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Date: Sat, 13 Jun 2009 12:33:11 -0400
From: Theodore Ts'o <tytso@....edu>
To: Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc: Theodore Ts'o <tytso@....edu>
Subject: [PATCH 1/2] 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: "Theodore Ts'o" <tytso@....edu>
---
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
--
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