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From:   Andreas Dilger <adilger@dilger.ca>
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Subject: Re: [PATCH v3] ext4: fix log printing of ext4_mb_regular_allocator()
Date:   Sat, 15 Aug 2020 15:47:51 -0600
In-Reply-To: <0a165ac0-1912-aebd-8a0d-b42e7cd1aea1@gmail.com>
Cc:     Theodore Ts'o <tytso@mit.edu>,
        Ext4 Developers List <linux-ext4@vger.kernel.org>,
        Ritesh Harjani <riteshh@linux.ibm.com>
To:     brookxu <brookxu.cn@gmail.com>
References: <0a165ac0-1912-aebd-8a0d-b42e7cd1aea1@gmail.com>
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On Aug 14, 2020, at 6:10 PM, brookxu <brookxu.cn@gmail.com> wrote:
>=20
> Fix log printing of ext4_mb_regular_allocator()=EF=BC=8Cit may be an
> unintentional behavior.
>=20
> V3:
> It may be better to add a comma between start and len, which is
> convenient for script processing.
>=20
> V2:
> Add more valuable information, such as group, start, len, lost.
>=20
> Signed-off-by: Chunguang Xu <brookxu@tencent.com>

A very minor cleanup possible, but not really worthwhile to resubmit if
Ted wants to apply it.  Either way, it looks good.

Reviewed-by: Andreas Dilger <adilger@dilger.ca>

> ---
> fs/ext4/mballoc.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>=20
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index c0a331e..70b110f 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -2218,6 +2218,7 @@ static int ext4_mb_good_group_nolock(struct =
ext4_allocation_context *ac,
> 	struct ext4_sb_info *sbi;
> 	struct super_block *sb;
> 	struct ext4_buddy e4b;
> +	unsigned int lost;
>=20
> 	sb =3D ac->ac_sb;
> 	sbi =3D EXT4_SB(sb);
> @@ -2341,22 +2342,24 @@ static int ext4_mb_good_group_nolock(struct =
ext4_allocation_context *ac,
> 		 * We've been searching too long. Let's try to allocate
> 		 * the best chunk we've found so far
> 		 */
> -
> 		ext4_mb_try_best_found(ac, &e4b);
> 		if (ac->ac_status !=3D AC_STATUS_FOUND) {
> 			/*
> 			 * Someone more lucky has already allocated it.
> 			 * The only thing we can do is just take first
> 			 * found block(s)
> -			printk(KERN_DEBUG "EXT4-fs: someone won our =
chunk\n");
> 			 */
> +			lost =3D (unsigned =
int)atomic_inc_return(&sbi->s_mb_lost_chunks);

(minor) no need for a typecast here?  The return type is already "int", =
so it
would be better to declare "int lost" and that would make the line a bit =
shorter.

> +			mb_debug(sb, "lost chunk, group: %u, start: %d, =
len: %d, lost: %u\n",
> +				 ac->ac_b_ex.fe_group, =
ac->ac_b_ex.fe_start,
> +				 ac->ac_b_ex.fe_len, lost);
> +
> 			ac->ac_b_ex.fe_group =3D 0;
> 			ac->ac_b_ex.fe_start =3D 0;
> 			ac->ac_b_ex.fe_len =3D 0;
> 			ac->ac_status =3D AC_STATUS_CONTINUE;
> 			ac->ac_flags |=3D EXT4_MB_HINT_FIRST;
> 			cr =3D 3;
> -			atomic_inc(&sbi->s_mb_lost_chunks);
> 			goto repeat;
> 		}
> 	}
> --
> 1.8.3.1
>=20
>=20


Cheers, Andreas


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