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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>
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parent
3cea11cd5e
commit
d4d50710a8
2 changed files with 33 additions and 13 deletions
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@ -18,6 +18,7 @@
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#include <linux/mm.h>
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#include <linux/printk.h>
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#include <linux/string_helpers.h>
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#include <linux/uio.h>
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#include <linux/uaccess.h>
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#include <asm/page.h>
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@ -146,7 +147,28 @@ static int traverse(struct seq_file *m, loff_t offset)
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*/
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ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
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{
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struct seq_file *m = file->private_data;
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struct iovec iov = { .iov_base = buf, .iov_len = size};
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struct kiocb kiocb;
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struct iov_iter iter;
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ssize_t ret;
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init_sync_kiocb(&kiocb, file);
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iov_iter_init(&iter, READ, &iov, 1, size);
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kiocb.ki_pos = *ppos;
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ret = seq_read_iter(&kiocb, &iter);
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*ppos = kiocb.ki_pos;
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return ret;
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}
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EXPORT_SYMBOL(seq_read);
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/*
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* Ready-made ->f_op->read_iter()
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*/
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ssize_t seq_read_iter(struct kiocb *iocb, struct iov_iter *iter)
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{
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struct seq_file *m = iocb->ki_filp->private_data;
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size_t size = iov_iter_count(iter);
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size_t copied = 0;
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size_t n;
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void *p;
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@ -158,14 +180,14 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
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* if request is to read from zero offset, reset iterator to first
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* record as it might have been already advanced by previous requests
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*/
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if (*ppos == 0) {
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if (iocb->ki_pos == 0) {
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m->index = 0;
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m->count = 0;
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}
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/* Don't assume *ppos is where we left it */
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if (unlikely(*ppos != m->read_pos)) {
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while ((err = traverse(m, *ppos)) == -EAGAIN)
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/* Don't assume ki_pos is where we left it */
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if (unlikely(iocb->ki_pos != m->read_pos)) {
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while ((err = traverse(m, iocb->ki_pos)) == -EAGAIN)
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;
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if (err) {
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/* With prejudice... */
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@ -174,7 +196,7 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
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m->count = 0;
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goto Done;
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} else {
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m->read_pos = *ppos;
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m->read_pos = iocb->ki_pos;
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}
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}
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@ -187,13 +209,11 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
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/* if not empty - flush it first */
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if (m->count) {
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n = min(m->count, size);
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err = copy_to_user(buf, m->buf + m->from, n);
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if (err)
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if (copy_to_iter(m->buf + m->from, n, iter) != n)
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goto Efault;
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m->count -= n;
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m->from += n;
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size -= n;
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buf += n;
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copied += n;
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if (!size)
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goto Done;
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@ -254,8 +274,7 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
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}
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m->op->stop(m, p);
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n = min(m->count, size);
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err = copy_to_user(buf, m->buf, n);
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if (err)
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if (copy_to_iter(m->buf, n, iter) != n)
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goto Efault;
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copied += n;
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m->count -= n;
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@ -264,7 +283,7 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
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if (!copied)
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copied = err;
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else {
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*ppos += copied;
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iocb->ki_pos += copied;
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m->read_pos += copied;
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}
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mutex_unlock(&m->lock);
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@ -276,7 +295,7 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
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err = -EFAULT;
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goto Done;
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}
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EXPORT_SYMBOL(seq_read);
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EXPORT_SYMBOL(seq_read_iter);
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/**
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* seq_lseek - ->llseek() method for sequential files.
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@ -107,6 +107,7 @@ void seq_pad(struct seq_file *m, char c);
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char *mangle_path(char *s, const char *p, const char *esc);
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int seq_open(struct file *, const struct seq_operations *);
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ssize_t seq_read(struct file *, char __user *, size_t, loff_t *);
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ssize_t seq_read_iter(struct kiocb *iocb, struct iov_iter *iter);
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loff_t seq_lseek(struct file *, loff_t, int);
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int seq_release(struct inode *, struct file *);
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int seq_write(struct seq_file *seq, const void *data, size_t len);
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