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Thu, 25 Jun 2026 01:35:12 -0700 (PDT) Received: from localhost ([212.73.77.104]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-46c9ed7491esm9926887f8f.37.2026.06.25.01.35.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 25 Jun 2026 01:35:11 -0700 (PDT) From: Askar Safin To: linux-fsdevel@vger.kernel.org, Christian Brauner , Alexander Viro , Jan Kara Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, netdev@vger.kernel.org, fuse-devel@lists.linux.dev, Linus Torvalds , Matthew Wilcox , Jens Axboe , Christoph Hellwig , David Howells , Andrew Morton , David Hildenbrand , Pedro Falcato , Miklos Szeredi , Andy Lutomirski , Collin Funk , David Laight , Stefan Metzmacher , The 8472 , Willy Tarreau , Joanne Koong , Val Packett , Andrei Vagin , patches@lists.linux.dev Subject: [PATCH v2 1/7] vmsplice: open-code do_writev and do_readv Date: Thu, 25 Jun 2026 08:34:03 +0000 Message-ID: <20260625083409.3769242-2-safinaskar@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260625083409.3769242-1-safinaskar@gmail.com> References: <20260625083409.3769242-1-safinaskar@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 836E84000A X-Stat-Signature: yichpgqj8wqs6xwt9s4arg3z83y8qsbh X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1782376514-603016 X-HE-Meta: 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 LLBlgxvo 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: My previous vmsplice patch did the following mistake: I did "CLASS(fd, f)(fd)", then did some checks on resulting "struct file", then passed numeric (!) file descriptor to a function. This is somewhat okay in this particular case, but I still think this is code smell, so I fix this by open-coding do_writev and do_readv. Also I insert a comment to warn other developers to keep do_writev and do_readv in sync with vmsplice(2). Signed-off-by: Askar Safin --- fs/read_write.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/fs/read_write.c b/fs/read_write.c index 1e5444f4d..e224e7cb8 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -1070,6 +1070,7 @@ static ssize_t vfs_writev(struct file *file, const struct iovec __user *vec, static ssize_t do_readv(unsigned long fd, const struct iovec __user *vec, unsigned long vlen, rwf_t flags) { + /* All future changes to this function should be kept in sync with vmsplice(2). */ CLASS(fd_pos, f)(fd); ssize_t ret = -EBADF; @@ -1093,6 +1094,7 @@ static ssize_t do_readv(unsigned long fd, const struct iovec __user *vec, static ssize_t do_writev(unsigned long fd, const struct iovec __user *vec, unsigned long vlen, rwf_t flags) { + /* All future changes to this function should be kept in sync with vmsplice(2). */ CLASS(fd_pos, f)(fd); ssize_t ret = -EBADF; @@ -1226,14 +1228,24 @@ SYSCALL_DEFINE4(vmsplice, unsigned long, fd, const struct iovec __user *, vec, if (fd_empty(f)) return -EBADF; - /* We do do_writev/do_readv, so it is okay to pass "false" here */ + /* We do vfs_writev/vfs_readv, so it is okay to pass "false" here */ if (!get_pipe_info(fd_file(f), /* for_splice = */ false)) return -EBADF; - if (fd_file(f)->f_mode & FMODE_WRITE) - return do_writev(fd, vec, vlen, (flags & SPLICE_F_NONBLOCK) ? RWF_NOWAIT : 0); - else - return do_readv(fd, vec, vlen, (flags & SPLICE_F_NONBLOCK) ? RWF_NOWAIT : 0); + if (fd_file(f)->f_mode & FMODE_WRITE) { + ssize_t ret = vfs_writev(fd_file(f), vec, vlen, NULL, (flags & SPLICE_F_NONBLOCK) ? RWF_NOWAIT : 0); + if (ret > 0) + add_wchar(current, ret); + inc_syscw(current); + return ret; + } else { + ssize_t ret = vfs_readv(fd_file(f), vec, vlen, NULL, (flags & SPLICE_F_NONBLOCK) ? RWF_NOWAIT : 0); + + if (ret > 0) + add_rchar(current, ret); + inc_syscr(current); + return ret; + } } /* -- 2.47.3