On 2011-07-17, at 7:25 PM, Ted Ts'o wrote:
> On Tue, Jul 12, 2011 at 03:40:46PM -0600, Andreas Dilger wrote:
>> For very large ext4 filesystems (128TB and larger) kmalloc() of
>> some per-group structures can fail at mount time due to memory
>> fragmentation. If kmalloc() fails, fall back to vmalloc() for
>> the s_group_info and s_group_desc arrays.
>>
>> Signed-off-by: Yu Jian <yujian@xxxxxxxxxxxxx>
>> Signed-off-by: Andreas Dilger <adilger@xxxxxxxxxxxxx>
>
> Andreas, was this patch authored by Yu Jian or by you?
Yu Jian wrote it with help from me, and I made some modifications afterward,
so I put both of our names down.
>> sbi->s_buddy_cache = new_inode(sb);
>> if (sbi->s_buddy_cache == NULL) {
>> - printk(KERN_ERR "EXT4-fs: can't get new inode\n");
>> + ext4_msg(sb, KERN_ERR, "can't get new inode\n");
>> goto err_freesgi;
>> }
>
> Using ext4_msg instead of printk is good, but that really should be a
> separate patch.
>
>> - sbi->s_buddy_cache->i_ino = get_next_ino();
>> + /* To avoid potentially colliding with an valid on-disk inode number,
>> + * use EXT4_BAD_INO for the buddy cache inode number. This inode is
>> + * not in the inode hash, so it should never be found by iget(), but
>> + * this will avoid confusion if it ever shows up during debugging. */
>> + sbi->s_buddy_cache->i_ino = EXT4_BAD_INO;
>
> This should be a separate patch.
Sure.
>> @@ -2457,12 +2472,6 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
>> i++;
>> } while (i <= sb->s_blocksize_bits + 1);
>>
>> - /* init file for buddy data */
>> - ret = ext4_mb_init_backend(sb);
>> - if (ret != 0) {
>> - goto out;
>> - }
>> -
>> spin_lock_init(&sbi->s_md_lock);
>> spin_lock_init(&sbi->s_bal_lock);
>>
>> @@ -2487,6 +2496,11 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
>> spin_lock_init(&lg->lg_prealloc_lock);
>> }
>>
>> + /* init file for buddy data */
>> + ret = ext4_mb_init_backend(sb);
>> + if (ret != 0)
>> + goto out;
>> +
>> if (sbi->s_proc)
>> proc_create_data("mb_groups", S_IRUGO, sbi->s_proc,
>> &ext4_mb_seq_groups_fops, sb);
>
> Why are you moving ext4_mb_init_backend()? This should be a separate
> patch, with an explanation of what is going on....
In ext4_mb_init(), if the s_locality_group allocation fails it will
currently cause the allocations made in ext4_mb_init_backend() to
be leaked. Moving the ext4_mb_init_backend() allocation after the
s_locality_group allocation avoids that problem.
Cheers, Andreas
--
Andreas Dilger
Principal Engineer
Whamcloud, Inc.
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