From 5f0d594c602f870e3a3872f7ea42bf846a1d26cf Mon Sep 17 00:00:00 2001 From: Tony Solomonik Date: Fri, 2 Feb 2024 14:17:23 +0200 Subject: [PATCH] Add do_ftruncate that truncates a struct file 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 Reviewed-by: Christian Brauner Link: https://lore.kernel.org/r/20240202121724.17461-2-tony.solomonik@gmail.com Signed-off-by: Jens Axboe --- fs/internal.h | 1 + fs/open.c | 65 +++++++++++++++++++++++++++------------------------ 2 files changed, 35 insertions(+), 31 deletions(-) diff --git a/fs/internal.h b/fs/internal.h index b67406435fc0..8509cbd6d115 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -183,6 +183,7 @@ 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); struct file *file_close_fd_locked(struct files_struct *files, unsigned fd); +long do_ftruncate(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 a84d21e55c39..0410cb52bb4b 100644 --- a/fs/open.c +++ b/fs/open.c @@ -154,49 +154,52 @@ 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; + int error; + + /* explicitly opened as large or we are on 64-bit box */ + if (file->f_flags & O_LARGEFILE) + small = 0; + + dentry = file->f_path.dentry; + inode = dentry->d_inode; + if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE)) + return -EINVAL; + + /* Cannot ftruncate over 2^31 bytes without large file support */ + if (small && length > MAX_NON_LFS) + 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; + error = do_ftruncate(f.file, length, small); - dentry = f.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; - - error = -EINVAL; - /* Cannot ftruncate over 2^31 bytes without large file support */ - if (small && length > MAX_NON_LFS) - goto out_putf; - - error = -EPERM; - /* Check IS_APPEND on real upper inode */ - if (IS_APPEND(file_inode(f.file))) - goto out_putf; - sb_start_write(inode->i_sb); - error = security_file_truncate(f.file); - if (!error) - error = do_truncate(file_mnt_idmap(f.file), dentry, length, - ATTR_MTIME | ATTR_CTIME, f.file); - sb_end_write(inode->i_sb); -out_putf: fdput(f); -out: return error; }