f2fs: reduce stack memory cost by using bitfield in struct f2fs_io_info

This patch tries to use bitfield in struct f2fs_io_info to improve
memory usage.

struct f2fs_io_info {
...
	unsigned int need_lock:8;	/* indicate we need to lock cp_rwsem */
	unsigned int version:8;		/* version of the node */
	unsigned int submitted:1;	/* indicate IO submission */
	unsigned int in_list:1;		/* indicate fio is in io_list */
	unsigned int is_por:1;		/* indicate IO is from recovery or not */
	unsigned int retry:1;		/* need to reallocate block address */
	unsigned int encrypted:1;	/* indicate file is encrypted */
	unsigned int post_read:1;	/* require post read */
...
};

After this patch, size of struct f2fs_io_info reduces from 136 to 120.

[Nathan: fix a compile warning (single-bit-bitfield-constant-conversion)]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/checkpoint.c

@@ -70,7 +70,7 @@ static struct page *__get_meta_page(struct f2fs_sb_info *sbi, pgoff_t index,
 		.old_blkaddr = index,
 		.new_blkaddr = index,
 		.encrypted_page = NULL,
-		.is_por = !is_meta,
+		.is_por = !is_meta ? 1 : 0,
 	};
 	int err;
 
@@ -237,8 +237,8 @@ int f2fs_ra_meta_pages(struct f2fs_sb_info *sbi, block_t start, int nrpages,
 		.op = REQ_OP_READ,
 		.op_flags = sync ? (REQ_META | REQ_PRIO) : REQ_RAHEAD,
 		.encrypted_page = NULL,
-		.in_list = false,
+		.in_list = 0,
-		.is_por = (type == META_POR),
+		.is_por = (type == META_POR) ? 1 : 0,
 	};
 	struct blk_plug plug;
 	int err;

fs/f2fs/compress.c

@@ -1213,10 +1213,11 @@ static int f2fs_write_compressed_pages(struct compress_ctx *cc,
 		.page = NULL,
 		.encrypted_page = NULL,
 		.compressed_page = NULL,
-		.submitted = false,
+		.submitted = 0,
 		.io_type = io_type,
 		.io_wbc = wbc,
-		.encrypted = fscrypt_inode_uses_fs_layer_crypto(cc->inode),
+		.encrypted = fscrypt_inode_uses_fs_layer_crypto(cc->inode) ?
+									1 : 0,
 	};
 	struct dnode_of_data dn;
 	struct node_info ni;

fs/f2fs/data.c

@@ -992,7 +992,7 @@ next:
 		bio_page = fio->page;
 
 	/* set submitted = true as a return value */
-	fio->submitted = true;
+	fio->submitted = 1;
 
 	inc_page_count(sbi, WB_DATA_TYPE(bio_page));
 
@@ -1008,7 +1008,7 @@ alloc_new:
 				(fio->type == DATA || fio->type == NODE) &&
 				fio->new_blkaddr & F2FS_IO_SIZE_MASK(sbi)) {
 			dec_page_count(sbi, WB_DATA_TYPE(bio_page));
-			fio->retry = true;
+			fio->retry = 1;
 			goto skip;
 		}
 		io->bio = __bio_alloc(fio, BIO_MAX_VECS);
@@ -2776,10 +2776,10 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
 		.old_blkaddr = NULL_ADDR,
 		.page = page,
 		.encrypted_page = NULL,
-		.submitted = false,
+		.submitted = 0,
 		.compr_blocks = compr_blocks,
 		.need_lock = LOCK_RETRY,
-		.post_read = f2fs_post_read_required(inode),
+		.post_read = f2fs_post_read_required(inode) ? 1 : 0,
 		.io_type = io_type,
 		.io_wbc = wbc,
 		.bio = bio,
@@ -2900,7 +2900,7 @@ out:
 	}
 
 	if (submitted)
-		*submitted = fio.submitted ? 1 : 0;
+		*submitted = fio.submitted;
 
 	return 0;
 

fs/f2fs/f2fs.h

@@ -1210,19 +1210,19 @@ struct f2fs_io_info {
 	struct page *encrypted_page;	/* encrypted page */
 	struct page *compressed_page;	/* compressed page */
 	struct list_head list;		/* serialize IOs */
-	bool submitted;		/* indicate IO submission */
+	unsigned int compr_blocks;	/* # of compressed block addresses */
-	int need_lock;		/* indicate we need to lock cp_rwsem */
+	unsigned int need_lock:8;	/* indicate we need to lock cp_rwsem */
-	bool in_list;		/* indicate fio is in io_list */
+	unsigned int version:8;		/* version of the node */
-	bool is_por;		/* indicate IO is from recovery or not */
+	unsigned int submitted:1;	/* indicate IO submission */
-	bool retry;		/* need to reallocate block address */
+	unsigned int in_list:1;		/* indicate fio is in io_list */
-	int compr_blocks;	/* # of compressed block addresses */
+	unsigned int is_por:1;		/* indicate IO is from recovery or not */
-	bool encrypted;		/* indicate file is encrypted */
+	unsigned int retry:1;		/* need to reallocate block address */
-	bool post_read;		/* require post read */
+	unsigned int encrypted:1;	/* indicate file is encrypted */
+	unsigned int post_read:1;	/* require post read */
 	enum iostat_type io_type;	/* io type */
 	struct writeback_control *io_wbc; /* writeback control */
 	struct bio **bio;		/* bio for ipu */
 	sector_t *last_block;		/* last block number in bio */
-	unsigned char version;		/* version of the node */
 };
 
 struct bio_entry {

fs/f2fs/gc.c

@@ -1156,8 +1156,8 @@ static int ra_data_block(struct inode *inode, pgoff_t index)
 		.op = REQ_OP_READ,
 		.op_flags = 0,
 		.encrypted_page = NULL,
-		.in_list = false,
+		.in_list = 0,
-		.retry = false,
+		.retry = 0,
 	};
 	int err;
 
@@ -1245,8 +1245,8 @@ static int move_data_block(struct inode *inode, block_t bidx,
 		.op = REQ_OP_READ,
 		.op_flags = 0,
 		.encrypted_page = NULL,
-		.in_list = false,
+		.in_list = 0,
-		.retry = false,
+		.retry = 0,
 	};
 	struct dnode_of_data dn;
 	struct f2fs_summary sum;

fs/f2fs/node.c

@@ -1586,7 +1586,7 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
 		.op_flags = wbc_to_write_flags(wbc),
 		.page = page,
 		.encrypted_page = NULL,
-		.submitted = false,
+		.submitted = 0,
 		.io_type = io_type,
 		.io_wbc = wbc,
 	};

fs/f2fs/segment.c

@@ -3314,10 +3314,10 @@ void f2fs_allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
 		struct f2fs_bio_info *io;
 
 		if (F2FS_IO_ALIGNED(sbi))
-			fio->retry = false;
+			fio->retry = 0;
 
 		INIT_LIST_HEAD(&fio->list);
-		fio->in_list = true;
+		fio->in_list = 1;
 		io = sbi->write_io[fio->type] + fio->temp;
 		spin_lock(&io->io_lock);
 		list_add_tail(&fio->list, &io->io_list);
@@ -3398,7 +3398,7 @@ void f2fs_do_write_meta_page(struct f2fs_sb_info *sbi, struct page *page,
 		.new_blkaddr = page->index,
 		.page = page,
 		.encrypted_page = NULL,
-		.in_list = false,
+		.in_list = 0,
 	};
 
 	if (unlikely(page->index >= MAIN_BLKADDR(sbi)))