Messages in this thread Patch in this message | | | Date | Tue, 10 Feb 2009 11:01:01 -0800 | From | Greg KH <> | Subject | [patch 37/53] seq_file: move traverse so it can be used from seq_read |
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2.6.28-stable review patch. If anyone has any objections, please let us know. ------------------
From: Eric Biederman <ebiederm@xmission.com>
commit 33da8892a2f9e7d4b2d9a35fc80833ba2d2b1aa6 upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/seq_file.c | 114 +++++++++++++++++++++++++++++----------------------------- 1 file changed, 57 insertions(+), 57 deletions(-)
--- a/fs/seq_file.c +++ b/fs/seq_file.c @@ -54,6 +54,63 @@ int seq_open(struct file *file, const st } EXPORT_SYMBOL(seq_open); +static int traverse(struct seq_file *m, loff_t offset) +{ + loff_t pos = 0, index; + int error = 0; + void *p; + + m->version = 0; + index = 0; + m->count = m->from = 0; + if (!offset) { + m->index = index; + return 0; + } + if (!m->buf) { + m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL); + if (!m->buf) + return -ENOMEM; + } + p = m->op->start(m, &index); + while (p) { + error = PTR_ERR(p); + if (IS_ERR(p)) + break; + error = m->op->show(m, p); + if (error < 0) + break; + if (unlikely(error)) { + error = 0; + m->count = 0; + } + if (m->count == m->size) + goto Eoverflow; + if (pos + m->count > offset) { + m->from = offset - pos; + m->count -= m->from; + m->index = index; + break; + } + pos += m->count; + m->count = 0; + if (pos == offset) { + index++; + m->index = index; + break; + } + p = m->op->next(m, p, &index); + } + m->op->stop(m, p); + return error; + +Eoverflow: + m->op->stop(m, p); + kfree(m->buf); + m->buf = kmalloc(m->size <<= 1, GFP_KERNEL); + return !m->buf ? -ENOMEM : -EAGAIN; +} + /** * seq_read - ->read() method for sequential files. * @file: the file to read from @@ -186,63 +243,6 @@ Efault: } EXPORT_SYMBOL(seq_read); -static int traverse(struct seq_file *m, loff_t offset) -{ - loff_t pos = 0, index; - int error = 0; - void *p; - - m->version = 0; - index = 0; - m->count = m->from = 0; - if (!offset) { - m->index = index; - return 0; - } - if (!m->buf) { - m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL); - if (!m->buf) - return -ENOMEM; - } - p = m->op->start(m, &index); - while (p) { - error = PTR_ERR(p); - if (IS_ERR(p)) - break; - error = m->op->show(m, p); - if (error < 0) - break; - if (unlikely(error)) { - error = 0; - m->count = 0; - } - if (m->count == m->size) - goto Eoverflow; - if (pos + m->count > offset) { - m->from = offset - pos; - m->count -= m->from; - m->index = index; - break; - } - pos += m->count; - m->count = 0; - if (pos == offset) { - index++; - m->index = index; - break; - } - p = m->op->next(m, p, &index); - } - m->op->stop(m, p); - return error; - -Eoverflow: - m->op->stop(m, p); - kfree(m->buf); - m->buf = kmalloc(m->size <<= 1, GFP_KERNEL); - return !m->buf ? -ENOMEM : -EAGAIN; -} - /** * seq_lseek - ->llseek() method for sequential files. * @file: the file in question
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