[PATCH] Btrfs: avoid build warning on 32-bit

[Arnd Bergmann <arnd@arndb.de>]

A recent change introduced a type cast from a private 64-bit
value to a pointer, which works fine on 64-bit architectures,
but not on 32-bit ones, where it produces a harmless compiler
warning:

fs/btrfs/extent_io.c: In function 'btrfs_free_io_failure_record':
fs/btrfs/extent_io.c:2193:13: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]

This adds an intermediate cast to 'unsigned long', which tells
the compiler to ignore the type mismatch.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: f612496bca664 ("Btrfs: cleanup the read failure record after write
			or when the inode is freeing")

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 4ebabd237153..790dbae3343c 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2190,7 +2190,7 @@ void btrfs_free_io_failure_record(struct inode *inode, u64 start, u64 end)
 
 		next = next_state(state);
 
-		failrec = (struct io_failure_record *)state->private;
+		failrec = (struct io_failure_record *)(unsigned long)state->private;
 		free_extent_state(state);
 		kfree(failrec);