[PATCH RFC 10/20] ext2: store cookie in private data

[Christian Brauner <brauner@kernel.org>]

Store the cookie to detect concurrent seeks on directories in
file->private_data.

Signed-off-by: Christian Brauner <brauner@kernel.org>
---
 fs/ext2/dir.c | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index 087457061c6e..6622c582f550 100644
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -263,7 +263,7 @@ ext2_readdir(struct file *file, struct dir_context *ctx)
 	unsigned long n = pos >> PAGE_SHIFT;
 	unsigned long npages = dir_pages(inode);
 	unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
-	bool need_revalidate = !inode_eq_iversion(inode, file->f_version);
+	bool need_revalidate = !inode_eq_iversion(inode, *(u64 *)file->private_data);
 	bool has_filetype;
 
 	if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
@@ -290,7 +290,7 @@ ext2_readdir(struct file *file, struct dir_context *ctx)
 				offset = ext2_validate_entry(kaddr, offset, chunk_mask);
 				ctx->pos = (n<<PAGE_SHIFT) + offset;
 			}
-			file->f_version = inode_query_iversion(inode);
+			*(u64 *)file->private_data = inode_query_iversion(inode);
 			need_revalidate = false;
 		}
 		de = (ext2_dirent *)(kaddr+offset);
@@ -703,8 +703,30 @@ int ext2_empty_dir(struct inode *inode)
 	return 0;
 }
 
+static int ext2_dir_open(struct inode *inode, struct file *file)
+{
+	file->private_data = kzalloc(sizeof(u64), GFP_KERNEL);
+	if (!file->private_data)
+		return -ENOMEM;
+	return 0;
+}
+
+static int ext2_dir_release(struct inode *inode, struct file *file)
+{
+	kfree(file->private_data);
+	return 0;
+}
+
+static loff_t ext2_dir_llseek(struct file *file, loff_t offset, int whence)
+{
+	return generic_llseek_cookie(file, offset, whence,
+				     (u64 *)file->private_data);
+}
+
 const struct file_operations ext2_dir_operations = {
-	.llseek		= generic_file_llseek,
+	.open		= ext2_dir_open,
+	.release	= ext2_dir_release,
+	.llseek		= ext2_dir_llseek,
 	.read		= generic_read_dir,
 	.iterate_shared	= ext2_readdir,
 	.unlocked_ioctl = ext2_ioctl,

-- 
2.45.2