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Commit 5c27f4ee authored by Chao Yu's avatar Chao Yu Committed by Jaegeuk Kim
Browse files

f2fs: merge two uchar variable in struct node_info to reduce memory cost 



This patch moves one member of struct nat_entry: _flag_ to struct node_info,
so _version_ in struct node_info and _flag_ which are unsigned char type will
merge to one 32-bit space in register/memory. So the size of nat_entry will be
reduced from 28 bytes to 24 bytes (for 64-bit machine, reduce its size from 40
bytes to 32 bytes) and then slab memory using by f2fs will be reduced.

changes from v2:
 o update description of memory usage gain for 64-bit machine suggested by
   Changman Lee.
changes from v1:
 o introduce inline copy_node_info() to copy valid data from node info suggested
   by Jaegeuk Kim, it can avoid bug.

Reviewed-by: default avatarChangman Lee <cm224.lee@samsung.com>
Signed-off-by: default avatarChao Yu <chao2.yu@samsung.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 3fa06d7b

fs/f2fs/node.c

+2 −2
Original line number Diff line number Diff line
@@ -269,7 +269,7 @@ static void set_node_addr(struct f2fs_sb_info *sbi, struct node_info *ni, 
	e = __lookup_nat_cache(nm_i, ni->nid);

	if (!e) {

		e = grab_nat_entry(nm_i, ni->nid);

		e->ni = *ni;

		copy_node_info(&e->ni, ni);

		f2fs_bug_on(sbi, ni->blk_addr == NEW_ADDR);

	} else if (new_blkaddr == NEW_ADDR) {

		/*
@@ -277,7 +277,7 @@ static void set_node_addr(struct f2fs_sb_info *sbi, struct node_info *ni, 
		 * previous nat entry can be remained in nat cache.

		 * So, reinitialize it with new information.

		 */

		e->ni = *ni;

		copy_node_info(&e->ni, ni);

		f2fs_bug_on(sbi, ni->blk_addr != NULL_ADDR);

	}

fs/f2fs/node.h

+22 −11
Original line number Diff line number Diff line
@@ -29,6 +29,14 @@ 
/* return value for read_node_page */

#define LOCKED_PAGE	1



/* For flag in struct node_info */

enum {

	IS_CHECKPOINTED,	/* is it checkpointed before? */

	HAS_FSYNCED_INODE,	/* is the inode fsynced before? */

	HAS_LAST_FSYNC,		/* has the latest node fsync mark? */

	IS_DIRTY,		/* this nat entry is dirty? */

};



/*

 * For node information

 */
@@ -37,18 +45,11 @@ struct node_info { 
	nid_t ino;		/* inode number of the node's owner */

	block_t	blk_addr;	/* block address of the node */

	unsigned char version;	/* version of the node */

};



enum {

	IS_CHECKPOINTED,	/* is it checkpointed before? */

	HAS_FSYNCED_INODE,	/* is the inode fsynced before? */

	HAS_LAST_FSYNC,		/* has the latest node fsync mark? */

	IS_DIRTY,		/* this nat entry is dirty? */

	unsigned char flag;	/* for node information bits */

};



struct nat_entry {

	struct list_head list;	/* for clean or dirty nat list */

	unsigned char flag;	/* for node information bits */

	struct node_info ni;	/* in-memory node information */

};
@@ -63,20 +64,30 @@ struct nat_entry { 


#define inc_node_version(version)	(++version)



static inline void copy_node_info(struct node_info *dst,

						struct node_info *src)

{

	dst->nid = src->nid;

	dst->ino = src->ino;

	dst->blk_addr = src->blk_addr;

	dst->version = src->version;

	/* should not copy flag here */

}



static inline void set_nat_flag(struct nat_entry *ne,

				unsigned int type, bool set)

{

	unsigned char mask = 0x01 << type;

	if (set)

		ne->flag |= mask;

		ne->ni.flag |= mask;

	else

		ne->flag &= ~mask;

		ne->ni.flag &= ~mask;

}



static inline bool get_nat_flag(struct nat_entry *ne, unsigned int type)

{

	unsigned char mask = 0x01 << type;

	return ne->flag & mask;

	return ne->ni.flag & mask;

}



static inline void nat_reset_flag(struct nat_entry *ne)