/* * linux/fs/fat/file.c * * Written 1992,1993 by Werner Almesberger * * regular file handling primitives for fat-based filesystems */ #include <linux/capability.h> #include <linux/module.h> #include <linux/time.h> #include <linux/msdos_fs.h> #include <linux/smp_lock.h> #include <linux/buffer_head.h> #include <linux/writeback.h> #include <linux/backing-dev.h> #include <linux/blkdev.h> int fat_generic_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg) { struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); u32 __user *user_attr = (u32 __user *)arg; switch (cmd) { case FAT_IOCTL_GET_ATTRIBUTES: { u32 attr; if (inode->i_ino == MSDOS_ROOT_INO) attr = ATTR_DIR; else attr = fat_attr(inode); return put_user(attr, user_attr); } case FAT_IOCTL_SET_ATTRIBUTES: { u32 attr, oldattr; int err, is_dir = S_ISDIR(inode->i_mode); struct iattr ia; err = get_user(attr, user_attr); if (err) return err; mutex_lock(&inode->i_mutex); if (IS_RDONLY(inode)) { err = -EROFS; goto up; } /* * ATTR_VOLUME and ATTR_DIR cannot be changed; this also * prevents the user from turning us into a VFAT * longname entry. Also, we obviously can't set * any of the NTFS attributes in the high 24 bits. */ attr &= 0xff & ~(ATTR_VOLUME | ATTR_DIR); /* Merge in ATTR_VOLUME and ATTR_DIR */ attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) | (is_dir ? ATTR_DIR : 0); oldattr = fat_attr(inode); /* Equivalent to a chmod() */ ia.ia_valid = ATTR_MODE | ATTR_CTIME; if (is_dir) { ia.ia_mode = MSDOS_MKMODE(attr, S_IRWXUGO & ~sbi->options.fs_dmask) | S_IFDIR; } else { ia.ia_mode = MSDOS_MKMODE(attr, (S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO)) & ~sbi->options.fs_fmask) | S_IFREG; } /* The root directory has no attributes */ if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) { err = -EINVAL; goto up; } if (sbi->options.sys_immutable) { if ((attr | oldattr) & ATTR_SYS) { if (!capable(CAP_LINUX_IMMUTABLE)) { err = -EPERM; goto up; } } } /* This MUST be done before doing anything irreversible... */ err = notify_change(filp->f_path.dentry, &ia); if (err) goto up; if (sbi->options.sys_immutable) { if (attr & ATTR_SYS) inode->i_flags |= S_IMMUTABLE; else inode->i_flags &= S_IMMUTABLE; } MSDOS_I(inode)->i_attrs = attr & ATTR_UNUSED; mark_inode_dirty(inode); up: mutex_unlock(&inode->i_mutex); return err; } default: return -ENOTTY; /* Inappropriate ioctl for device */ } } static int fat_file_release(struct inode *inode, struct file *filp) { if ((filp->f_mode & FMODE_WRITE) && MSDOS_SB(inode->i_sb)->options.flush) { fat_flush_inodes(inode->i_sb, inode, NULL); congestion_wait(WRITE, HZ/10); } return 0; } const struct file_operations fat_file_operations = { .llseek = generic_file_llseek, .read = do_sync_read, .write = do_sync_write, .aio_read = generic_file_aio_read, .aio_write = generic_file_aio_write, .mmap = generic_file_mmap, .release = fat_file_release, .ioctl = fat_generic_ioctl, .fsync = file_fsync, .splice_read = generic_file_splice_read, }; static int fat_cont_expand(struct inode *inode, loff_t size) { struct address_space *mapping = inode->i_mapping; loff_t start = inode->i_size, count = size - inode->i_size; int err; err = generic_cont_expand_simple(inode, size); if (err) goto out; inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; mark_inode_dirty(inode); if (IS_SYNC(inode)) err = sync_page_range_nolock(inode, mapping, start, count); out: return err; } static int check_mode(const struct msdos_sb_info *sbi, mode_t mode) { mode_t req = mode & ~S_IFMT; /* * Of the r and x bits, all (subject to umask) must be present. Of the * w bits, either all (subject to umask) or none must be present. */ if (S_ISREG(mode)) { req &= ~sbi->options.fs_fmask; if ((req & (S_IRUGO | S_IXUGO)) != ((S_IRUGO | S_IXUGO) & ~sbi->options.fs_fmask)) return -EPERM; if ((req & S_IWUGO) != 0 && (req & S_IWUGO) != (S_IWUGO & ~sbi->options.fs_fmask)) return -EPERM; } else if (S_ISDIR(mode)) { req &= ~sbi->options.fs_dmask; if ((req & (S_IRUGO | S_IXUGO)) != ((S_IRUGO | S_IXUGO) & ~sbi->options.fs_dmask)) return -EPERM; if ((req & S_IWUGO) != 0 && (req & S_IWUGO) != (S_IWUGO & ~sbi->options.fs_dmask)) return -EPERM; } else { return -EPERM; } return 0; } int fat_notify_change(struct dentry *dentry, struct iattr *attr) { struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb); struct inode *inode = dentry->d_inode; int mask, error = 0; lock_kernel(); /* * Expand the file. Since inode_setattr() updates ->i_size * before calling the ->truncate(), but FAT needs to fill the * hole before it. */ if (attr->ia_valid & ATTR_SIZE) { if (attr->ia_size > inode->i_size) { error = fat_cont_expand(inode, attr->ia_size); if (error || attr->ia_valid == ATTR_SIZE) goto out; attr->ia_valid &= ~ATTR_SIZE; } } error = inode_change_ok(inode, attr); if (error) { if (sbi->options.quiet) error = 0; goto out; } if (((attr->ia_valid & ATTR_UID) && (attr->ia_uid != sbi->options.fs_uid)) || ((attr->ia_valid & ATTR_GID) && (attr->ia_gid != sbi->options.fs_gid))) error = -EPERM; if (error) { if (sbi->options.quiet) error = 0; goto out; } if (attr->ia_valid & ATTR_MODE) { error = check_mode(sbi, attr->ia_mode); if (error != 0 && !sbi->options.quiet) goto out; } error = inode_setattr(inode, attr); if (error) goto out; if (S_ISDIR(inode->i_mode)) mask = sbi->options.fs_dmask; else mask = sbi->options.fs_fmask; inode->i_mode &= S_IFMT | (S_IRWXUGO & ~mask); out: unlock_kernel(); return error; } EXPORT_SYMBOL_GPL(fat_notify_change); /* Free all clusters after the skip'th cluster. */ static int fat_free(struct inode *inode, int skip) { struct super_block *sb = inode->i_sb; int err, wait, free_start, i_start, i_logstart; if (MSDOS_I(inode)->i_start == 0) return 0; fat_cache_inval_inode(inode); wait = IS_DIRSYNC(inode); i_start = free_start = MSDOS_I(inode)->i_start; i_logstart = MSDOS_I(inode)->i_logstart; /* First, we write the new file size. */ if (!skip) { MSDOS_I(inode)->i_start = 0; MSDOS_I(inode)->i_logstart = 0; } MSDOS_I(inode)->i_attrs |= ATTR_ARCH; inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; if (wait) { err = fat_sync_inode(inode); if (err) { MSDOS_I(inode)->i_start = i_start; MSDOS_I(inode)->i_logstart = i_logstart; return err; } } else mark_inode_dirty(inode); /* Write a new EOF, and get the remaining cluster chain for freeing. */ if (skip) { struct fat_entry fatent; int ret, fclus, dclus; ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus); if (ret < 0) return ret; else if (ret == FAT_ENT_EOF) return 0; fatent_init(&fatent); ret = fat_ent_read(inode, &fatent, dclus); if (ret == FAT_ENT_EOF) { fatent_brelse(&fatent); return 0; } else if (ret == FAT_ENT_FREE) { fat_fs_panic(sb, "%s: invalid cluster chain (i_pos %lld)", __FUNCTION__, MSDOS_I(inode)->i_pos); ret = -EIO; } else if (ret > 0) { err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait); if (err) ret = err; } fatent_brelse(&fatent); if (ret < 0) return ret; free_start = ret; } inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9); /* Freeing the remained cluster chain */ return fat_free_clusters(inode, free_start); } void fat_truncate(struct inode *inode) { struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); const unsigned int cluster_size = sbi->cluster_size; int nr_clusters; /* * This protects against truncating a file bigger than it was then * trying to write into the hole. */ if (MSDOS_I(inode)->mmu_private > inode->i_size) MSDOS_I(inode)->mmu_private = inode->i_size; nr_clusters = (inode->i_size + (cluster_size - 1)) >> sbi->cluster_bits; lock_kernel(); fat_free(inode, nr_clusters); unlock_kernel(); fat_flush_inodes(inode->i_sb, inode, NULL); } int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) { struct inode *inode = dentry->d_inode; generic_fillattr(inode, stat); stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size; return 0; } EXPORT_SYMBOL_GPL(fat_getattr); const struct inode_operations fat_file_inode_operations = { .truncate = fat_truncate, .setattr = fat_notify_change, .getattr = fat_getattr, };