ext4: Use bitops to read/modify EXT4_I(inode)->i_state

At several places we modify EXT4_I(inode)->i_state without holding
i_mutex (ext4_release_file, ext4_bmap, ext4_journalled_writepage,
ext4_do_update_inode, ...). These modifications are racy and we can
lose updates to i_state. So convert handling of i_state to use bitops
which are atomic.

Cc: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/migrate.c

diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
index 8141581..46a4101 100644
--- a/fs/ext4/migrate.c
+++ b/fs/ext4/migrate.c
@@ -365,12 +365,12 @@
 	 * happened after we started the migrate. We need to
 	 * fail the migrate
 	 */
-	if (!(EXT4_I(inode)->i_state & EXT4_STATE_EXT_MIGRATE)) {
+	if (!ext4_test_inode_state(inode, EXT4_STATE_EXT_MIGRATE)) {
 		retval = -EAGAIN;
 		up_write(&EXT4_I(inode)->i_data_sem);
 		goto err_out;
 	} else
-		EXT4_I(inode)->i_state &= ~EXT4_STATE_EXT_MIGRATE;
+		ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
 	/*
 	 * We have the extent map build with the tmp inode.
 	 * Now copy the i_data across
@@ -533,7 +533,7 @@
 	 * allocation.
 	 */
 	down_read((&EXT4_I(inode)->i_data_sem));
-	EXT4_I(inode)->i_state |= EXT4_STATE_EXT_MIGRATE;
+	ext4_set_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
 	up_read((&EXT4_I(inode)->i_data_sem));
 
 	handle = ext4_journal_start(inode, 1);