ssize_t read(int fd, void *buf, size_t count);
ssize_t write(int fd, const void *buf, size_t count);

static ssize_t nvram_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
static ssize_t nvram_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)

391 SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count)
392 {
393 struct file *file;
394 ssize_t ret = -EBADF;
395 int fput_needed;
396
397 file = fget_light(fd, &fput_needed);
398 if (file) {
399 loff_t pos = file_pos_read(file);
400 ret = vfs_read(file, buf, count, &pos);
401 file_pos_write(file, pos);
402 fput_light(file, fput_needed);
403 }
404
405 return ret;
406 }

918 struct file {
 919 /*
 920 * fu_list becomes invalid after file_free is called and queued via
 921 * fu_rcuhead for RCU freeing
 922 */
 923 union {
 924 struct list_head fu_list;
 925 struct rcu_head fu_rcuhead;
 926 } f_u;
 927 struct path f_path;
 928 #define f_dentry f_path.dentry
 929 #define f_vfsmnt f_path.mnt
 930 const struct file_operations *f_op;
 931 spinlock_t f_lock; /* f_ep_links, f_flags, no IRQ */
 932 atomic_long_t f_count;
 933 unsigned int f_flags;
 934 fmode_t f_mode;
 935 loff_t f_pos;
 936 struct fown_struct f_owner;
 937 const struct cred *f_cred;
 938 struct file_ra_state f_ra;
 939
 940 u64 f_version;
 941 #ifdef CONFIG_SECURITY
 942 void *f_security;
 943 #endif
 944 /* needed for tty driver, and maybe others */
 945 void *private_data;
 946
 947 #ifdef CONFIG_EPOLL
 948 /* Used by fs/eventpoll.c to link all the hooks to this file */
 949 struct list_head f_ep_links;
 950 #endif /* #ifdef CONFIG_EPOLL */
 951 struct address_space *f_mapping;
 952 #ifdef CONFIG_DEBUG_WRITECOUNT
 953 unsigned long f_mnt_write_state;
 954 #endif
 955 };

381 static inline loff_t file_pos_read(struct file *file)
382 {
383 return file->f_pos;
384 }

295 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
296 {
297 ssize_t ret;
298
299 if (!(file->f_mode & FMODE_READ))
300 return -EBADF;
301 if (!file->f_op || (!file->f_op->read && !file->f_op->aio_read))
302 return -EINVAL;
303 if (unlikely(!access_ok(VERIFY_WRITE, buf, count)))
304 return -EFAULT;
305
306 ret = rw_verify_area(READ, file, pos, count);
307 if (ret >= 0) {
308 count = ret;
309 if (file->f_op->read)
310 ret = file->f_op->read(file, buf, count, pos);
311 else
312 ret = do_sync_read(file, buf, count, pos);
313 if (ret > 0) {
314 fsnotify_access(file);
315 add_rchar(current, ret);
316 }
317 inc_syscr(current);
318 }
319
320 return ret;
321 }

231 static ssize_t nvram_read(struct file *file, char __user *buf,
232 size_t count, loff_t *ppos)
233 {
234 unsigned char contents[NVRAM_BYTES];
235 unsigned i = *ppos;
236 unsigned char *tmp;
237
238 spin_lock_irq(&rtc_lock);
239
240 if (!__nvram_check_checksum())
241 goto checksum_err;
242
243 for (tmp = contents; count-- > 0 && i < NVRAM_BYTES; ++i, ++tmp)
244 *tmp = __nvram_read_byte(i);
245
246 spin_unlock_irq(&rtc_lock);
247
248 if (copy_to_user(buf, contents, tmp - contents))
249 return -EFAULT;
250
251 *ppos = i;
252
253 return tmp - contents;
254
255 checksum_err:
256 spin_unlock_irq(&rtc_lock);
257 return -EIO;
258 }

struct inode *ext4_iget(struct super_block *sb, unsigned long ino)


5165 if (S_ISREG(inode->i_mode)) {
5166 inode->i_op = &ext4_file_inode_operations;
5167 inode->i_fop = &ext4_file_operations;
5168 ext4_set_aops(inode);
5169 } else if (S_ISDIR(inode->i_mode)) {
5170 inode->i_op = &ext4_dir_inode_operations;
5171 inode->i_fop = &ext4_dir_operations;
5172 } else if (S_ISLNK(inode->i_mode)) {
5173 if (ext4_inode_is_fast_symlink(inode)) {
5174 inode->i_op = &ext4_fast_symlink_inode_operations;
5175 nd_terminate_link(ei->i_data, inode->i_size,
5176 sizeof(ei->i_data) - 1);
5177 } else {
5178 inode->i_op = &ext4_symlink_inode_operations;
5179 ext4_set_aops(inode);
5180 }
5181 } else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
5182 S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
5183 inode->i_op = &ext4_special_inode_operations;
5184 if (raw_inode->i_block[0])
5185 init_special_inode(inode, inode->i_mode,
5186 old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
5187 else
5188 init_special_inode(inode, inode->i_mode,
5189 new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
5190 } else {

133 const struct file_operations ext4_file_operations = {
134 .llseek = generic_file_llseek,
135 .read = do_sync_read,
136 .write = do_sync_write,
137 .aio_read = generic_file_aio_read,
138 .aio_write = ext4_file_write,
139 .unlocked_ioctl = ext4_ioctl,
140 #ifdef CONFIG_COMPAT
141 .compat_ioctl = ext4_compat_ioctl,
142 #endif
143 .mmap = ext4_file_mmap,
144 .open = ext4_file_open,
145 .release = ext4_release_file,
146 .fsync = ext4_sync_file,
147 .splice_read = generic_file_splice_read,
148 .splice_write = generic_file_splice_write,
149 };
150