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Commit f157a4aa authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: Use a hash of the topdir directory name for the Orlov parent group 



Instead of using a random number to determine the goal parent grop for
the Orlov top directories, use a hash of the directory name.  This
allows for repeatable results when trying to benchmark filesystem
layout algorithms.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 8a8a2050

fs/ext4/ext4.h

+2 −1
Original line number Diff line number Diff line
@@ -1315,7 +1315,8 @@ extern int ext4fs_dirhash(const char *name, int len, struct 
			  dx_hash_info *hinfo);



/* ialloc.c */

extern struct inode * ext4_new_inode(handle_t *, struct inode *, int);

extern struct inode *ext4_new_inode(handle_t *, struct inode *, int,

				    const struct qstr *qstr);

extern void ext4_free_inode(handle_t *, struct inode *);

extern struct inode * ext4_orphan_get(struct super_block *, unsigned long);

extern unsigned long ext4_count_free_inodes(struct super_block *);

fs/ext4/ialloc.c

+14 −5
Original line number Diff line number Diff line
@@ -470,7 +470,8 @@ void get_orlov_stats(struct super_block *sb, ext4_group_t g, 
 */



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

			    ext4_group_t *group, int mode)

			    ext4_group_t *group, int mode,

			    const struct qstr *qstr)

{

	ext4_group_t parent_group = EXT4_I(parent)->i_block_group;

	struct ext4_sb_info *sbi = EXT4_SB(sb);
@@ -485,6 +486,7 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent, 
	struct ext4_group_desc *desc;

	struct orlov_stats stats;

	int flex_size = ext4_flex_bg_size(sbi);

	struct dx_hash_info hinfo;



	ngroups = real_ngroups;

	if (flex_size > 1) {
@@ -506,6 +508,12 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent, 
		int best_ndir = inodes_per_group;

		int ret = -1;



		if (qstr) {

			hinfo.hash_version = DX_HASH_HALF_MD4;

			hinfo.seed = sbi->s_hash_seed;

			ext4fs_dirhash(qstr->name, qstr->len, &hinfo);

			grp = hinfo.hash;

		} else

			get_random_bytes(&grp, sizeof(grp));

		parent_group = (unsigned)grp % ngroups;

		for (i = 0; i < ngroups; i++) {
@@ -649,7 +657,7 @@ static int find_group_other(struct super_block *sb, struct inode *parent, 
		*group = parent_group + flex_size;

		if (*group > ngroups)

			*group = 0;

		return find_group_orlov(sb, parent, group, mode);

		return find_group_orlov(sb, parent, group, mode, 0);

	}



	/*
@@ -790,7 +798,8 @@ err_ret: 
 * For other inodes, search forward from the parent directory's block

 * group to find a free inode.

 */

struct inode *ext4_new_inode(handle_t *handle, struct inode *dir, int mode)

struct inode *ext4_new_inode(handle_t *handle, struct inode *dir, int mode,

			     const struct qstr *qstr)

{

	struct super_block *sb;

	struct buffer_head *inode_bitmap_bh = NULL;
@@ -839,7 +848,7 @@ struct inode *ext4_new_inode(handle_t *handle, struct inode *dir, int mode) 
		if (test_opt(sb, OLDALLOC))

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

		else

			ret2 = find_group_orlov(sb, dir, &group, mode);

			ret2 = find_group_orlov(sb, dir, &group, mode, qstr);

	} else

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

fs/ext4/migrate.c

+2 −3
Original line number Diff line number Diff line
@@ -483,9 +483,8 @@ int ext4_ext_migrate(struct inode *inode) 
		retval = PTR_ERR(handle);

		return retval;

	}

	tmp_inode = ext4_new_inode(handle,

				inode->i_sb->s_root->d_inode,

				S_IFREG);

	tmp_inode = ext4_new_inode(handle, inode->i_sb->s_root->d_inode,

				   S_IFREG, 0);

	if (IS_ERR(tmp_inode)) {

		retval = -ENOMEM;

		ext4_journal_stop(handle);

fs/ext4/namei.c

+4 −4
Original line number Diff line number Diff line
@@ -1782,7 +1782,7 @@ retry: 
	if (IS_DIRSYNC(dir))

		ext4_handle_sync(handle);



	inode = ext4_new_inode (handle, dir, mode);

	inode = ext4_new_inode(handle, dir, mode, &dentry->d_name);

	err = PTR_ERR(inode);

	if (!IS_ERR(inode)) {

		inode->i_op = &ext4_file_inode_operations;
@@ -1816,7 +1816,7 @@ retry: 
	if (IS_DIRSYNC(dir))

		ext4_handle_sync(handle);



	inode = ext4_new_inode(handle, dir, mode);

	inode = ext4_new_inode(handle, dir, mode, &dentry->d_name);

	err = PTR_ERR(inode);

	if (!IS_ERR(inode)) {

		init_special_inode(inode, inode->i_mode, rdev);
@@ -1853,7 +1853,7 @@ retry: 
	if (IS_DIRSYNC(dir))

		ext4_handle_sync(handle);



	inode = ext4_new_inode(handle, dir, S_IFDIR | mode);

	inode = ext4_new_inode(handle, dir, S_IFDIR | mode, &dentry->d_name);

	err = PTR_ERR(inode);

	if (IS_ERR(inode))

		goto out_stop;
@@ -2264,7 +2264,7 @@ retry: 
	if (IS_DIRSYNC(dir))

		ext4_handle_sync(handle);



	inode = ext4_new_inode(handle, dir, S_IFLNK|S_IRWXUGO);

	inode = ext4_new_inode(handle, dir, S_IFLNK|S_IRWXUGO, &dentry->d_name);

	err = PTR_ERR(inode);

	if (IS_ERR(inode))

		goto out_stop;