]> bbs.cooldavid.org Git - net-next-2.6.git/blobdiff - fs/splice.c
[PATCH] introduce a "kernel-internal pipe object" abstraction
[net-next-2.6.git] / fs / splice.c
index b5fb2f3e3ac6c3525c6567f56288ea4553e2568d..ed91a62402e028e81e4ebedb895fae6556b17a38 100644 (file)
@@ -67,16 +67,7 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *info,
        if (!remove_mapping(mapping, page))
                return 1;
 
-       if (PageLRU(page)) {
-               struct zone *zone = page_zone(page);
-
-               spin_lock_irq(&zone->lru_lock);
-               BUG_ON(!PageLRU(page));
-               __ClearPageLRU(page);
-               del_page_from_lru(zone, page);
-               spin_unlock_irq(&zone->lru_lock);
-       }
-
+       buf->flags |= PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU;
        return 0;
 }
 
@@ -85,6 +76,7 @@ static void page_cache_pipe_buf_release(struct pipe_inode_info *info,
 {
        page_cache_release(buf->page);
        buf->page = NULL;
+       buf->flags &= ~(PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU);
 }
 
 static void *page_cache_pipe_buf_map(struct file *file,
@@ -92,26 +84,43 @@ 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);
+
+               /*
+                * Page got truncated/unhashed. This will cause a 0-byte
+                * splice, if this is the first page
+                */
+               if (!page->mapping) {
+                       err = -ENODATA;
+                       goto error;
+               }
 
-       if (!page->mapping) {
+               /*
+                * 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)
 {
-       unlock_page(buf->page);
        kunmap(buf->page);
 }
 
@@ -127,34 +136,33 @@ static struct pipe_buf_operations page_cache_pipe_buf_ops = {
  * 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 inode *inode, struct page **pages,
+static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages,
                            int nr_pages, unsigned long offset,
                            unsigned long len, 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;
+               bufs = pipe->nrbufs;
                if (bufs < PIPE_BUFFERS) {
-                       int newbuf = (info->curbuf + bufs) & (PIPE_BUFFERS - 1);
-                       struct pipe_buffer *buf = info->bufs + newbuf;
+                       int newbuf = (pipe->curbuf + bufs) & (PIPE_BUFFERS - 1);
+                       struct pipe_buffer *buf = pipe->bufs + newbuf;
                        struct page *page = pages[i++];
                        unsigned long this_len;
 
@@ -166,7 +174,7 @@ static ssize_t move_to_pipe(struct inode *inode, struct page **pages,
                        buf->offset = offset;
                        buf->len = this_len;
                        buf->ops = &page_cache_pipe_buf_ops;
-                       info->nrbufs = ++bufs;
+                       pipe->nrbufs = ++bufs;
                        do_wakeup = 1;
 
                        ret += this_len;
@@ -195,22 +203,26 @@ static ssize_t move_to_pipe(struct inode *inode, struct page **pages,
                }
 
                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)
@@ -219,15 +231,16 @@ static ssize_t move_to_pipe(struct inode *inode, struct page **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, 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];
+       struct page *pages[PIPE_BUFFERS];
        struct page *page;
-       pgoff_t index, pidx;
-       int i, j;
+       pgoff_t index;
+       int i;
 
        index = in->f_pos >> PAGE_CACHE_SHIFT;
        offset = in->f_pos & ~PAGE_CACHE_MASK;
@@ -237,46 +250,21 @@ static int __generic_file_splice_read(struct file *in, struct inode *pipe,
                nr_pages = PIPE_BUFFERS;
 
        /*
-        * initiate read-ahead on this page range
-        */
-       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).
-        */
-       i = find_get_pages(mapping, index, nr_pages, pages);
-
-       /*
-        * common case - we found all pages and they are contiguous,
-        * kick them off
+        * 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.
         */
-       if (i && (pages[i - 1]->index == index + i - 1))
-               goto splice_them;
-
-       /*
-        * fill shadow[] with pages at the right locations, so we only
-        * have to fill holes
-        */
-       memset(shadow, 0, nr_pages * sizeof(struct page *));
-       for (j = 0; j < i; j++)
-               shadow[pages[j]->index - index] = pages[j];
+       if (!offset || nr_pages > 1)
+               do_page_cache_readahead(mapping, in, index, nr_pages);
 
        /*
         * now fill in the holes
         */
-       for (i = 0, pidx = index; i < nr_pages; pidx++, i++) {
-               int error;
-
-               if (shadow[i])
-                       continue;
-
+       for (i = 0; i < nr_pages; i++, index++) {
                /*
                 * no page there, look one up / create it
                 */
-               page = find_or_create_page(mapping, pidx,
+               page = find_or_create_page(mapping, index,
                                                   mapping_gfp_mask(mapping));
                if (!page)
                        break;
@@ -284,31 +272,20 @@ static int __generic_file_splice_read(struct file *in, struct inode *pipe,
                if (PageUptodate(page))
                        unlock_page(page);
                else {
-                       error = mapping->a_ops->readpage(in, page);
+                       int error = mapping->a_ops->readpage(in, page);
 
                        if (unlikely(error)) {
                                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]);
-               }
-               return 0;
+               pages[i] = page;
        }
 
-       memcpy(pages, shadow, i * sizeof(struct page *));
+       if (i)
+               return move_to_pipe(pipe, pages, i, offset, len, flags);
 
-       /*
-        * Now we splice them into the pipe..
-        */
-splice_them:
-       return move_to_pipe(pipe, pages, i, offset, len, flags);
+       return 0;
 }
 
 /**
@@ -321,7 +298,7 @@ splice_them:
  * Will read pages from given file and fill them into a pipe.
  *
  */
-ssize_t generic_file_splice_read(struct file *in, struct inode *pipe,
+ssize_t generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
                                 size_t len, unsigned int flags)
 {
        ssize_t spliced;
@@ -329,6 +306,7 @@ ssize_t generic_file_splice_read(struct file *in, struct inode *pipe,
 
        ret = 0;
        spliced = 0;
+
        while (len) {
                ret = __generic_file_splice_read(in, pipe, len, flags);
 
@@ -414,14 +392,15 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
 {
        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;
        char *src;
-       int ret, stolen;
+       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))
@@ -429,7 +408,6 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
 
        index = sd->pos >> PAGE_CACHE_SHIFT;
        offset = sd->pos & ~PAGE_CACHE_MASK;
-       stolen = 0;
 
        /*
         * reuse buf page, if SPLICE_F_MOVE is set
@@ -442,18 +420,21 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
                if (buf->ops->steal(info, buf))
                        goto find_page;
 
+               /*
+                * this will also set the page locked
+                */
                page = buf->page;
-               stolen = 1;
-               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));
+               page = find_or_create_page(mapping, index, gfp_mask);
                if (!page)
-                       goto out;
+                       goto out_nomem;
 
                /*
                 * If the page is uptodate, it is also locked. If it isn't
@@ -494,7 +475,7 @@ find_page:
        } else if (ret)
                goto out;
 
-       if (!stolen) {
+       if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {
                char *dst = kmap_atomic(page, KM_USER0);
 
                memcpy(dst + offset, src + buf->offset, sd->len);
@@ -509,12 +490,14 @@ find_page:
        } else if (ret)
                goto out;
 
+       mark_page_accessed(page);
        balance_dirty_pages_ratelimited(mapping);
 out:
-       if (!stolen) {
+       if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {
                page_cache_release(page);
                unlock_page(page);
        }
+out_nomem:
        buf->ops->unmap(info, buf);
        return ret;
 }
@@ -527,11 +510,10 @@ typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
  * 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 inode *inode, struct file *out,
+static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
                              size_t len, unsigned int flags,
                              splice_actor *actor)
 {
-       struct pipe_inode_info *info;
        int ret, do_wakeup, err;
        struct splice_desc sd;
 
@@ -543,22 +525,22 @@ static ssize_t move_from_pipe(struct inode *inode, struct file *out,
        sd.file = out;
        sd.pos = out->f_pos;
 
-       mutex_lock(PIPE_MUTEX(*inode));
+       if (pipe->inode)
+               mutex_lock(&pipe->inode->i_mutex);
 
-       info = inode->i_pipe;
        for (;;) {
-               int bufs = info->nrbufs;
+               int bufs = pipe->nrbufs;
 
                if (bufs) {
-                       int curbuf = info->curbuf;
-                       struct pipe_buffer *buf = info->bufs + curbuf;
+                       int curbuf = pipe->curbuf;
+                       struct pipe_buffer *buf = pipe->bufs + 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;
@@ -571,10 +553,10 @@ static ssize_t move_from_pipe(struct inode *inode, struct file *out,
                        buf->len -= sd.len;
                        if (!buf->len) {
                                buf->ops = NULL;
-                               ops->release(info, buf);
+                               ops->release(pipe, buf);
                                curbuf = (curbuf + 1) & (PIPE_BUFFERS - 1);
-                               info->curbuf = curbuf;
-                               info->nrbufs = --bufs;
+                               pipe->curbuf = curbuf;
+                               pipe->nrbufs = --bufs;
                                do_wakeup = 1;
                        }
 
@@ -586,9 +568,9 @@ static ssize_t move_from_pipe(struct inode *inode, struct file *out,
 
                if (bufs)
                        continue;
-               if (!PIPE_WRITERS(*inode))
+               if (!pipe->writers)
                        break;
-               if (!PIPE_WAITING_WRITERS(*inode)) {
+               if (!pipe->waiting_writers) {
                        if (ret)
                                break;
                }
@@ -606,19 +588,24 @@ static ssize_t move_from_pipe(struct inode *inode, struct file *out,
                }
 
                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);
@@ -630,7 +617,7 @@ static ssize_t move_from_pipe(struct inode *inode, struct file *out,
 
 /**
  * generic_file_splice_write - splice data from a pipe to a file
- * @inode:     pipe inode
+ * @pipe:      pipe info
  * @out:       file to write to
  * @len:       number of bytes to splice
  * @flags:     splice modifier flags
@@ -639,11 +626,14 @@ static ssize_t move_from_pipe(struct inode *inode, struct file *out,
  * the given pipe inode to the given file.
  *
  */
-ssize_t generic_file_splice_write(struct inode *inode, struct file *out,
-                                 size_t len, unsigned int flags)
+ssize_t
+generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
+                         size_t len, unsigned int flags)
 {
        struct address_space *mapping = out->f_mapping;
-       ssize_t ret = move_from_pipe(inode, out, len, flags, pipe_to_file);
+       ssize_t ret;
+
+       ret = move_from_pipe(pipe, out, len, flags, pipe_to_file);
 
        /*
         * if file or inode is SYNC and we actually wrote some data, sync it
@@ -678,10 +668,10 @@ EXPORT_SYMBOL(generic_file_splice_write);
  * is involved.
  *
  */
-ssize_t generic_splice_sendpage(struct inode *inode, struct file *out,
+ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
                                size_t len, unsigned int flags)
 {
-       return move_from_pipe(inode, out, len, flags, pipe_to_sendpage);
+       return move_from_pipe(pipe, out, len, flags, pipe_to_sendpage);
 }
 
 EXPORT_SYMBOL(generic_splice_sendpage);
@@ -689,8 +679,8 @@ EXPORT_SYMBOL(generic_splice_sendpage);
 /*
  * Attempt to initiate a splice from pipe to file.
  */
-static long do_splice_from(struct inode *pipe, struct file *out, size_t len,
-                          unsigned int flags)
+static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
+                          size_t len, unsigned int flags)
 {
        loff_t pos;
        int ret;
@@ -712,8 +702,8 @@ static long do_splice_from(struct inode *pipe, struct file *out, size_t len,
 /*
  * Attempt to initiate a splice from a file to a pipe.
  */
-static long do_splice_to(struct file *in, struct inode *pipe, size_t len,
-                        unsigned int flags)
+static long do_splice_to(struct file *in, struct pipe_inode_info *pipe,
+                        size_t len, unsigned int flags)
 {
        loff_t pos, isize, left;
        int ret;
@@ -746,14 +736,14 @@ static long do_splice_to(struct file *in, struct inode *pipe, size_t len,
 static long do_splice(struct file *in, struct file *out, size_t len,
                      unsigned int flags)
 {
-       struct inode *pipe;
+       struct pipe_inode_info *pipe;
 
-       pipe = in->f_dentry->d_inode;
-       if (pipe->i_pipe)
+       pipe = in->f_dentry->d_inode->i_pipe;
+       if (pipe)
                return do_splice_from(pipe, out, len, flags);
 
-       pipe = out->f_dentry->d_inode;
-       if (pipe->i_pipe)
+       pipe = out->f_dentry->d_inode->i_pipe;
+       if (pipe)
                return do_splice_to(in, pipe, len, flags);
 
        return -EINVAL;