[RFC PATCH 13/21] Make relay buffers variable-length.

From: Tom Zanussi
Date: Thu Oct 16 2008 - 02:16:41 EST

Make everything use variable-length relay buffers and remove
everything that this change makes obsolete, including mmap.
---
include/linux/relay.h | 69 +++-------
kernel/relay.c | 385 +++++++++++++------------------------------------
2 files changed, 121 insertions(+), 333 deletions(-)

diff --git a/include/linux/relay.h b/include/linux/relay.h
index 35912d6..91e253f 100644
--- a/include/linux/relay.h
+++ b/include/linux/relay.h
@@ -27,8 +27,7 @@
/*
* relay channel flags
*/
-#define RCHAN_MODE_OVERWRITE 0x00000001 /* 'flight' mode */
-#define RCHAN_GLOBAL_BUFFER 0x00000002 /* not using per-cpu */
+#define RCHAN_GLOBAL_BUFFER 0x00000001 /* not using per-cpu */

struct relay_page
{
@@ -44,16 +43,15 @@ struct rchan_buf
void *data; /* address of current page */
struct relay_page *page; /* current write page */
size_t offset; /* current offset into page */
- size_t consumed_offset; /* bytes consumed in cur page */
- size_t produced; /* count of pages produced */
- size_t consumed; /* count of pages consumed */
struct rchan *chan; /* associated channel */
wait_queue_head_t read_wait; /* reader wait queue */
struct timer_list timer; /* reader wake-up timer */
struct dentry *dentry; /* channel file dentry */
struct kref kref; /* channel buffer refcount */
struct list_head pages; /* current set of unconsumed pages */
- unsigned int page_count; /* number of current buffer pages */
+ size_t consumed_offset; /* bytes consumed in cur page */
+ size_t nr_pages; /* number of unconsumed pages */
+ struct list_head pool; /* current set of unused pages */
unsigned int finalized; /* buffer has been finalized */
size_t early_bytes; /* bytes consumed before VFS inited */
unsigned int cpu; /* this buf's cpu */
@@ -67,7 +65,6 @@ struct rchan
u32 version; /* the version of this struct */
size_t n_pages; /* number of pages per buffer */
size_t n_pages_wakeup; /* wake up readers after filling n */
- size_t alloc_size; /* total buffer size allocated */
struct rchan_callbacks *cb; /* client callbacks */
struct kref kref; /* channel refcount */
void *private_data; /* for user-defined data */
@@ -107,25 +104,6 @@ struct rchan_callbacks
void *page_data);

/*
- * buf_mapped - relay buffer mmap notification
- * @buf: the channel buffer
- * @filp: relay file pointer
- *
- * Called when a relay file is successfully mmapped
- */
- void (*buf_mapped)(struct rchan_buf *buf,
- struct file *filp);
-
- /*
- * buf_unmapped - relay buffer unmap notification
- * @buf: the channel buffer
- * @filp: relay file pointer
- *
- * Called when a relay file is successfully unmapped
- */
- void (*buf_unmapped)(struct rchan_buf *buf,
- struct file *filp);
- /*
* create_buf_file - create file to represent a relay channel buffer
* @filename: the name of the file to create
* @parent: the parent of the file to create
@@ -184,23 +162,21 @@ struct rchan_callbacks
* CONFIG_RELAY kernel API, kernel/relay.c
*/

-struct rchan *relay_open(const char *base_filename,
- struct dentry *parent,
- size_t n_pages,
- size_t n_pages_wakeup,
- struct rchan_callbacks *cb,
- void *private_data,
- unsigned long rchan_flags);
-extern int relay_late_setup_files(struct rchan *chan,
- const char *base_filename,
- struct dentry *parent);
+extern struct rchan *relay_open(const char *base_filename,
+ struct dentry *parent,
+ size_t n_pages,
+ size_t n_pages_wakeup,
+ struct rchan_callbacks *cb,
+ void *private_data,
+ unsigned long rchan_flags);
extern void relay_close(struct rchan *chan);
extern void relay_flush(struct rchan *chan);
-extern void relay_pages_consumed(struct rchan *chan,
- unsigned int cpu,
- size_t consumed);
extern void relay_reset(struct rchan *chan);
-extern int relay_buf_full(struct rchan_buf *buf);
+extern void relay_add_page(struct rchan_buf *buf, struct page *page);
+
+extern int relay_late_setup_files(struct rchan *chan,
+ const char *base_filename,
+ struct dentry *parent);

extern size_t relay_switch_page_default_callback(struct rchan_buf *buf,
size_t length,
@@ -221,7 +197,7 @@ static inline void relay_wakeup_readers(struct rchan_buf *buf)
{
size_t wakeup = buf->chan->n_pages_wakeup;

- if (wakeup && (buf->produced % wakeup == 0) &&
+ if (wakeup && (buf->nr_pages % wakeup == 0) &&
(waitqueue_active(&buf->read_wait)))
/*
* Calling wake_up_interruptible() from here
@@ -264,17 +240,6 @@ static inline void relay_update_filesize(struct rchan_buf *buf, size_t length)
}

/**
- * relay_inc_produced - increase number of pages produced by 1
- * @buf: relay channel buffer
- *
- * switch_page() helper function.
- */
-static inline void relay_inc_produced(struct rchan_buf *buf)
-{
- buf->produced++;
-}
-
-/**
* relay_write - write data into the channel
* @chan: relay channel
* @data: data to be written
diff --git a/kernel/relay.c b/kernel/relay.c
index 198301d..574b995 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -27,96 +27,83 @@
static DEFINE_MUTEX(relay_channels_mutex);
static LIST_HEAD(relay_channels);

-/*
- * close() vm_op implementation for relay file mapping.
+/**
+ * __relay_get_rpage - get an empty relay page struct
+ * @buf: the buffer struct
*/
-static void relay_file_mmap_close(struct vm_area_struct *vma)
+struct relay_page *__relay_get_rpage(struct rchan_buf *buf)
{
- struct rchan_buf *buf = vma->vm_private_data;
- buf->chan->cb->buf_unmapped(buf, vma->vm_file);
+ return kmalloc(sizeof(struct relay_page), GFP_ATOMIC);
}

-/* yeah, stupid, but temporary */
-static struct relay_page *find_buf_page_n(struct rchan_buf *buf, int n)
+/**
+ * __relay_remove_page - remove a page from relay and add to free pool
+ * @buf: the buffer struct
+ * @rpage: struct relay_page
+ */
+static void __relay_remove_page(struct rchan_buf *buf,
+ struct relay_page *rpage)
{
- struct list_head *page = buf->pages.next;
- struct relay_page *rpage;
-
- while(n--)
- page = page->next;
-
- rpage = list_entry(page, struct relay_page, list);
-
- return rpage;
+ list_del(&rpage->list);
+ buf->nr_pages--;
+ list_add_tail(&rpage->list, &buf->pool);
}

-/*
- * fault() vm_op implementation for relay file mapping.
+/**
+ * __relay_add_page - add a relay page to relay
+ * @buf: the buffer struct
+ * @rpage: struct relay_page
*/
-static int relay_buf_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+static void __relay_add_page(struct rchan_buf *buf, struct relay_page *rpage)
{
- struct page *page;
- struct relay_page *rpage;
- struct rchan_buf *buf = vma->vm_private_data;
- pgoff_t pgoff = vmf->pgoff;
-
- if (!buf)
- return VM_FAULT_OOM;
-
- rpage = find_buf_page_n(buf, pgoff);
- page = rpage->page;
-
- if (!page)
- return VM_FAULT_SIGBUS;
- get_page(page);
- vmf->page = page;
-
- return 0;
+ list_add_tail(&rpage->list, &buf->pages);
+ buf->nr_pages++;
+ relay_update_filesize(buf, PAGE_SIZE);
}

-/*
- * vm_ops for relay file mappings.
- */
-static struct vm_operations_struct relay_file_mmap_ops = {
- .fault = relay_buf_fault,
- .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
+ * relay_add_page - add a page to relay
+ * @buf: the buffer struct
+ * @page: struct page
*
- * Caller should already have grabbed mmap_sem.
+ * relay now owns the page.
*/
-static int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma)
+void relay_add_page(struct rchan_buf *buf, struct page *page)
{
- unsigned long length = vma->vm_end - vma->vm_start;
- struct file *filp = vma->vm_file;
+ struct relay_page *rpage = __relay_get_rpage(buf);

- if (!buf)
- return -EBADF;
+ if (likely(rpage)) {
+ rpage->page = page;
+ __relay_add_page(buf, rpage);
+ }
+}
+EXPORT_SYMBOL_GPL(relay_add_page);

- if (length != (unsigned long)buf->chan->alloc_size)
- return -EINVAL;
+/**
+ * relay_get_page - get a free relay page from the pool
+ * @buf: the buffer struct
+ *
+ * Returns relay page if successful, NULL if not.
+ */
+static struct relay_page *relay_get_free_page(struct rchan_buf *buf)
+{
+ struct relay_page *rpage = NULL;

- vma->vm_ops = &relay_file_mmap_ops;
- vma->vm_flags |= VM_DONTEXPAND;
- vma->vm_private_data = buf;
- buf->chan->cb->buf_mapped(buf, filp);
+ if (!list_empty(&buf->pool)) {
+ rpage = list_first_entry(&buf->pool, struct relay_page, list);
+ list_del(&rpage->list);
+ }

- return 0;
+ return rpage;
}

/**
- * relay_alloc_buf - allocate a channel buffer
+ * relay_alloc_pool - allocate a pool of pages for writers
* @buf: the buffer struct
*
* Returns 0 if successful.
*/
-static int relay_alloc_buf(struct rchan_buf *buf)
+static int relay_alloc_pool(struct rchan_buf *buf)
{
unsigned int i;
struct relay_page *rpage = NULL;
@@ -129,14 +116,13 @@ static int relay_alloc_buf(struct rchan_buf *buf)
if (unlikely(!rpage->page))
goto depopulate;
set_page_private(rpage->page, (unsigned long)buf);
- list_add_tail(&rpage->list, &buf->pages);
+ list_add_tail(&rpage->list, &buf->pool);
}

- buf->page_count = buf->chan->n_pages;
return 0;

depopulate:
- list_for_each_entry(rpage, &buf->pages, list) {
+ list_for_each_entry(rpage, &buf->pool, list) {
__free_page(rpage->page);
list_del(&rpage->list);
}
@@ -156,11 +142,12 @@ static struct rchan_buf *relay_create_buf(struct rchan *chan)
if (!buf)
return NULL;

+ INIT_LIST_HEAD(&buf->pool);
INIT_LIST_HEAD(&buf->pages);
buf->chan = chan;
kref_get(&buf->chan->kref);

- if (relay_alloc_buf(buf))
+ if (relay_alloc_pool(buf))
goto free_buf;

return buf;
@@ -191,7 +178,7 @@ static void relay_destroy_buf(struct rchan_buf *buf)
struct rchan *chan = buf->chan;
struct relay_page *rpage, *rpage2;

- list_for_each_entry_safe(rpage, rpage2, &buf->pages, list) {
+ list_for_each_entry_safe(rpage, rpage2, &buf->pool, list) {
__free_page(rpage->page);
list_del(&rpage->list);
kfree(rpage);
@@ -225,22 +212,9 @@ static void relay_remove_buf(struct kref *kref)
*/
static int relay_buf_empty(struct rchan_buf *buf)
{
- return (buf->produced - buf->consumed) ? 0 : 1;
+ return !buf->nr_pages;
}

-/**
- * relay_buf_full - boolean, is the channel buffer full?
- * @buf: channel buffer
- *
- * Returns 1 if the buffer is full, 0 otherwise.
- */
-int relay_buf_full(struct rchan_buf *buf)
-{
- size_t ready = buf->produced - buf->consumed;
- return (ready >= buf->chan->n_pages) ? 1 : 0;
-}
-EXPORT_SYMBOL_GPL(relay_buf_full);
-
/*
* High-level relay kernel API and associated functions.
*/
@@ -251,22 +225,6 @@ EXPORT_SYMBOL_GPL(relay_buf_full);
*/

/*
- * buf_mapped() default callback. Does nothing.
- */
-static void buf_mapped_default_callback(struct rchan_buf *buf,
- struct file *filp)
-{
-}
-
-/*
- * buf_unmapped() default callback. Does nothing.
- */
-static void buf_unmapped_default_callback(struct rchan_buf *buf,
- struct file *filp)
-{
-}
-
-/*
* create_buf_file_create() default callback. Does nothing.
*/
static struct dentry *create_buf_file_default_callback(const char *filename,
@@ -297,8 +255,6 @@ static void new_page_default_callback(struct rchan_buf *buf,
/* relay channel default callbacks */
static struct rchan_callbacks default_channel_callbacks = {
.new_page = new_page_default_callback,
- .buf_mapped = buf_mapped_default_callback,
- .buf_unmapped = buf_unmapped_default_callback,
.create_buf_file = create_buf_file_default_callback,
.remove_buf_file = remove_buf_file_default_callback,
.switch_page = relay_switch_page_default_callback,
@@ -332,11 +288,9 @@ static void __relay_reset(struct rchan_buf *buf, unsigned int init)
} else
del_timer_sync(&buf->timer);

- buf->produced = 0;
- buf->consumed = 0;
buf->consumed_offset = 0;
buf->finalized = 0;
- buf->page = list_first_entry(&buf->pages, struct relay_page, list);
+ buf->page = relay_get_free_page(buf);
buf->data = page_address(buf->page->page);
buf->offset = 0;

@@ -464,10 +418,6 @@ static void setup_callbacks(struct rchan *chan,
return;
}

- if (!cb->buf_mapped)
- cb->buf_mapped = buf_mapped_default_callback;
- if (!cb->buf_unmapped)
- cb->buf_unmapped = buf_unmapped_default_callback;
if (!cb->create_buf_file)
cb->create_buf_file = create_buf_file_default_callback;
if (!cb->remove_buf_file)
@@ -558,7 +508,6 @@ struct rchan *relay_open(const char *base_filename,
chan->version = RELAYFS_CHANNEL_VERSION;
chan->n_pages = n_pages;
chan->n_pages_wakeup = n_pages_wakeup;
- chan->alloc_size = PAGE_SIZE * n_pages;
chan->parent = parent;
chan->flags = rchan_flags;
atomic_set(&chan->dropped, 0);
@@ -683,18 +632,6 @@ int relay_late_setup_files(struct rchan *chan,
return err;
}

-static inline int next_page_free(struct rchan_buf *buf)
-{
- size_t full_pages;
-
- if (buf->chan->flags & RCHAN_MODE_OVERWRITE)
- return 1;
-
- full_pages = buf->produced - buf->consumed;
-
- return (full_pages < buf->chan->n_pages - 1);
-}
-
/**
* relay_switch_page_default_callback - switch to a new page
* @buf: channel buffer
@@ -711,13 +648,14 @@ size_t relay_switch_page_default_callback(struct rchan_buf *buf,
void **reserved)
{
size_t remainder;
- struct list_head *next_page;
+ struct relay_page *new_page;

if (unlikely(relay_event_toobig(buf, length)))
goto toobig;

/* don't write anything unless we can write it all. */
- if (!next_page_free(buf)) {
+ new_page = relay_get_free_page(buf);
+ if (!new_page) {
if (reserved)
*reserved = NULL;
atomic_inc(&buf->chan->dropped);
@@ -725,13 +663,10 @@ size_t relay_switch_page_default_callback(struct rchan_buf *buf,
}

remainder = length - (PAGE_SIZE - buf->offset);
- relay_inc_produced(buf);
- relay_update_filesize(buf, PAGE_SIZE + remainder);

- next_page = buf->page->list.next;
- if (next_page == &buf->pages)
- next_page = buf->pages.next;
- buf->page = list_entry(next_page, struct relay_page, list);
+ __relay_add_page(buf, buf->page);
+
+ buf->page = new_page;
buf->data = page_address(buf->page->page);

buf->offset = 0; /* remainder will be added by caller */
@@ -751,38 +686,6 @@ toobig:
EXPORT_SYMBOL_GPL(relay_switch_page_default_callback);

/**
- * relay_pages_consumed - update the buffer's pages-consumed count
- * @chan: the channel
- * @cpu: the cpu associated with the channel buffer to update
- * @consumed: number of pages to add to current buf's count
- *
- * Adds to the channel buffer's consumed page count.
- * consumed should be the number of pages newly consumed,
- * not the total consumed.
- *
- * NOTE. Kernel clients don't need to call this function if the channel
- * mode is 'overwrite'.
- */
-void relay_pages_consumed(struct rchan *chan,
- unsigned int cpu,
- size_t consumed)
-{
- struct rchan_buf *buf;
-
- if (!chan)
- return;
-
- if (cpu >= NR_CPUS || !chan->buf[cpu])
- return;
-
- buf = chan->buf[cpu];
- buf->consumed += consumed;
- if (buf->consumed > buf->produced)
- buf->consumed = buf->produced;
-}
-EXPORT_SYMBOL_GPL(relay_pages_consumed);
-
-/**
* relay_close - close the channel
* @chan: the channel
*
@@ -863,19 +766,6 @@ static int relay_file_open(struct inode *inode, struct file *filp)
}

/**
- * 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
@@ -915,91 +805,40 @@ static int relay_file_release(struct inode *inode, struct file *filp)
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)
-{
- buf->consumed_offset += bytes_consumed;
-
- if (buf->consumed_offset == PAGE_SIZE) {
- relay_pages_consumed(buf->chan, buf->cpu, 1);
- buf->consumed_offset = 0;
- }
-}
-
/**
- * relay_file_read_page_avail - return bytes available in page
- * @read_pos: file read position
+ * relay_file_read_page_avail - return bytes available in next page
* @buf: relay channel buffer
*/
-static size_t relay_file_read_page_avail(size_t read_pos,
- struct rchan_buf *buf)
+static size_t relay_file_read_page_avail(struct rchan_buf *buf)
{
- size_t avail;
- struct relay_page *read_page, *write_page;
- size_t read_offset, write_offset;
+ size_t avail = 0;

- write_page = buf->page;
- write_offset = buf->offset;
- read_page = find_buf_page_n(buf, read_pos / PAGE_SIZE);
- read_offset = read_pos % PAGE_SIZE;
-
- if (read_page == write_page && read_offset == write_offset)
- return 0;
-
- avail = PAGE_SIZE - read_offset;
-
- if (read_page == write_page && read_offset < write_offset)
- avail = write_offset - read_offset;
+ if (!list_empty(&buf->pages))
+ avail = PAGE_SIZE - buf->consumed_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 0, return the position of the first
- * unconsumed byte, otherwise return the original value.
- */
-static size_t relay_file_read_start_pos(size_t read_pos,
- struct rchan_buf *buf)
-{
- size_t consumed = buf->consumed % buf->chan->n_pages;
-
- if (!read_pos)
- read_pos = consumed * PAGE_SIZE + buf->consumed_offset;
-
- 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
+/*
+ * relay_consume - update the consumed count for the buffer
*/
-static size_t relay_file_read_end_pos(struct rchan_buf *buf,
- size_t read_pos,
- size_t count)
+static void relay_consume(struct rchan_buf *buf, int bytes_consumed)
{
- size_t end_pos = read_pos + count;
+ buf->consumed_offset += bytes_consumed;

- if (end_pos >= PAGE_SIZE * buf->chan->n_pages)
- end_pos = 0;
+ if (buf->consumed_offset == PAGE_SIZE) {
+ struct relay_page *rpage;
+ rpage = list_first_entry(&buf->pages, struct relay_page, list);
+ __relay_remove_page(buf, rpage);

- return end_pos;
+ buf->consumed_offset = 0;
+ }
}

/*
* page_read_actor - read up to one page's worth of data
*/
-static int page_read_actor(size_t read_start,
- struct rchan_buf *buf,
+static int page_read_actor(struct rchan_buf *buf,
size_t avail,
read_descriptor_t *desc,
read_actor_t actor)
@@ -1008,9 +847,10 @@ static int page_read_actor(size_t read_start,
int ret = 0;
struct relay_page *rpage;

- rpage = find_buf_page_n(buf, read_start / PAGE_SIZE);
+ rpage = list_first_entry(&buf->pages, struct relay_page, list);
+
from = page_address(rpage->page);
- from += read_start % PAGE_SIZE;
+ from += PAGE_SIZE - avail;
ret = avail;
if (copy_to_user(desc->arg.buf, from, avail)) {
desc->error = -EFAULT;
@@ -1023,8 +863,7 @@ static int page_read_actor(size_t read_start,
return ret;
}

-typedef int (*page_actor_t) (size_t read_start,
- struct rchan_buf *buf,
+typedef int (*page_actor_t) (struct rchan_buf *buf,
size_t avail,
read_descriptor_t *desc,
read_actor_t actor);
@@ -1038,7 +877,7 @@ static ssize_t relay_file_read_pages(struct file *filp, loff_t *ppos,
read_descriptor_t *desc)
{
struct rchan_buf *buf = filp->private_data;
- size_t read_start, avail;
+ size_t avail;
int ret;

if (!desc->count)
@@ -1046,17 +885,16 @@ static ssize_t relay_file_read_pages(struct file *filp, loff_t *ppos,

mutex_lock(&filp->f_path.dentry->d_inode->i_mutex);
do {
- read_start = relay_file_read_start_pos(*ppos, buf);
- avail = relay_file_read_page_avail(read_start, buf);
+ avail = relay_file_read_page_avail(buf);
if (!avail)
break;
avail = min(desc->count, avail);
- ret = page_actor(read_start, buf, avail, desc, actor);
+ ret = page_actor(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);
+ relay_consume(buf, ret);
+ *ppos += ret;
}
} while (desc->count && ret);
mutex_unlock(&filp->f_path.dentry->d_inode->i_mutex);
@@ -1078,23 +916,13 @@ static ssize_t relay_file_read(struct file *filp,
NULL, &desc);
}

-static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed)
-{
- rbuf->consumed_offset += bytes_consumed;
-
- if (rbuf->consumed_offset >= PAGE_SIZE) {
- relay_pages_consumed(rbuf->chan, rbuf->cpu, 1);
- rbuf->consumed_offset %= PAGE_SIZE;
- }
-}
-
static void relay_pipe_buf_release(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
struct rchan_buf *rbuf;

rbuf = (struct rchan_buf *)page_private(buf->page);
- relay_consume_bytes(rbuf, buf->private);
+ relay_consume(rbuf, buf->private);
}

static struct pipe_buf_operations relay_pipe_buf_ops = {
@@ -1115,16 +943,13 @@ static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i)
* page_splice_actor - splice available data
*/
static int page_splice_actor(struct file *in,
- loff_t *ppos,
struct pipe_inode_info *pipe,
size_t len,
unsigned int flags)
{
- unsigned int pidx, poff, total_len, buf_pages, nr_pages, ret;
- struct rchan_buf *rbuf = in->private_data;
- uint64_t pos = (uint64_t) *ppos;
- uint32_t alloc_size = (uint32_t) rbuf->chan->alloc_size;
- size_t read_start = (size_t) do_div(pos, alloc_size);
+ unsigned int poff, total_len, nr_pages, ret;
+ struct rchan_buf *buf = in->private_data;
+ struct relay_page *rpage;
struct page *pages[PIPE_BUFFERS];
struct partial_page partial[PIPE_BUFFERS];
struct splice_pipe_desc spd = {
@@ -1136,34 +961,33 @@ static int page_splice_actor(struct file *in,
.spd_release = relay_page_release,
};

- if (rbuf->produced == rbuf->consumed &&
- rbuf->offset == rbuf->consumed_offset)
+ if (list_empty(&buf->pages))
return 0;

- buf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT;
- pidx = (read_start / PAGE_SIZE) % buf_pages;
- poff = read_start & ~PAGE_MASK;
- nr_pages = min_t(unsigned int, buf_pages, PIPE_BUFFERS);
+ poff = buf->consumed_offset;
+ nr_pages = min_t(unsigned int, buf->nr_pages, PIPE_BUFFERS);
+ total_len = 0;

- for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) {
+ list_for_each_entry(rpage, &buf->pages, list) {
unsigned int this_len;
- struct relay_page *rpage;
+
+ if (spd.nr_pages >= nr_pages)
+ break;

if (!len)
break;

this_len = min_t(unsigned long, len, PAGE_SIZE - poff);

- rpage = find_buf_page_n(rbuf, pidx);
spd.pages[spd.nr_pages] = rpage->page;
spd.partial[spd.nr_pages].offset = poff;
-
spd.partial[spd.nr_pages].len = this_len;
+ spd.partial[spd.nr_pages].private = this_len;

len -= this_len;
total_len += this_len;
poff = 0;
- pidx = (pidx + 1) % buf_pages;
+ spd.nr_pages++;
}

ret = splice_to_pipe(pipe, &spd);
@@ -1184,7 +1008,7 @@ static ssize_t relay_file_splice_read(struct file *in,
spliced = 0;

while (len && !spliced) {
- ret = page_splice_actor(in, ppos, pipe, len, flags);
+ ret = page_splice_actor(in, pipe, len, flags);
if (ret < 0)
break;
else if (!ret) {
@@ -1213,7 +1037,6 @@ static ssize_t relay_file_splice_read(struct file *in,
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,
--
1.5.3.5



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