![Josef "Jeff" Sipek](/assets/img/avatar_default.png)
Change all the uses of f_{dentry,vfsmnt} to f_path.{dentry,mnt} in linux/kernel/. Signed-off-by: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1026 lines
24 KiB
C
1026 lines
24 KiB
C
/*
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* Public API and common code for kernel->userspace relay file support.
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*
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* See Documentation/filesystems/relayfs.txt for an overview of relayfs.
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*
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* Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
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* Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com)
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*
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* Moved to kernel/relay.c by Paul Mundt, 2006.
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*
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* This file is released under the GPL.
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*/
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#include <linux/errno.h>
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#include <linux/stddef.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/string.h>
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#include <linux/relay.h>
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#include <linux/vmalloc.h>
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#include <linux/mm.h>
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/*
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* close() vm_op implementation for relay file mapping.
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*/
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static void relay_file_mmap_close(struct vm_area_struct *vma)
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{
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struct rchan_buf *buf = vma->vm_private_data;
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buf->chan->cb->buf_unmapped(buf, vma->vm_file);
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}
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/*
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* nopage() vm_op implementation for relay file mapping.
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*/
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static struct page *relay_buf_nopage(struct vm_area_struct *vma,
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unsigned long address,
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int *type)
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{
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struct page *page;
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struct rchan_buf *buf = vma->vm_private_data;
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unsigned long offset = address - vma->vm_start;
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if (address > vma->vm_end)
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return NOPAGE_SIGBUS; /* Disallow mremap */
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if (!buf)
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return NOPAGE_OOM;
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page = vmalloc_to_page(buf->start + offset);
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if (!page)
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return NOPAGE_OOM;
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get_page(page);
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if (type)
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*type = VM_FAULT_MINOR;
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return page;
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}
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/*
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* vm_ops for relay file mappings.
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*/
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static struct vm_operations_struct relay_file_mmap_ops = {
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.nopage = relay_buf_nopage,
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.close = relay_file_mmap_close,
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};
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/**
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* relay_mmap_buf: - mmap channel buffer to process address space
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* @buf: relay channel buffer
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* @vma: vm_area_struct describing memory to be mapped
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*
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* Returns 0 if ok, negative on error
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*
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* Caller should already have grabbed mmap_sem.
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*/
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int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma)
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{
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unsigned long length = vma->vm_end - vma->vm_start;
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struct file *filp = vma->vm_file;
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if (!buf)
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return -EBADF;
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if (length != (unsigned long)buf->chan->alloc_size)
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return -EINVAL;
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vma->vm_ops = &relay_file_mmap_ops;
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vma->vm_private_data = buf;
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buf->chan->cb->buf_mapped(buf, filp);
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return 0;
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}
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/**
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* relay_alloc_buf - allocate a channel buffer
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* @buf: the buffer struct
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* @size: total size of the buffer
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*
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* Returns a pointer to the resulting buffer, %NULL if unsuccessful. The
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* passed in size will get page aligned, if it isn't already.
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*/
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static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size)
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{
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void *mem;
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unsigned int i, j, n_pages;
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*size = PAGE_ALIGN(*size);
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n_pages = *size >> PAGE_SHIFT;
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buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
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if (!buf->page_array)
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return NULL;
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for (i = 0; i < n_pages; i++) {
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buf->page_array[i] = alloc_page(GFP_KERNEL);
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if (unlikely(!buf->page_array[i]))
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goto depopulate;
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}
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mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL);
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if (!mem)
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goto depopulate;
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memset(mem, 0, *size);
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buf->page_count = n_pages;
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return mem;
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depopulate:
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for (j = 0; j < i; j++)
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__free_page(buf->page_array[j]);
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kfree(buf->page_array);
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return NULL;
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}
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/**
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* relay_create_buf - allocate and initialize a channel buffer
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* @chan: the relay channel
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*
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* Returns channel buffer if successful, %NULL otherwise.
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*/
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struct rchan_buf *relay_create_buf(struct rchan *chan)
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{
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struct rchan_buf *buf = kcalloc(1, sizeof(struct rchan_buf), GFP_KERNEL);
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if (!buf)
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return NULL;
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buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL);
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if (!buf->padding)
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goto free_buf;
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buf->start = relay_alloc_buf(buf, &chan->alloc_size);
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if (!buf->start)
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goto free_buf;
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buf->chan = chan;
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kref_get(&buf->chan->kref);
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return buf;
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free_buf:
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kfree(buf->padding);
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kfree(buf);
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return NULL;
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}
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/**
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* relay_destroy_channel - free the channel struct
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* @kref: target kernel reference that contains the relay channel
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*
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* Should only be called from kref_put().
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*/
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void relay_destroy_channel(struct kref *kref)
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{
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struct rchan *chan = container_of(kref, struct rchan, kref);
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kfree(chan);
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}
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/**
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* relay_destroy_buf - destroy an rchan_buf struct and associated buffer
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* @buf: the buffer struct
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*/
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void relay_destroy_buf(struct rchan_buf *buf)
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{
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struct rchan *chan = buf->chan;
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unsigned int i;
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if (likely(buf->start)) {
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vunmap(buf->start);
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for (i = 0; i < buf->page_count; i++)
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__free_page(buf->page_array[i]);
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kfree(buf->page_array);
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}
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kfree(buf->padding);
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kfree(buf);
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kref_put(&chan->kref, relay_destroy_channel);
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}
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/**
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* relay_remove_buf - remove a channel buffer
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* @kref: target kernel reference that contains the relay buffer
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*
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* Removes the file from the fileystem, which also frees the
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* rchan_buf_struct and the channel buffer. Should only be called from
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* kref_put().
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*/
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void relay_remove_buf(struct kref *kref)
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{
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struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref);
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buf->chan->cb->remove_buf_file(buf->dentry);
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relay_destroy_buf(buf);
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}
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/**
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* relay_buf_empty - boolean, is the channel buffer empty?
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* @buf: channel buffer
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*
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* Returns 1 if the buffer is empty, 0 otherwise.
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*/
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int relay_buf_empty(struct rchan_buf *buf)
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{
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return (buf->subbufs_produced - buf->subbufs_consumed) ? 0 : 1;
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}
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EXPORT_SYMBOL_GPL(relay_buf_empty);
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/**
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* relay_buf_full - boolean, is the channel buffer full?
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* @buf: channel buffer
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*
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* Returns 1 if the buffer is full, 0 otherwise.
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*/
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int relay_buf_full(struct rchan_buf *buf)
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{
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size_t ready = buf->subbufs_produced - buf->subbufs_consumed;
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return (ready >= buf->chan->n_subbufs) ? 1 : 0;
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}
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EXPORT_SYMBOL_GPL(relay_buf_full);
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/*
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* High-level relay kernel API and associated functions.
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*/
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/*
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* rchan_callback implementations defining default channel behavior. Used
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* in place of corresponding NULL values in client callback struct.
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*/
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/*
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* subbuf_start() default callback. Does nothing.
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*/
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static int subbuf_start_default_callback (struct rchan_buf *buf,
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void *subbuf,
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void *prev_subbuf,
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size_t prev_padding)
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{
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if (relay_buf_full(buf))
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return 0;
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return 1;
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}
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/*
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* buf_mapped() default callback. Does nothing.
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*/
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static void buf_mapped_default_callback(struct rchan_buf *buf,
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struct file *filp)
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{
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}
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/*
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* buf_unmapped() default callback. Does nothing.
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*/
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static void buf_unmapped_default_callback(struct rchan_buf *buf,
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struct file *filp)
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{
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}
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/*
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* create_buf_file_create() default callback. Does nothing.
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*/
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static struct dentry *create_buf_file_default_callback(const char *filename,
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struct dentry *parent,
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int mode,
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struct rchan_buf *buf,
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int *is_global)
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{
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return NULL;
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}
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/*
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* remove_buf_file() default callback. Does nothing.
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*/
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static int remove_buf_file_default_callback(struct dentry *dentry)
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{
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return -EINVAL;
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}
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/* relay channel default callbacks */
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static struct rchan_callbacks default_channel_callbacks = {
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.subbuf_start = subbuf_start_default_callback,
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.buf_mapped = buf_mapped_default_callback,
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.buf_unmapped = buf_unmapped_default_callback,
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.create_buf_file = create_buf_file_default_callback,
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.remove_buf_file = remove_buf_file_default_callback,
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};
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/**
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* wakeup_readers - wake up readers waiting on a channel
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* @private: the channel buffer
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*
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* This is the work function used to defer reader waking. The
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* reason waking is deferred is that calling directly from write
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* causes problems if you're writing from say the scheduler.
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*/
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static void wakeup_readers(struct work_struct *work)
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{
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struct rchan_buf *buf =
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container_of(work, struct rchan_buf, wake_readers.work);
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wake_up_interruptible(&buf->read_wait);
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}
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/**
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* __relay_reset - reset a channel buffer
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* @buf: the channel buffer
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* @init: 1 if this is a first-time initialization
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*
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* See relay_reset for description of effect.
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*/
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static inline void __relay_reset(struct rchan_buf *buf, unsigned int init)
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{
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size_t i;
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if (init) {
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init_waitqueue_head(&buf->read_wait);
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kref_init(&buf->kref);
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INIT_DELAYED_WORK(&buf->wake_readers, NULL);
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} else {
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cancel_delayed_work(&buf->wake_readers);
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flush_scheduled_work();
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}
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buf->subbufs_produced = 0;
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buf->subbufs_consumed = 0;
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buf->bytes_consumed = 0;
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buf->finalized = 0;
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buf->data = buf->start;
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buf->offset = 0;
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for (i = 0; i < buf->chan->n_subbufs; i++)
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buf->padding[i] = 0;
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buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0);
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}
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/**
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* relay_reset - reset the channel
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* @chan: the channel
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*
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* This has the effect of erasing all data from all channel buffers
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* and restarting the channel in its initial state. The buffers
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* are not freed, so any mappings are still in effect.
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*
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* NOTE: Care should be taken that the channel isn't actually
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* being used by anything when this call is made.
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*/
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void relay_reset(struct rchan *chan)
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{
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unsigned int i;
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struct rchan_buf *prev = NULL;
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if (!chan)
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return;
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for (i = 0; i < NR_CPUS; i++) {
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if (!chan->buf[i] || chan->buf[i] == prev)
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break;
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__relay_reset(chan->buf[i], 0);
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prev = chan->buf[i];
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}
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}
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EXPORT_SYMBOL_GPL(relay_reset);
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/*
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* relay_open_buf - create a new relay channel buffer
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*
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* Internal - used by relay_open().
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*/
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static struct rchan_buf *relay_open_buf(struct rchan *chan,
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const char *filename,
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struct dentry *parent,
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int *is_global)
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{
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struct rchan_buf *buf;
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struct dentry *dentry;
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if (*is_global)
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return chan->buf[0];
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buf = relay_create_buf(chan);
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if (!buf)
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return NULL;
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/* Create file in fs */
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dentry = chan->cb->create_buf_file(filename, parent, S_IRUSR,
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buf, is_global);
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if (!dentry) {
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relay_destroy_buf(buf);
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return NULL;
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}
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buf->dentry = dentry;
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__relay_reset(buf, 1);
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return buf;
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}
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/**
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* relay_close_buf - close a channel buffer
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* @buf: channel buffer
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*
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* Marks the buffer finalized and restores the default callbacks.
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* The channel buffer and channel buffer data structure are then freed
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* automatically when the last reference is given up.
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*/
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static inline void relay_close_buf(struct rchan_buf *buf)
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{
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buf->finalized = 1;
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cancel_delayed_work(&buf->wake_readers);
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flush_scheduled_work();
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kref_put(&buf->kref, relay_remove_buf);
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}
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static inline void setup_callbacks(struct rchan *chan,
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struct rchan_callbacks *cb)
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{
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if (!cb) {
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chan->cb = &default_channel_callbacks;
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return;
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}
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if (!cb->subbuf_start)
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cb->subbuf_start = subbuf_start_default_callback;
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if (!cb->buf_mapped)
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cb->buf_mapped = buf_mapped_default_callback;
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if (!cb->buf_unmapped)
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cb->buf_unmapped = buf_unmapped_default_callback;
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if (!cb->create_buf_file)
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cb->create_buf_file = create_buf_file_default_callback;
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if (!cb->remove_buf_file)
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cb->remove_buf_file = remove_buf_file_default_callback;
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chan->cb = cb;
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}
|
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|
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/**
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* relay_open - create a new relay channel
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* @base_filename: base name of files to create
|
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* @parent: dentry of parent directory, %NULL for root directory
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* @subbuf_size: size of sub-buffers
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* @n_subbufs: number of sub-buffers
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* @cb: client callback functions
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*
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* Returns channel pointer if successful, %NULL otherwise.
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*
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* Creates a channel buffer for each cpu using the sizes and
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* attributes specified. The created channel buffer files
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* will be named base_filename0...base_filenameN-1. File
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* permissions will be S_IRUSR.
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*/
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struct rchan *relay_open(const char *base_filename,
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struct dentry *parent,
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size_t subbuf_size,
|
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size_t n_subbufs,
|
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struct rchan_callbacks *cb)
|
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{
|
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unsigned int i;
|
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struct rchan *chan;
|
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char *tmpname;
|
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int is_global = 0;
|
|
|
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if (!base_filename)
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return NULL;
|
|
|
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if (!(subbuf_size && n_subbufs))
|
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return NULL;
|
|
|
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chan = kcalloc(1, sizeof(struct rchan), GFP_KERNEL);
|
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if (!chan)
|
|
return NULL;
|
|
|
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chan->version = RELAYFS_CHANNEL_VERSION;
|
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chan->n_subbufs = n_subbufs;
|
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chan->subbuf_size = subbuf_size;
|
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chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs);
|
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setup_callbacks(chan, cb);
|
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kref_init(&chan->kref);
|
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|
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tmpname = kmalloc(NAME_MAX + 1, GFP_KERNEL);
|
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if (!tmpname)
|
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goto free_chan;
|
|
|
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for_each_online_cpu(i) {
|
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sprintf(tmpname, "%s%d", base_filename, i);
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chan->buf[i] = relay_open_buf(chan, tmpname, parent,
|
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&is_global);
|
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if (!chan->buf[i])
|
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goto free_bufs;
|
|
|
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chan->buf[i]->cpu = i;
|
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}
|
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|
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kfree(tmpname);
|
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return chan;
|
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|
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free_bufs:
|
|
for (i = 0; i < NR_CPUS; i++) {
|
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if (!chan->buf[i])
|
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break;
|
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relay_close_buf(chan->buf[i]);
|
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if (is_global)
|
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break;
|
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}
|
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kfree(tmpname);
|
|
|
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free_chan:
|
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kref_put(&chan->kref, relay_destroy_channel);
|
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return NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(relay_open);
|
|
|
|
/**
|
|
* relay_switch_subbuf - switch to a new sub-buffer
|
|
* @buf: channel buffer
|
|
* @length: size of current event
|
|
*
|
|
* Returns either the length passed in or 0 if full.
|
|
*
|
|
* Performs sub-buffer-switch tasks such as invoking callbacks,
|
|
* updating padding counts, waking up readers, etc.
|
|
*/
|
|
size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
|
|
{
|
|
void *old, *new;
|
|
size_t old_subbuf, new_subbuf;
|
|
|
|
if (unlikely(length > buf->chan->subbuf_size))
|
|
goto toobig;
|
|
|
|
if (buf->offset != buf->chan->subbuf_size + 1) {
|
|
buf->prev_padding = buf->chan->subbuf_size - buf->offset;
|
|
old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
|
|
buf->padding[old_subbuf] = buf->prev_padding;
|
|
buf->subbufs_produced++;
|
|
buf->dentry->d_inode->i_size += buf->chan->subbuf_size -
|
|
buf->padding[old_subbuf];
|
|
smp_mb();
|
|
if (waitqueue_active(&buf->read_wait)) {
|
|
PREPARE_DELAYED_WORK(&buf->wake_readers,
|
|
wakeup_readers);
|
|
schedule_delayed_work(&buf->wake_readers, 1);
|
|
}
|
|
}
|
|
|
|
old = buf->data;
|
|
new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
|
|
new = buf->start + new_subbuf * buf->chan->subbuf_size;
|
|
buf->offset = 0;
|
|
if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) {
|
|
buf->offset = buf->chan->subbuf_size + 1;
|
|
return 0;
|
|
}
|
|
buf->data = new;
|
|
buf->padding[new_subbuf] = 0;
|
|
|
|
if (unlikely(length + buf->offset > buf->chan->subbuf_size))
|
|
goto toobig;
|
|
|
|
return length;
|
|
|
|
toobig:
|
|
buf->chan->last_toobig = length;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(relay_switch_subbuf);
|
|
|
|
/**
|
|
* relay_subbufs_consumed - update the buffer's sub-buffers-consumed count
|
|
* @chan: the channel
|
|
* @cpu: the cpu associated with the channel buffer to update
|
|
* @subbufs_consumed: number of sub-buffers to add to current buf's count
|
|
*
|
|
* Adds to the channel buffer's consumed sub-buffer count.
|
|
* subbufs_consumed should be the number of sub-buffers newly consumed,
|
|
* not the total consumed.
|
|
*
|
|
* NOTE: Kernel clients don't need to call this function if the channel
|
|
* mode is 'overwrite'.
|
|
*/
|
|
void relay_subbufs_consumed(struct rchan *chan,
|
|
unsigned int cpu,
|
|
size_t subbufs_consumed)
|
|
{
|
|
struct rchan_buf *buf;
|
|
|
|
if (!chan)
|
|
return;
|
|
|
|
if (cpu >= NR_CPUS || !chan->buf[cpu])
|
|
return;
|
|
|
|
buf = chan->buf[cpu];
|
|
buf->subbufs_consumed += subbufs_consumed;
|
|
if (buf->subbufs_consumed > buf->subbufs_produced)
|
|
buf->subbufs_consumed = buf->subbufs_produced;
|
|
}
|
|
EXPORT_SYMBOL_GPL(relay_subbufs_consumed);
|
|
|
|
/**
|
|
* relay_close - close the channel
|
|
* @chan: the channel
|
|
*
|
|
* Closes all channel buffers and frees the channel.
|
|
*/
|
|
void relay_close(struct rchan *chan)
|
|
{
|
|
unsigned int i;
|
|
struct rchan_buf *prev = NULL;
|
|
|
|
if (!chan)
|
|
return;
|
|
|
|
for (i = 0; i < NR_CPUS; i++) {
|
|
if (!chan->buf[i] || chan->buf[i] == prev)
|
|
break;
|
|
relay_close_buf(chan->buf[i]);
|
|
prev = chan->buf[i];
|
|
}
|
|
|
|
if (chan->last_toobig)
|
|
printk(KERN_WARNING "relay: one or more items not logged "
|
|
"[item size (%Zd) > sub-buffer size (%Zd)]\n",
|
|
chan->last_toobig, chan->subbuf_size);
|
|
|
|
kref_put(&chan->kref, relay_destroy_channel);
|
|
}
|
|
EXPORT_SYMBOL_GPL(relay_close);
|
|
|
|
/**
|
|
* relay_flush - close the channel
|
|
* @chan: the channel
|
|
*
|
|
* Flushes all channel buffers, i.e. forces buffer switch.
|
|
*/
|
|
void relay_flush(struct rchan *chan)
|
|
{
|
|
unsigned int i;
|
|
struct rchan_buf *prev = NULL;
|
|
|
|
if (!chan)
|
|
return;
|
|
|
|
for (i = 0; i < NR_CPUS; i++) {
|
|
if (!chan->buf[i] || chan->buf[i] == prev)
|
|
break;
|
|
relay_switch_subbuf(chan->buf[i], 0);
|
|
prev = chan->buf[i];
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(relay_flush);
|
|
|
|
/**
|
|
* relay_file_open - open file op for relay files
|
|
* @inode: the inode
|
|
* @filp: the file
|
|
*
|
|
* Increments the channel buffer refcount.
|
|
*/
|
|
static int relay_file_open(struct inode *inode, struct file *filp)
|
|
{
|
|
struct rchan_buf *buf = inode->i_private;
|
|
kref_get(&buf->kref);
|
|
filp->private_data = buf;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* relay_file_mmap - mmap file op for relay files
|
|
* @filp: the file
|
|
* @vma: the vma describing what to map
|
|
*
|
|
* Calls upon relay_mmap_buf to map the file into user space.
|
|
*/
|
|
static int relay_file_mmap(struct file *filp, struct vm_area_struct *vma)
|
|
{
|
|
struct rchan_buf *buf = filp->private_data;
|
|
return relay_mmap_buf(buf, vma);
|
|
}
|
|
|
|
/**
|
|
* relay_file_poll - poll file op for relay files
|
|
* @filp: the file
|
|
* @wait: poll table
|
|
*
|
|
* Poll implemention.
|
|
*/
|
|
static unsigned int relay_file_poll(struct file *filp, poll_table *wait)
|
|
{
|
|
unsigned int mask = 0;
|
|
struct rchan_buf *buf = filp->private_data;
|
|
|
|
if (buf->finalized)
|
|
return POLLERR;
|
|
|
|
if (filp->f_mode & FMODE_READ) {
|
|
poll_wait(filp, &buf->read_wait, wait);
|
|
if (!relay_buf_empty(buf))
|
|
mask |= POLLIN | POLLRDNORM;
|
|
}
|
|
|
|
return mask;
|
|
}
|
|
|
|
/**
|
|
* relay_file_release - release file op for relay files
|
|
* @inode: the inode
|
|
* @filp: the file
|
|
*
|
|
* Decrements the channel refcount, as the filesystem is
|
|
* no longer using it.
|
|
*/
|
|
static int relay_file_release(struct inode *inode, struct file *filp)
|
|
{
|
|
struct rchan_buf *buf = filp->private_data;
|
|
kref_put(&buf->kref, relay_remove_buf);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* relay_file_read_consume - update the consumed count for the buffer
|
|
*/
|
|
static void relay_file_read_consume(struct rchan_buf *buf,
|
|
size_t read_pos,
|
|
size_t bytes_consumed)
|
|
{
|
|
size_t subbuf_size = buf->chan->subbuf_size;
|
|
size_t n_subbufs = buf->chan->n_subbufs;
|
|
size_t read_subbuf;
|
|
|
|
if (buf->bytes_consumed + bytes_consumed > subbuf_size) {
|
|
relay_subbufs_consumed(buf->chan, buf->cpu, 1);
|
|
buf->bytes_consumed = 0;
|
|
}
|
|
|
|
buf->bytes_consumed += bytes_consumed;
|
|
read_subbuf = read_pos / buf->chan->subbuf_size;
|
|
if (buf->bytes_consumed + buf->padding[read_subbuf] == subbuf_size) {
|
|
if ((read_subbuf == buf->subbufs_produced % n_subbufs) &&
|
|
(buf->offset == subbuf_size))
|
|
return;
|
|
relay_subbufs_consumed(buf->chan, buf->cpu, 1);
|
|
buf->bytes_consumed = 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* relay_file_read_avail - boolean, are there unconsumed bytes available?
|
|
*/
|
|
static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos)
|
|
{
|
|
size_t subbuf_size = buf->chan->subbuf_size;
|
|
size_t n_subbufs = buf->chan->n_subbufs;
|
|
size_t produced = buf->subbufs_produced;
|
|
size_t consumed = buf->subbufs_consumed;
|
|
|
|
relay_file_read_consume(buf, read_pos, 0);
|
|
|
|
if (unlikely(buf->offset > subbuf_size)) {
|
|
if (produced == consumed)
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
if (unlikely(produced - consumed >= n_subbufs)) {
|
|
consumed = (produced / n_subbufs) * n_subbufs;
|
|
buf->subbufs_consumed = consumed;
|
|
}
|
|
|
|
produced = (produced % n_subbufs) * subbuf_size + buf->offset;
|
|
consumed = (consumed % n_subbufs) * subbuf_size + buf->bytes_consumed;
|
|
|
|
if (consumed > produced)
|
|
produced += n_subbufs * subbuf_size;
|
|
|
|
if (consumed == produced)
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/**
|
|
* relay_file_read_subbuf_avail - return bytes available in sub-buffer
|
|
* @read_pos: file read position
|
|
* @buf: relay channel buffer
|
|
*/
|
|
static size_t relay_file_read_subbuf_avail(size_t read_pos,
|
|
struct rchan_buf *buf)
|
|
{
|
|
size_t padding, avail = 0;
|
|
size_t read_subbuf, read_offset, write_subbuf, write_offset;
|
|
size_t subbuf_size = buf->chan->subbuf_size;
|
|
|
|
write_subbuf = (buf->data - buf->start) / subbuf_size;
|
|
write_offset = buf->offset > subbuf_size ? subbuf_size : buf->offset;
|
|
read_subbuf = read_pos / subbuf_size;
|
|
read_offset = read_pos % subbuf_size;
|
|
padding = buf->padding[read_subbuf];
|
|
|
|
if (read_subbuf == write_subbuf) {
|
|
if (read_offset + padding < write_offset)
|
|
avail = write_offset - (read_offset + padding);
|
|
} else
|
|
avail = (subbuf_size - padding) - read_offset;
|
|
|
|
return avail;
|
|
}
|
|
|
|
/**
|
|
* relay_file_read_start_pos - find the first available byte to read
|
|
* @read_pos: file read position
|
|
* @buf: relay channel buffer
|
|
*
|
|
* If the read_pos is in the middle of padding, return the
|
|
* position of the first actually available byte, otherwise
|
|
* return the original value.
|
|
*/
|
|
static size_t relay_file_read_start_pos(size_t read_pos,
|
|
struct rchan_buf *buf)
|
|
{
|
|
size_t read_subbuf, padding, padding_start, padding_end;
|
|
size_t subbuf_size = buf->chan->subbuf_size;
|
|
size_t n_subbufs = buf->chan->n_subbufs;
|
|
|
|
read_subbuf = read_pos / subbuf_size;
|
|
padding = buf->padding[read_subbuf];
|
|
padding_start = (read_subbuf + 1) * subbuf_size - padding;
|
|
padding_end = (read_subbuf + 1) * subbuf_size;
|
|
if (read_pos >= padding_start && read_pos < padding_end) {
|
|
read_subbuf = (read_subbuf + 1) % n_subbufs;
|
|
read_pos = read_subbuf * subbuf_size;
|
|
}
|
|
|
|
return read_pos;
|
|
}
|
|
|
|
/**
|
|
* relay_file_read_end_pos - return the new read position
|
|
* @read_pos: file read position
|
|
* @buf: relay channel buffer
|
|
* @count: number of bytes to be read
|
|
*/
|
|
static size_t relay_file_read_end_pos(struct rchan_buf *buf,
|
|
size_t read_pos,
|
|
size_t count)
|
|
{
|
|
size_t read_subbuf, padding, end_pos;
|
|
size_t subbuf_size = buf->chan->subbuf_size;
|
|
size_t n_subbufs = buf->chan->n_subbufs;
|
|
|
|
read_subbuf = read_pos / subbuf_size;
|
|
padding = buf->padding[read_subbuf];
|
|
if (read_pos % subbuf_size + count + padding == subbuf_size)
|
|
end_pos = (read_subbuf + 1) * subbuf_size;
|
|
else
|
|
end_pos = read_pos + count;
|
|
if (end_pos >= subbuf_size * n_subbufs)
|
|
end_pos = 0;
|
|
|
|
return end_pos;
|
|
}
|
|
|
|
/*
|
|
* subbuf_read_actor - read up to one subbuf's worth of data
|
|
*/
|
|
static int subbuf_read_actor(size_t read_start,
|
|
struct rchan_buf *buf,
|
|
size_t avail,
|
|
read_descriptor_t *desc,
|
|
read_actor_t actor)
|
|
{
|
|
void *from;
|
|
int ret = 0;
|
|
|
|
from = buf->start + read_start;
|
|
ret = avail;
|
|
if (copy_to_user(desc->arg.buf, from, avail)) {
|
|
desc->error = -EFAULT;
|
|
ret = 0;
|
|
}
|
|
desc->arg.data += ret;
|
|
desc->written += ret;
|
|
desc->count -= ret;
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* subbuf_send_actor - send up to one subbuf's worth of data
|
|
*/
|
|
static int subbuf_send_actor(size_t read_start,
|
|
struct rchan_buf *buf,
|
|
size_t avail,
|
|
read_descriptor_t *desc,
|
|
read_actor_t actor)
|
|
{
|
|
unsigned long pidx, poff;
|
|
unsigned int subbuf_pages;
|
|
int ret = 0;
|
|
|
|
subbuf_pages = buf->chan->alloc_size >> PAGE_SHIFT;
|
|
pidx = (read_start / PAGE_SIZE) % subbuf_pages;
|
|
poff = read_start & ~PAGE_MASK;
|
|
while (avail) {
|
|
struct page *p = buf->page_array[pidx];
|
|
unsigned int len;
|
|
|
|
len = PAGE_SIZE - poff;
|
|
if (len > avail)
|
|
len = avail;
|
|
|
|
len = actor(desc, p, poff, len);
|
|
if (desc->error)
|
|
break;
|
|
|
|
avail -= len;
|
|
ret += len;
|
|
poff = 0;
|
|
pidx = (pidx + 1) % subbuf_pages;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
typedef int (*subbuf_actor_t) (size_t read_start,
|
|
struct rchan_buf *buf,
|
|
size_t avail,
|
|
read_descriptor_t *desc,
|
|
read_actor_t actor);
|
|
|
|
/*
|
|
* relay_file_read_subbufs - read count bytes, bridging subbuf boundaries
|
|
*/
|
|
static inline ssize_t relay_file_read_subbufs(struct file *filp,
|
|
loff_t *ppos,
|
|
subbuf_actor_t subbuf_actor,
|
|
read_actor_t actor,
|
|
read_descriptor_t *desc)
|
|
{
|
|
struct rchan_buf *buf = filp->private_data;
|
|
size_t read_start, avail;
|
|
int ret;
|
|
|
|
if (!desc->count)
|
|
return 0;
|
|
|
|
mutex_lock(&filp->f_path.dentry->d_inode->i_mutex);
|
|
do {
|
|
if (!relay_file_read_avail(buf, *ppos))
|
|
break;
|
|
|
|
read_start = relay_file_read_start_pos(*ppos, buf);
|
|
avail = relay_file_read_subbuf_avail(read_start, buf);
|
|
if (!avail)
|
|
break;
|
|
|
|
avail = min(desc->count, avail);
|
|
ret = subbuf_actor(read_start, buf, avail, desc, actor);
|
|
if (desc->error < 0)
|
|
break;
|
|
|
|
if (ret) {
|
|
relay_file_read_consume(buf, read_start, ret);
|
|
*ppos = relay_file_read_end_pos(buf, read_start, ret);
|
|
}
|
|
} while (desc->count && ret);
|
|
mutex_unlock(&filp->f_path.dentry->d_inode->i_mutex);
|
|
|
|
return desc->written;
|
|
}
|
|
|
|
static ssize_t relay_file_read(struct file *filp,
|
|
char __user *buffer,
|
|
size_t count,
|
|
loff_t *ppos)
|
|
{
|
|
read_descriptor_t desc;
|
|
desc.written = 0;
|
|
desc.count = count;
|
|
desc.arg.buf = buffer;
|
|
desc.error = 0;
|
|
return relay_file_read_subbufs(filp, ppos, subbuf_read_actor,
|
|
NULL, &desc);
|
|
}
|
|
|
|
static ssize_t relay_file_sendfile(struct file *filp,
|
|
loff_t *ppos,
|
|
size_t count,
|
|
read_actor_t actor,
|
|
void *target)
|
|
{
|
|
read_descriptor_t desc;
|
|
desc.written = 0;
|
|
desc.count = count;
|
|
desc.arg.data = target;
|
|
desc.error = 0;
|
|
return relay_file_read_subbufs(filp, ppos, subbuf_send_actor,
|
|
actor, &desc);
|
|
}
|
|
|
|
const struct file_operations relay_file_operations = {
|
|
.open = relay_file_open,
|
|
.poll = relay_file_poll,
|
|
.mmap = relay_file_mmap,
|
|
.read = relay_file_read,
|
|
.llseek = no_llseek,
|
|
.release = relay_file_release,
|
|
.sendfile = relay_file_sendfile,
|
|
};
|
|
EXPORT_SYMBOL_GPL(relay_file_operations);
|