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Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.1 Subject: Re: [PATCH v2] nvmet: fix mar and mor off-by-one errors To: Chaitanya Kulkarni , Dennis Maisenbacher , "linux-nvme@lists.infradead.org" Cc: Niklas Cassel , Christoph Hellwig , Sagi Grimberg , Damien Le Moal , "linux-kernel@vger.kernel.org" References: <20220906073929.3292899-1-Dennis.Maisenbacher@wdc.com> Content-Language: en-US From: Damien Le Moal Organization: Western Digital Research In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/7/22 06:53, Chaitanya Kulkarni wrote: > On 9/6/22 00:39, Dennis Maisenbacher wrote: >> From: Dennis Maisenbacher >> >> Maximum Active Resources (MAR) and Maximum Open Resources (MOR) are 0's >> based vales where a value of 0xffffffff indicates that there is no limit. >> >> Decrement the values that are returned by bdev_max_open_zones and >> bdev_max_active_zones as the block layer helpers are not 0's based. >> A 0 returned by the block layer helpers indicates no limit, thus convert >> it to 0xffffffff (U32_MAX). >> >> Fixes: aaf2e048af27 ("nvmet: add ZBD over ZNS backend support") >> Suggested-by: Niklas Cassel >> Signed-off-by: Dennis Maisenbacher >> --- >> Changes in v2: >> - Add explicit check if block layer helpers return a 0 and if so >> convert it to U32_MAX. >> - Add Fixes tag. >> >> drivers/nvme/target/zns.c | 17 +++++++++++++++-- >> 1 file changed, 15 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/nvme/target/zns.c b/drivers/nvme/target/zns.c >> index c7ef69f29fe4..eae81f939067 100644 >> --- a/drivers/nvme/target/zns.c >> +++ b/drivers/nvme/target/zns.c >> @@ -100,6 +100,7 @@ void nvmet_execute_identify_cns_cs_ns(struct nvmet_req *req) >> struct nvme_id_ns_zns *id_zns; >> u64 zsze; >> u16 status; >> + u32 mar, mor; > > consider :- > + u32 mar, mor; > u64 zsze; > u16 status; > >> >> if (le32_to_cpu(req->cmd->identify.nsid) == NVME_NSID_ALL) { >> req->error_loc = offsetof(struct nvme_identify, nsid); >> @@ -130,8 +131,20 @@ void nvmet_execute_identify_cns_cs_ns(struct nvmet_req *req) >> zsze = (bdev_zone_sectors(req->ns->bdev) << 9) >> >> req->ns->blksize_shift; >> id_zns->lbafe[0].zsze = cpu_to_le64(zsze); >> - id_zns->mor = cpu_to_le32(bdev_max_open_zones(req->ns->bdev)); >> - id_zns->mar = cpu_to_le32(bdev_max_active_zones(req->ns->bdev)); >> + >> + mor = bdev_max_open_zones(req->ns->bdev); >> + if (!mor) >> + mor = U32_MAX; >> + else >> + --mor; >> + id_zns->mor = cpu_to_le32(mor); >> + >> + mar = bdev_max_active_zones(req->ns->bdev); >> + if (!mar) >> + mar = U32_MAX; >> + else >> + --mar; >> + id_zns->mar = cpu_to_le32(mar); >> > > above 14 lines of code can be simplified as in 4-5 lines :- Simplified ? It is much harder to read in my opinion... > > mor = bdev_max_open_zones(req->ns->bdev); > id->zns->mor = cpu_tp_le32(mor ? mor - 1 : U32_MAX); > > mar = bdev_max_active_zones(req->ns->bdev); > id->zns->mar = cpu_tp_le32(mar ? mar - 1 : U32_MAX); > >> done: >> status = nvmet_copy_to_sgl(req, 0, id_zns, sizeof(*id_zns)); > > > either way, > > Reviewed-by: Chaitanya Kulkarni > -- Damien Le Moal Western Digital Research