From: Theodore Ts'o Subject: [PATCH 1/2] ext4: Use a hash of the topdir directory name for the Orlov parent group Date: Sat, 13 Jun 2009 12:33:11 -0400 Message-ID: <1244910792-29062-1-git-send-email-tytso@mit.edu> References: <20090613154811.GL24336@mit.edu> Cc: Theodore Ts'o To: Ext4 Developers List Return-path: Received: from thunk.org ([69.25.196.29]:59908 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755788AbZFMQdU (ORCPT ); Sat, 13 Jun 2009 12:33:20 -0400 In-Reply-To: <20090613154811.GL24336@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: 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: "Theodore Ts'o" --- fs/ext4/ext4.h | 3 ++- fs/ext4/ialloc.c | 19 ++++++++++++++----- fs/ext4/migrate.c | 5 ++--- fs/ext4/namei.c | 8 ++++---- 4 files changed, 22 insertions(+), 13 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 06ee5a5..d035cf1 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -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 *); diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c index 7d502f3..3f98ee7 100644 --- a/fs/ext4/ialloc.c +++ b/fs/ext4/ialloc.c @@ -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) { @@ -506,7 +508,13 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent, int best_ndir = inodes_per_group; int ret = -1; - get_random_bytes(&grp, sizeof(grp)); + 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++) { g = (parent_group + i) % ngroups; @@ -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); diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c index fe64d9f..80d075b 100644 --- a/fs/ext4/migrate.c +++ b/fs/ext4/migrate.c @@ -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); diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 07eb664..5f00d24 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -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; -- 1.6.3.2.1.gb9f7d.dirty