seq_file: move traverse so it can be used from seq_read
In 2.6.25 some /proc files were converted to use the seq_file infrastructure. But seq_files do not correctly support pread(), which broke some usersapce applications. To handle pread correctly we can't assume that f_pos is where we left it in seq_read. So move traverse() so that we can eventually use it in seq_read and do thus some day support pread(). Signed-off-by: Eric Biederman <ebiederm@xmission.com> Cc: Paul Turner <pjt@google.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Родитель
361916a943
Коммит
33da8892a2
114
fs/seq_file.c
114
fs/seq_file.c
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@ -54,6 +54,63 @@ int seq_open(struct file *file, const struct seq_operations *op)
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}
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EXPORT_SYMBOL(seq_open);
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static int traverse(struct seq_file *m, loff_t offset)
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{
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loff_t pos = 0, index;
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int error = 0;
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void *p;
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m->version = 0;
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index = 0;
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m->count = m->from = 0;
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if (!offset) {
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m->index = index;
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return 0;
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}
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if (!m->buf) {
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m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
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if (!m->buf)
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return -ENOMEM;
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}
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p = m->op->start(m, &index);
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while (p) {
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error = PTR_ERR(p);
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if (IS_ERR(p))
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break;
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error = m->op->show(m, p);
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if (error < 0)
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break;
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if (unlikely(error)) {
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error = 0;
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m->count = 0;
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}
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if (m->count == m->size)
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goto Eoverflow;
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if (pos + m->count > offset) {
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m->from = offset - pos;
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m->count -= m->from;
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m->index = index;
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break;
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}
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pos += m->count;
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m->count = 0;
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if (pos == offset) {
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index++;
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m->index = index;
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break;
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}
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p = m->op->next(m, p, &index);
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}
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m->op->stop(m, p);
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return error;
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Eoverflow:
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m->op->stop(m, p);
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kfree(m->buf);
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m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
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return !m->buf ? -ENOMEM : -EAGAIN;
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}
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/**
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* seq_read - ->read() method for sequential files.
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* @file: the file to read from
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@ -186,63 +243,6 @@ Efault:
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}
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EXPORT_SYMBOL(seq_read);
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static int traverse(struct seq_file *m, loff_t offset)
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{
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loff_t pos = 0, index;
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int error = 0;
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void *p;
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m->version = 0;
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index = 0;
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m->count = m->from = 0;
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if (!offset) {
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m->index = index;
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return 0;
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}
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if (!m->buf) {
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m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
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if (!m->buf)
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return -ENOMEM;
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}
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p = m->op->start(m, &index);
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while (p) {
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error = PTR_ERR(p);
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if (IS_ERR(p))
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break;
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error = m->op->show(m, p);
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if (error < 0)
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break;
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if (unlikely(error)) {
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error = 0;
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m->count = 0;
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}
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if (m->count == m->size)
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goto Eoverflow;
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if (pos + m->count > offset) {
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m->from = offset - pos;
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m->count -= m->from;
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m->index = index;
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break;
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}
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pos += m->count;
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m->count = 0;
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if (pos == offset) {
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index++;
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m->index = index;
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break;
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}
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p = m->op->next(m, p, &index);
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}
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m->op->stop(m, p);
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return error;
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Eoverflow:
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m->op->stop(m, p);
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kfree(m->buf);
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m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
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return !m->buf ? -ENOMEM : -EAGAIN;
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}
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/**
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* seq_lseek - ->llseek() method for sequential files.
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* @file: the file in question
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