- 根目录:
- fs
- fat
- file.c
/*
* 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/compat.h>
#include <linux/mount.h>
#include <linux/time.h>
#include <linux/buffer_head.h>
#include <linux/writeback.h>
#include <linux/backing-dev.h>
#include <linux/blkdev.h>
#include <linux/fsnotify.h>
#include <linux/security.h>
#include "fat.h"
static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
{
u32 attr;
mutex_lock(&inode->i_mutex);
attr = fat_make_attrs(inode);
mutex_unlock(&inode->i_mutex);
return put_user(attr, user_attr);
}
static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
{
struct inode *inode = file_inode(file);
struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
int is_dir = S_ISDIR(inode->i_mode);
u32 attr, oldattr;
struct iattr ia;
int err;
err = get_user(attr, user_attr);
if (err)
goto out;
err = mnt_want_write_file(file);
if (err)
goto out;
mutex_lock(&inode->i_mutex);
/*
* 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_make_attrs(inode);
/* Equivalent to a chmod() */
ia.ia_valid = ATTR_MODE | ATTR_CTIME;
ia.ia_ctime = current_fs_time(inode->i_sb);
if (is_dir)
ia.ia_mode = fat_make_mode(sbi, attr, S_IRWXUGO);
else {
ia.ia_mode = fat_make_mode(sbi, attr,
S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO));
}
/* The root directory has no attributes */
if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {
err = -EINVAL;
goto out_unlock_inode;
}
if (sbi->options.sys_immutable &&
((attr | oldattr) & ATTR_SYS) &&
!capable(CAP_LINUX_IMMUTABLE)) {
err = -EPERM;
goto out_unlock_inode;
}
/*
* The security check is questionable... We single
* out the RO attribute for checking by the security
* module, just because it maps to a file mode.
*/
err = security_inode_setattr(file->f_path.dentry, &ia);
if (err)
goto out_unlock_inode;
/* This MUST be done before doing anything irreversible... */
err = fat_setattr(file->f_path.dentry, &ia);
if (err)
goto out_unlock_inode;
fsnotify_change(file->f_path.dentry, ia.ia_valid);
if (sbi->options.sys_immutable) {
if (attr & ATTR_SYS)
inode->i_flags |= S_IMMUTABLE;
else
inode->i_flags &= ~S_IMMUTABLE;
}
fat_save_attrs(inode, attr);
mark_inode_dirty(inode);
out_unlock_inode:
mutex_unlock(&inode->i_mutex);
mnt_drop_write_file(file);
out:
return err;
}
static int fat_ioctl_get_volume_id(struct inode *inode, u32 __user *user_attr)
{
struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
return put_user(sbi->vol_id, user_attr);
}
long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct inode *inode = file_inode(filp);
u32 __user *user_attr = (u32 __user *)arg;
switch (cmd) {
case FAT_IOCTL_GET_ATTRIBUTES:
return fat_ioctl_get_attributes(inode, user_attr);
case FAT_IOCTL_SET_ATTRIBUTES:
return fat_ioctl_set_attributes(filp, user_attr);
case FAT_IOCTL_GET_VOLUME_ID:
return fat_ioctl_get_volume_id(inode, user_attr);
default:
return -ENOTTY; /* Inappropriate ioctl for device */
}
}
#ifdef CONFIG_COMPAT
static long fat_generic_compat_ioctl(struct file *filp, unsigned int cmd,
unsigned long arg)
{
return fat_generic_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
}
#endif
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(BLK_RW_ASYNC, HZ/10);
}
return 0;
}
int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
{
struct inode *inode = filp->f_mapping->host;
int res, err;
res = generic_file_fsync(filp, start, end, datasync);
err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
return res ? res : err;
}
const struct file_operations fat_file_operations = {
.llseek = generic_file_llseek,
.read = new_sync_read,
.write = new_sync_write,
.read_iter = generic_file_read_iter,
.write_iter = generic_file_write_iter,
.mmap = generic_file_mmap,
.release = fat_file_release,
.unlocked_ioctl = fat_generic_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = fat_generic_compat_ioctl,
#endif
.fsync = fat_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)) {
int err2;
/*
* Opencode syncing since we don't have a file open to use
* standard fsync path.
*/
err = filemap_fdatawrite_range(mapping, start,
start + count - 1);
err2 = sync_mapping_buffers(mapping);
if (!err)
err = err2;
err2 = write_inode_now(inode, 1);
if (!err)
err = err2;
if (!err) {
err = filemap_fdatawait_range(mapping, start,
start + count - 1);
}
}
out:
return err;
}
/* 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_error(sb,
"%s: invalid cluster chain (i_pos %lld)",
__func__, 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_blocks(struct inode *inode, loff_t offset)
{
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 > offset)
MSDOS_I(inode)->mmu_private = offset;
nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits;
fat_free(inode, nr_clusters);
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;
if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
/* Use i_pos for ino. This is used as fileid of nfs. */
stat->ino = fat_i_pos_read(MSDOS_SB(inode->i_sb), inode);
}
return 0;
}
EXPORT_SYMBOL_GPL(fat_getattr);
static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
struct inode *inode, umode_t *mode_ptr)
{
umode_t mask, perm;
/*
* Note, the basic check is already done by a caller of
* (attr->ia_mode & ~FAT_VALID_MODE)
*/
if (S_ISREG(inode->i_mode))
mask = sbi->options.fs_fmask;
else
mask = sbi->options.fs_dmask;
perm = *mode_ptr & ~(S_IFMT | mask);
/*
* 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 fat_mode_can_hold_ro(inode) is false, can't change w bits.
*/
if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
return -EPERM;
if (fat_mode_can_hold_ro(inode)) {
if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
return -EPERM;
} else {
if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
return -EPERM;
}
*mode_ptr &= S_IFMT | perm;
return 0;
}
static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
{
umode_t allow_utime = sbi->options.allow_utime;
if (!uid_eq(current_fsuid(), inode->i_uid)) {
if (in_group_p(inode->i_gid))
allow_utime >>= 3;
if (allow_utime & MAY_WRITE)
return 1;
}
/* use a default check */
return 0;
}
#define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
/* valid file mode bits */
#define FAT_VALID_MODE (S_IFREG | S_IFDIR | S_IRWXUGO)
int fat_setattr(struct dentry *dentry, struct iattr *attr)
{
struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
struct inode *inode = dentry->d_inode;
unsigned int ia_valid;
int error;
/* Check for setting the inode time. */
ia_valid = attr->ia_valid;
if (ia_valid & TIMES_SET_FLAGS) {
if (fat_allow_set_time(sbi, inode))
attr->ia_valid &= ~TIMES_SET_FLAGS;
}
error = inode_change_ok(inode, attr);
attr->ia_valid = ia_valid;
if (error) {
if (sbi->options.quiet)
error = 0;
goto out;
}
/*
* Expand the file. Since inode_setattr() updates ->i_size
* before calling the ->truncate(), but FAT needs to fill the
* hole before it. XXX: this is no longer true with new truncate
* sequence.
*/
if (attr->ia_valid & ATTR_SIZE) {
inode_dio_wait(inode);
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;
}
}
if (((attr->ia_valid & ATTR_UID) &&
(!uid_eq(attr->ia_uid, sbi->options.fs_uid))) ||
((attr->ia_valid & ATTR_GID) &&
(!gid_eq(attr->ia_gid, sbi->options.fs_gid))) ||
((attr->ia_valid & ATTR_MODE) &&
(attr->ia_mode & ~FAT_VALID_MODE)))
error = -EPERM;
if (error) {
if (sbi->options.quiet)
error = 0;
goto out;
}
/*
* We don't return -EPERM here. Yes, strange, but this is too
* old behavior.
*/
if (attr->ia_valid & ATTR_MODE) {
if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
attr->ia_valid &= ~ATTR_MODE;
}
if (attr->ia_valid & ATTR_SIZE) {
down_write(&MSDOS_I(inode)->truncate_lock);
truncate_setsize(inode, attr->ia_size);
fat_truncate_blocks(inode, attr->ia_size);
up_write(&MSDOS_I(inode)->truncate_lock);
}
setattr_copy(inode, attr);
mark_inode_dirty(inode);
out:
return error;
}
EXPORT_SYMBOL_GPL(fat_setattr);
const struct inode_operations fat_file_inode_operations = {
.setattr = fat_setattr,
.getattr = fat_getattr,
};