[Ocfs2-devel] Large (> 16TiB) volumes revisited

[Sunil Mushran <sunil.mushran@oracle.com>]

On 06/28/2010 03:32 PM, Patrick J. LoPresti wrote:
> Current version of my proposed patch is appended.
>
> The good news is that I have tested it, and it "works for me".
>
> The bad news is that it performs the check fairly late (in
> ocfs2_check_volume(), just after the call to ocfs2_journal_load()),
> because this is the earliest I have the journal flags available to
> test.
>
>    

That should be ok. Afterall we have to handle journal_load()
failing for other reasons too. BTW, have you tested with cleared
INCOMPAT_64BIT journal flag?

Hopefully, we'll never trigger this condition... that is if we are
careful when making the same change in mkfs/tunefs.

> We can:
>
> (a) Run with this patch pretty much as-is; or
> (b) Move the jbd2_journal_load() call out of ocfs2_journal_load() so
> that the flags will be in memory sooner; or
> (c) Do something else (ideas welcome)
>
> Let me know what you think.  Thanks!
>
>   - Pat
>
>
> diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
> index 0eaa929..3db233d 100644
> --- a/fs/ocfs2/super.c
> +++ b/fs/ocfs2/super.c
> @@ -1991,6 +1991,47 @@ static int ocfs2_setup_osb_uuid(struct
> ocfs2_super *osb, const unsigned char *uu
>   	return 0;
>   }
>
> +/* Check to make sure entire volume is addressable on this system.
> +   Requires osb_clusters_at_boot to be valid and for the journal to
> +   have been read by jbd2_journal_load(). */
> +static int ocfs2_check_addressable(struct ocfs2_super *osb)
> +{
> +	int status = 0;
> +	u64 max_block =
> +		ocfs2_clusters_to_blocks(osb->sb,
> +					 osb->osb_clusters_at_boot) - 1;
> +
> +	/* Absolute addressability check (borrowed from ext4/super.c) */
> +	if ((max_block>
> +	     (sector_t)(~0LL)>>  (osb->sb->s_blocksize_bits - 9)) ||
> +	    (max_block>  (pgoff_t)(~0LL)>>  (PAGE_CACHE_SHIFT -
> +					     osb->sb->s_blocksize_bits))) {
> +		mlog(ML_ERROR, "Volume too large "
> +		     "to mount safely on this system");
> +		status = -EFBIG;
> +		goto out;
> +	}
> +
> +	/* 32-bit block number is always OK. */
> +	if (max_block<= (u32)~0UL)
> +		goto out;
> +
> +	/* Volume is "huge", so see if our journal is new enough to
> +	   support it. */
> +	if (!(OCFS2_HAS_COMPAT_FEATURE(osb->sb,
> +				       OCFS2_FEATURE_COMPAT_JBD2_SB)&&
> +	      jbd2_journal_check_used_features(osb->journal->j_journal, 0, 0,
> +					       JBD2_FEATURE_INCOMPAT_64BIT))) {
> +		mlog(ML_ERROR, "The journal cannot address the entire volume. "
> +		     "Enable the 'block64' journal option with tunefs.ocfs2");
> +		status = -EFBIG;
> +		goto out;
> +	}
> +
> + out:
> +	return status;
> +}
> +
>   static int ocfs2_initialize_super(struct super_block *sb,
>   				  struct buffer_head *bh,
>   				  int sector_size,
> @@ -2215,14 +2256,6 @@ static int ocfs2_initialize_super(struct super_block *sb,
>   		goto bail;
>   	}
>
> -	if (ocfs2_clusters_to_blocks(osb->sb, le32_to_cpu(di->i_clusters) - 1)
> -	>  (u32)~0UL) {
> -		mlog(ML_ERROR, "Volume might try to write to blocks beyond "
> -		     "what jbd can address in 32 bits.\n");
> -		status = -EINVAL;
> -		goto bail;
> -	}
> -
>   	if (ocfs2_setup_osb_uuid(osb, di->id2.i_super.s_uuid,
>   				 sizeof(di->id2.i_super.s_uuid))) {
>   		mlog(ML_ERROR, "Out of memory trying to setup our uuid.\n");
> @@ -2404,6 +2437,12 @@ static int ocfs2_check_volume(struct ocfs2_super *osb)
>   		goto finally;
>   	}
>
> +	/* Now that journal has been loaded, check to make sure entire
> +	   volume is addressable. */
> +	status = ocfs2_check_addressable(osb);
> +	if (status)
> +		goto finally;
> +
>   	if (dirty) {
>   		/* recover my local alloc if we didn't unmount cleanly. */
>   		status = ocfs2_begin_local_alloc_recovery(osb,
>
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