* that transfers data buffers to or from a pipe buffer.
*
* Named by Larry McVoy, original implementation from Linus, extended by
- * Jens to support splicing to files and fixing the initial implementation
- * bugs.
+ * Jens to support splicing to files, network, direct splicing, etc and
+ * fixing lots of bugs.
*
- * Copyright (C) 2005 Jens Axboe <axboe@suse.de>
- * Copyright (C) 2005 Linus Torvalds <torvalds@osdl.org>
+ * Copyright (C) 2005-2006 Jens Axboe <axboe@suse.de>
+ * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org>
+ * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu>
*
*/
#include <linux/fs.h>
#include <linux/pipe_fs_i.h>
#include <linux/mm_inline.h>
#include <linux/swap.h>
+#include <linux/writeback.h>
+#include <linux/buffer_head.h>
#include <linux/module.h>
+#include <linux/syscalls.h>
/*
* Passed to the actors
loff_t pos; /* file position */
};
+/*
+ * Attempt to steal a page from a pipe buffer. This should perhaps go into
+ * a vm helper function, it's already simplified quite a bit by the
+ * addition of remove_mapping(). If success is returned, the caller may
+ * attempt to reuse this page for another destination.
+ */
static int page_cache_pipe_buf_steal(struct pipe_inode_info *info,
struct pipe_buffer *buf)
{
struct page *page = buf->page;
+ struct address_space *mapping = page_mapping(page);
+
+ lock_page(page);
- WARN_ON(!PageLocked(page));
WARN_ON(!PageUptodate(page));
- if (!remove_mapping(page_mapping(page), page))
- return 1;
+ /*
+ * At least for ext2 with nobh option, we need to wait on writeback
+ * completing on this page, since we'll remove it from the pagecache.
+ * Otherwise truncate wont wait on the page, allowing the disk
+ * blocks to be reused by someone else before we actually wrote our
+ * data to them. fs corruption ensues.
+ */
+ wait_on_page_writeback(page);
- if (PageLRU(page)) {
- struct zone *zone = page_zone(page);
+ if (PagePrivate(page))
+ try_to_release_page(page, mapping_gfp_mask(mapping));
- spin_lock_irq(&zone->lru_lock);
- BUG_ON(!PageLRU(page));
- __ClearPageLRU(page);
- del_page_from_lru(zone, page);
- spin_unlock_irq(&zone->lru_lock);
+ if (!remove_mapping(mapping, page)) {
+ unlock_page(page);
+ return 1;
}
- buf->stolen = 1;
+ buf->flags |= PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU;
return 0;
}
{
page_cache_release(buf->page);
buf->page = NULL;
- buf->stolen = 0;
+ buf->flags &= ~(PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU);
}
static void *page_cache_pipe_buf_map(struct file *file,
struct pipe_buffer *buf)
{
struct page *page = buf->page;
-
- lock_page(page);
+ int err;
if (!PageUptodate(page)) {
- unlock_page(page);
- return ERR_PTR(-EIO);
- }
+ lock_page(page);
- if (!page->mapping) {
+ /*
+ * Page got truncated/unhashed. This will cause a 0-byte
+ * splice, if this is the first page.
+ */
+ if (!page->mapping) {
+ err = -ENODATA;
+ goto error;
+ }
+
+ /*
+ * Uh oh, read-error from disk.
+ */
+ if (!PageUptodate(page)) {
+ err = -EIO;
+ goto error;
+ }
+
+ /*
+ * Page is ok afterall, fall through to mapping.
+ */
unlock_page(page);
- return ERR_PTR(-ENODATA);
}
- return kmap(buf->page);
+ return kmap(page);
+error:
+ unlock_page(page);
+ return ERR_PTR(err);
}
static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info,
struct pipe_buffer *buf)
{
- if (!buf->stolen)
- unlock_page(buf->page);
kunmap(buf->page);
}
+static void page_cache_pipe_buf_get(struct pipe_inode_info *info,
+ struct pipe_buffer *buf)
+{
+ page_cache_get(buf->page);
+}
+
static struct pipe_buf_operations page_cache_pipe_buf_ops = {
.can_merge = 0,
.map = page_cache_pipe_buf_map,
.unmap = page_cache_pipe_buf_unmap,
.release = page_cache_pipe_buf_release,
.steal = page_cache_pipe_buf_steal,
+ .get = page_cache_pipe_buf_get,
};
-static ssize_t move_to_pipe(struct inode *inode, struct page **pages,
- int nr_pages, unsigned long offset,
- unsigned long len, unsigned int flags)
+/*
+ * Pipe output worker. This sets up our pipe format with the page cache
+ * pipe buffer operations. Otherwise very similar to the regular pipe_writev().
+ */
+static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages,
+ int nr_pages, unsigned long len,
+ unsigned int offset, unsigned int flags)
{
- struct pipe_inode_info *info;
int ret, do_wakeup, i;
ret = 0;
do_wakeup = 0;
i = 0;
- mutex_lock(PIPE_MUTEX(*inode));
+ if (pipe->inode)
+ mutex_lock(&pipe->inode->i_mutex);
- info = inode->i_pipe;
for (;;) {
- int bufs;
-
- if (!PIPE_READERS(*inode)) {
+ if (!pipe->readers) {
send_sig(SIGPIPE, current, 0);
if (!ret)
ret = -EPIPE;
break;
}
- bufs = info->nrbufs;
- if (bufs < PIPE_BUFFERS) {
- int newbuf = (info->curbuf + bufs) & (PIPE_BUFFERS - 1);
- struct pipe_buffer *buf = info->bufs + newbuf;
+ if (pipe->nrbufs < PIPE_BUFFERS) {
+ int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1);
+ struct pipe_buffer *buf = pipe->bufs + newbuf;
struct page *page = pages[i++];
unsigned long this_len;
buf->offset = offset;
buf->len = this_len;
buf->ops = &page_cache_pipe_buf_ops;
- info->nrbufs = ++bufs;
- do_wakeup = 1;
+ pipe->nrbufs++;
+ if (pipe->inode)
+ do_wakeup = 1;
ret += this_len;
len -= this_len;
break;
if (!len)
break;
- if (bufs < PIPE_BUFFERS)
+ if (pipe->nrbufs < PIPE_BUFFERS)
continue;
break;
}
if (do_wakeup) {
- wake_up_interruptible_sync(PIPE_WAIT(*inode));
- kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO,
- POLL_IN);
+ smp_mb();
+ if (waitqueue_active(&pipe->wait))
+ wake_up_interruptible_sync(&pipe->wait);
+ kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
do_wakeup = 0;
}
- PIPE_WAITING_WRITERS(*inode)++;
- pipe_wait(inode);
- PIPE_WAITING_WRITERS(*inode)--;
+ pipe->waiting_writers++;
+ pipe_wait(pipe);
+ pipe->waiting_writers--;
}
- mutex_unlock(PIPE_MUTEX(*inode));
+ if (pipe->inode)
+ mutex_unlock(&pipe->inode->i_mutex);
if (do_wakeup) {
- wake_up_interruptible(PIPE_WAIT(*inode));
- kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
+ smp_mb();
+ if (waitqueue_active(&pipe->wait))
+ wake_up_interruptible(&pipe->wait);
+ kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
}
while (i < nr_pages)
return ret;
}
-static int __generic_file_splice_read(struct file *in, struct inode *pipe,
- size_t len, unsigned int flags)
+static int
+__generic_file_splice_read(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags)
{
struct address_space *mapping = in->f_mapping;
- unsigned int offset, nr_pages;
- struct page *pages[PIPE_BUFFERS], *shadow[PIPE_BUFFERS];
+ unsigned int loff, offset, nr_pages;
+ struct page *pages[PIPE_BUFFERS];
struct page *page;
- pgoff_t index, pidx;
- int i, j;
+ pgoff_t index, end_index;
+ loff_t isize;
+ size_t bytes;
+ int i, error;
- index = in->f_pos >> PAGE_CACHE_SHIFT;
- offset = in->f_pos & ~PAGE_CACHE_MASK;
+ index = *ppos >> PAGE_CACHE_SHIFT;
+ loff = offset = *ppos & ~PAGE_CACHE_MASK;
nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
if (nr_pages > PIPE_BUFFERS)
nr_pages = PIPE_BUFFERS;
/*
- * initiate read-ahead on this page range
+ * Initiate read-ahead on this page range. however, don't call into
+ * read-ahead if this is a non-zero offset (we are likely doing small
+ * chunk splice and the page is already there) for a single page.
*/
- do_page_cache_readahead(mapping, in, index, nr_pages);
+ if (!offset || nr_pages > 1)
+ do_page_cache_readahead(mapping, in, index, nr_pages);
/*
- * Get as many pages from the page cache as possible..
- * Start IO on the page cache entries we create (we
- * can assume that any pre-existing ones we find have
- * already had IO started on them).
+ * Now fill in the holes:
*/
- i = find_get_pages(mapping, index, nr_pages, pages);
+ error = 0;
+ bytes = 0;
+ for (i = 0; i < nr_pages; i++, index++) {
+ unsigned int this_len;
- /*
- * common case - we found all pages and they are contiguous,
- * kick them off
- */
- if (i && (pages[i - 1]->index == index + i - 1))
- goto splice_them;
+ if (!len)
+ break;
- /*
- * fill shadow[] with pages at the right locations, so we only
- * have to fill holes
- */
- memset(shadow, 0, i * sizeof(struct page *));
- for (j = 0, pidx = index; j < i; pidx++, j++)
- shadow[pages[j]->index - pidx] = pages[j];
+ /*
+ * this_len is the max we'll use from this page
+ */
+ this_len = min(len, PAGE_CACHE_SIZE - loff);
+find_page:
+ /*
+ * lookup the page for this index
+ */
+ page = find_get_page(mapping, index);
+ if (!page) {
+ /*
+ * page didn't exist, allocate one
+ */
+ page = page_cache_alloc_cold(mapping);
+ if (!page)
+ break;
- /*
- * now fill in the holes
- */
- for (i = 0, pidx = index; i < nr_pages; pidx++, i++) {
- int error;
+ error = add_to_page_cache_lru(page, mapping, index,
+ mapping_gfp_mask(mapping));
+ if (unlikely(error)) {
+ page_cache_release(page);
+ break;
+ }
- if (shadow[i])
- continue;
+ goto readpage;
+ }
/*
- * no page there, look one up / create it
+ * If the page isn't uptodate, we may need to start io on it
*/
- page = find_or_create_page(mapping, pidx,
- mapping_gfp_mask(mapping));
- if (!page)
- break;
+ if (!PageUptodate(page)) {
+ /*
+ * If in nonblock mode then dont block on waiting
+ * for an in-flight io page
+ */
+ if (flags & SPLICE_F_NONBLOCK)
+ break;
+
+ lock_page(page);
- if (PageUptodate(page))
- unlock_page(page);
- else {
+ /*
+ * page was truncated, stop here. if this isn't the
+ * first page, we'll just complete what we already
+ * added
+ */
+ if (!page->mapping) {
+ unlock_page(page);
+ page_cache_release(page);
+ break;
+ }
+ /*
+ * page was already under io and is now done, great
+ */
+ if (PageUptodate(page)) {
+ unlock_page(page);
+ goto fill_it;
+ }
+
+readpage:
+ /*
+ * need to read in the page
+ */
error = mapping->a_ops->readpage(in, page);
if (unlikely(error)) {
+ page_cache_release(page);
+ if (error == AOP_TRUNCATED_PAGE)
+ goto find_page;
+ break;
+ }
+
+ /*
+ * i_size must be checked after ->readpage().
+ */
+ isize = i_size_read(mapping->host);
+ end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
+ if (unlikely(!isize || index > end_index)) {
page_cache_release(page);
break;
}
- }
- shadow[i] = page;
- }
- if (!i) {
- for (i = 0; i < nr_pages; i++) {
- if (shadow[i])
- page_cache_release(shadow[i]);
+ /*
+ * if this is the last page, see if we need to shrink
+ * the length and stop
+ */
+ if (end_index == index) {
+ loff = PAGE_CACHE_SIZE - (isize & ~PAGE_CACHE_MASK);
+ if (bytes + loff > isize) {
+ page_cache_release(page);
+ break;
+ }
+ /*
+ * force quit after adding this page
+ */
+ nr_pages = i;
+ this_len = min(this_len, loff);
+ }
}
- return 0;
+fill_it:
+ pages[i] = page;
+ bytes += this_len;
+ len -= this_len;
+ loff = 0;
}
- memcpy(pages, shadow, i * sizeof(struct page *));
+ if (i)
+ return move_to_pipe(pipe, pages, i, bytes, offset, flags);
- /*
- * Now we splice them into the pipe..
- */
-splice_them:
- return move_to_pipe(pipe, pages, i, offset, len, flags);
+ return error;
}
-ssize_t generic_file_splice_read(struct file *in, struct inode *pipe,
- size_t len, unsigned int flags)
+/**
+ * generic_file_splice_read - splice data from file to a pipe
+ * @in: file to splice from
+ * @pipe: pipe to splice to
+ * @len: number of bytes to splice
+ * @flags: splice modifier flags
+ *
+ * Will read pages from given file and fill them into a pipe.
+ */
+ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags)
{
ssize_t spliced;
int ret;
ret = 0;
spliced = 0;
+
while (len) {
- ret = __generic_file_splice_read(in, pipe, len, flags);
+ ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
- if (ret <= 0)
+ if (ret < 0)
break;
+ else if (!ret) {
+ if (spliced)
+ break;
+ if (flags & SPLICE_F_NONBLOCK) {
+ ret = -EAGAIN;
+ break;
+ }
+ }
- in->f_pos += ret;
+ *ppos += ret;
len -= ret;
spliced += ret;
-
- if (!(flags & SPLICE_F_NONBLOCK))
- continue;
- ret = -EAGAIN;
- break;
}
if (spliced)
return ret;
}
+EXPORT_SYMBOL(generic_file_splice_read);
+
/*
- * Send 'len' bytes to socket from 'file' at position 'pos' using sendpage().
+ * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
+ * using sendpage().
*/
static int pipe_to_sendpage(struct pipe_inode_info *info,
struct pipe_buffer *buf, struct splice_desc *sd)
unsigned int offset;
ssize_t ret;
void *ptr;
+ int more;
/*
- * sub-optimal, but we are limited by the pipe ->map. we don't
+ * Sub-optimal, but we are limited by the pipe ->map. We don't
* need a kmap'ed buffer here, we just want to make sure we
* have the page pinned if the pipe page originates from the
- * page cache
+ * page cache.
*/
ptr = buf->ops->map(file, info, buf);
if (IS_ERR(ptr))
return PTR_ERR(ptr);
offset = pos & ~PAGE_CACHE_MASK;
+ more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
- ret = file->f_op->sendpage(file, buf->page, offset, sd->len, &pos,
- sd->len < sd->total_len);
+ ret = file->f_op->sendpage(file, buf->page, offset, sd->len, &pos,more);
buf->ops->unmap(info, buf);
if (ret == sd->len)
* - Destination page does not exist, we can add the pipe page to
* the page cache and avoid the copy.
*
- * For now we just do the slower thing and always copy pages over, it's
- * easier than migrating pages from the pipe to the target file. For the
- * case of doing file | file splicing, the migrate approach had some LRU
- * nastiness...
+ * If asked to move pages to the output file (SPLICE_F_MOVE is set in
+ * sd->flags), we attempt to migrate pages from the pipe to the output
+ * file address space page cache. This is possible if no one else has
+ * the pipe page referenced outside of the pipe and page cache. If
+ * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
+ * a new page in the output file page cache and fill/dirty that.
*/
static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
struct splice_desc *sd)
{
struct file *file = sd->file;
struct address_space *mapping = file->f_mapping;
+ gfp_t gfp_mask = mapping_gfp_mask(mapping);
unsigned int offset;
struct page *page;
pgoff_t index;
int ret;
/*
- * after this, page will be locked and unmapped
+ * make sure the data in this buffer is uptodate
*/
src = buf->ops->map(file, info, buf);
if (IS_ERR(src))
offset = sd->pos & ~PAGE_CACHE_MASK;
/*
- * reuse buf page, if SPLICE_F_MOVE is set
+ * Reuse buf page, if SPLICE_F_MOVE is set.
*/
if (sd->flags & SPLICE_F_MOVE) {
+ /*
+ * If steal succeeds, buf->page is now pruned from the vm
+ * side (LRU and page cache) and we can reuse it. The page
+ * will also be looked on successful return.
+ */
if (buf->ops->steal(info, buf))
goto find_page;
page = buf->page;
- if (add_to_page_cache_lru(page, mapping, index,
- mapping_gfp_mask(mapping)))
+ if (add_to_page_cache(page, mapping, index, gfp_mask))
goto find_page;
+
+ if (!(buf->flags & PIPE_BUF_FLAG_LRU))
+ lru_cache_add(page);
} else {
find_page:
- ret = -ENOMEM;
- page = find_or_create_page(mapping, index,
- mapping_gfp_mask(mapping));
- if (!page)
- goto out;
+ page = find_lock_page(mapping, index);
+ if (!page) {
+ ret = -ENOMEM;
+ page = page_cache_alloc_cold(mapping);
+ if (unlikely(!page))
+ goto out_nomem;
+
+ /*
+ * This will also lock the page
+ */
+ ret = add_to_page_cache_lru(page, mapping, index,
+ gfp_mask);
+ if (unlikely(ret))
+ goto out;
+ }
/*
- * If the page is uptodate, it is also locked. If it isn't
- * uptodate, we can mark it uptodate if we are filling the
- * full page. Otherwise we need to read it in first...
+ * We get here with the page locked. If the page is also
+ * uptodate, we don't need to do more. If it isn't, we
+ * may need to bring it in if we are not going to overwrite
+ * the full page.
*/
if (!PageUptodate(page)) {
if (sd->len < PAGE_CACHE_SIZE) {
if (!PageUptodate(page)) {
/*
- * page got invalidated, repeat
+ * Page got invalidated, repeat.
*/
if (!page->mapping) {
unlock_page(page);
ret = -EIO;
goto out;
}
- } else {
- WARN_ON(!PageLocked(page));
+ } else
SetPageUptodate(page);
- }
}
}
ret = mapping->a_ops->prepare_write(file, page, 0, sd->len);
- if (ret)
+ if (ret == AOP_TRUNCATED_PAGE) {
+ page_cache_release(page);
+ goto find_page;
+ } else if (ret)
goto out;
- if (!buf->stolen) {
+ if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {
char *dst = kmap_atomic(page, KM_USER0);
memcpy(dst + offset, src + buf->offset, sd->len);
}
ret = mapping->a_ops->commit_write(file, page, 0, sd->len);
- if (ret < 0)
+ if (ret == AOP_TRUNCATED_PAGE) {
+ page_cache_release(page);
+ goto find_page;
+ } else if (ret)
goto out;
- set_page_dirty(page);
- ret = write_one_page(page, 0);
+ mark_page_accessed(page);
+ balance_dirty_pages_ratelimited(mapping);
out:
- if (ret < 0)
- unlock_page(page);
- if (!buf->stolen)
+ if (!(buf->flags & PIPE_BUF_FLAG_STOLEN))
page_cache_release(page);
+
+ unlock_page(page);
+out_nomem:
buf->ops->unmap(info, buf);
return ret;
}
typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
struct splice_desc *);
-static ssize_t move_from_pipe(struct inode *inode, struct file *out,
- size_t len, unsigned int flags,
+/*
+ * Pipe input worker. Most of this logic works like a regular pipe, the
+ * key here is the 'actor' worker passed in that actually moves the data
+ * to the wanted destination. See pipe_to_file/pipe_to_sendpage above.
+ */
+static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
+ loff_t *ppos, size_t len, unsigned int flags,
splice_actor *actor)
{
- struct pipe_inode_info *info;
int ret, do_wakeup, err;
struct splice_desc sd;
sd.total_len = len;
sd.flags = flags;
sd.file = out;
- sd.pos = out->f_pos;
+ sd.pos = *ppos;
- mutex_lock(PIPE_MUTEX(*inode));
+ if (pipe->inode)
+ mutex_lock(&pipe->inode->i_mutex);
- info = inode->i_pipe;
for (;;) {
- int bufs = info->nrbufs;
-
- if (bufs) {
- int curbuf = info->curbuf;
- struct pipe_buffer *buf = info->bufs + curbuf;
+ if (pipe->nrbufs) {
+ struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
struct pipe_buf_operations *ops = buf->ops;
sd.len = buf->len;
if (sd.len > sd.total_len)
sd.len = sd.total_len;
- err = actor(info, buf, &sd);
+ err = actor(pipe, buf, &sd);
if (err) {
if (!ret && err != -ENODATA)
ret = err;
ret += sd.len;
buf->offset += sd.len;
buf->len -= sd.len;
+
if (!buf->len) {
buf->ops = NULL;
- ops->release(info, buf);
- curbuf = (curbuf + 1) & (PIPE_BUFFERS - 1);
- info->curbuf = curbuf;
- info->nrbufs = --bufs;
- do_wakeup = 1;
+ ops->release(pipe, buf);
+ pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
+ pipe->nrbufs--;
+ if (pipe->inode)
+ do_wakeup = 1;
}
sd.pos += sd.len;
break;
}
- if (bufs)
+ if (pipe->nrbufs)
continue;
- if (!PIPE_WRITERS(*inode))
+ if (!pipe->writers)
break;
- if (!PIPE_WAITING_WRITERS(*inode)) {
+ if (!pipe->waiting_writers) {
if (ret)
break;
}
}
if (do_wakeup) {
- wake_up_interruptible_sync(PIPE_WAIT(*inode));
- kill_fasync(PIPE_FASYNC_WRITERS(*inode),SIGIO,POLL_OUT);
+ smp_mb();
+ if (waitqueue_active(&pipe->wait))
+ wake_up_interruptible_sync(&pipe->wait);
+ kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
do_wakeup = 0;
}
- pipe_wait(inode);
+ pipe_wait(pipe);
}
- mutex_unlock(PIPE_MUTEX(*inode));
+ if (pipe->inode)
+ mutex_unlock(&pipe->inode->i_mutex);
if (do_wakeup) {
- wake_up_interruptible(PIPE_WAIT(*inode));
- kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
+ smp_mb();
+ if (waitqueue_active(&pipe->wait))
+ wake_up_interruptible(&pipe->wait);
+ kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
}
- mutex_lock(&out->f_mapping->host->i_mutex);
- out->f_pos = sd.pos;
- mutex_unlock(&out->f_mapping->host->i_mutex);
return ret;
-
}
-ssize_t generic_file_splice_write(struct inode *inode, struct file *out,
- size_t len, unsigned int flags)
+/**
+ * generic_file_splice_write - splice data from a pipe to a file
+ * @pipe: pipe info
+ * @out: file to write to
+ * @len: number of bytes to splice
+ * @flags: splice modifier flags
+ *
+ * Will either move or copy pages (determined by @flags options) from
+ * the given pipe inode to the given file.
+ *
+ */
+ssize_t
+generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
+ loff_t *ppos, size_t len, unsigned int flags)
{
- return move_from_pipe(inode, out, len, flags, pipe_to_file);
+ struct address_space *mapping = out->f_mapping;
+ ssize_t ret;
+
+ ret = move_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
+ if (ret > 0) {
+ struct inode *inode = mapping->host;
+
+ *ppos += ret;
+
+ /*
+ * If file or inode is SYNC and we actually wrote some data,
+ * sync it.
+ */
+ if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
+ int err;
+
+ mutex_lock(&inode->i_mutex);
+ err = generic_osync_inode(inode, mapping,
+ OSYNC_METADATA|OSYNC_DATA);
+ mutex_unlock(&inode->i_mutex);
+
+ if (err)
+ ret = err;
+ }
+ }
+
+ return ret;
}
-ssize_t generic_splice_sendpage(struct inode *inode, struct file *out,
- size_t len, unsigned int flags)
+EXPORT_SYMBOL(generic_file_splice_write);
+
+/**
+ * generic_splice_sendpage - splice data from a pipe to a socket
+ * @inode: pipe inode
+ * @out: socket to write to
+ * @len: number of bytes to splice
+ * @flags: splice modifier flags
+ *
+ * Will send @len bytes from the pipe to a network socket. No data copying
+ * is involved.
+ *
+ */
+ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
+ loff_t *ppos, size_t len, unsigned int flags)
{
- return move_from_pipe(inode, out, len, flags, pipe_to_sendpage);
+ return move_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
}
-EXPORT_SYMBOL(generic_file_splice_write);
-EXPORT_SYMBOL(generic_file_splice_read);
+EXPORT_SYMBOL(generic_splice_sendpage);
-static long do_splice_from(struct inode *pipe, struct file *out, size_t len,
- unsigned int flags)
+/*
+ * Attempt to initiate a splice from pipe to file.
+ */
+static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
+ loff_t *ppos, size_t len, unsigned int flags)
{
- loff_t pos;
int ret;
- if (!out->f_op || !out->f_op->splice_write)
+ if (unlikely(!out->f_op || !out->f_op->splice_write))
return -EINVAL;
- if (!(out->f_mode & FMODE_WRITE))
+ if (unlikely(!(out->f_mode & FMODE_WRITE)))
return -EBADF;
- pos = out->f_pos;
- ret = rw_verify_area(WRITE, out, &pos, len);
+ ret = rw_verify_area(WRITE, out, ppos, len);
if (unlikely(ret < 0))
return ret;
- return out->f_op->splice_write(pipe, out, len, flags);
+ return out->f_op->splice_write(pipe, out, ppos, len, flags);
}
-static long do_splice_to(struct file *in, struct inode *pipe, size_t len,
+/*
+ * Attempt to initiate a splice from a file to a pipe.
+ */
+static long do_splice_to(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
{
- loff_t pos, isize, left;
+ loff_t isize, left;
int ret;
- if (!in->f_op || !in->f_op->splice_read)
+ if (unlikely(!in->f_op || !in->f_op->splice_read))
return -EINVAL;
- if (!(in->f_mode & FMODE_READ))
+ if (unlikely(!(in->f_mode & FMODE_READ)))
return -EBADF;
- pos = in->f_pos;
- ret = rw_verify_area(READ, in, &pos, len);
+ ret = rw_verify_area(READ, in, ppos, len);
if (unlikely(ret < 0))
return ret;
isize = i_size_read(in->f_mapping->host);
- if (unlikely(in->f_pos >= isize))
+ if (unlikely(*ppos >= isize))
return 0;
- left = isize - in->f_pos;
- if (left < len)
+ left = isize - *ppos;
+ if (unlikely(left < len))
len = left;
- return in->f_op->splice_read(in, pipe, len, flags);
+ return in->f_op->splice_read(in, ppos, pipe, len, flags);
+}
+
+long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
+ size_t len, unsigned int flags)
+{
+ struct pipe_inode_info *pipe;
+ long ret, bytes;
+ loff_t out_off;
+ umode_t i_mode;
+ int i;
+
+ /*
+ * We require the input being a regular file, as we don't want to
+ * randomly drop data for eg socket -> socket splicing. Use the
+ * piped splicing for that!
+ */
+ i_mode = in->f_dentry->d_inode->i_mode;
+ if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
+ return -EINVAL;
+
+ /*
+ * neither in nor out is a pipe, setup an internal pipe attached to
+ * 'out' and transfer the wanted data from 'in' to 'out' through that
+ */
+ pipe = current->splice_pipe;
+ if (unlikely(!pipe)) {
+ pipe = alloc_pipe_info(NULL);
+ if (!pipe)
+ return -ENOMEM;
+
+ /*
+ * We don't have an immediate reader, but we'll read the stuff
+ * out of the pipe right after the move_to_pipe(). So set
+ * PIPE_READERS appropriately.
+ */
+ pipe->readers = 1;
+
+ current->splice_pipe = pipe;
+ }
+
+ /*
+ * Do the splice.
+ */
+ ret = 0;
+ bytes = 0;
+ out_off = 0;
+
+ while (len) {
+ size_t read_len, max_read_len;
+
+ /*
+ * Do at most PIPE_BUFFERS pages worth of transfer:
+ */
+ max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE));
+
+ ret = do_splice_to(in, ppos, pipe, max_read_len, flags);
+ if (unlikely(ret < 0))
+ goto out_release;
+
+ read_len = ret;
+
+ /*
+ * NOTE: nonblocking mode only applies to the input. We
+ * must not do the output in nonblocking mode as then we
+ * could get stuck data in the internal pipe:
+ */
+ ret = do_splice_from(pipe, out, &out_off, read_len,
+ flags & ~SPLICE_F_NONBLOCK);
+ if (unlikely(ret < 0))
+ goto out_release;
+
+ bytes += ret;
+ len -= ret;
+
+ /*
+ * In nonblocking mode, if we got back a short read then
+ * that was due to either an IO error or due to the
+ * pagecache entry not being there. In the IO error case
+ * the _next_ splice attempt will produce a clean IO error
+ * return value (not a short read), so in both cases it's
+ * correct to break out of the loop here:
+ */
+ if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len))
+ break;
+ }
+
+ pipe->nrbufs = pipe->curbuf = 0;
+
+ return bytes;
+
+out_release:
+ /*
+ * If we did an incomplete transfer we must release
+ * the pipe buffers in question:
+ */
+ for (i = 0; i < PIPE_BUFFERS; i++) {
+ struct pipe_buffer *buf = pipe->bufs + i;
+
+ if (buf->ops) {
+ buf->ops->release(pipe, buf);
+ buf->ops = NULL;
+ }
+ }
+ pipe->nrbufs = pipe->curbuf = 0;
+
+ /*
+ * If we transferred some data, return the number of bytes:
+ */
+ if (bytes > 0)
+ return bytes;
+
+ return ret;
}
-static long do_splice(struct file *in, struct file *out, size_t len,
- unsigned int flags)
+EXPORT_SYMBOL(do_splice_direct);
+
+/*
+ * Determine where to splice to/from.
+ */
+static long do_splice(struct file *in, loff_t __user *off_in,
+ struct file *out, loff_t __user *off_out,
+ size_t len, unsigned int flags)
{
- struct inode *pipe;
+ struct pipe_inode_info *pipe;
+ loff_t offset, *off;
+ long ret;
+
+ pipe = in->f_dentry->d_inode->i_pipe;
+ if (pipe) {
+ if (off_in)
+ return -ESPIPE;
+ if (off_out) {
+ if (out->f_op->llseek == no_llseek)
+ return -EINVAL;
+ if (copy_from_user(&offset, off_out, sizeof(loff_t)))
+ return -EFAULT;
+ off = &offset;
+ } else
+ off = &out->f_pos;
+
+ ret = do_splice_from(pipe, out, off, len, flags);
+
+ if (off_out && copy_to_user(off_out, off, sizeof(loff_t)))
+ ret = -EFAULT;
+
+ return ret;
+ }
- pipe = in->f_dentry->d_inode;
- if (pipe->i_pipe)
- return do_splice_from(pipe, out, len, flags);
+ pipe = out->f_dentry->d_inode->i_pipe;
+ if (pipe) {
+ if (off_out)
+ return -ESPIPE;
+ if (off_in) {
+ if (in->f_op->llseek == no_llseek)
+ return -EINVAL;
+ if (copy_from_user(&offset, off_in, sizeof(loff_t)))
+ return -EFAULT;
+ off = &offset;
+ } else
+ off = &in->f_pos;
- pipe = out->f_dentry->d_inode;
- if (pipe->i_pipe)
- return do_splice_to(in, pipe, len, flags);
+ ret = do_splice_to(in, off, pipe, len, flags);
+
+ if (off_in && copy_to_user(off_in, off, sizeof(loff_t)))
+ ret = -EFAULT;
+
+ return ret;
+ }
return -EINVAL;
}
-asmlinkage long sys_splice(int fdin, int fdout, size_t len, unsigned int flags)
+asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
+ int fd_out, loff_t __user *off_out,
+ size_t len, unsigned int flags)
{
long error;
struct file *in, *out;
return 0;
error = -EBADF;
- in = fget_light(fdin, &fput_in);
+ in = fget_light(fd_in, &fput_in);
if (in) {
if (in->f_mode & FMODE_READ) {
- out = fget_light(fdout, &fput_out);
+ out = fget_light(fd_out, &fput_out);
if (out) {
if (out->f_mode & FMODE_WRITE)
- error = do_splice(in, out, len, flags);
+ error = do_splice(in, off_in,
+ out, off_out,
+ len, flags);
fput_light(out, fput_out);
}
}
return error;
}
+
+/*
+ * Link contents of ipipe to opipe.
+ */
+static int link_pipe(struct pipe_inode_info *ipipe,
+ struct pipe_inode_info *opipe,
+ size_t len, unsigned int flags)
+{
+ struct pipe_buffer *ibuf, *obuf;
+ int ret, do_wakeup, i, ipipe_first;
+
+ ret = do_wakeup = ipipe_first = 0;
+
+ /*
+ * Potential ABBA deadlock, work around it by ordering lock
+ * grabbing by inode address. Otherwise two different processes
+ * could deadlock (one doing tee from A -> B, the other from B -> A).
+ */
+ if (ipipe->inode < opipe->inode) {
+ ipipe_first = 1;
+ mutex_lock(&ipipe->inode->i_mutex);
+ mutex_lock(&opipe->inode->i_mutex);
+ } else {
+ mutex_lock(&opipe->inode->i_mutex);
+ mutex_lock(&ipipe->inode->i_mutex);
+ }
+
+ for (i = 0;; i++) {
+ if (!opipe->readers) {
+ send_sig(SIGPIPE, current, 0);
+ if (!ret)
+ ret = -EPIPE;
+ break;
+ }
+ if (ipipe->nrbufs - i) {
+ ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1));
+
+ /*
+ * If we have room, fill this buffer
+ */
+ if (opipe->nrbufs < PIPE_BUFFERS) {
+ int nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1);
+
+ /*
+ * Get a reference to this pipe buffer,
+ * so we can copy the contents over.
+ */
+ ibuf->ops->get(ipipe, ibuf);
+
+ obuf = opipe->bufs + nbuf;
+ *obuf = *ibuf;
+
+ if (obuf->len > len)
+ obuf->len = len;
+
+ opipe->nrbufs++;
+ do_wakeup = 1;
+ ret += obuf->len;
+ len -= obuf->len;
+
+ if (!len)
+ break;
+ if (opipe->nrbufs < PIPE_BUFFERS)
+ continue;
+ }
+
+ /*
+ * We have input available, but no output room.
+ * If we already copied data, return that. If we
+ * need to drop the opipe lock, it must be ordered
+ * last to avoid deadlocks.
+ */
+ if ((flags & SPLICE_F_NONBLOCK) || !ipipe_first) {
+ if (!ret)
+ ret = -EAGAIN;
+ break;
+ }
+ if (signal_pending(current)) {
+ if (!ret)
+ ret = -ERESTARTSYS;
+ break;
+ }
+ if (do_wakeup) {
+ smp_mb();
+ if (waitqueue_active(&opipe->wait))
+ wake_up_interruptible(&opipe->wait);
+ kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
+ do_wakeup = 0;
+ }
+
+ opipe->waiting_writers++;
+ pipe_wait(opipe);
+ opipe->waiting_writers--;
+ continue;
+ }
+
+ /*
+ * No input buffers, do the usual checks for available
+ * writers and blocking and wait if necessary
+ */
+ if (!ipipe->writers)
+ break;
+ if (!ipipe->waiting_writers) {
+ if (ret)
+ break;
+ }
+ /*
+ * pipe_wait() drops the ipipe mutex. To avoid deadlocks
+ * with another process, we can only safely do that if
+ * the ipipe lock is ordered last.
+ */
+ if ((flags & SPLICE_F_NONBLOCK) || ipipe_first) {
+ if (!ret)
+ ret = -EAGAIN;
+ break;
+ }
+ if (signal_pending(current)) {
+ if (!ret)
+ ret = -ERESTARTSYS;
+ break;
+ }
+
+ if (waitqueue_active(&ipipe->wait))
+ wake_up_interruptible_sync(&ipipe->wait);
+ kill_fasync(&ipipe->fasync_writers, SIGIO, POLL_OUT);
+
+ pipe_wait(ipipe);
+ }
+
+ mutex_unlock(&ipipe->inode->i_mutex);
+ mutex_unlock(&opipe->inode->i_mutex);
+
+ if (do_wakeup) {
+ smp_mb();
+ if (waitqueue_active(&opipe->wait))
+ wake_up_interruptible(&opipe->wait);
+ kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
+ }
+
+ return ret;
+}
+
+/*
+ * This is a tee(1) implementation that works on pipes. It doesn't copy
+ * any data, it simply references the 'in' pages on the 'out' pipe.
+ * The 'flags' used are the SPLICE_F_* variants, currently the only
+ * applicable one is SPLICE_F_NONBLOCK.
+ */
+static long do_tee(struct file *in, struct file *out, size_t len,
+ unsigned int flags)
+{
+ struct pipe_inode_info *ipipe = in->f_dentry->d_inode->i_pipe;
+ struct pipe_inode_info *opipe = out->f_dentry->d_inode->i_pipe;
+
+ /*
+ * Link ipipe to the two output pipes, consuming as we go along.
+ */
+ if (ipipe && opipe)
+ return link_pipe(ipipe, opipe, len, flags);
+
+ return -EINVAL;
+}
+
+asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags)
+{
+ struct file *in;
+ int error, fput_in;
+
+ if (unlikely(!len))
+ return 0;
+
+ error = -EBADF;
+ in = fget_light(fdin, &fput_in);
+ if (in) {
+ if (in->f_mode & FMODE_READ) {
+ int fput_out;
+ struct file *out = fget_light(fdout, &fput_out);
+
+ if (out) {
+ if (out->f_mode & FMODE_WRITE)
+ error = do_tee(in, out, len, flags);
+ fput_light(out, fput_out);
+ }
+ }
+ fput_light(in, fput_in);
+ }
+
+ return error;
+}
git.openpandora.org / pandora-kernel.git / blobdiff