ext4: store EXT4_EXT_MIGRATE in i_state instead of i_flags

EXT4_EXT_MIGRATE is only intended to be used for an in-memory flag,
and the hex value assigned to it collides with FS_DIRECTIO_FL (which
is also stored in i_flags).  There's no reason for the
EXT4_EXT_MIGRATE bit to be stored in i_flags, so we switch it to use
i_state instead.

Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
index 05361ad..bf519f2 100644
--- a/fs/ext4/migrate.c
+++ b/fs/ext4/migrate.c
@@ -353,17 +353,16 @@
 
 	down_write(&EXT4_I(inode)->i_data_sem);
 	/*
-	 * if EXT4_EXT_MIGRATE is cleared a block allocation
+	 * if EXT4_STATE_EXT_MIGRATE is cleared a block allocation
 	 * happened after we started the migrate. We need to
 	 * fail the migrate
 	 */
-	if (!(EXT4_I(inode)->i_flags & EXT4_EXT_MIGRATE)) {
+	if (!(EXT4_I(inode)->i_state & EXT4_STATE_EXT_MIGRATE)) {
 		retval = -EAGAIN;
 		up_write(&EXT4_I(inode)->i_data_sem);
 		goto err_out;
 	} else
-		EXT4_I(inode)->i_flags = EXT4_I(inode)->i_flags &
-							~EXT4_EXT_MIGRATE;
+		EXT4_I(inode)->i_state &= ~EXT4_STATE_EXT_MIGRATE;
 	/*
 	 * We have the extent map build with the tmp inode.
 	 * Now copy the i_data across
@@ -517,14 +516,15 @@
 	 * when we add extents we extent the journal
 	 */
 	/*
-	 * Even though we take i_mutex we can still cause block allocation
-	 * via mmap write to holes. If we have allocated new blocks we fail
-	 * migrate.  New block allocation will clear EXT4_EXT_MIGRATE flag.
-	 * The flag is updated with i_data_sem held to prevent racing with
-	 * block allocation.
+	 * Even though we take i_mutex we can still cause block
+	 * allocation via mmap write to holes. If we have allocated
+	 * new blocks we fail migrate.  New block allocation will
+	 * clear EXT4_STATE_EXT_MIGRATE flag.  The flag is updated
+	 * with i_data_sem held to prevent racing with block
+	 * allocation.
 	 */
 	down_read((&EXT4_I(inode)->i_data_sem));
-	EXT4_I(inode)->i_flags = EXT4_I(inode)->i_flags | EXT4_EXT_MIGRATE;
+	EXT4_I(inode)->i_state |= EXT4_STATE_EXT_MIGRATE;
 	up_read((&EXT4_I(inode)->i_data_sem));
 
 	handle = ext4_journal_start(inode, 1);