Re: [PATCH 2/3 V2] xfs: make xfs_btree_magic more generic

From: Eric Sandeen <sandeen@sandeen.net>
To: Brian Foster <bfoster@redhat.com>
Cc: Eric Sandeen <sandeen@redhat.com>, linux-xfs <linux-xfs@vger.kernel.org>
Subject: Re: [PATCH 2/3 V2] xfs: make xfs_btree_magic more generic
Date: Tue, 3 Jan 2017 12:34:56 -0600	[thread overview]
Message-ID: <8205ee7f-790f-e5f1-916e-7c4c15a0a818@sandeen.net> (raw)
In-Reply-To: <20170103182823.GC18120@bfoster.bfoster>

On 1/3/17 12:28 PM, Brian Foster wrote:
> On Thu, Dec 22, 2016 at 01:43:55PM -0600, Eric Sandeen wrote:
>> Right now the xfs_btree_magic() define takes only a cursor;
>> change this to take crc and btnum args to make it more generically
>> useful, and move to a function.
>>
>> This will allow xfs_btree_init_block_int callers which don't
>> have a cursor to make use of the xfs_magics array, which will
>> happen in the next patch.
>>
>> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
>> ---
>>
>> V2: turn xfs_btree_magic into a function with a built-in ASSERT
>>
>> diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
>> index f49fc2f..81866dd 100644
>> --- a/fs/xfs/libxfs/xfs_btree.c
>> +++ b/fs/xfs/libxfs/xfs_btree.c
>> @@ -50,8 +50,15 @@
>>  	  XFS_BMAP_CRC_MAGIC, XFS_IBT_CRC_MAGIC, XFS_FIBT_CRC_MAGIC,
>>  	  XFS_REFC_CRC_MAGIC }
>>  };
>> -#define xfs_btree_magic(cur) \
>> -	xfs_magics[!!((cur)->bc_flags & XFS_BTREE_CRC_BLOCKS)][cur->bc_btnum]
>> +
>> +__uint32_t xfs_btree_magic(int crc, xfs_btnum_t btnum)
>> +{
>> +	__uint32_t magic = xfs_magics[crc][btnum];
>> +
>> +	/* Ensure we asked for crc for crc-only magics. */
> 
> Purely a nit, but for whatever reason this sentence confused me.
> Perhaps just drop it, or say something like "ensure we asked for a valid
> magic?"

Hm, ok, it's supposed to mean "make sure CRC ==1 if we are asking for a
magic number for a structure which exists only on filesystems w/ CRCs"

If not, we'd get 0 for magic, and that's the assert.  But yeah, I can
see how the sentence isn't very clear.  :(

-Eric

> Either way:
> 
> Reviewed-by: Brian Foster <bfoster@redhat.com>
> 
>> +	ASSERT(magic != 0);
>> +	return magic;
>> +}
>>  
>>  STATIC int				/* error (0 or EFSCORRUPTED) */
>>  xfs_btree_check_lblock(
>> @@ -62,10 +69,13 @@
>>  {
>>  	int			lblock_ok = 1; /* block passes checks */
>>  	struct xfs_mount	*mp;	/* file system mount point */
>> +	xfs_btnum_t		btnum = cur->bc_btnum;
>> +	int			crc;
>>  
>>  	mp = cur->bc_mp;
>> +	crc = xfs_sb_version_hascrc(&mp->m_sb);
>>  
>> -	if (xfs_sb_version_hascrc(&mp->m_sb)) {
>> +	if (crc) {
>>  		lblock_ok = lblock_ok &&
>>  			uuid_equal(&block->bb_u.l.bb_uuid,
>>  				   &mp->m_sb.sb_meta_uuid) &&
>> @@ -74,7 +84,7 @@
>>  	}
>>  
>>  	lblock_ok = lblock_ok &&
>> -		be32_to_cpu(block->bb_magic) == xfs_btree_magic(cur) &&
>> +		be32_to_cpu(block->bb_magic) == xfs_btree_magic(crc, btnum) &&
>>  		be16_to_cpu(block->bb_level) == level &&
>>  		be16_to_cpu(block->bb_numrecs) <=
>>  			cur->bc_ops->get_maxrecs(cur, level) &&
>> @@ -110,13 +120,16 @@
>>  	struct xfs_agf		*agf;	/* ag. freespace structure */
>>  	xfs_agblock_t		agflen;	/* native ag. freespace length */
>>  	int			sblock_ok = 1; /* block passes checks */
>> +	xfs_btnum_t		btnum = cur->bc_btnum;
>> +	int			crc;
>>  
>>  	mp = cur->bc_mp;
>> +	crc = xfs_sb_version_hascrc(&mp->m_sb);
>>  	agbp = cur->bc_private.a.agbp;
>>  	agf = XFS_BUF_TO_AGF(agbp);
>>  	agflen = be32_to_cpu(agf->agf_length);
>>  
>> -	if (xfs_sb_version_hascrc(&mp->m_sb)) {
>> +	if (crc) {
>>  		sblock_ok = sblock_ok &&
>>  			uuid_equal(&block->bb_u.s.bb_uuid,
>>  				   &mp->m_sb.sb_meta_uuid) &&
>> @@ -125,7 +138,7 @@
>>  	}
>>  
>>  	sblock_ok = sblock_ok &&
>> -		be32_to_cpu(block->bb_magic) == xfs_btree_magic(cur) &&
>> +		be32_to_cpu(block->bb_magic) == xfs_btree_magic(crc, btnum) &&
>>  		be16_to_cpu(block->bb_level) == level &&
>>  		be16_to_cpu(block->bb_numrecs) <=
>>  			cur->bc_ops->get_maxrecs(cur, level) &&
>> @@ -1142,7 +1155,9 @@ static inline size_t xfs_btree_ptr_len(struct xfs_btree_cur *cur)
>>  	int			level,
>>  	int			numrecs)
>>  {
>> -	__u64 owner;
>> +	__u64			owner;
>> +	int			crc = xfs_sb_version_hascrc(&cur->bc_mp->m_sb);
>> +	xfs_btnum_t		btnum = cur->bc_btnum;
>>  
>>  	/*
>>  	 * we can pull the owner from the cursor right now as the different
>> @@ -1156,7 +1171,7 @@ static inline size_t xfs_btree_ptr_len(struct xfs_btree_cur *cur)
>>  		owner = cur->bc_private.a.agno;
>>  
>>  	xfs_btree_init_block_int(cur->bc_mp, XFS_BUF_TO_BLOCK(bp), bp->b_bn,
>> -				 xfs_btree_magic(cur), level, numrecs,
>> +				 xfs_btree_magic(crc, btnum), level, numrecs,
>>  				 owner, cur->bc_flags);
>>  }
>>  
>> diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
>> index c2b01d1..3aaced3 100644
>> --- a/fs/xfs/libxfs/xfs_btree.h
>> +++ b/fs/xfs/libxfs/xfs_btree.h
>> @@ -76,6 +76,8 @@
>>  #define	XFS_BTNUM_RMAP	((xfs_btnum_t)XFS_BTNUM_RMAPi)
>>  #define	XFS_BTNUM_REFC	((xfs_btnum_t)XFS_BTNUM_REFCi)
>>  
>> +__uint32_t xfs_btree_magic(int crc, xfs_btnum_t btnum);
>> +
>>  /*
>>   * For logging record fields.
>>   */
>>
>> --
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> 