ntfs: drop stale page-cache when shrinking a non-resident attr

ntfs_non_resident_attr_shrink() shrinks attribute sizes but fails to
trim the page cache. This leaves orphaned dirty folios beyond the new
end of the attribute, leading to writeback failures (-ENOENT), data
loss, and $EA chain corruption.

Fix this by truncating the page cache to the new size immediately after
updating the sizes, preventing writeback from flushing out-of-range folios.

Fixes: 495e90fa33 ("ntfs: update attrib operations")
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

fs/ntfs/attrib.c

@@ -4293,6 +4293,16 @@ static int ntfs_non_resident_attr_shrink(struct ntfs_inode *ni, const s64 newsiz
 		ni->initialized_size = newsize;
 		ctx->attr->data.non_resident.initialized_size = cpu_to_le64(newsize);
 	}
+
+	/*
+	 * Drop any page-cache folios that now lie beyond the shrunk
+	 * attribute. The clusters backing them have just been freed and the
+	 * runlist truncated, so leaving stale dirty folios around makes a
+	 * later writeback map a vcn past the new allocation, which fails with
+	 * -ENOENT and loses the write.
+	 */
+	truncate_inode_pages(VFS_I(ni)->i_mapping, newsize);
+
 	/* Update data size in the index. */
 	if (ni->type == AT_DATA && ni->name == AT_UNNAMED)
 		NInoSetFileNameDirty(ni);