Merge tag 'locking-urgent-2026-09-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipgrafted

Pull futex fix from Ingo Molnar:

 - Also allocate a default private futex hash on vfork() as well, to
   avoid races with (private) futex waiters (Peter Zijlstra)

* tag 'locking-urgent-2026-09-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Also allocate private hash on vfork()

1 files changed, 52 insertions, 0 deletions

diff --git a/fs/ext4/truncate.h b/fs/ext4/truncate.h
new file mode 100644
index 000000000..ce84aa278
--- /dev/null
+++ b/fs/ext4/truncate.h
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/ext4/truncate.h
+ *
+ * Common inline functions needed for truncate support
+ */
+
+/*
+ * Truncate blocks that were not used by write. We have to truncate the
+ * pagecache as well so that corresponding buffers get properly unmapped.
+ */
+static inline void ext4_truncate_failed_write(struct inode *inode)
+{
+	struct address_space *mapping = inode->i_mapping;
+
+	/*
+	 * We don't need to call ext4_break_layouts() because the blocks we
+	 * are truncating were never visible to userspace.
+	 */
+	filemap_invalidate_lock(mapping);
+	truncate_inode_pages(mapping, inode->i_size);
+	ext4_truncate(inode);
+	filemap_invalidate_unlock(mapping);
+}
+
+/*
+ * Work out how many blocks we need to proceed with the next chunk of a
+ * truncate transaction.
+ */
+static inline unsigned long ext4_blocks_for_truncate(struct inode *inode)
+{
+	ext4_lblk_t needed;
+
+	needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
+
+	/* Give ourselves just enough room to cope with inodes in which
+	 * i_blocks is corrupt: we've seen disk corruptions in the past
+	 * which resulted in random data in an inode which looked enough
+	 * like a regular file for ext4 to try to delete it.  Things
+	 * will go a bit crazy if that happens, but at least we should
+	 * try not to panic the whole kernel. */
+	if (needed < 2)
+		needed = 2;
+
+	/* But we need to bound the transaction so we don't overflow the
+	 * journal. */
+	if (needed > EXT4_MAX_TRANS_DATA)
+		needed = EXT4_MAX_TRANS_DATA;
+
+	return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
+}
+