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Date: Tue, 07 Jun 2011 09:53:01 -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 9:50 AM, Eric Sandeen wrote:
> 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...
Ah, ok:
commit a4912123b688e057084e6557cef8924f7ae5bbde
Author: Theodore Ts'o <tytso@....edu>
Date: Thu Mar 12 12:18:34 2009 -0400
ext4: New inode/block allocation algorithms for flex_bg filesystems
The find_group_flex() inode allocator is now only used if the
filesystem is mounted using the "oldalloc" mount option. It is
replaced with the original Orlov allocator that has been updated for
flex_bg filesystems <snip>
So:
Reviewed-by: Eric Sandeen <sandeen@...hat.com>
> -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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