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>

fs/ext4/ext4.h

@@ -268,7 +268,6 @@ struct flex_groups {
 #define EXT4_TOPDIR_FL			0x00020000 /* Top of directory hierarchies*/
 #define EXT4_HUGE_FILE_FL               0x00040000 /* Set to each huge file */
 #define EXT4_EXTENTS_FL			0x00080000 /* Inode uses extents */
-#define EXT4_EXT_MIGRATE		0x00100000 /* Inode is migrating */
 #define EXT4_RESERVED_FL		0x80000000 /* reserved for ext4 lib */
 
 #define EXT4_FL_USER_VISIBLE		0x000BDFFF /* User visible flags */
@@ -306,6 +305,7 @@ static inline __u32 ext4_mask_flags(umode_t mode, __u32 flags)
 #define EXT4_STATE_XATTR		0x00000004 /* has in-inode xattrs */
 #define EXT4_STATE_NO_EXPAND		0x00000008 /* No space for expansion */
 #define EXT4_STATE_DA_ALLOC_CLOSE	0x00000010 /* Alloc DA blks on close */
+#define EXT4_STATE_EXT_MIGRATE		0x00000020 /* Inode is migrating */
 
 /* Used to pass group descriptor data when online resize is done */
 struct ext4_new_group_input {

fs/ext4/inode.c

@@ -1255,8 +1255,7 @@ int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
 			 * i_data's format changing.  Force the migrate
 			 * to fail by clearing migrate flags
 			 */
-			EXT4_I(inode)->i_flags = EXT4_I(inode)->i_flags &
-							~EXT4_EXT_MIGRATE;
+			EXT4_I(inode)->i_state &= ~EXT4_STATE_EXT_MIGRATE;
 		}
 	}
 
@@ -4596,8 +4595,7 @@ static int ext4_do_update_inode(handle_t *handle,
 	if (ext4_inode_blocks_set(handle, raw_inode, ei))
 		goto out_brelse;
 	raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
-	/* clear the migrate flag in the raw_inode */
-	raw_inode->i_flags = cpu_to_le32(ei->i_flags & ~EXT4_EXT_MIGRATE);
+	raw_inode->i_flags = cpu_to_le32(ei->i_flags);
 	if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
 	    cpu_to_le32(EXT4_OS_HURD))
 		raw_inode->i_file_acl_high =

fs/ext4/migrate.c

@@ -353,17 +353,16 @@ static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
 
 	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 @@ int ext4_ext_migrate(struct inode *inode)
 	 * 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);