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Tue, 23 Jan 2024 03:33:36 -0800 (PST) Received: from localhost.localdomain ([147.235.201.119]) by smtp.gmail.com with ESMTPSA id x8-20020a5d4448000000b0033925e94c89sm9078884wrr.12.2024.01.23.03.33.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Jan 2024 03:33:36 -0800 (PST) From: Tony Solomonik To: axboe@kernel.dk Cc: krisman@suse.de, leitao@debian.org, io-uring@vger.kernel.org, asml.silence@gmail.com, Tony Solomonik Subject: [PATCH v2 1/2] Add __do_ftruncate that truncates a struct file* Date: Tue, 23 Jan 2024 13:33:32 +0200 Message-Id: <20240123113333.79503-1-tony.solomonik@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit do_sys_ftruncate receives a file descriptor, fgets the struct file*, and finally actually truncates the file. __do_ftruncate allows for truncating a file without fgets. --- fs/open.c | 52 ++++++++++++++++++++++++---------------- include/linux/syscalls.h | 2 ++ 2 files changed, 33 insertions(+), 21 deletions(-) diff --git a/fs/open.c b/fs/open.c index 02dc608d40d8..b32ac430666c 100644 --- a/fs/open.c +++ b/fs/open.c @@ -154,47 +154,57 @@ COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length } #endif -long do_sys_ftruncate(unsigned int fd, loff_t length, int small) +long __do_ftruncate(struct file *file, loff_t length, int small) { struct inode *inode; struct dentry *dentry; - struct fd f; int error; - error = -EINVAL; - if (length < 0) - goto out; - error = -EBADF; - f = fdget(fd); - if (!f.file) - goto out; - /* explicitly opened as large or we are on 64-bit box */ - if (f.file->f_flags & O_LARGEFILE) + if (file->f_flags & O_LARGEFILE) small = 0; - dentry = f.file->f_path.dentry; + dentry = file->f_path.dentry; inode = dentry->d_inode; error = -EINVAL; - if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE)) - goto out_putf; + if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE)) + goto out; error = -EINVAL; /* Cannot ftruncate over 2^31 bytes without large file support */ if (small && length > MAX_NON_LFS) - goto out_putf; + goto out; error = -EPERM; /* Check IS_APPEND on real upper inode */ - if (IS_APPEND(file_inode(f.file))) - goto out_putf; + if (IS_APPEND(file_inode(file))) + goto out; sb_start_write(inode->i_sb); - error = security_file_truncate(f.file); + error = security_file_truncate(file); if (!error) - error = do_truncate(file_mnt_idmap(f.file), dentry, length, - ATTR_MTIME | ATTR_CTIME, f.file); + error = do_truncate(file_mnt_idmap(file), dentry, length, + ATTR_MTIME | ATTR_CTIME, file); sb_end_write(inode->i_sb); -out_putf: + +out: + return error; +} + +long do_sys_ftruncate(unsigned int fd, loff_t length, int small) +{ + struct fd f; + int error; + + error = -EINVAL; + if (length < 0) + goto out; + error = -EBADF; + f = fdget(fd); + if (!f.file) + goto out; + + error = __do_ftruncate(f.file, length, small); + fdput(f); out: return error; diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index fd9d12de7e92..e8c56986e751 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -1229,6 +1229,8 @@ static inline long ksys_lchown(const char __user *filename, uid_t user, AT_SYMLINK_NOFOLLOW); } +extern long __do_ftruncate(struct file *file, loff_t length, int small); + extern long do_sys_ftruncate(unsigned int fd, loff_t length, int small); static inline long ksys_ftruncate(unsigned int fd, loff_t length) -- 2.34.1