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[2403:580d:fda1::299]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2c8255602fcsm57452465ad.60.2026.06.29.03.14.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 29 Jun 2026 03:14:18 -0700 (PDT) Message-ID: <0a3b352d-a267-46a8-84b4-ba97def25f5c@suse.com> Date: Mon, 29 Jun 2026 19:44:13 +0930 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] btrfs: compression: allocate buckets with workspace To: Rosen Penev , linux-btrfs@vger.kernel.org Cc: Chris Mason , David Sterba , open list References: <20260629002505.1552238-1-rosenp@gmail.com> Content-Language: en-US From: Qu Wenruo Autocrypt: addr=wqu@suse.com; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNGFF1IFdlbnJ1byA8d3F1QHN1c2UuY29tPsLAlAQTAQgAPgIbAwULCQgHAgYVCAkKCwIE FgIDAQIeAQIXgBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJnEXVgBQkQ/lqxAAoJEMI9kfOh Jf6o+jIH/2KhFmyOw4XWAYbnnijuYqb/obGae8HhcJO2KIGcxbsinK+KQFTSZnkFxnbsQ+VY fvtWBHGt8WfHcNmfjdejmy9si2jyy8smQV2jiB60a8iqQXGmsrkuR+AM2V360oEbMF3gVvim 2VSX2IiW9KERuhifjseNV1HLk0SHw5NnXiWh1THTqtvFFY+CwnLN2GqiMaSLF6gATW05/sEd V17MdI1z4+WSk7D57FlLjp50F3ow2WJtXwG8yG8d6S40dytZpH9iFuk12Sbg7lrtQxPPOIEU rpmZLfCNJJoZj603613w/M8EiZw6MohzikTWcFc55RLYJPBWQ+9puZtx1DopW2jOwE0EWdWB rwEIAKpT62HgSzL9zwGe+WIUCMB+nOEjXAfvoUPUwk+YCEDcOdfkkM5FyBoJs8TCEuPXGXBO Cl5P5B8OYYnkHkGWutAVlUTV8KESOIm/KJIA7jJA+Ss9VhMjtePfgWexw+P8itFRSRrrwyUf E+0WcAevblUi45LjWWZgpg3A80tHP0iToOZ5MbdYk7YFBE29cDSleskfV80ZKxFv6koQocq0 vXzTfHvXNDELAuH7Ms/WJcdUzmPyBf3Oq6mKBBH8J6XZc9LjjNZwNbyvsHSrV5bgmu/THX2n g/3be+iqf6OggCiy3I1NSMJ5KtR0q2H2Nx2Vqb1fYPOID8McMV9Ll6rh8S8AEQEAAcLAfAQY AQgAJgIbDBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJnEXWBBQkQ/lrSAAoJEMI9kfOhJf6o cakH+QHwDszsoYvmrNq36MFGgvAHRjdlrHRBa4A1V1kzd4kOUokongcrOOgHY9yfglcvZqlJ qfa4l+1oxs1BvCi29psteQTtw+memmcGruKi+YHD7793zNCMtAtYidDmQ2pWaLfqSaryjlzR /3tBWMyvIeWZKURnZbBzWRREB7iWxEbZ014B3gICqZPDRwwitHpH8Om3eZr7ygZck6bBa4MU o1XgbZcspyCGqu1xF/bMAY2iCDcq6ULKQceuKkbeQ8qxvt9hVxJC2W3lHq8dlK1pkHPDg9wO JoAXek8MF37R8gpLoGWl41FIUb3hFiu3zhDDvslYM4BmzI18QgQTQnotJH8= In-Reply-To: <20260629002505.1552238-1-rosenp@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2026/6/29 09:55, Rosen Penev 写道: > Convert 3 allocations into one. Simplifies code slightly. > > Signed-off-by: Rosen Penev > --- > fs/btrfs/compression.c | 18 +++++------------- > 1 file changed, 5 insertions(+), 13 deletions(-) > > diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c > index ffb6b52863a7..da6749ff5924 100644 > --- a/fs/btrfs/compression.c > +++ b/fs/btrfs/compression.c > @@ -650,11 +650,11 @@ struct heuristic_ws { > /* Partial copy of input data */ > u8 *sample; > u32 sample_size; > - /* Buckets store counters for each byte value */ > - struct bucket_item *bucket; > /* Sorting buffer */ > struct bucket_item *bucket_b; > struct list_head list; > + /* Buckets store counters for each byte value */ > + struct bucket_item bucket[]; > }; > > static void free_heuristic_ws(struct list_head *ws) > @@ -664,8 +664,6 @@ static void free_heuristic_ws(struct list_head *ws) > workspace = list_entry(ws, struct heuristic_ws, list); > > kvfree(workspace->sample); > - kfree(workspace->bucket); > - kfree(workspace->bucket_b); > kfree(workspace); > } > > @@ -673,22 +671,16 @@ static struct list_head *alloc_heuristic_ws(struct btrfs_fs_info *fs_info) > { > struct heuristic_ws *ws; > > - ws = kzalloc_obj(*ws); > + ws = kzalloc(struct_size(ws, bucket, BUCKET_SIZE * 2), GFP_KERNEL); > if (!ws) > return ERR_PTR(-ENOMEM); > > + ws->bucket_b = ws->bucket + BUCKET_SIZE; > + This barely improves any readability. We have two different bucket pointers, one is a variable sized member, one (bucket_b) is a pointer. Not a fan of this at all. > ws->sample = kvmalloc(MAX_SAMPLE_SIZE, GFP_KERNEL); > if (!ws->sample) > goto fail; > > - ws->bucket = kzalloc_objs(*ws->bucket, BUCKET_SIZE); > - if (!ws->bucket) > - goto fail; > - > - ws->bucket_b = kzalloc_objs(*ws->bucket_b, BUCKET_SIZE); > - if (!ws->bucket_b) > - goto fail; > - > INIT_LIST_HEAD(&ws->list); > return &ws->list; > fail: