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Message-ID: <4DEE3AA8.4080504@redhat.com>
Date: Tue, 07 Jun 2011 09:50:16 -0500
From: Eric Sandeen <sandeen@...hat.com>
To: Lukas Czerner <lczerner@...hat.com>
CC: linux-ext4@...r.kernel.org, tytso@....edu
Subject: Re: [PATCH] ext4: remove deprecated oldalloc
On 6/7/11 8:35 AM, Lukas Czerner wrote:
> For a long time now orlov is the default block allocator in the ext4. It
> performs better than the old one and no one seems to claim otherwise so
> we can safely drop it and make oldalloc and orlov mount option
> deprecated.
>
> This is a part of the effort to reduce number of ext4 options hence the
> test matrix.
>
> Signed-off-by: Lukas Czerner <lczerner@...hat.com>
Seems like a good idea to me.
But I'm doing a little digging into why find_group_flex() was there;
why all that flex_bg-related inode allocation work for a deprecated option?
commit 772cb7c83ba256a11c7bf99a11bef3858d23767c
Author: Jose R. Santos <jrs@...ibm.com>
Date: Fri Jul 11 19:27:31 2008 -0400
ext4: New inode allocation for FLEX_BG meta-data groups.
This patch mostly controls the way inode are allocated in order to
make ialloc aware of flex_bg block group grouping. It achieves this
by bypassing the Orlov allocator when block group meta-data are packed
toghether through mke2fs. <snip>
find_group_flex() used to be called by ext4_new_inode() regardless of
OLDALLOC, (I think) so just want to see for sure what happened to that plan...
-eric
> ---
> Documentation/filesystems/ext4.txt | 8 --
> fs/ext4/ext4.h | 1 -
> fs/ext4/ialloc.c | 136 +-----------------------------------
> fs/ext4/super.c | 8 +-
> 4 files changed, 7 insertions(+), 146 deletions(-)
>
> diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
> index 3ae9bc9..ec469fa 100644
> --- a/Documentation/filesystems/ext4.txt
> +++ b/Documentation/filesystems/ext4.txt
> @@ -201,14 +201,6 @@ inode_readahead_blks=n This tuning parameter controls the maximum
> table readahead algorithm will pre-read into
> the buffer cache. The default value is 32 blocks.
>
> -orlov (*) This enables the new Orlov block allocator. It is
> - enabled by default.
> -
> -oldalloc This disables the Orlov block allocator and enables
> - the old block allocator. Orlov should have better
> - performance - we'd like to get some feedback if it's
> - the contrary for you.
> -
> user_xattr Enables Extended User Attributes. Additionally, you
> need to have extended attribute support enabled in the
> kernel configuration (CONFIG_EXT4_FS_XATTR). See the
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 1921392..7e0b8aa 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -884,7 +884,6 @@ struct ext4_inode_info {
> /*
> * Mount flags
> */
> -#define EXT4_MOUNT_OLDALLOC 0x00002 /* Don't use the new Orlov allocator */
> #define EXT4_MOUNT_GRPID 0x00004 /* Create files with directory's group */
> #define EXT4_MOUNT_DEBUG 0x00008 /* Some debugging messages */
> #define EXT4_MOUNT_ERRORS_CONT 0x00010 /* Continue on errors */
> diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
> index 21bb2f6..0b5ec23 100644
> --- a/fs/ext4/ialloc.c
> +++ b/fs/ext4/ialloc.c
> @@ -293,118 +293,6 @@ error_return:
> ext4_std_error(sb, fatal);
> }
>
> -/*
> - * There are two policies for allocating an inode. If the new inode is
> - * a directory, then a forward search is made for a block group with both
> - * free space and a low directory-to-inode ratio; if that fails, then of
> - * the groups with above-average free space, that group with the fewest
> - * directories already is chosen.
> - *
> - * For other inodes, search forward from the parent directory\'s block
> - * group to find a free inode.
> - */
> -static int find_group_dir(struct super_block *sb, struct inode *parent,
> - ext4_group_t *best_group)
> -{
> - ext4_group_t ngroups = ext4_get_groups_count(sb);
> - unsigned int freei, avefreei;
> - struct ext4_group_desc *desc, *best_desc = NULL;
> - ext4_group_t group;
> - int ret = -1;
> -
> - freei = percpu_counter_read_positive(&EXT4_SB(sb)->s_freeinodes_counter);
> - avefreei = freei / ngroups;
> -
> - for (group = 0; group < ngroups; group++) {
> - desc = ext4_get_group_desc(sb, group, NULL);
> - if (!desc || !ext4_free_inodes_count(sb, desc))
> - continue;
> - if (ext4_free_inodes_count(sb, desc) < avefreei)
> - continue;
> - if (!best_desc ||
> - (ext4_free_blks_count(sb, desc) >
> - ext4_free_blks_count(sb, best_desc))) {
> - *best_group = group;
> - best_desc = desc;
> - ret = 0;
> - }
> - }
> - return ret;
> -}
> -
> -#define free_block_ratio 10
> -
> -static int find_group_flex(struct super_block *sb, struct inode *parent,
> - ext4_group_t *best_group)
> -{
> - struct ext4_sb_info *sbi = EXT4_SB(sb);
> - struct ext4_group_desc *desc;
> - struct flex_groups *flex_group = sbi->s_flex_groups;
> - ext4_group_t parent_group = EXT4_I(parent)->i_block_group;
> - ext4_group_t parent_fbg_group = ext4_flex_group(sbi, parent_group);
> - ext4_group_t ngroups = ext4_get_groups_count(sb);
> - int flex_size = ext4_flex_bg_size(sbi);
> - ext4_group_t best_flex = parent_fbg_group;
> - int blocks_per_flex = sbi->s_blocks_per_group * flex_size;
> - int flexbg_free_blocks;
> - int flex_freeb_ratio;
> - ext4_group_t n_fbg_groups;
> - ext4_group_t i;
> -
> - n_fbg_groups = (ngroups + flex_size - 1) >>
> - sbi->s_log_groups_per_flex;
> -
> -find_close_to_parent:
> - flexbg_free_blocks = atomic_read(&flex_group[best_flex].free_blocks);
> - flex_freeb_ratio = flexbg_free_blocks * 100 / blocks_per_flex;
> - if (atomic_read(&flex_group[best_flex].free_inodes) &&
> - flex_freeb_ratio > free_block_ratio)
> - goto found_flexbg;
> -
> - if (best_flex && best_flex == parent_fbg_group) {
> - best_flex--;
> - goto find_close_to_parent;
> - }
> -
> - for (i = 0; i < n_fbg_groups; i++) {
> - if (i == parent_fbg_group || i == parent_fbg_group - 1)
> - continue;
> -
> - 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 &&
> - (atomic_read(&flex_group[i].free_inodes))) {
> - best_flex = i;
> - goto found_flexbg;
> - }
> -
> - 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 (!atomic_read(&flex_group[best_flex].free_inodes) ||
> - !atomic_read(&flex_group[best_flex].free_blocks))
> - return -1;
> -
> -found_flexbg:
> - for (i = best_flex * flex_size; i < ngroups &&
> - i < (best_flex + 1) * flex_size; i++) {
> - desc = ext4_get_group_desc(sb, i, NULL);
> - if (ext4_free_inodes_count(sb, desc)) {
> - *best_group = i;
> - goto out;
> - }
> - }
> -
> - return -1;
> -out:
> - return 0;
> -}
> -
> struct orlov_stats {
> __u32 free_inodes;
> __u32 free_blocks;
> @@ -817,7 +705,6 @@ struct inode *ext4_new_inode(handle_t *handle, struct inode *dir, int mode,
> struct inode *ret;
> ext4_group_t i;
> int free = 0;
> - static int once = 1;
> ext4_group_t flex_group;
>
> /* Cannot create files in a deleted directory */
> @@ -843,26 +730,9 @@ struct inode *ext4_new_inode(handle_t *handle, struct inode *dir, int mode,
> goto got_group;
> }
>
> - if (sbi->s_log_groups_per_flex && test_opt(sb, OLDALLOC)) {
> - ret2 = find_group_flex(sb, dir, &group);
> - if (ret2 == -1) {
> - ret2 = find_group_other(sb, dir, &group, mode);
> - if (ret2 == 0 && once) {
> - once = 0;
> - printk(KERN_NOTICE "ext4: find_group_flex "
> - "failed, fallback succeeded dir %lu\n",
> - dir->i_ino);
> - }
> - }
> - goto got_group;
> - }
> -
> - if (S_ISDIR(mode)) {
> - if (test_opt(sb, OLDALLOC))
> - ret2 = find_group_dir(sb, dir, &group);
> - else
> - ret2 = find_group_orlov(sb, dir, &group, mode, qstr);
> - } else
> + if (S_ISDIR(mode))
> + ret2 = find_group_orlov(sb, dir, &group, mode, qstr);
> + else
> ret2 = find_group_other(sb, dir, &group, mode);
>
> got_group:
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index cc5c157..e1f8f73 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1031,8 +1031,6 @@ static int ext4_show_options(struct seq_file *seq, struct vfsmount *vfs)
> seq_puts(seq, ",nouid32");
> if (test_opt(sb, DEBUG) && !(def_mount_opts & EXT4_DEFM_DEBUG))
> seq_puts(seq, ",debug");
> - if (test_opt(sb, OLDALLOC))
> - seq_puts(seq, ",oldalloc");
> #ifdef CONFIG_EXT4_FS_XATTR
> if (test_opt(sb, XATTR_USER))
> seq_puts(seq, ",user_xattr");
> @@ -1541,10 +1539,12 @@ static int parse_options(char *options, struct super_block *sb,
> set_opt(sb, DEBUG);
> break;
> case Opt_oldalloc:
> - set_opt(sb, OLDALLOC);
> + ext4_msg(sb, KERN_WARNING,
> + "Ignoring deprecated oldalloc option");
> break;
> case Opt_orlov:
> - clear_opt(sb, OLDALLOC);
> + ext4_msg(sb, KERN_WARNING,
> + "Ignoring deprecated orlov option");
> break;
> #ifdef CONFIG_EXT4_FS_XATTR
> case Opt_user_xattr:
--
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