X-Git-Url: http://git.rot13.org/?a=blobdiff_plain;f=fs%2Fsplice.c;h=59a941d404d9c60b46a83ced4472ee915a7fe93c;hb=f563d53c30f3e60cde3a194cc1a87284ee0b3366;hp=53fc2082a4681fdc311adcf0596f11fb6d45a8c5;hpb=49c13b51a15f1ba9f6d47e26e4a3886c4f3931e2;p=powerpc.git diff --git a/fs/splice.c b/fs/splice.c index 53fc2082a4..59a941d404 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -164,7 +164,7 @@ static const struct pipe_buf_operations user_page_pipe_buf_ops = { * @spd: data to fill * * Description: - * @spd contains a map of pages and len/offset tupples, a long with + * @spd contains a map of pages and len/offset tuples, along with * the struct pipe_buf_operations associated with these pages. This * function will link that data to the pipe. * @@ -265,7 +265,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, unsigned int flags) { struct address_space *mapping = in->f_mapping; - unsigned int loff, nr_pages; + unsigned int loff, nr_pages, req_pages; struct page *pages[PIPE_BUFFERS]; struct partial_page partial[PIPE_BUFFERS]; struct page *page; @@ -281,28 +281,24 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, index = *ppos >> 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; - - /* - * Don't try to 2nd guess the read-ahead logic, call into - * page_cache_readahead() like the page cache reads would do. - */ - page_cache_readahead(mapping, &in->f_ra, in, index, nr_pages); + req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; + nr_pages = min(req_pages, (unsigned)PIPE_BUFFERS); /* * Lookup the (hopefully) full range of pages we need. */ spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages); + index += spd.nr_pages; /* * If find_get_pages_contig() returned fewer pages than we needed, - * allocate the rest and fill in the holes. + * readahead/allocate the rest and fill in the holes. */ + if (spd.nr_pages < nr_pages) + page_cache_sync_readahead(mapping, &in->f_ra, in, + index, req_pages - spd.nr_pages); + error = 0; - index += spd.nr_pages; while (spd.nr_pages < nr_pages) { /* * Page could be there, find_get_pages_contig() breaks on @@ -310,12 +306,6 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, */ page = find_get_page(mapping, index); if (!page) { - /* - * 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. */ @@ -361,6 +351,10 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); page = pages[page_nr]; + if (PageReadahead(page)) + page_cache_async_readahead(mapping, &in->f_ra, in, + page, index, req_pages - page_nr); + /* * If the page isn't uptodate, we may need to start io on it */ @@ -453,6 +447,7 @@ fill_it: */ while (page_nr < nr_pages) page_cache_release(pages[page_nr++]); + in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; if (spd.nr_pages) return splice_to_pipe(pipe, &spd); @@ -568,7 +563,7 @@ static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf, struct address_space *mapping = file->f_mapping; unsigned int offset, this_len; struct page *page; - pgoff_t index; + void *fsdata; int ret; /* @@ -578,49 +573,16 @@ static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *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; -find_page: - page = find_lock_page(mapping, index); - if (!page) { - ret = -ENOMEM; - page = page_cache_alloc_cold(mapping); - if (unlikely(!page)) - goto out_ret; - - /* - * This will also lock the page - */ - ret = add_to_page_cache_lru(page, mapping, index, - GFP_KERNEL); - if (unlikely(ret)) - goto out; - } - - 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); - 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_ret; - } + ret = pagecache_write_begin(file, mapping, sd->pos, this_len, + AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); + if (unlikely(ret)) + goto out; if (buf->page != page) { /* @@ -634,30 +596,9 @@ find_page: kunmap_atomic(dst, KM_USER1); buf->ops->unmap(pipe, buf, src); } - - ret = mapping->a_ops->commit_write(file, page, offset, offset+this_len); - if (ret) { - if (ret == AOP_TRUNCATED_PAGE) { - page_cache_release(page); - goto find_page; - } - if (ret < 0) - goto out; - /* - * Partial write has happened, so 'ret' already initialized by - * number of bytes written, Where is nothing we have to do here. - */ - } else - ret = this_len; - /* - * Return the number of bytes written and mark page as - * accessed, we are now done! - */ - mark_page_accessed(page); + ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len, + page, fsdata); out: - page_cache_release(page); - unlock_page(page); -out_ret: return ret; } @@ -1004,7 +945,7 @@ static long do_splice_to(struct file *in, loff_t *ppos, * Description: * This is a special case helper to splice directly between two * points, without requiring an explicit pipe. Internally an allocated - * pipe is cached in the process, and reused during the life time of + * pipe is cached in the process, and reused during the lifetime of * that process. * */ @@ -1227,6 +1168,33 @@ static long do_splice(struct file *in, loff_t __user *off_in, return -EINVAL; } +/* + * Do a copy-from-user while holding the mmap_semaphore for reading, in a + * manner safe from deadlocking with simultaneous mmap() (grabbing mmap_sem + * for writing) and page faulting on the user memory pointed to by src. + * This assumes that we will very rarely hit the partial != 0 path, or this + * will not be a win. + */ +static int copy_from_user_mmap_sem(void *dst, const void __user *src, size_t n) +{ + int partial; + + pagefault_disable(); + partial = __copy_from_user_inatomic(dst, src, n); + pagefault_enable(); + + /* + * Didn't copy everything, drop the mmap_sem and do a faulting copy + */ + if (unlikely(partial)) { + up_read(¤t->mm->mmap_sem); + partial = copy_from_user(dst, src, n); + down_read(¤t->mm->mmap_sem); + } + + return partial; +} + /* * 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 @@ -1240,31 +1208,26 @@ static int get_iovec_page_array(const struct iovec __user *iov, { 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; + struct iovec entry; 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)) + error = -EFAULT; + if (copy_from_user_mmap_sem(&entry, iov, sizeof(entry))) break; + base = entry.iov_base; + len = entry.iov_len; + /* * Sanity check this iovec. 0 read succeeds. */ + error = 0; if (unlikely(!len)) break; error = -EFAULT; @@ -1372,10 +1335,10 @@ static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len)) ret = -EFAULT; + buf->ops->unmap(pipe, buf, src); out: if (ret > 0) sd->u.userptr += ret; - buf->ops->unmap(pipe, buf, src); return ret; }