| Message ID | 20240123211952.32342-2-tony.solomonik@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Add ftruncate to io_uring | expand |
On 1/23/24 2:19 PM, Tony Solomonik wrote: > do_sys_ftruncate receives a file descriptor, fgets the struct file*, and > finally actually truncates the file. Just do struct file and get rid of '*', kernel style would otherwise dictate it should be struct file * but there's no point in mentioning this is a pointer. It's the only case that makes sense. > ftruncate_file allows for truncating a file without fgets. I'd rephrase that last sentence, as it reads as you could do this without holding a file reference. That is obviously not true. You could make it: ftruncate_file allows for passing in a file directly, with the caller already holding a reference to it. > > Signed-off-by: Tony Solomonik <tony.solomonik@gmail.com> > --- > fs/internal.h | 1 + > fs/open.c | 51 ++++++++++++++++++++++++++++++--------------------- > 2 files changed, 31 insertions(+), 21 deletions(-) > > diff --git a/fs/internal.h b/fs/internal.h > index 58e43341aebf..78a641ebd16e 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 ftruncate_file(struct file *file, loff_t length, int small); > 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..0c505402e93d 100644 > --- a/fs/open.c > +++ b/fs/open.c > @@ -154,47 +154,56 @@ 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 ftruncate_file(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)) > + return error; > > error = -EINVAL; > /* Cannot ftruncate over 2^31 bytes without large file support */ > if (small && length > MAX_NON_LFS) > - goto out_putf; > + return error; > > 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))) > + return error; > 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: > + > + return error; White space issue here with 'error'. And see below comments for error assignment in general. > +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 = ftruncate_file(f.file, length, small); > + > fdput(f); > out: > return error; No reason for the goto's here anymore, just do: long do_sys_ftruncate(unsigned int fd, loff_t length, int small) { struct fd f; int error; if (length < 0) return -EINVAL; error = -EBADF; f = fdget(fd); if (f.file) error = ftruncate_file(f.file, length, small); fdput(f); return error; } Same for the above helper, save error for when you actually need it rather than do: error = -EFOO; if (some_error) return error; That only really makes sense when you assign error through eg calling a function, not when you know what error you are returning. Makes it easier to read the code as well.
diff --git a/fs/internal.h b/fs/internal.h index 58e43341aebf..78a641ebd16e 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 ftruncate_file(struct file *file, loff_t length, int small); 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..0c505402e93d 100644 --- a/fs/open.c +++ b/fs/open.c @@ -154,47 +154,56 @@ 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 ftruncate_file(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)) + return error; error = -EINVAL; /* Cannot ftruncate over 2^31 bytes without large file support */ if (small && length > MAX_NON_LFS) - goto out_putf; + return error; 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))) + return error; 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: + + 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 = ftruncate_file(f.file, length, small); + fdput(f); out: return error;
do_sys_ftruncate receives a file descriptor, fgets the struct file*, and finally actually truncates the file. ftruncate_file allows for truncating a file without fgets. Signed-off-by: Tony Solomonik <tony.solomonik@gmail.com> --- fs/internal.h | 1 + fs/open.c | 51 ++++++++++++++++++++++++++++++--------------------- 2 files changed, 31 insertions(+), 21 deletions(-)