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Commit 9f24e420 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: Use atomic_t's in struct flex_groups 



Reduce pressure on the sb_bgl_lock family of locks by using atomic_t's
to track the number of free blocks and inodes in each flex_group.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent b713a5ec

fs/ext4/balloc.c

+2 −3
Original line number Diff line number Diff line
@@ -470,9 +470,8 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb, 


	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 += blocks_freed;

		spin_unlock(sb_bgl_lock(sbi, flex_group));

		atomic_add(blocks_freed,

			   &sbi->s_flex_groups[flex_group].free_blocks);

	}

	/*

	 * request to reload the buddy with the

fs/ext4/ext4.h

+2 −2
Original line number Diff line number Diff line
@@ -170,8 +170,8 @@ struct ext4_group_desc 
 */



struct flex_groups {

	__u32 free_inodes;

	__u32 free_blocks;

	atomic_t free_inodes;

	atomic_t free_blocks;

};



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

fs/ext4/ialloc.c

+15 −18
Original line number Diff line number Diff line
@@ -189,7 +189,6 @@ void ext4_free_inode(handle_t *handle, struct inode *inode) 
	struct ext4_super_block *es;

	struct ext4_sb_info *sbi;

	int fatal = 0, err, count, cleared;

	ext4_group_t flex_group;



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

		printk(KERN_ERR "ext4_free_inode: inode has count=%d\n",
@@ -277,10 +276,10 @@ void ext4_free_inode(handle_t *handle, struct inode *inode) 
				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));

				ext4_group_t f;



				f = ext4_flex_group(sbi, block_group);

				atomic_inc(&sbi->s_flex_groups[f].free_inodes);

			}

		}

		BUFFER_TRACE(bh2, "call ext4_handle_dirty_metadata");
@@ -360,9 +359,9 @@ static int find_group_flex(struct super_block *sb, struct inode *parent, 
		sbi->s_log_groups_per_flex;



find_close_to_parent:

	flexbg_free_blocks = flex_group[best_flex].free_blocks;

	flexbg_free_blocks = atomic_read(&flex_group[best_flex].free_blocks);

	flex_freeb_ratio = flexbg_free_blocks * 100 / blocks_per_flex;

	if (flex_group[best_flex].free_inodes &&

	if (atomic_read(&flex_group[best_flex].free_inodes) &&

	    flex_freeb_ratio > free_block_ratio)

		goto found_flexbg;
@@ -375,24 +374,24 @@ find_close_to_parent: 
		if (i == parent_fbg_group || i == parent_fbg_group - 1)

			continue;



		flexbg_free_blocks = flex_group[i].free_blocks;

		flexbg_free_blocks = atomic_read(&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) {

		    (atomic_read(&flex_group[i].free_inodes))) {

			best_flex = i;

			goto found_flexbg;

		}



		if (flex_group[best_flex].free_inodes == 0 ||

		    (flex_group[i].free_blocks >

		     flex_group[best_flex].free_blocks &&

		     flex_group[i].free_inodes))

		if ((atomic_read(&flex_group[best_flex].free_inodes) == 0) ||

		    ((atomic_read(&flex_group[i].free_blocks) >

		      atomic_read(&flex_group[best_flex].free_blocks)) &&

		     atomic_read(&flex_group[i].free_inodes)))

			best_flex = i;

	}



	if (!flex_group[best_flex].free_inodes ||

	    !flex_group[best_flex].free_blocks)

	if (!atomic_read(&flex_group[best_flex].free_inodes) ||

	    !atomic_read(&flex_group[best_flex].free_blocks))

		return -1;



found_flexbg:
@@ -960,9 +959,7 @@ got: 


	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));

		atomic_dec(&sbi->s_flex_groups[flex_group].free_inodes);

	}



	inode->i_uid = current_fsuid();

fs/ext4/mballoc.c

+3 −6
Original line number Diff line number Diff line
@@ -3044,9 +3044,8 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac, 
	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));

		atomic_sub(ac->ac_b_ex.fe_len,

			   &sbi->s_flex_groups[flex_group].free_blocks);

	}



	err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
@@ -4884,9 +4883,7 @@ do_more: 


	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));

		atomic_add(count, &sbi->s_flex_groups[flex_group].free_blocks);

	}



	ext4_mb_release_desc(&e4b);

fs/ext4/resize.c

+4 −4
Original line number Diff line number Diff line
@@ -938,10 +938,10 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input) 
	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {

		ext4_group_t flex_group;

		flex_group = ext4_flex_group(sbi, input->group);

		sbi->s_flex_groups[flex_group].free_blocks +=

			input->free_blocks_count;

		sbi->s_flex_groups[flex_group].free_inodes +=

			EXT4_INODES_PER_GROUP(sb);

		atomic_add(input->free_blocks_count,

			   &sbi->s_flex_groups[flex_group].free_blocks);

		atomic_add(EXT4_INODES_PER_GROUP(sb),

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

	}



	ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);