CVE-2026-72187: ntfs: avoid self-deadlock during inode eviction

In the Linux kernel, the following vulnerability has been resolved:

ntfs: avoid self-deadlock during inode eviction

An attribute-list update performed while allocating clusters can drop the last reference to the temporary attribute inode. Evicting that inode drops its reference to the base inode and can invoke ntfsdropbiginode() for the base inode from within the base inode's own writeback path.

If the base inode is unlinked, ntfsdropbiginode() calls truncatesetsize(), which waits for the inode's folio writeback to complete. The same writeback worker is responsible for completing that writeback, so it waits for itself indefinitely.

Prevent this self-deadlock by grabbing a reference to the base inode at the beginning of ntfswritepages() and releasing it at the end of the function. This defers eviction until all bios have been submitted, allowing the wait for folio writeback to complete safely.