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Date: Tue, 7 Jun 2011 17:29:51 +0200 (CEST)
From: Lukas Czerner <lczerner@...hat.com>
To: Eric Sandeen <sandeen@...hat.com>
cc: Lukas Czerner <lczerner@...hat.com>, linux-ext4@...r.kernel.org,
tytso@....edu
Subject: Re: [PATCH] ext4: remove deprecated oldalloc
On Tue, 7 Jun 2011, Eric Sandeen wrote:
> 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>
Thanks Eric, but I need to take it back for the moment. You've pointed
me to more code which is not needed anymore, so I have to update the patch
to remove all the useless pieces.
Thanks!
-Lukas
>
>
> > -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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>
>
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