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authorChristoph Hellwig <hch@lst.de>2020-11-04 11:27:33 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-11-06 21:05:18 +0300
commitd4d50710a8b46082224376ef119a4dbb75b25c56 (patch)
tree318208ce4e81d298e7ed236f0475dfcd191c3936
parent3cea11cd5e3b00d91caf0b4730194039b45c5891 (diff)
downloadlinux-d4d50710a8b46082224376ef119a4dbb75b25c56.tar.xz
seq_file: add seq_read_iter
iov_iter based variant for reading a seq_file. seq_read is reimplemented on top of the iter variant. Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/seq_file.c45
-rw-r--r--include/linux/seq_file.h1
2 files changed, 33 insertions, 13 deletions
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 31219c1db17d..3b20e21604e7 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -18,6 +18,7 @@
#include <linux/mm.h>
#include <linux/printk.h>
#include <linux/string_helpers.h>
+#include <linux/uio.h>
#include <linux/uaccess.h>
#include <asm/page.h>
@@ -146,7 +147,28 @@ Eoverflow:
*/
ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
- struct seq_file *m = file->private_data;
+ struct iovec iov = { .iov_base = buf, .iov_len = size};
+ struct kiocb kiocb;
+ struct iov_iter iter;
+ ssize_t ret;
+
+ init_sync_kiocb(&kiocb, file);
+ iov_iter_init(&iter, READ, &iov, 1, size);
+
+ kiocb.ki_pos = *ppos;
+ ret = seq_read_iter(&kiocb, &iter);
+ *ppos = kiocb.ki_pos;
+ return ret;
+}
+EXPORT_SYMBOL(seq_read);
+
+/*
+ * Ready-made ->f_op->read_iter()
+ */
+ssize_t seq_read_iter(struct kiocb *iocb, struct iov_iter *iter)
+{
+ struct seq_file *m = iocb->ki_filp->private_data;
+ size_t size = iov_iter_count(iter);
size_t copied = 0;
size_t n;
void *p;
@@ -158,14 +180,14 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
* if request is to read from zero offset, reset iterator to first
* record as it might have been already advanced by previous requests
*/
- if (*ppos == 0) {
+ if (iocb->ki_pos == 0) {
m->index = 0;
m->count = 0;
}
- /* Don't assume *ppos is where we left it */
- if (unlikely(*ppos != m->read_pos)) {
- while ((err = traverse(m, *ppos)) == -EAGAIN)
+ /* Don't assume ki_pos is where we left it */
+ if (unlikely(iocb->ki_pos != m->read_pos)) {
+ while ((err = traverse(m, iocb->ki_pos)) == -EAGAIN)
;
if (err) {
/* With prejudice... */
@@ -174,7 +196,7 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
m->count = 0;
goto Done;
} else {
- m->read_pos = *ppos;
+ m->read_pos = iocb->ki_pos;
}
}
@@ -187,13 +209,11 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
/* if not empty - flush it first */
if (m->count) {
n = min(m->count, size);
- err = copy_to_user(buf, m->buf + m->from, n);
- if (err)
+ if (copy_to_iter(m->buf + m->from, n, iter) != n)
goto Efault;
m->count -= n;
m->from += n;
size -= n;
- buf += n;
copied += n;
if (!size)
goto Done;
@@ -254,8 +274,7 @@ Fill:
}
m->op->stop(m, p);
n = min(m->count, size);
- err = copy_to_user(buf, m->buf, n);
- if (err)
+ if (copy_to_iter(m->buf, n, iter) != n)
goto Efault;
copied += n;
m->count -= n;
@@ -264,7 +283,7 @@ Done:
if (!copied)
copied = err;
else {
- *ppos += copied;
+ iocb->ki_pos += copied;
m->read_pos += copied;
}
mutex_unlock(&m->lock);
@@ -276,7 +295,7 @@ Efault:
err = -EFAULT;
goto Done;
}
-EXPORT_SYMBOL(seq_read);
+EXPORT_SYMBOL(seq_read_iter);
/**
* seq_lseek - ->llseek() method for sequential files.
diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 813614d4b71f..b83b3ae3c877 100644
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -107,6 +107,7 @@ void seq_pad(struct seq_file *m, char c);
char *mangle_path(char *s, const char *p, const char *esc);
int seq_open(struct file *, const struct seq_operations *);
ssize_t seq_read(struct file *, char __user *, size_t, loff_t *);
+ssize_t seq_read_iter(struct kiocb *iocb, struct iov_iter *iter);
loff_t seq_lseek(struct file *, loff_t, int);
int seq_release(struct inode *, struct file *);
int seq_write(struct seq_file *seq, const void *data, size_t len);