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Subject[PATCH 18/23] proc: add a read_iter method to proc proc_ops
Date
This will allow proc files to implement iter read semantics.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/proc/inode.c | 53 ++++++++++++++++++++++++++++++++++++++---
include/linux/proc_fs.h | 1 +
2 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 93dd2045737504..58c075e2a452d6 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -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;
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
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