Commit 772cb7c8 authored by Jose R. Santos's avatar Jose R. Santos Committed by Theodore Ts'o
Browse files

ext4: New inode allocation for FLEX_BG meta-data groups. 



This patch mostly controls the way inode are allocated in order to
make ialloc aware of flex_bg block group grouping.  It achieves this
by bypassing the Orlov allocator when block group meta-data are packed
toghether through mke2fs.  Since the impact on the block allocator is
minimal, this patch should have little or no effect on other block
allocation algorithms. By controlling the inode allocation, it can
basically control where the initial search for new block begins and
thus indirectly manipulate the block allocator.

This allocator favors data and meta-data locality so the disk will
gradually be filled from block group zero upward.  This helps improve
performance by reducing seek time.  Since the group of inode tables
within one flex_bg are treated as one giant inode table, uninitialized
block groups would not need to partially initialize as many inode
table as with Orlov which would help fsck time as the filesystem usage
goes up.

Signed-off-by: default avatarJose R. Santos <jrs@us.ibm.com>
Signed-off-by: default avatarValerie Clement <valerie.clement@bull.net>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 736603ab

fs/ext4/balloc.c

+14 −0
Original line number Diff line number Diff line
@@ -809,6 +809,13 @@ do_more: 
	spin_unlock(sb_bgl_lock(sbi, block_group));

	percpu_counter_add(&sbi->s_freeblocks_counter, count);



	if (sbi->s_log_groups_per_flex) {

		ext4_group_t flex_group = ext4_flex_group(sbi, block_group);

		spin_lock(sb_bgl_lock(sbi, flex_group));

		sbi->s_flex_groups[flex_group].free_blocks += count;

		spin_unlock(sb_bgl_lock(sbi, flex_group));

	}



	/* We dirtied the bitmap block */

	BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");

	err = ext4_journal_dirty_metadata(handle, bitmap_bh);
@@ -1883,6 +1890,13 @@ allocated: 
	spin_unlock(sb_bgl_lock(sbi, group_no));

	percpu_counter_sub(&sbi->s_freeblocks_counter, num);



	if (sbi->s_log_groups_per_flex) {

		ext4_group_t flex_group = ext4_flex_group(sbi, group_no);

		spin_lock(sb_bgl_lock(sbi, flex_group));

		sbi->s_flex_groups[flex_group].free_blocks -= num;

		spin_unlock(sb_bgl_lock(sbi, flex_group));

	}



	BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");

	err = ext4_journal_dirty_metadata(handle, gdp_bh);

	if (!fatal)

fs/ext4/ext4.h

+24 −1
Original line number Diff line number Diff line
@@ -170,6 +170,15 @@ struct ext4_group_desc 
	__u32	bg_reserved2[3];

};



/*

 * Structure of a flex block group info

 */



struct flex_groups {

	__u32 free_inodes;

	__u32 free_blocks;

};



#define EXT4_BG_INODE_UNINIT	0x0001 /* Inode table/bitmap not in use */

#define EXT4_BG_BLOCK_UNINIT	0x0002 /* Block bitmap not in use */

#define EXT4_BG_INODE_ZEROED	0x0004 /* On-disk itable initialized to zero */
@@ -647,7 +656,10 @@ struct ext4_super_block { 
	__le16  s_mmp_interval;         /* # seconds to wait in MMP checking */

	__le64  s_mmp_block;            /* Block for multi-mount protection */

	__le32  s_raid_stripe_width;    /* blocks on all data disks (N*stride)*/

	__u32   s_reserved[163];        /* Padding to the end of the block */

	__u8	s_log_groups_per_flex;  /* FLEX_BG group size */

	__u8	s_reserved_char_pad2;

	__le16  s_reserved_pad;

	__u32   s_reserved[162];        /* Padding to the end of the block */

};



#ifdef __KERNEL__
@@ -1160,6 +1172,17 @@ struct ext4_group_info *ext4_get_group_info(struct super_block *sb, 
}





static inline ext4_group_t ext4_flex_group(struct ext4_sb_info *sbi,

					     ext4_group_t block_group)

{

	return block_group >> sbi->s_log_groups_per_flex;

}



static inline unsigned int ext4_flex_bg_size(struct ext4_sb_info *sbi)

{

	return 1 << sbi->s_log_groups_per_flex;

}



#define ext4_std_error(sb, errno)				\

do {								\

	if ((errno))						\

fs/ext4/ext4_sb.h

+3 −0
Original line number Diff line number Diff line
@@ -143,6 +143,9 @@ struct ext4_sb_info { 


	/* locality groups */

	struct ext4_locality_group *s_locality_groups;



	unsigned int s_log_groups_per_flex;

	struct flex_groups *s_flex_groups;

};



#endif	/* _EXT4_SB */

fs/ext4/ialloc.c

+96 −0
Original line number Diff line number Diff line
@@ -157,6 +157,7 @@ void ext4_free_inode (handle_t *handle, struct inode * inode) 
	struct ext4_super_block * es;

	struct ext4_sb_info *sbi;

	int fatal = 0, err;

	ext4_group_t flex_group;



	if (atomic_read(&inode->i_count) > 1) {

		printk ("ext4_free_inode: inode has count=%d\n",
@@ -232,6 +233,12 @@ void ext4_free_inode (handle_t *handle, struct inode * inode) 
			if (is_directory)

				percpu_counter_dec(&sbi->s_dirs_counter);



			if (sbi->s_log_groups_per_flex) {

				flex_group = ext4_flex_group(sbi, block_group);

				spin_lock(sb_bgl_lock(sbi, flex_group));

				sbi->s_flex_groups[flex_group].free_inodes++;

				spin_unlock(sb_bgl_lock(sbi, flex_group));

			}

		}

		BUFFER_TRACE(bh2, "call ext4_journal_dirty_metadata");

		err = ext4_journal_dirty_metadata(handle, bh2);
@@ -286,6 +293,80 @@ static int find_group_dir(struct super_block *sb, struct inode *parent, 
	return ret;

}



#define free_block_ratio 10



static int find_group_flex(struct super_block *sb, struct inode *parent,

			   ext4_group_t *best_group)

{

	struct ext4_sb_info *sbi = EXT4_SB(sb);

	struct ext4_group_desc *desc;

	struct buffer_head *bh;

	struct flex_groups *flex_group = sbi->s_flex_groups;

	ext4_group_t parent_group = EXT4_I(parent)->i_block_group;

	ext4_group_t parent_fbg_group = ext4_flex_group(sbi, parent_group);

	ext4_group_t ngroups = sbi->s_groups_count;

	int flex_size = ext4_flex_bg_size(sbi);

	ext4_group_t best_flex = parent_fbg_group;

	int blocks_per_flex = sbi->s_blocks_per_group * flex_size;

	int flexbg_free_blocks;

	int flex_freeb_ratio;

	ext4_group_t n_fbg_groups;

	ext4_group_t i;



	n_fbg_groups = (sbi->s_groups_count + flex_size - 1) >>

		sbi->s_log_groups_per_flex;



find_close_to_parent:

	flexbg_free_blocks = flex_group[best_flex].free_blocks;

	flex_freeb_ratio = flexbg_free_blocks * 100 / blocks_per_flex;

	if (flex_group[best_flex].free_inodes &&

	    flex_freeb_ratio > free_block_ratio)

		goto found_flexbg;



	if (best_flex && best_flex == parent_fbg_group) {

		best_flex--;

		goto find_close_to_parent;

	}



	for (i = 0; i < n_fbg_groups; i++) {

		if (i == parent_fbg_group || i == parent_fbg_group - 1)

			continue;



		flexbg_free_blocks = flex_group[i].free_blocks;

		flex_freeb_ratio = flexbg_free_blocks * 100 / blocks_per_flex;



		if (flex_freeb_ratio > free_block_ratio &&

		    flex_group[i].free_inodes) {

			best_flex = i;

			goto found_flexbg;

		}



		if (best_flex < 0 ||

		    (flex_group[i].free_blocks >

		     flex_group[best_flex].free_blocks &&

		     flex_group[i].free_inodes))

			best_flex = i;

	}



	if (!flex_group[best_flex].free_inodes ||

	    !flex_group[best_flex].free_blocks)

		return -1;



found_flexbg:

	for (i = best_flex * flex_size; i < ngroups &&

		     i < (best_flex + 1) * flex_size; i++) {

		desc = ext4_get_group_desc(sb, i, &bh);

		if (le16_to_cpu(desc->bg_free_inodes_count)) {

			*best_group = i;

			goto out;

		}

	}



	return -1;

out:

	return 0;

}



/*

 * Orlov's allocator for directories.

 *
@@ -501,6 +582,7 @@ struct inode *ext4_new_inode(handle_t *handle, struct inode * dir, int mode) 
	struct inode *ret;

	ext4_group_t i;

	int free = 0;

	ext4_group_t flex_group;



	/* Cannot create files in a deleted directory */

	if (!dir || !dir->i_nlink)
@@ -514,6 +596,12 @@ struct inode *ext4_new_inode(handle_t *handle, struct inode * dir, int mode) 


	sbi = EXT4_SB(sb);

	es = sbi->s_es;



	if (sbi->s_log_groups_per_flex) {

		ret2 = find_group_flex(sb, dir, &group);

		goto got_group;

	}



	if (S_ISDIR(mode)) {

		if (test_opt (sb, OLDALLOC))

			ret2 = find_group_dir(sb, dir, &group);
@@ -522,6 +610,7 @@ struct inode *ext4_new_inode(handle_t *handle, struct inode * dir, int mode) 
	} else

		ret2 = find_group_other(sb, dir, &group);



got_group:

	err = -ENOSPC;

	if (ret2 == -1)

		goto out;
@@ -676,6 +765,13 @@ got: 
		percpu_counter_inc(&sbi->s_dirs_counter);

	sb->s_dirt = 1;



	if (sbi->s_log_groups_per_flex) {

		flex_group = ext4_flex_group(sbi, group);

		spin_lock(sb_bgl_lock(sbi, flex_group));

		sbi->s_flex_groups[flex_group].free_inodes--;

		spin_unlock(sb_bgl_lock(sbi, flex_group));

	}



	inode->i_uid = current->fsuid;

	if (test_opt (sb, GRPID))

		inode->i_gid = dir->i_gid;

fs/ext4/mballoc.c

+15 −0
Original line number Diff line number Diff line
@@ -2842,6 +2842,14 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac, 
	spin_unlock(sb_bgl_lock(sbi, ac->ac_b_ex.fe_group));

	percpu_counter_sub(&sbi->s_freeblocks_counter, ac->ac_b_ex.fe_len);



	if (sbi->s_log_groups_per_flex) {

		ext4_group_t flex_group = ext4_flex_group(sbi,

							  ac->ac_b_ex.fe_group);

		spin_lock(sb_bgl_lock(sbi, flex_group));

		sbi->s_flex_groups[flex_group].free_blocks -= ac->ac_b_ex.fe_len;

		spin_unlock(sb_bgl_lock(sbi, flex_group));

	}



	err = ext4_journal_dirty_metadata(handle, bitmap_bh);

	if (err)

		goto out_err;
@@ -4342,6 +4350,13 @@ do_more: 
	spin_unlock(sb_bgl_lock(sbi, block_group));

	percpu_counter_add(&sbi->s_freeblocks_counter, count);



	if (sbi->s_log_groups_per_flex) {

		ext4_group_t flex_group = ext4_flex_group(sbi, block_group);

		spin_lock(sb_bgl_lock(sbi, flex_group));

		sbi->s_flex_groups[flex_group].free_blocks += count;

		spin_unlock(sb_bgl_lock(sbi, flex_group));

	}



	ext4_mb_release_desc(&e4b);



	*freed += count;

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