Re: [PATCH 2/2] ntfs: take invalidate_lock in ntfs_filemap_page_mkwrite()

[Namjae Jeon]

>         if (NInoWofCompressed(NTFS_I(inode)))
> @@ -684,7 +685,14 @@ static vm_fault_t ntfs_filemap_page_mkwrite(struct vm_fault *vmf)
>         sb_start_pagefault(inode->i_sb);
>         file_update_time(vmf->vma->vm_file);
>
> +       /*
> +        * Serialize against truncate/fallocate which hold the lock
> +        * exclusively while invalidating pagecache and changing extents.
> +        */
> +       filemap_invalidate_lock_shared(mapping);
>         ret = iomap_page_mkwrite(vmf, &ntfs_page_mkwrite_iomap_ops, NULL);
> +       filemap_invalidate_unlock_shared(mapping);
> +
Please move filemap_invalidate_unlock() after truncate_pagecache() and
pagecache_isize_extended(). Otherwise, ntfs_filemap_page_mkwrite() can
race with the page-cache cleanup after fallocate extends the file.

diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index 1969e4f444f7..a266105180a9 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -1178,13 +1178,15 @@ static long ntfs_fallocate(struct file *file,
int mode, loff_t offset, loff_t le

        err = file_modified(file);
 out:
+       if (!err && mode == 0 && NInoNonResident(ni) &&
+           offset > old_size) {
+               truncate_pagecache(vi, old_size);
+               pagecache_isize_extended(vi, old_size, offset);
+       }
+
        filemap_invalidate_unlock(vi->i_mapping);
+
        if (!err) {
-               if (mode == 0 && NInoNonResident(ni) &&
-                   offset > old_size) {
-                       truncate_pagecache(vi, old_size);
-                       pagecache_isize_extended(vi, old_size, offset);
-               }
                NInoSetFileNameDirty(ni);
                inode_set_mtime_to_ts(vi, inode_set_ctime_current(vi));
                mark_inode_dirty(vi);