
 }
 EXPORT_SYMBOL(invalidate_mapping_pages);
 
+/**
+ * invalidate_inode_pages - Invalidate all clean, unlocked cache of one inode
+ * @mapping: the address_space which holds the cache to invalidate
+ *
+ * This function removes all pages that are clean, unmapped and unlocked,
+ * as well as shadow entries. It will not block on IO activity.
+ */
+int invalidate_inode_pages(struct address_space *mapping)
+{
+       invalidate_mapping_pages(mapping, 0, -1);
+
+       return 0;
+}
+EXPORT_SYMBOL(invalidate_inode_pages);
+
 /*
  * This is like invalidate_inode_page(), except it ignores the page's
  * refcount.  We do this because invalidate_inode_pages2() needs stronger
-- 
2.37.3


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