From: Al Viro Date: Thu, 3 Apr 2014 19:05:18 +0000 (-0400) Subject: new helper: copy_page_from_iter() X-Git-Tag: next-20140428~60^2~14 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=83f241c03065c7824d9fd964709d9c92bf85c13f;p=karo-tx-linux.git new helper: copy_page_from_iter() parallel to copy_page_to_iter(). pipe_write() switched to it (and became ->write_iter()). Signed-off-by: Al Viro --- diff --git a/fs/pipe.c b/fs/pipe.c index 05ccb00cb407..21981e58e2a6 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -116,50 +116,6 @@ void pipe_wait(struct pipe_inode_info *pipe) pipe_lock(pipe); } -static int -pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len, - int atomic) -{ - unsigned long copy; - - while (len > 0) { - while (!iov->iov_len) - iov++; - copy = min_t(unsigned long, len, iov->iov_len); - - if (atomic) { - if (__copy_from_user_inatomic(to, iov->iov_base, copy)) - return -EFAULT; - } else { - if (copy_from_user(to, iov->iov_base, copy)) - return -EFAULT; - } - to += copy; - len -= copy; - iov->iov_base += copy; - iov->iov_len -= copy; - } - return 0; -} - -/* - * Pre-fault in the user memory, so we can use atomic copies. - */ -static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len) -{ - while (!iov->iov_len) - iov++; - - while (len > 0) { - unsigned long this_len; - - this_len = min_t(unsigned long, len, iov->iov_len); - fault_in_pages_readable(iov->iov_base, this_len); - len -= this_len; - iov++; - } -} - static void anon_pipe_buf_release(struct pipe_inode_info *pipe, struct pipe_buffer *buf) { @@ -380,24 +336,19 @@ static inline int is_packetized(struct file *file) } static ssize_t -pipe_write(struct kiocb *iocb, const struct iovec *_iov, - unsigned long nr_segs, loff_t ppos) +pipe_write(struct kiocb *iocb, struct iov_iter *from) { struct file *filp = iocb->ki_filp; struct pipe_inode_info *pipe = filp->private_data; - ssize_t ret; - int do_wakeup; - struct iovec *iov = (struct iovec *)_iov; - size_t total_len; + ssize_t ret = 0; + int do_wakeup = 0; + size_t total_len = iov_iter_count(from); ssize_t chars; - total_len = iov_length(iov, nr_segs); /* Null write succeeds. */ if (unlikely(total_len == 0)) return 0; - do_wakeup = 0; - ret = 0; __pipe_lock(pipe); if (!pipe->readers) { @@ -416,38 +367,19 @@ pipe_write(struct kiocb *iocb, const struct iovec *_iov, int offset = buf->offset + buf->len; if (ops->can_merge && offset + chars <= PAGE_SIZE) { - int error, atomic = 1; - void *addr; - - error = ops->confirm(pipe, buf); + int error = ops->confirm(pipe, buf); if (error) goto out; - iov_fault_in_pages_read(iov, chars); -redo1: - if (atomic) - addr = kmap_atomic(buf->page); - else - addr = kmap(buf->page); - error = pipe_iov_copy_from_user(offset + addr, iov, - chars, atomic); - if (atomic) - kunmap_atomic(addr); - else - kunmap(buf->page); - ret = error; - do_wakeup = 1; - if (error) { - if (atomic) { - atomic = 0; - goto redo1; - } + ret = copy_page_from_iter(buf->page, offset, chars, from); + if (unlikely(ret < chars)) { + error = -EFAULT; goto out; } + do_wakeup = 1; buf->len += chars; - total_len -= chars; ret = chars; - if (!total_len) + if (!iov_iter_count(from)) goto out; } } @@ -466,8 +398,7 @@ redo1: int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1); struct pipe_buffer *buf = pipe->bufs + newbuf; struct page *page = pipe->tmp_page; - char *src; - int error, atomic = 1; + int copied; if (!page) { page = alloc_page(GFP_HIGHUSER); @@ -483,40 +414,19 @@ redo1: * FIXME! Is this really true? */ do_wakeup = 1; - chars = PAGE_SIZE; - if (chars > total_len) - chars = total_len; - - iov_fault_in_pages_read(iov, chars); -redo2: - if (atomic) - src = kmap_atomic(page); - else - src = kmap(page); - - error = pipe_iov_copy_from_user(src, iov, chars, - atomic); - if (atomic) - kunmap_atomic(src); - else - kunmap(page); - - if (unlikely(error)) { - if (atomic) { - atomic = 0; - goto redo2; - } + copied = copy_page_from_iter(page, 0, PAGE_SIZE, from); + if (unlikely(copied < PAGE_SIZE && iov_iter_count(from))) { if (!ret) - ret = error; + ret = -EFAULT; break; } - ret += chars; + ret += copied; /* Insert it into the buffer array */ buf->page = page; buf->ops = &anon_pipe_buf_ops; buf->offset = 0; - buf->len = chars; + buf->len = copied; buf->flags = 0; if (is_packetized(filp)) { buf->ops = &packet_pipe_buf_ops; @@ -525,8 +435,7 @@ redo2: pipe->nrbufs = ++bufs; pipe->tmp_page = NULL; - total_len -= chars; - if (!total_len) + if (!iov_iter_count(from)) break; } if (bufs < pipe->buffers) @@ -1040,8 +949,8 @@ const struct file_operations pipefifo_fops = { .llseek = no_llseek, .read = new_sync_read, .read_iter = pipe_read, - .write = do_sync_write, - .aio_write = pipe_write, + .write = new_sync_write, + .write_iter = pipe_write, .poll = pipe_poll, .unlocked_ioctl = pipe_ioctl, .release = pipe_release, diff --git a/include/linux/uio.h b/include/linux/uio.h index 532f59d0adbb..66012352d333 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -68,6 +68,8 @@ int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes); size_t iov_iter_single_seg_count(const struct iov_iter *i); size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, struct iov_iter *i); +size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, + struct iov_iter *i); unsigned long iov_iter_alignment(const struct iov_iter *i); void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov, unsigned long nr_segs, size_t count); diff --git a/mm/iov_iter.c b/mm/iov_iter.c index a5c691c1a283..081e3273085b 100644 --- a/mm/iov_iter.c +++ b/mm/iov_iter.c @@ -82,6 +82,84 @@ done: } EXPORT_SYMBOL(copy_page_to_iter); +size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, + struct iov_iter *i) +{ + size_t skip, copy, left, wanted; + const struct iovec *iov; + char __user *buf; + void *kaddr, *to; + + if (unlikely(bytes > i->count)) + bytes = i->count; + + if (unlikely(!bytes)) + return 0; + + wanted = bytes; + iov = i->iov; + skip = i->iov_offset; + buf = iov->iov_base + skip; + copy = min(bytes, iov->iov_len - skip); + + if (!fault_in_pages_readable(buf, copy)) { + kaddr = kmap_atomic(page); + to = kaddr + offset; + + /* first chunk, usually the only one */ + left = __copy_from_user_inatomic(to, buf, copy); + copy -= left; + skip += copy; + to += copy; + bytes -= copy; + + while (unlikely(!left && bytes)) { + iov++; + buf = iov->iov_base; + copy = min(bytes, iov->iov_len); + left = __copy_from_user_inatomic(to, buf, copy); + copy -= left; + skip = copy; + to += copy; + bytes -= copy; + } + if (likely(!bytes)) { + kunmap_atomic(kaddr); + goto done; + } + offset = to - kaddr; + buf += copy; + kunmap_atomic(kaddr); + copy = min(bytes, iov->iov_len - skip); + } + /* Too bad - revert to non-atomic kmap */ + kaddr = kmap(page); + to = kaddr + offset; + left = __copy_from_user(to, buf, copy); + copy -= left; + skip += copy; + to += copy; + bytes -= copy; + while (unlikely(!left && bytes)) { + iov++; + buf = iov->iov_base; + copy = min(bytes, iov->iov_len); + left = __copy_from_user(to, buf, copy); + copy -= left; + skip = copy; + to += copy; + bytes -= copy; + } + kunmap(page); +done: + i->count -= wanted - bytes; + i->nr_segs -= iov - i->iov; + i->iov = iov; + i->iov_offset = skip; + return wanted - bytes; +} +EXPORT_SYMBOL(copy_page_from_iter); + static size_t __iovec_copy_from_user_inatomic(char *vaddr, const struct iovec *iov, size_t base, size_t bytes) {