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Fri, 06 Feb 2026 23:40:05 -0800 (PST) From: Adarsh Das To: Zhihao Cheng Cc: dwmw2@infradead.org, richard@nod.at, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, Adarsh Das Subject: Re: [PATCH] jffs2: use fs_umode_to_dtype() for dirent type Date: Sat, 7 Feb 2026 13:09:48 +0530 Message-ID: <20260207073948.48144-1-adarshdas950@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <134dec36-3bcf-89a4-2817-a880afa4280f@huawei.com> References: <134dec36-3bcf-89a4-2817-a880afa4280f@huawei.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Zhihao, Thank you for taking the time to review my patch! I'm trying to understand the issue you've identified. I looked at the fs_umode_to_dtype() implementation in fs/fs_types.c: unsigned char fs_umode_to_dtype(umode_t mode) { return fs_ftype_to_dtype(fs_umode_to_ftype(mode)); } >From what I can see, it seems like the function does produce FT_FIFO (5) as an intermediate value, but then converts it back before returning. Here's what I think happens for S_IFIFO (0010000): Old bit-shift code: type = (mode & S_IFMT) >> 12 = (0010000 & 00170000) >> 12 = 0010000 >> 12 = 1 (DT_FIFO) New fs_umode_to_dtype() code: Step 1: fs_umode_to_ftype(0010000) = fs_ftype_by_dtype[S_DT(0010000)] = fs_ftype_by_dtype[1] = FT_FIFO = 5 Step 2: fs_ftype_to_dtype(5) = fs_dtype_by_ftype[5] = DT_FIFO = 1 I'm not sure how FT_FIFO (5) would remain after the function returns, since it seems to get converted back to DT_FIFO (1) in step 2. If there's an issue with this approach, I can edit my patch and keep changes in only jffs2_mknod.