On Mon, Jan 29, 2024 at 05:15:06PM +0200, Tony Solomonik wrote:
> do_sys_ftruncate receives a file descriptor, fgets the struct file, and
> finally actually truncates the file.
>
> do_ftruncate allows for passing in a file directly, with the caller
> already holding a reference to it.
>
> Signed-off-by: Tony Solomonik <tony.solomonik@xxxxxxxxx>
> ---
> fs/internal.h | 1 +
> fs/open.c | 52 ++++++++++++++++++++++++++++-----------------------
> 2 files changed, 30 insertions(+), 23 deletions(-)
>
> diff --git a/fs/internal.h b/fs/internal.h
> index 58e43341aebf..d35b1c05cf6d 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -182,6 +182,7 @@ extern struct open_how build_open_how(int flags, umode_t mode);
> extern int build_open_flags(const struct open_how *how, struct open_flags *op);
> extern struct file *__close_fd_get_file(unsigned int fd);
>
> +long do_ftruncate(struct file *file, loff_t length);
> long do_sys_ftruncate(unsigned int fd, loff_t length, int small);
> int chmod_common(const struct path *path, umode_t mode);
> int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
> diff --git a/fs/open.c b/fs/open.c
> index 02dc608d40d8..6d608ff4a3f7 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -154,49 +154,55 @@ 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)
> {
> struct inode *inode;
> struct dentry *dentry;
> + int error;
> +
> + dentry = file->f_path.dentry;
> + inode = dentry->d_inode;
> + if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
> + return -EINVAL;
> +
> + /* Check IS_APPEND on real upper inode */
> + if (IS_APPEND(file_inode(file)))
> + return -EPERM;
> + sb_start_write(inode->i_sb);
> + error = security_file_truncate(file);
> + if (!error)
> + error = do_truncate(file_mnt_idmap(file), dentry, length,
> + ATTR_MTIME | ATTR_CTIME, file);
> + sb_end_write(inode->i_sb);
> +
> + 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;
> + return -EINVAL;
> f = fdget(fd);
> if (!f.file)
> - goto out;
> + return -EBADF;
>
> /* explicitly opened as large or we are on 64-bit box */
> if (f.file->f_flags & O_LARGEFILE)
> small = 0;
Why is the O_LARGEFILE handling not needed when used from io_uring?
