ext2: store cookie in private data

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

Link: https://lore.kernel.org/r/20240830-vfs-file-f_version-v1-10-6d3e4816aa7b@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index 087457061c6ef40fb3135d0f2dd0a1210ef454b8..6622c582f5502aa3622f8447feee2515b092fba6 100644 (file)
--- 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 @@ not_empty:
        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,