summaryrefslogtreecommitdiff
path: root/fs/relayfs/buffers.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/relayfs/buffers.c')
-rw-r--r--fs/relayfs/buffers.c189
1 files changed, 189 insertions, 0 deletions
diff --git a/fs/relayfs/buffers.c b/fs/relayfs/buffers.c
new file mode 100644
index 000000000000..2aa8e2719999
--- /dev/null
+++ b/fs/relayfs/buffers.c
@@ -0,0 +1,189 @@
+/*
+ * RelayFS buffer management code.
+ *
+ * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
+ * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com)
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/relayfs_fs.h>
+#include "relay.h"
+#include "buffers.h"
+
+/*
+ * close() vm_op implementation for relayfs file mapping.
+ */
+static void relay_file_mmap_close(struct vm_area_struct *vma)
+{
+ struct rchan_buf *buf = vma->vm_private_data;
+ buf->chan->cb->buf_unmapped(buf, vma->vm_file);
+}
+
+/*
+ * nopage() vm_op implementation for relayfs file mapping.
+ */
+static struct page *relay_buf_nopage(struct vm_area_struct *vma,
+ unsigned long address,
+ int *type)
+{
+ struct page *page;
+ struct rchan_buf *buf = vma->vm_private_data;
+ unsigned long offset = address - vma->vm_start;
+
+ if (address > vma->vm_end)
+ return NOPAGE_SIGBUS; /* Disallow mremap */
+ if (!buf)
+ return NOPAGE_OOM;
+
+ page = vmalloc_to_page(buf->start + offset);
+ if (!page)
+ return NOPAGE_OOM;
+ get_page(page);
+
+ if (type)
+ *type = VM_FAULT_MINOR;
+
+ return page;
+}
+
+/*
+ * vm_ops for relay file mappings.
+ */
+static struct vm_operations_struct relay_file_mmap_ops = {
+ .nopage = relay_buf_nopage,
+ .close = relay_file_mmap_close,
+};
+
+/**
+ * relay_mmap_buf: - mmap channel buffer to process address space
+ * @buf: relay channel buffer
+ * @vma: vm_area_struct describing memory to be mapped
+ *
+ * Returns 0 if ok, negative on error
+ *
+ * Caller should already have grabbed mmap_sem.
+ */
+int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma)
+{
+ unsigned long length = vma->vm_end - vma->vm_start;
+ struct file *filp = vma->vm_file;
+
+ if (!buf)
+ return -EBADF;
+
+ if (length != (unsigned long)buf->chan->alloc_size)
+ return -EINVAL;
+
+ vma->vm_ops = &relay_file_mmap_ops;
+ vma->vm_private_data = buf;
+ buf->chan->cb->buf_mapped(buf, filp);
+
+ return 0;
+}
+
+/**
+ * relay_alloc_buf - allocate a channel buffer
+ * @buf: the buffer struct
+ * @size: total size of the buffer
+ *
+ * Returns a pointer to the resulting buffer, NULL if unsuccessful
+ */
+static void *relay_alloc_buf(struct rchan_buf *buf, unsigned long size)
+{
+ void *mem;
+ unsigned int i, j, n_pages;
+
+ size = PAGE_ALIGN(size);
+ n_pages = size >> PAGE_SHIFT;
+
+ buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
+ if (!buf->page_array)
+ return NULL;
+
+ for (i = 0; i < n_pages; i++) {
+ buf->page_array[i] = alloc_page(GFP_KERNEL);
+ if (unlikely(!buf->page_array[i]))
+ goto depopulate;
+ }
+ mem = vmap(buf->page_array, n_pages, GFP_KERNEL, PAGE_KERNEL);
+ if (!mem)
+ goto depopulate;
+
+ memset(mem, 0, size);
+ buf->page_count = n_pages;
+ return mem;
+
+depopulate:
+ for (j = 0; j < i; j++)
+ __free_page(buf->page_array[j]);
+ kfree(buf->page_array);
+ return NULL;
+}
+
+/**
+ * relay_create_buf - allocate and initialize a channel buffer
+ * @alloc_size: size of the buffer to allocate
+ * @n_subbufs: number of sub-buffers in the channel
+ *
+ * Returns channel buffer if successful, NULL otherwise
+ */
+struct rchan_buf *relay_create_buf(struct rchan *chan)
+{
+ struct rchan_buf *buf = kcalloc(1, sizeof(struct rchan_buf), GFP_KERNEL);
+ if (!buf)
+ return NULL;
+
+ buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL);
+ if (!buf->padding)
+ goto free_buf;
+
+ buf->start = relay_alloc_buf(buf, chan->alloc_size);
+ if (!buf->start)
+ goto free_buf;
+
+ buf->chan = chan;
+ kref_get(&buf->chan->kref);
+ return buf;
+
+free_buf:
+ kfree(buf->padding);
+ kfree(buf);
+ return NULL;
+}
+
+/**
+ * relay_destroy_buf - destroy an rchan_buf struct and associated buffer
+ * @buf: the buffer struct
+ */
+void relay_destroy_buf(struct rchan_buf *buf)
+{
+ struct rchan *chan = buf->chan;
+ unsigned int i;
+
+ if (likely(buf->start)) {
+ vunmap(buf->start);
+ for (i = 0; i < buf->page_count; i++)
+ __free_page(buf->page_array[i]);
+ kfree(buf->page_array);
+ }
+ kfree(buf->padding);
+ kfree(buf);
+ kref_put(&chan->kref, relay_destroy_channel);
+}
+
+/**
+ * relay_remove_buf - remove a channel buffer
+ *
+ * Removes the file from the relayfs fileystem, which also frees the
+ * rchan_buf_struct and the channel buffer. Should only be called from
+ * kref_put().
+ */
+void relay_remove_buf(struct kref *kref)
+{
+ struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref);
+ relayfs_remove(buf->dentry);
+}