ext4: replace i_delalloc_reserved_flag with EXT4_STATE_DELALLOC_RESERVED

Remove the short element i_delalloc_reserved_flag from the
ext4_inode_info structure and replace it a new bit in i_state_flags.
Since we have an ext4_inode_info for every ext4 inode cached in the
inode cache, any savings we can produce here is a very good thing from
a memory utilization perspective.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/balloc.c

@@ -592,7 +592,8 @@ ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 	 * Account for the allocated meta blocks.  We will never
 	 * fail EDQUOT for metdata, but we do account for it.
 	 */
-	if (!(*errp) && EXT4_I(inode)->i_delalloc_reserved_flag) {
+	if (!(*errp) &&
+	    ext4_test_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED)) {
 		spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
 		EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
 		spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);

fs/ext4/ext4.h

@@ -828,7 +828,6 @@ struct ext4_inode_info {
 	unsigned int i_reserved_data_blocks;
 	unsigned int i_reserved_meta_blocks;
 	unsigned int i_allocated_meta_blocks;
-	unsigned short i_delalloc_reserved_flag;
 	sector_t i_da_metadata_calc_last_lblock;
 	int i_da_metadata_calc_len;
 
@@ -1235,6 +1234,7 @@ enum {
 	EXT4_STATE_EXT_MIGRATE,		/* Inode is migrating */
 	EXT4_STATE_DIO_UNWRITTEN,	/* need convert on dio done*/
 	EXT4_STATE_NEWENTRY,		/* File just added to dir */
+	EXT4_STATE_DELALLOC_RESERVED,	/* blks already reserved for delalloc */
 };
 
 #define EXT4_INODE_BIT_FNS(name, field)					\

fs/ext4/inode.c

@@ -1330,7 +1330,7 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
 	 * avoid double accounting
 	 */
 	if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
-		EXT4_I(inode)->i_delalloc_reserved_flag = 1;
+		ext4_set_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED);
 	/*
 	 * We need to check for EXT4 here because migrate
 	 * could have changed the inode type in between
@@ -1360,7 +1360,7 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
 			ext4_da_update_reserve_space(inode, retval, 1);
 	}
 	if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
-		EXT4_I(inode)->i_delalloc_reserved_flag = 0;
+		ext4_clear_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED);
 
 	up_write((&EXT4_I(inode)->i_data_sem));
 	if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
@@ -2249,7 +2249,7 @@ static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
 	 * affects functions in many different parts of the allocation
 	 * call path.  This flag exists primarily because we don't
 	 * want to change *many* call functions, so ext4_map_blocks()
-	 * will set the magic i_delalloc_reserved_flag once the
+	 * will set the EXT4_STATE_DELALLOC_RESERVED flag once the
 	 * inode's allocation semaphore is taken.
 	 *
 	 * If the blocks in questions were delalloc blocks, set

fs/ext4/mballoc.c

@@ -4283,7 +4283,7 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
 	 * EDQUOT check, as blocks and quotas have been already
 	 * reserved when data being copied into pagecache.
 	 */
-	if (EXT4_I(ar->inode)->i_delalloc_reserved_flag)
+	if (ext4_test_inode_state(ar->inode, EXT4_STATE_DELALLOC_RESERVED))
 		ar->flags |= EXT4_MB_DELALLOC_RESERVED;
 	else {
 		/* Without delayed allocation we need to verify
@@ -4380,7 +4380,8 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
 	if (inquota && ar->len < inquota)
 		dquot_free_block(ar->inode, inquota - ar->len);
 	if (!ar->len) {
-		if (!EXT4_I(ar->inode)->i_delalloc_reserved_flag)
+		if (!ext4_test_inode_state(ar->inode,
+					   EXT4_STATE_DELALLOC_RESERVED))
 			/* release all the reserved blocks if non delalloc */
 			percpu_counter_sub(&sbi->s_dirtyblocks_counter,
 						reserv_blks);

fs/ext4/super.c

@@ -828,7 +828,6 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
 	ei->i_reserved_meta_blocks = 0;
 	ei->i_allocated_meta_blocks = 0;
 	ei->i_da_metadata_calc_len = 0;
-	ei->i_delalloc_reserved_flag = 0;
 	spin_lock_init(&(ei->i_block_reservation_lock));
 #ifdef CONFIG_QUOTA
 	ei->i_reserved_quota = 0;