[lustre-devel] [PATCH 11/30] lustre: mdc: allow setting readdir RPC size parameter

[Andreas Dilger]

On Sep 18, 2018, at 09:14, NeilBrown <neilb at suse.com> wrote:
> 
> On Mon, Sep 17 2018, James Simmons wrote:
> 
>> From: Andreas Dilger <adilger at whamcloud.com>
>> 
>> diff --git a/drivers/staging/lustre/lustre/include/lustre_net.h b/drivers/staging/lustre/lustre/include/lustre_net.h
>> index 2dbd208..cf630db 100644
>> --- a/drivers/staging/lustre/lustre/include/lustre_net.h
>> +++ b/drivers/staging/lustre/lustre/include/lustre_net.h
>> @@ -104,15 +104,15 @@
>>  * currently supported maximum between peers at connect via ocd_brw_size.
>>  */
>> #define PTLRPC_MAX_BRW_BITS	(LNET_MTU_BITS + PTLRPC_BULK_OPS_BITS)
>> -#define PTLRPC_MAX_BRW_SIZE	(1 << PTLRPC_MAX_BRW_BITS)
>> +#define PTLRPC_MAX_BRW_SIZE	BIT(PTLRPC_MAX_BRW_BITS)
>> #define PTLRPC_MAX_BRW_PAGES	(PTLRPC_MAX_BRW_SIZE >> PAGE_SHIFT)
>> 
>> -#define ONE_MB_BRW_SIZE		(1 << LNET_MTU_BITS)
>> -#define MD_MAX_BRW_SIZE		(1 << LNET_MTU_BITS)
>> +#define ONE_MB_BRW_SIZE		BIT(LNET_MTU_BITS)
>> +#define MD_MAX_BRW_SIZE		BIT(LNET_MTU_BITS)
>> #define MD_MAX_BRW_PAGES	(MD_MAX_BRW_SIZE >> PAGE_SHIFT)
>> #define DT_MAX_BRW_SIZE		PTLRPC_MAX_BRW_SIZE
>> #define DT_MAX_BRW_PAGES	(DT_MAX_BRW_SIZE >> PAGE_SHIFT)
>> -#define OFD_MAX_BRW_SIZE	(1 << LNET_MTU_BITS)
>> +#define OFD_MAX_BRW_SIZE	BIT(LNET_MTU_BITS)
> 
> Argg!!  No!!  Names are important.
> "SIZE" means the value is a size, a number.  The bit-representation is
> largely irrelevant, it is the number that is important.
> BIT(x) returns a single bit - lots of zeros and just one '1' bit.  This
> is not a number, it is a bit pattern.
> 
> So settings FOO_SIZE to BIT(bar) is wrong.  It is a type error.  It uses
> a bit pattern when a number is expected.  The C compiler won't notice, but I will.
> 
> When I apply this (which probably won't be until next week), I'll just
> remove this section of the patch.

Just to confirm, my original patch didn't have these BIT() macros in it,
and I agree with your statements, so I'm fine with you removing them again.

>> diff --git a/drivers/staging/lustre/lustre/llite/lcommon_cl.c b/drivers/staging/lustre/lustre/llite/lcommon_cl.c
>> index 6c9fe49..d3b0445 100644
>> --- a/drivers/staging/lustre/lustre/llite/lcommon_cl.c
>> +++ b/drivers/staging/lustre/lustre/llite/lcommon_cl.c
>> @@ -267,27 +267,22 @@ void cl_inode_fini(struct inode *inode)
>> /**
>>  * build inode number from passed @fid
>>  */
>> -__u64 cl_fid_build_ino(const struct lu_fid *fid, int api32)
>> +u64 cl_fid_build_ino(const struct lu_fid *fid, int api32)
>> {
>> 	if (BITS_PER_LONG == 32 || api32)
>> 		return fid_flatten32(fid);
>> -	else
>> -		return fid_flatten(fid);
>> +
>> +	return fid_flatten(fid);
> 
> I preferred that as it was - it makes the either/or nature more obvious.

Kernel style generally recommends no "else" after a return, and checkpatch.pl will complain in this case.

Cheers, Andreas
---
Andreas Dilger
Principal Lustre Architect
Whamcloud







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