From d4d50710a8b46082224376ef119a4dbb75b25c56 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 4 Nov 2020 09:27:33 +0100 Subject: 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 Tested-by: Greg Kroah-Hartman Signed-off-by: Linus Torvalds --- fs/seq_file.c | 45 ++++++++++++++++++++++++++++++++------------- include/linux/seq_file.h | 1 + 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 #include #include +#include #include #include @@ -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); -- cgit v1.2.3