[PATCH 2/9] proc: add a read_iter method to proc proc_ops

Christoph Hellwig
2020-06-26T07:59:10Z

This will allow proc files to implement iter read semantics.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/proc/inode.c | 28 ++++++++++++++++++++++++++++
include/linux/proc_fs.h | 1 +
2 files changed, 29 insertions(+)

diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 28d6105e908e4c..fa86619cebc2be 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -297,6 +297,29 @@ static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
return rv;
}

+static ssize_t pde_read_iter(struct proc_dir_entry *pde, struct kiocb *iocb,
+ struct iov_iter *iter)
+{
+ if (!pde->proc_ops->proc_read_iter)
+ return -EINVAL;
+ return pde->proc_ops->proc_read_iter(iocb, iter);
+}
+
+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_read_iter(pde, iocb, iter);
+
+ if (!use_pde(pde))
+ return -EIO;
+ ret = pde_read_iter(pde, 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;
@@ -312,6 +335,9 @@ static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count,
struct proc_dir_entry *pde = PDE(file_inode(file));
ssize_t rv = -EIO;

+ if (pde->proc_ops->proc_read_iter)
+ return iter_read(file, buf, count, ppos, proc_reg_read_iter);
+
if (pde_is_permanent(pde)) {
return pde_read(pde, file, buf, count, ppos);
} else if (use_pde(pde)) {
@@ -569,6 +595,7 @@ static int proc_reg_release(struct inode *inode, struct file *file)
static const struct file_operations proc_reg_file_ops = {
.llseek = proc_reg_llseek,
.read = proc_reg_read,
+ .read_iter = proc_reg_read_iter,
.write = proc_reg_write,
.poll = proc_reg_poll,
.unlocked_ioctl = proc_reg_unlocked_ioctl,
@@ -585,6 +612,7 @@ static const struct file_operations proc_reg_file_ops = {
static const struct file_operations proc_reg_file_ops_no_compat = {
.llseek = proc_reg_llseek,
.read = proc_reg_read,
+ .read_iter = proc_reg_read_iter,
.write = proc_reg_write,
.poll = proc_reg_poll,
.unlocked_ioctl = proc_reg_unlocked_ioctl,
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index d1eed1b4365172..97b3f5f06db9d8 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -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 *);
--
2.26.2