[PATCH 01/17] nilfs2: move page release outside of nilfs_delete_entry and nilfs_set_link

[Ryusuke Konishi]

In a few directory operations, the call to nilfs_put_page() for a page
obtained using nilfs_find_entry() or nilfs_dotdot() is hidden in
nilfs_set_link() and nilfs_delete_entry(), making it difficult to track
page release and preventing change of its call position.

By moving nilfs_put_page() out of these functions, this makes the page
get/put correspondence clearer and makes it easier to swap
nilfs_put_page() calls (and kunmap calls within them) when modifying
multiple directory entries simultaneously in nilfs_rename().

Also, update comments for nilfs_set_link() and nilfs_delete_entry() to
reflect changes in their behavior.

To make nilfs_put_page() visible from namei.c, this moves its definition
to nilfs.h and replaces existing equivalents to use it, but the exposure
of that definition is temporary and will be removed on a later
kmap -> kmap_local conversion.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
 fs/nilfs2/dir.c   | 11 +----------
 fs/nilfs2/namei.c | 13 +++++++------
 fs/nilfs2/nilfs.h |  6 ++++++
 3 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/fs/nilfs2/dir.c b/fs/nilfs2/dir.c
index de2073c47651..b9f13bdf8fba 100644
--- a/fs/nilfs2/dir.c
+++ b/fs/nilfs2/dir.c
@@ -64,12 +64,6 @@ static inline unsigned int nilfs_chunk_size(struct inode *inode)
 	return inode->i_sb->s_blocksize;
 }
 
-static inline void nilfs_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.
@@ -413,7 +407,6 @@ ino_t nilfs_inode_by_name(struct inode *dir, const struct qstr *qstr)
 	return res;
 }
 
-/* Releases the page */
 void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
 		    struct page *page, struct inode *inode)
 {
@@ -428,7 +421,6 @@ void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
 	de->inode = cpu_to_le64(inode->i_ino);
 	nilfs_set_de_type(de, inode);
 	nilfs_commit_chunk(page, mapping, from, to);
-	nilfs_put_page(page);
 	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
 }
 
@@ -533,7 +525,7 @@ int nilfs_add_link(struct dentry *dentry, struct inode *inode)
 
 /*
  * nilfs_delete_entry deletes a directory entry by merging it with the
- * previous entry. Page is up-to-date. Releases the page.
+ * previous entry. Page is up-to-date.
  */
 int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct page *page)
 {
@@ -569,7 +561,6 @@ int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct page *page)
 	nilfs_commit_chunk(page, mapping, from, to);
 	inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
 out:
-	nilfs_put_page(page);
 	return err;
 }
 
diff --git a/fs/nilfs2/namei.c b/fs/nilfs2/namei.c
index 2a4e7f4a8102..99255694cbe9 100644
--- a/fs/nilfs2/namei.c
+++ b/fs/nilfs2/namei.c
@@ -280,6 +280,7 @@ static int nilfs_do_unlink(struct inode *dir, struct dentry *dentry)
 		set_nlink(inode, 1);
 	}
 	err = nilfs_delete_entry(de, page);
+	nilfs_put_page(page);
 	if (err)
 		goto out;
 
@@ -386,6 +387,7 @@ static int nilfs_rename(struct mnt_idmap *idmap,
 		if (!new_de)
 			goto out_dir;
 		nilfs_set_link(new_dir, new_de, new_page, old_inode);
+		nilfs_put_page(new_page);
 		nilfs_mark_inode_dirty(new_dir);
 		inode_set_ctime_current(new_inode);
 		if (dir_de)
@@ -409,9 +411,11 @@ static int nilfs_rename(struct mnt_idmap *idmap,
 	inode_set_ctime_current(old_inode);
 
 	nilfs_delete_entry(old_de, old_page);
+	nilfs_put_page(old_page);
 
 	if (dir_de) {
 		nilfs_set_link(old_inode, dir_de, dir_page, new_dir);
+		nilfs_put_page(dir_page);
 		drop_nlink(old_dir);
 	}
 	nilfs_mark_inode_dirty(old_dir);
@@ -421,13 +425,10 @@ static int nilfs_rename(struct mnt_idmap *idmap,
 	return err;
 
 out_dir:
-	if (dir_de) {
-		kunmap(dir_page);
-		put_page(dir_page);
-	}
+	if (dir_de)
+		nilfs_put_page(dir_page);
 out_old:
-	kunmap(old_page);
-	put_page(old_page);
+	nilfs_put_page(old_page);
 out:
 	nilfs_transaction_abort(old_dir->i_sb);
 	return err;
diff --git a/fs/nilfs2/nilfs.h b/fs/nilfs2/nilfs.h
index 8046490cd7fe..afd700f5dc4e 100644
--- a/fs/nilfs2/nilfs.h
+++ b/fs/nilfs2/nilfs.h
@@ -237,6 +237,12 @@ extern struct nilfs_dir_entry *nilfs_dotdot(struct inode *, struct page **);
 extern void nilfs_set_link(struct inode *, struct nilfs_dir_entry *,
 			   struct page *, struct inode *);
 
+static inline void nilfs_put_page(struct page *page)
+{
+	kunmap(page);
+	put_page(page);
+}
+
 /* file.c */
 extern int nilfs_sync_file(struct file *, loff_t, loff_t, int);
 
-- 
2.34.1