fs: add a __kernel_read helper
This is the counterpart to __kernel_write, and skip the rw_verify_area call compared to kernel_read. Signed-off-by: Christoph Hellwig <hch@lst.de>
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61a707c543
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@ -430,6 +430,29 @@ ssize_t __vfs_read(struct file *file, char __user *buf, size_t count,
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return -EINVAL;
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}
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ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
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{
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mm_segment_t old_fs = get_fs();
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ssize_t ret;
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if (WARN_ON_ONCE(!(file->f_mode & FMODE_READ)))
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return -EINVAL;
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if (!(file->f_mode & FMODE_CAN_READ))
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return -EINVAL;
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if (count > MAX_RW_COUNT)
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count = MAX_RW_COUNT;
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set_fs(KERNEL_DS);
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ret = __vfs_read(file, (void __user *)buf, count, pos);
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set_fs(old_fs);
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if (ret > 0) {
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fsnotify_access(file);
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add_rchar(current, ret);
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}
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inc_syscr(current);
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return ret;
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}
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ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
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{
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mm_segment_t old_fs;
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@ -3033,6 +3033,7 @@ extern int kernel_read_file_from_path_initns(const char *, void **, loff_t *, lo
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extern int kernel_read_file_from_fd(int, void **, loff_t *, loff_t,
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enum kernel_read_file_id);
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extern ssize_t kernel_read(struct file *, void *, size_t, loff_t *);
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ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos);
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extern ssize_t kernel_write(struct file *, const void *, size_t, loff_t *);
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extern ssize_t __kernel_write(struct file *, const void *, size_t, loff_t *);
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extern struct file * open_exec(const char *);
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