linux-ext4 - Re: [PATCH] ext4: recalculate s_blockfile

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Message-ID: <5187108E.5000105@redhat.com>
Date:	Sun, 05 May 2013 21:08:14 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	Lachlan McIlroy <lmcilroy@...hat.com>
CC:	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] ext4: recalculate s_blockfile_groups during resize2fs

On 5/5/13 7:36 PM, Lachlan McIlroy wrote:
> ----- Original Message -----
>> s_blockfile_groups is used to limit allocations for non-extent
>> files to block groups with block numbers less than 2^32.
>> However, it's not updated when the filesystem is resized online,
>> so the new groups are unavailable to non-extent files until a remount.
>>
>> Fix this by updating the value in ext4_update_super() at
>> resize time.
>>
>> Signed-off-by: Eric Sandeen <sandeen@...hat.com>
>> ---
>>
>> diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
>> index c169477..1357260 100644
>> --- a/fs/ext4/resize.c
>> +++ b/fs/ext4/resize.c
>> @@ -1341,6 +1341,8 @@ static void ext4_update_super(struct super_block *sb,
>>  
>>  	/* Update the global fs size fields */
>>  	sbi->s_groups_count += flex_gd->count;
>> +	sbi->s_blockfile_groups = min_t(ext4_group_t, sbi->s_groups_count,
>> +			(EXT4_MAX_BLOCK_FILE_PHYS / EXT4_BLOCKS_PER_GROUP(sb)));
>>  
>>  	/* Update the reserved block counts only once the new group is
>>  	 * active. */
>>
>> --
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>>
> 
> Good catch Eric - this would have prevented the bug in
> ext4_mb_regular_allocator() too.  Looks good to me.

Yep - at least until the filesystem grows > 16TB :)

-Eric

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