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| author | Theodore Ts'o <tytso@mit.edu> | 2009-06-13 11:09:42 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2009-06-13 11:09:42 -0400 |
| commit | f157a4aa98a18bd3817a72bea90d48494e2586e7 (patch) | |
| tree | 105547639a67296b4ea7acdc35c9e65ee2a85fd8 /fs/ext4/ialloc.c | |
| parent | 8a8a2050c844d9de224ff591e91bda3f77bd6eda (diff) | |
| download | lwn-f157a4aa98a18bd3817a72bea90d48494e2586e7.tar.gz lwn-f157a4aa98a18bd3817a72bea90d48494e2586e7.zip | |
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@mit.edu>
Diffstat (limited to 'fs/ext4/ialloc.c')
| -rw-r--r-- | fs/ext4/ialloc.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c index 7d502f3be914..3f98ee712ff4 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); |