#include <linux/buffer_head.h>
#include <linux/module.h>
#include <linux/syscalls.h>
+#include <linux/uio.h>
+
+struct partial_page {
+ unsigned int offset;
+ unsigned int len;
+};
/*
- * Passed to the actors
+ * Passed to splice_to_pipe
*/
-struct splice_desc {
- unsigned int len, total_len; /* current and remaining length */
+struct splice_pipe_desc {
+ struct page **pages; /* page map */
+ struct partial_page *partial; /* pages[] may not be contig */
+ int nr_pages; /* number of pages in map */
unsigned int flags; /* splice flags */
- struct file *file; /* file to read/write */
- loff_t pos; /* file position */
+ struct pipe_buf_operations *ops;/* ops associated with output pipe */
};
/*
* 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,
+static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
struct page *page = buf->page;
- struct address_space *mapping = page_mapping(page);
+ struct address_space *mapping;
- WARN_ON(!PageLocked(page));
- WARN_ON(!PageUptodate(page));
+ lock_page(page);
- /*
- * 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);
+ mapping = page_mapping(page);
+ if (mapping) {
+ WARN_ON(!PageUptodate(page));
+
+ /*
+ * 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 (PagePrivate(page))
- try_to_release_page(page, mapping_gfp_mask(mapping));
+ if (PagePrivate(page))
+ try_to_release_page(page, mapping_gfp_mask(mapping));
- if (!remove_mapping(mapping, page))
- return 1;
+ /*
+ * If we succeeded in removing the mapping, set LRU flag
+ * and return good.
+ */
+ if (remove_mapping(mapping, page)) {
+ buf->flags |= PIPE_BUF_FLAG_LRU;
+ return 0;
+ }
+ }
- buf->flags |= PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU;
- return 0;
+ /*
+ * Raced with truncate or failed to remove page from current
+ * address space, unlock and return failure.
+ */
+ unlock_page(page);
+ return 1;
}
-static void page_cache_pipe_buf_release(struct pipe_inode_info *info,
+static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
page_cache_release(buf->page);
- buf->page = NULL;
- buf->flags &= ~(PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU);
+ buf->flags &= ~PIPE_BUF_FLAG_LRU;
}
-static void *page_cache_pipe_buf_map(struct file *file,
- struct pipe_inode_info *info,
- struct pipe_buffer *buf)
+static int page_cache_pipe_buf_pin(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf)
{
struct page *page = buf->page;
int err;
}
/*
- * Page is ok afterall, fall through to mapping.
+ * Page is ok afterall, we are done.
*/
unlock_page(page);
}
- return kmap(page);
+ return 0;
error:
unlock_page(page);
- return ERR_PTR(err);
+ return err;
}
-static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info,
- struct pipe_buffer *buf)
-{
- kunmap(buf->page);
-}
+static struct pipe_buf_operations page_cache_pipe_buf_ops = {
+ .can_merge = 0,
+ .map = generic_pipe_buf_map,
+ .unmap = generic_pipe_buf_unmap,
+ .pin = page_cache_pipe_buf_pin,
+ .release = page_cache_pipe_buf_release,
+ .steal = page_cache_pipe_buf_steal,
+ .get = generic_pipe_buf_get,
+};
-static void page_cache_pipe_buf_get(struct pipe_inode_info *info,
+static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
- page_cache_get(buf->page);
+ if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
+ return 1;
+
+ buf->flags |= PIPE_BUF_FLAG_LRU;
+ return generic_pipe_buf_steal(pipe, buf);
}
-static struct pipe_buf_operations page_cache_pipe_buf_ops = {
+static struct pipe_buf_operations user_page_pipe_buf_ops = {
.can_merge = 0,
- .map = page_cache_pipe_buf_map,
- .unmap = page_cache_pipe_buf_unmap,
+ .map = generic_pipe_buf_map,
+ .unmap = generic_pipe_buf_unmap,
+ .pin = generic_pipe_buf_pin,
.release = page_cache_pipe_buf_release,
- .steal = page_cache_pipe_buf_steal,
- .get = page_cache_pipe_buf_get,
+ .steal = user_page_pipe_buf_steal,
+ .get = generic_pipe_buf_get,
};
/*
* 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)
+static ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
+ struct splice_pipe_desc *spd)
{
- int ret, do_wakeup, i;
+ int ret, do_wakeup, page_nr;
ret = 0;
do_wakeup = 0;
- i = 0;
+ page_nr = 0;
if (pipe->inode)
mutex_lock(&pipe->inode->i_mutex);
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;
- this_len = PAGE_CACHE_SIZE - offset;
- if (this_len > len)
- this_len = len;
+ buf->page = spd->pages[page_nr];
+ buf->offset = spd->partial[page_nr].offset;
+ buf->len = spd->partial[page_nr].len;
+ buf->ops = spd->ops;
+ if (spd->flags & SPLICE_F_GIFT)
+ buf->flags |= PIPE_BUF_FLAG_GIFT;
- buf->page = page;
- buf->offset = offset;
- buf->len = this_len;
- buf->ops = &page_cache_pipe_buf_ops;
pipe->nrbufs++;
+ page_nr++;
+ ret += buf->len;
+
if (pipe->inode)
do_wakeup = 1;
- ret += this_len;
- len -= this_len;
- offset = 0;
- if (!--nr_pages)
- break;
- if (!len)
+ if (!--spd->nr_pages)
break;
if (pipe->nrbufs < PIPE_BUFFERS)
continue;
break;
}
- if (flags & SPLICE_F_NONBLOCK) {
+ if (spd->flags & SPLICE_F_NONBLOCK) {
if (!ret)
ret = -EAGAIN;
break;
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
}
- while (i < nr_pages)
- page_cache_release(pages[i++]);
+ while (page_nr < spd->nr_pages)
+ page_cache_release(spd->pages[page_nr++]);
return ret;
}
unsigned int flags)
{
struct address_space *mapping = in->f_mapping;
- unsigned int loff, offset, nr_pages;
+ unsigned int loff, nr_pages;
struct page *pages[PIPE_BUFFERS];
+ struct partial_page partial[PIPE_BUFFERS];
struct page *page;
pgoff_t index, end_index;
loff_t isize;
- size_t bytes;
- int i, error;
+ size_t total_len;
+ int error, page_nr;
+ struct splice_pipe_desc spd = {
+ .pages = pages,
+ .partial = partial,
+ .flags = flags,
+ .ops = &page_cache_pipe_buf_ops,
+ };
index = *ppos >> PAGE_CACHE_SHIFT;
- loff = offset = *ppos & ~PAGE_CACHE_MASK;
- nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ loff = *ppos & ~PAGE_CACHE_MASK;
+ nr_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
if (nr_pages > PIPE_BUFFERS)
nr_pages = PIPE_BUFFERS;
* 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.
*/
- if (!offset || nr_pages > 1)
- do_page_cache_readahead(mapping, in, index, nr_pages);
+ if (!loff || nr_pages > 1)
+ page_cache_readahead(mapping, &in->f_ra, in, index, nr_pages);
/*
* Now fill in the holes:
*/
error = 0;
- bytes = 0;
- for (i = 0; i < nr_pages; i++, index++) {
-find_page:
+ total_len = 0;
+
+ /*
+ * Lookup the (hopefully) full range of pages we need.
+ */
+ spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages);
+
+ /*
+ * If find_get_pages_contig() returned fewer pages than we needed,
+ * allocate the rest.
+ */
+ index += spd.nr_pages;
+ while (spd.nr_pages < nr_pages) {
/*
- * lookup the page for this index
+ * Page could be there, find_get_pages_contig() breaks on
+ * the first hole.
*/
page = find_get_page(mapping, index);
if (!page) {
/*
- * page didn't exist, allocate one
+ * Make sure the read-ahead engine is notified
+ * about this failure.
+ */
+ handle_ra_miss(mapping, &in->f_ra, index);
+
+ /*
+ * page didn't exist, allocate one.
*/
page = page_cache_alloc_cold(mapping);
if (!page)
break;
error = add_to_page_cache_lru(page, mapping, index,
- mapping_gfp_mask(mapping));
+ mapping_gfp_mask(mapping));
if (unlikely(error)) {
page_cache_release(page);
+ if (error == -EEXIST)
+ continue;
break;
}
-
- goto readpage;
+ /*
+ * add_to_page_cache() locks the page, unlock it
+ * to avoid convoluting the logic below even more.
+ */
+ unlock_page(page);
}
+ pages[spd.nr_pages++] = page;
+ index++;
+ }
+
+ /*
+ * Now loop over the map and see if we need to start IO on any
+ * pages, fill in the partial map, etc.
+ */
+ index = *ppos >> PAGE_CACHE_SHIFT;
+ nr_pages = spd.nr_pages;
+ spd.nr_pages = 0;
+ for (page_nr = 0; page_nr < nr_pages; page_nr++) {
+ unsigned int this_len;
+
+ if (!len)
+ break;
+
+ /*
+ * this_len is the max we'll use from this page
+ */
+ this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
+ page = pages[page_nr];
+
/*
* If the page isn't uptodate, we may need to start io on it
*/
*/
if (!page->mapping) {
unlock_page(page);
- page_cache_release(page);
break;
}
/*
goto fill_it;
}
-readpage:
/*
* need to read in the page
*/
error = mapping->a_ops->readpage(in, page);
-
if (unlikely(error)) {
- page_cache_release(page);
+ /*
+ * We really should re-lookup the page here,
+ * but it complicates things a lot. Instead
+ * lets just do what we already stored, and
+ * we'll get it the next time we are called.
+ */
if (error == AOP_TRUNCATED_PAGE)
- goto find_page;
+ error = 0;
+
break;
}
*/
isize = i_size_read(mapping->host);
end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
- if (unlikely(!isize || index > end_index)) {
- page_cache_release(page);
+ if (unlikely(!isize || index > end_index))
break;
- }
/*
* if this is the last page, see if we need to shrink
*/
if (end_index == index) {
loff = PAGE_CACHE_SIZE - (isize & ~PAGE_CACHE_MASK);
- if (bytes + loff > isize) {
- page_cache_release(page);
+ if (total_len + loff > isize)
break;
- }
/*
* force quit after adding this page
*/
- nr_pages = i;
+ len = this_len;
+ this_len = min(this_len, loff);
+ loff = 0;
}
}
fill_it:
- pages[i] = page;
- bytes += PAGE_CACHE_SIZE - loff;
+ partial[page_nr].offset = loff;
+ partial[page_nr].len = this_len;
+ len -= this_len;
+ total_len += this_len;
loff = 0;
+ spd.nr_pages++;
+ index++;
}
- if (i)
- return move_to_pipe(pipe, pages, i, bytes, offset, flags);
+ /*
+ * Release any pages at the end, if we quit early. 'i' is how far
+ * we got, 'nr_pages' is how many pages are in the map.
+ */
+ while (page_nr < nr_pages)
+ page_cache_release(pages[page_nr++]);
+
+ if (spd.nr_pages)
+ return splice_to_pipe(pipe, &spd);
return error;
}
/*
* Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
- * using sendpage().
+ * using sendpage(). Return the number of bytes sent.
*/
-static int pipe_to_sendpage(struct pipe_inode_info *info,
+static int pipe_to_sendpage(struct pipe_inode_info *pipe,
struct pipe_buffer *buf, struct splice_desc *sd)
{
struct file *file = sd->file;
loff_t pos = sd->pos;
- unsigned int offset;
- ssize_t ret;
- void *ptr;
- int more;
+ int ret, more;
- /*
- * 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.
- */
- ptr = buf->ops->map(file, info, buf);
- if (IS_ERR(ptr))
- return PTR_ERR(ptr);
+ ret = buf->ops->pin(pipe, buf);
+ if (!ret) {
+ more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
- 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,more);
-
- buf->ops->unmap(info, buf);
- if (ret == sd->len)
- return 0;
+ ret = file->f_op->sendpage(file, buf->page, buf->offset,
+ sd->len, &pos, more);
+ }
- return -EIO;
+ return ret;
}
/*
* 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,
+static int pipe_to_file(struct pipe_inode_info *pipe, 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;
+ unsigned int offset, this_len;
struct page *page;
pgoff_t index;
- char *src;
int ret;
/*
* make sure the data in this buffer is uptodate
*/
- src = buf->ops->map(file, info, buf);
- if (IS_ERR(src))
- return PTR_ERR(src);
+ ret = buf->ops->pin(pipe, buf);
+ if (unlikely(ret))
+ return ret;
index = sd->pos >> PAGE_CACHE_SHIFT;
offset = sd->pos & ~PAGE_CACHE_MASK;
+ this_len = sd->len;
+ if (this_len + offset > PAGE_CACHE_SIZE)
+ this_len = PAGE_CACHE_SIZE - offset;
+
/*
- * Reuse buf page, if SPLICE_F_MOVE is set.
+ * Reuse buf page, if SPLICE_F_MOVE is set and we are doing a full
+ * page.
*/
- if (sd->flags & SPLICE_F_MOVE) {
+ if ((sd->flags & SPLICE_F_MOVE) && this_len == PAGE_CACHE_SIZE) {
/*
- * If steal succeeds, buf->page is now pruned from the vm
- * side (LRU and page cache) and we can reuse it.
+ * If steal succeeds, buf->page is now pruned from the
+ * pagecache and we can reuse it. The page will also be
+ * locked on successful return.
*/
- if (buf->ops->steal(info, buf))
+ if (buf->ops->steal(pipe, buf))
goto find_page;
- /*
- * this will also set the page locked
- */
page = buf->page;
- if (add_to_page_cache(page, mapping, index, gfp_mask))
+ if (add_to_page_cache(page, mapping, index, gfp_mask)) {
+ unlock_page(page);
goto find_page;
+ }
+
+ page_cache_get(page);
if (!(buf->flags & PIPE_BUF_FLAG_LRU))
lru_cache_add(page);
} else {
find_page:
- ret = -ENOMEM;
- page = find_or_create_page(mapping, index, gfp_mask);
- if (!page)
- goto out_nomem;
+ 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 (this_len < PAGE_CACHE_SIZE) {
ret = mapping->a_ops->readpage(file, page);
if (unlikely(ret))
goto out;
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 == AOP_TRUNCATED_PAGE) {
+ ret = mapping->a_ops->prepare_write(file, page, offset, offset+this_len);
+ if (unlikely(ret)) {
+ loff_t isize = i_size_read(mapping->host);
+
+ if (ret != AOP_TRUNCATED_PAGE)
+ unlock_page(page);
page_cache_release(page);
- goto find_page;
- } else if (ret)
+ if (ret == AOP_TRUNCATED_PAGE)
+ goto find_page;
+
+ /*
+ * prepare_write() may have instantiated a few blocks
+ * outside i_size. Trim these off again.
+ */
+ if (sd->pos + this_len > isize)
+ vmtruncate(mapping->host, isize);
+
goto out;
+ }
- if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {
- char *dst = kmap_atomic(page, KM_USER0);
+ if (buf->page != page) {
+ /*
+ * Careful, ->map() uses KM_USER0!
+ */
+ char *src = buf->ops->map(pipe, buf, 1);
+ char *dst = kmap_atomic(page, KM_USER1);
- memcpy(dst + offset, src + buf->offset, sd->len);
+ memcpy(dst + offset, src + buf->offset, this_len);
flush_dcache_page(page);
- kunmap_atomic(dst, KM_USER0);
+ kunmap_atomic(dst, KM_USER1);
+ buf->ops->unmap(pipe, buf, src);
}
- ret = mapping->a_ops->commit_write(file, page, 0, sd->len);
- if (ret == AOP_TRUNCATED_PAGE) {
+ ret = mapping->a_ops->commit_write(file, page, offset, offset+this_len);
+ if (!ret) {
+ /*
+ * Return the number of bytes written and mark page as
+ * accessed, we are now done!
+ */
+ ret = this_len;
+ mark_page_accessed(page);
+ balance_dirty_pages_ratelimited(mapping);
+ } else if (ret == AOP_TRUNCATED_PAGE) {
page_cache_release(page);
goto find_page;
- } else if (ret)
- goto out;
-
- mark_page_accessed(page);
- balance_dirty_pages_ratelimited(mapping);
-out:
- if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {
- page_cache_release(page);
- unlock_page(page);
}
+out:
+ 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 *);
-
/*
* 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)
+ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
+ loff_t *ppos, size_t len, unsigned int flags,
+ splice_actor *actor)
{
int ret, do_wakeup, err;
struct splice_desc sd;
sd.len = sd.total_len;
err = actor(pipe, buf, &sd);
- if (err) {
+ if (err <= 0) {
if (!ret && err != -ENODATA)
ret = err;
break;
}
- ret += sd.len;
- buf->offset += sd.len;
- buf->len -= sd.len;
+ ret += err;
+ buf->offset += err;
+ buf->len -= err;
+
+ sd.len -= err;
+ sd.pos += err;
+ sd.total_len -= err;
+ if (sd.len)
+ continue;
if (!buf->len) {
buf->ops = NULL;
do_wakeup = 1;
}
- sd.pos += sd.len;
- sd.total_len -= sd.len;
if (!sd.total_len)
break;
}
struct address_space *mapping = out->f_mapping;
ssize_t ret;
- ret = move_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
-
- /*
- * If file or inode is SYNC and we actually wrote some data, sync it.
- */
- if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(mapping->host))
- && ret > 0) {
+ ret = splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
+ if (ret > 0) {
struct inode *inode = mapping->host;
- int err;
- mutex_lock(&inode->i_mutex);
- err = generic_osync_inode(mapping->host, mapping,
- OSYNC_METADATA|OSYNC_DATA);
- mutex_unlock(&inode->i_mutex);
+ *ppos += ret;
- if (err)
- ret = err;
+ /*
+ * 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 pipe_inode_info *pipe, struct file *out,
loff_t *ppos, size_t len, unsigned int flags)
{
- return move_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
+ return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
}
EXPORT_SYMBOL(generic_splice_sendpage);
/*
* 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
+ * out of the pipe right after the splice_to_pipe(). So set
* PIPE_READERS appropriately.
*/
pipe->readers = 1;
{
struct pipe_inode_info *pipe;
loff_t offset, *off;
+ long ret;
pipe = in->f_dentry->d_inode->i_pipe;
if (pipe) {
} else
off = &out->f_pos;
- return do_splice_from(pipe, out, off, len, flags);
+ 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 = out->f_dentry->d_inode->i_pipe;
} else
off = &in->f_pos;
- return do_splice_to(in, off, 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;
}
+/*
+ * Map an iov into an array of pages and offset/length tupples. With the
+ * partial_page structure, we can map several non-contiguous ranges into
+ * our ones pages[] map instead of splitting that operation into pieces.
+ * Could easily be exported as a generic helper for other users, in which
+ * case one would probably want to add a 'max_nr_pages' parameter as well.
+ */
+static int get_iovec_page_array(const struct iovec __user *iov,
+ unsigned int nr_vecs, struct page **pages,
+ struct partial_page *partial, int aligned)
+{
+ int buffers = 0, error = 0;
+
+ /*
+ * It's ok to take the mmap_sem for reading, even
+ * across a "get_user()".
+ */
+ down_read(¤t->mm->mmap_sem);
+
+ while (nr_vecs) {
+ unsigned long off, npages;
+ void __user *base;
+ size_t len;
+ int i;
+
+ /*
+ * Get user address base and length for this iovec.
+ */
+ error = get_user(base, &iov->iov_base);
+ if (unlikely(error))
+ break;
+ error = get_user(len, &iov->iov_len);
+ if (unlikely(error))
+ break;
+
+ /*
+ * Sanity check this iovec. 0 read succeeds.
+ */
+ if (unlikely(!len))
+ break;
+ error = -EFAULT;
+ if (unlikely(!base))
+ break;
+
+ /*
+ * Get this base offset and number of pages, then map
+ * in the user pages.
+ */
+ off = (unsigned long) base & ~PAGE_MASK;
+
+ /*
+ * If asked for alignment, the offset must be zero and the
+ * length a multiple of the PAGE_SIZE.
+ */
+ error = -EINVAL;
+ if (aligned && (off || len & ~PAGE_MASK))
+ break;
+
+ npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ if (npages > PIPE_BUFFERS - buffers)
+ npages = PIPE_BUFFERS - buffers;
+
+ error = get_user_pages(current, current->mm,
+ (unsigned long) base, npages, 0, 0,
+ &pages[buffers], NULL);
+
+ if (unlikely(error <= 0))
+ break;
+
+ /*
+ * Fill this contiguous range into the partial page map.
+ */
+ for (i = 0; i < error; i++) {
+ const int plen = min_t(size_t, len, PAGE_SIZE - off);
+
+ partial[buffers].offset = off;
+ partial[buffers].len = plen;
+
+ off = 0;
+ len -= plen;
+ buffers++;
+ }
+
+ /*
+ * We didn't complete this iov, stop here since it probably
+ * means we have to move some of this into a pipe to
+ * be able to continue.
+ */
+ if (len)
+ break;
+
+ /*
+ * Don't continue if we mapped fewer pages than we asked for,
+ * or if we mapped the max number of pages that we have
+ * room for.
+ */
+ if (error < npages || buffers == PIPE_BUFFERS)
+ break;
+
+ nr_vecs--;
+ iov++;
+ }
+
+ up_read(¤t->mm->mmap_sem);
+
+ if (buffers)
+ return buffers;
+
+ return error;
+}
+
+/*
+ * vmsplice splices a user address range into a pipe. It can be thought of
+ * as splice-from-memory, where the regular splice is splice-from-file (or
+ * to file). In both cases the output is a pipe, naturally.
+ *
+ * Note that vmsplice only supports splicing _from_ user memory to a pipe,
+ * not the other way around. Splicing from user memory is a simple operation
+ * that can be supported without any funky alignment restrictions or nasty
+ * vm tricks. We simply map in the user memory and fill them into a pipe.
+ * The reverse isn't quite as easy, though. There are two possible solutions
+ * for that:
+ *
+ * - memcpy() the data internally, at which point we might as well just
+ * do a regular read() on the buffer anyway.
+ * - Lots of nasty vm tricks, that are neither fast nor flexible (it
+ * has restriction limitations on both ends of the pipe).
+ *
+ * Alas, it isn't here.
+ *
+ */
+static long do_vmsplice(struct file *file, const struct iovec __user *iov,
+ unsigned long nr_segs, unsigned int flags)
+{
+ struct pipe_inode_info *pipe = file->f_dentry->d_inode->i_pipe;
+ struct page *pages[PIPE_BUFFERS];
+ struct partial_page partial[PIPE_BUFFERS];
+ struct splice_pipe_desc spd = {
+ .pages = pages,
+ .partial = partial,
+ .flags = flags,
+ .ops = &user_page_pipe_buf_ops,
+ };
+
+ if (unlikely(!pipe))
+ return -EBADF;
+ if (unlikely(nr_segs > UIO_MAXIOV))
+ return -EINVAL;
+ else if (unlikely(!nr_segs))
+ return 0;
+
+ spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial,
+ flags & SPLICE_F_GIFT);
+ if (spd.nr_pages <= 0)
+ return spd.nr_pages;
+
+ return splice_to_pipe(pipe, &spd);
+}
+
+asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov,
+ unsigned long nr_segs, unsigned int flags)
+{
+ struct file *file;
+ long error;
+ int fput;
+
+ error = -EBADF;
+ file = fget_light(fd, &fput);
+ if (file) {
+ if (file->f_mode & FMODE_WRITE)
+ error = do_vmsplice(file, iov, nr_segs, flags);
+
+ fput_light(file, fput);
+ }
+
+ return error;
+}
+
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)
size_t len, unsigned int flags)
{
struct pipe_buffer *ibuf, *obuf;
- int ret = 0, do_wakeup = 0, i;
+ int ret, do_wakeup, i, ipipe_first;
+
+ ret = do_wakeup = ipipe_first = 0;
/*
* Potential ABBA deadlock, work around it by ordering lock
* 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 {
obuf = opipe->bufs + nbuf;
*obuf = *ibuf;
+ /*
+ * Don't inherit the gift flag, we need to
+ * prevent multiple steals of this page.
+ */
+ obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
+
if (obuf->len > len)
obuf->len = len;
/*
* We have input available, but no output room.
- * If we already copied data, return that.
+ * 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) {
+ if ((flags & SPLICE_F_NONBLOCK) || !ipipe_first) {
if (!ret)
ret = -EAGAIN;
break;
if (ret)
break;
}
- if (flags & SPLICE_F_NONBLOCK) {
+ /*
+ * 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;
git.openpandora.org / pandora-kernel.git / blobdiff