From: Ira Weiny <[email protected]>

There are 3 places in namei.c where the equivalent of ext2_put_page() is
open coded on a page which was returned from the ext2_get_page() call
[through the use of ext2_find_entry() and ext2_dotdot()].

Move ext2_get_page() and ext2_put_page() to ext2.h in order to help
clarify the use of the get/put and then use ext2_put_page() in namei.c

Also add a comment regarding the proper way to release the page returned
from ext2_find_entry() and ext2_dotdot().

Signed-off-by: Ira Weiny <[email protected]>

---

This was originally part of the kmap_thread() series here:

https://lore.kernel.org/lkml/[email protected]/

But this is really a valid clean up regardless of the
kmap_thread[local]() changes.
---
 fs/ext2/dir.c   | 33 ++++++++-------------------------
 fs/ext2/ext2.h  | 27 +++++++++++++++++++++++++++
 fs/ext2/namei.c | 15 +++++----------
 3 files changed, 40 insertions(+), 35 deletions(-)

diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index 70355ab6740e..8acd77a66ff4 100644
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -66,12 +66,6 @@ static inline unsigned ext2_chunk_size(struct inode *inode)
        return inode->i_sb->s_blocksize;
 }
 
-static inline void ext2_put_page(struct page *page)
-{
-       kunmap(page);
-       put_page(page);
-}
-
 /*
  * Return the offset into page `page_nr' of the last valid
  * byte in that page, plus one.
@@ -196,25 +190,6 @@ static bool ext2_check_page(struct page *page, int quiet)
        return false;
 }
 
-static struct page * ext2_get_page(struct inode *dir, unsigned long n,
-                                  int quiet)
-{
-       struct address_space *mapping = dir->i_mapping;
-       struct page *page = read_mapping_page(mapping, n, NULL);
-       if (!IS_ERR(page)) {
-               kmap(page);
-               if (unlikely(!PageChecked(page))) {
-                       if (PageError(page) || !ext2_check_page(page, quiet))
-                               goto fail;
-               }
-       }
-       return page;
-
-fail:
-       ext2_put_page(page);
-       return ERR_PTR(-EIO);
-}
-
 /*
  * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
  *
@@ -336,6 +311,8 @@ ext2_readdir(struct file *file, struct dir_context *ctx)
  * returns the page in which the entry was found (as a parameter - res_page),
  * and the entry itself. Page is returned mapped and unlocked.
  * Entry is guaranteed to be valid.
+ *
+ * On Success ext2_put_page() should be called on *res_page.
  */
 struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
                        const struct qstr *child, struct page **res_page)
@@ -401,6 +378,12 @@ struct ext2_dir_entry_2 *ext2_find_entry (struct inode 
*dir,
        return de;
 }
 
+/**
+ * Return the '..' directory entry and the page in which the entry was found
+ * (as a parameter - p).
+ *
+ * On Success ext2_put_page() should be called on *p.
+ */
 struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
 {
        struct page *page = ext2_get_page(dir, 0, 0);
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 5136b7289e8d..b4403f96858b 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -16,6 +16,8 @@
 #include <linux/blockgroup_lock.h>
 #include <linux/percpu_counter.h>
 #include <linux/rbtree.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
 
 /* XXX Here for now... not interested in restructing headers JUST now */
 
@@ -745,6 +747,31 @@ extern int ext2_delete_entry (struct ext2_dir_entry_2 *, 
struct page *);
 extern int ext2_empty_dir (struct inode *);
 extern struct ext2_dir_entry_2 * ext2_dotdot (struct inode *, struct page **);
 extern void ext2_set_link(struct inode *, struct ext2_dir_entry_2 *, struct 
page *, struct inode *, int);
+static inline void ext2_put_page(struct page *page)
+{
+       kunmap(page);
+       put_page(page);
+}
+
+static inline struct page * ext2_get_page(struct inode *dir, unsigned long n,
+                                  int quiet)
+{
+       struct address_space *mapping = dir->i_mapping;
+       struct page *page = read_mapping_page(mapping, n, NULL);
+       if (!IS_ERR(page)) {
+               kmap(page);
+               if (unlikely(!PageChecked(page))) {
+                       if (PageError(page) || !ext2_check_page(page, quiet))
+                               goto fail;
+               }
+       }
+       return page;
+
+fail:
+       ext2_put_page(page);
+       return ERR_PTR(-EIO);
+}
+
 
 /* ialloc.c */
 extern struct inode * ext2_new_inode (struct inode *, umode_t, const struct 
qstr *);
diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
index 5bf2c145643b..ea980f1e2e99 100644
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -389,23 +389,18 @@ static int ext2_rename (struct inode * old_dir, struct 
dentry * old_dentry,
        if (dir_de) {
                if (old_dir != new_dir)
                        ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
-               else {
-                       kunmap(dir_page);
-                       put_page(dir_page);
-               }
+               else
+                       ext2_put_page(dir_page);
                inode_dec_link_count(old_dir);
        }
        return 0;
 
 
 out_dir:
-       if (dir_de) {
-               kunmap(dir_page);
-               put_page(dir_page);
-       }
+       if (dir_de)
+               ext2_put_page(dir_page);
 out_old:
-       kunmap(old_page);
-       put_page(old_page);
+       ext2_put_page(old_page);
 out:
        return err;
 }
-- 
2.28.0.rc0.12.gb6a658bd00c9

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