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proc: add a read_iter method to proc proc_ops

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This will allow proc files to implement iter read semantics.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Christoph Hellwig 2020-09-03 16:22:31 +02:00 committed by Al Viro
parent 906146f449
commit fd5a13f489
2 changed files with 51 additions and 3 deletions
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53
fs/proc/inode.c
View File

@ -297,6 +297,21 @@ static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
return rv;
}
static ssize_t proc_reg_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{
struct proc_dir_entry *pde = PDE(file_inode(iocb->ki_filp));
ssize_t ret;
if (pde_is_permanent(pde))
return pde->proc_ops->proc_read_iter(iocb, iter);
if (!use_pde(pde))
return -EIO;
ret = pde->proc_ops->proc_read_iter(iocb, iter);
unuse_pde(pde);
return ret;
}
static ssize_t pde_read(struct proc_dir_entry *pde, struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
typeof_member(struct proc_ops, proc_read) read;
@ -578,6 +593,18 @@ static const struct file_operations proc_reg_file_ops = {
.release = proc_reg_release,
};
static const struct file_operations proc_iter_file_ops = {
.llseek = proc_reg_llseek,
.read_iter = proc_reg_read_iter,
.write = proc_reg_write,
.poll = proc_reg_poll,
.unlocked_ioctl = proc_reg_unlocked_ioctl,
.mmap = proc_reg_mmap,
.get_unmapped_area = proc_reg_get_unmapped_area,
.open = proc_reg_open,
.release = proc_reg_release,
};
#ifdef CONFIG_COMPAT
static const struct file_operations proc_reg_file_ops_compat = {
.llseek = proc_reg_llseek,
@ -591,6 +618,19 @@ static const struct file_operations proc_reg_file_ops_compat = {
.open = proc_reg_open,
.release = proc_reg_release,
};
static const struct file_operations proc_iter_file_ops_compat = {
.llseek = proc_reg_llseek,
.read_iter = proc_reg_read_iter,
.write = proc_reg_write,
.poll = proc_reg_poll,
.unlocked_ioctl = proc_reg_unlocked_ioctl,
.compat_ioctl = proc_reg_compat_ioctl,
.mmap = proc_reg_mmap,
.get_unmapped_area = proc_reg_get_unmapped_area,
.open = proc_reg_open,
.release = proc_reg_release,
};
#endif
static void proc_put_link(void *p)
@ -642,10 +682,17 @@ struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
if (S_ISREG(inode->i_mode)) {
inode->i_op = de->proc_iops;
inode->i_fop = &proc_reg_file_ops;
if (de->proc_ops->proc_read_iter)
inode->i_fop = &proc_iter_file_ops;
else
inode->i_fop = &proc_reg_file_ops;
#ifdef CONFIG_COMPAT
if (de->proc_ops->proc_compat_ioctl)
inode->i_fop = &proc_reg_file_ops_compat;
if (de->proc_ops->proc_compat_ioctl) {
if (de->proc_ops->proc_read_iter)
inode->i_fop = &proc_iter_file_ops_compat;
else
inode->i_fop = &proc_reg_file_ops_compat;
}
#endif
} else if (S_ISDIR(inode->i_mode)) {
inode->i_op = de->proc_iops;

1
include/linux/proc_fs.h
View File

@ -30,6 +30,7 @@ struct proc_ops {
unsigned int proc_flags;
int (*proc_open)(struct inode *, struct file *);
ssize_t (*proc_read)(struct file *, char __user *, size_t, loff_t *);
ssize_t (*proc_read_iter)(struct kiocb *, struct iov_iter *);
ssize_t (*proc_write)(struct file *, const char __user *, size_t, loff_t *);
loff_t (*proc_lseek)(struct file *, loff_t, int);
int (*proc_release)(struct inode *, struct file *);