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kernfs: implement ->read_iter 

Switch kernfs to implement the read_iter method instead of plain old
read to prepare to supporting splice and sendfile again.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210120204631.274206-2-hch@lst.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Christoph Hellwig 2021-01-20 21:46:29 +01:00 committed by Greg Kroah-Hartman
parent 895bee2708
commit 4eaad21a6a
1 changed files with 12 additions and 23 deletions
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35
fs/kernfs/file.c
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@ -14,6 +14,7 @@
#include <linux/pagemap.h> #include <linux/pagemap.h>
#include <linux/sched/mm.h> #include <linux/sched/mm.h>
#include <linux/fsnotify.h> #include <linux/fsnotify.h>
#include <linux/uio.h>
#include "kernfs-internal.h" #include "kernfs-internal.h"
@ -180,11 +181,10 @@ static const struct seq_operations kernfs_seq_ops = {
* it difficult to use seq_file. Implement simplistic custom buffering for * it difficult to use seq_file. Implement simplistic custom buffering for
* bin files. * bin files.
*/ */
static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of, static ssize_t kernfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
char __user *user_buf, size_t count,
loff_t *ppos)
{ {
ssize_t len = min_t(size_t, count, PAGE_SIZE); struct kernfs_open_file *of = kernfs_of(iocb->ki_filp);
ssize_t len = min_t(size_t, iov_iter_count(iter), PAGE_SIZE);
const struct kernfs_ops *ops; const struct kernfs_ops *ops;
char *buf; char *buf;
@ -210,7 +210,7 @@ static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of,
of->event = atomic_read(&of->kn->attr.open->event); of->event = atomic_read(&of->kn->attr.open->event);
ops = kernfs_ops(of->kn); ops = kernfs_ops(of->kn);
if (ops->read) if (ops->read)
len = ops->read(of, buf, len, *ppos); len = ops->read(of, buf, len, iocb->ki_pos);
else else
len = -EINVAL; len = -EINVAL;
@ -220,12 +220,12 @@ static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of,
if (len < 0) if (len < 0)
goto out_free; goto out_free;
if (copy_to_user(user_buf, buf, len)) { if (copy_to_iter(buf, len, iter) != len) {
len = -EFAULT; len = -EFAULT;
goto out_free; goto out_free;
} }
*ppos += len; iocb->ki_pos += len;
out_free: out_free:
if (buf == of->prealloc_buf) if (buf == of->prealloc_buf)
@ -235,22 +235,11 @@ static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of,
return len; return len;
} }
/** static ssize_t kernfs_fop_read_iter(struct kiocb *iocb, struct iov_iter *iter)
* kernfs_fop_read - kernfs vfs read callback
* @file: file pointer
* @user_buf: data to write
* @count: number of bytes
* @ppos: starting offset
*/
static ssize_t kernfs_fop_read(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos)
{ {
struct kernfs_open_file *of = kernfs_of(file); if (kernfs_of(iocb->ki_filp)->kn->flags & KERNFS_HAS_SEQ_SHOW)
return seq_read_iter(iocb, iter);
if (of->kn->flags & KERNFS_HAS_SEQ_SHOW) return kernfs_file_read_iter(iocb, iter);
return seq_read(file, user_buf, count, ppos);
else
return kernfs_file_direct_read(of, user_buf, count, ppos);
} }
/** /**
@ -960,7 +949,7 @@ void kernfs_notify(struct kernfs_node *kn)
EXPORT_SYMBOL_GPL(kernfs_notify); EXPORT_SYMBOL_GPL(kernfs_notify);
const struct file_operations kernfs_file_fops = { const struct file_operations kernfs_file_fops = {
.read = kernfs_fop_read, .read_iter = kernfs_fop_read_iter,
.write = kernfs_fop_write, .write = kernfs_fop_write,
.llseek = generic_file_llseek, .llseek = generic_file_llseek,
.mmap = kernfs_fop_mmap, .mmap = kernfs_fop_mmap,