2 files changed, 236 insertions, 60 deletions

diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 63e91c7..eeb789d 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -465,6 +465,8 @@ extern int SMBencrypt(unsigned char *passwd, const unsigned char *c8,
 /* asynchronous read support */
 struct cifs_readdata {
 	struct kref			refcount;
+	struct list_head		list;
+	struct completion		done;
 	struct cifsFileInfo		*cfile;
 	struct address_space		*mapping;
 	__u64				offset;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index d2a4259..4b5fe39 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2348,6 +2348,8 @@ cifs_readdata_alloc(unsigned int nr_vecs, work_func_t complete)
 			sizeof(struct kvec) * nr_vecs, GFP_KERNEL);
 	if (rdata != NULL) {
 		kref_init(&rdata->refcount);
+		INIT_LIST_HEAD(&rdata->list);
+		init_completion(&rdata->done);
 		INIT_WORK(&rdata->work, complete);
 		INIT_LIST_HEAD(&rdata->pages);
 	}
@@ -2367,6 +2369,45 @@ cifs_readdata_release(struct kref *refcount)
 }
 
 static int
+cifs_read_allocate_pages(struct list_head *list, unsigned int npages)
+{
+	int rc = 0;
+	struct page *page, *tpage;
+	unsigned int i;
+
+	for (i = 0; i < npages; i++) {
+		page = alloc_page(GFP_KERNEL|__GFP_HIGHMEM);
+		if (!page) {
+			rc = -ENOMEM;
+			break;
+		}
+		list_add(&page->lru, list);
+	}
+
+	if (rc) {
+		list_for_each_entry_safe(page, tpage, list, lru) {
+			list_del(&page->lru);
+			put_page(page);
+		}
+	}
+	return rc;
+}
+
+static void
+cifs_uncached_readdata_release(struct kref *refcount)
+{
+	struct page *page, *tpage;
+	struct cifs_readdata *rdata = container_of(refcount,
+					struct cifs_readdata, refcount);
+
+	list_for_each_entry_safe(page, tpage, &rdata->pages, lru) {
+		list_del(&page->lru);
+		put_page(page);
+	}
+	cifs_readdata_release(refcount);
+}
+
+static int
 cifs_retry_async_readv(struct cifs_readdata *rdata)
 {
 	int rc;
@@ -2383,24 +2424,139 @@ cifs_retry_async_readv(struct cifs_readdata *rdata)
 	return rc;
 }
 
+/**
+ * cifs_readdata_to_iov - copy data from pages in response to an iovec
+ * @rdata:	the readdata response with list of pages holding data
+ * @iov:	vector in which we should copy the data
+ * @nr_segs:	number of segments in vector
+ * @offset:	offset into file of the first iovec
+ * @copied:	used to return the amount of data copied to the iov
+ *
+ * This function copies data from a list of pages in a readdata response into
+ * an array of iovecs. It will first calculate where the data should go
+ * based on the info in the readdata and then copy the data into that spot.
+ */
+static ssize_t
+cifs_readdata_to_iov(struct cifs_readdata *rdata, const struct iovec *iov,
+			unsigned long nr_segs, loff_t offset, ssize_t *copied)
+{
+	int rc = 0;
+	struct iov_iter ii;
+	size_t pos = rdata->offset - offset;
+	struct page *page, *tpage;
+	ssize_t remaining = rdata->bytes;
+	unsigned char *pdata;
+
+	/* set up iov_iter and advance to the correct offset */
+	iov_iter_init(&ii, iov, nr_segs, iov_length(iov, nr_segs), 0);
+	iov_iter_advance(&ii, pos);
+
+	*copied = 0;
+	list_for_each_entry_safe(page, tpage, &rdata->pages, lru) {
+		ssize_t copy;
+
+		/* copy a whole page or whatever's left */
+		copy = min_t(ssize_t, remaining, PAGE_SIZE);
+
+		/* ...but limit it to whatever space is left in the iov */
+		copy = min_t(ssize_t, copy, iov_iter_count(&ii));
+
+		/* go while there's data to be copied and no errors */
+		if (copy && !rc) {
+			pdata = kmap(page);
+			rc = memcpy_toiovecend(ii.iov, pdata, ii.iov_offset,
+						(int)copy);
+			kunmap(page);
+			if (!rc) {
+				*copied += copy;
+				remaining -= copy;
+				iov_iter_advance(&ii, copy);
+			}
+		}
+
+		list_del(&page->lru);
+		put_page(page);
+	}
+
+	return rc;
+}
+
+static void
+cifs_uncached_readv_complete(struct work_struct *work)
+{
+	struct cifs_readdata *rdata = container_of(work,
+						struct cifs_readdata, work);
+
+	/* if the result is non-zero then the pages weren't kmapped */
+	if (rdata->result == 0) {
+		struct page *page;
+
+		list_for_each_entry(page, &rdata->pages, lru)
+			kunmap(page);
+	}
+
+	complete(&rdata->done);
+	kref_put(&rdata->refcount, cifs_uncached_readdata_release);
+}
+
+static int
+cifs_uncached_read_marshal_iov(struct cifs_readdata *rdata,
+				unsigned int remaining)
+{
+	int len = 0;
+	struct page *page, *tpage;
+
+	rdata->nr_iov = 1;
+	list_for_each_entry_safe(page, tpage, &rdata->pages, lru) {
+		if (remaining >= PAGE_SIZE) {
+			/* enough data to fill the page */
+			rdata->iov[rdata->nr_iov].iov_base = kmap(page);
+			rdata->iov[rdata->nr_iov].iov_len = PAGE_SIZE;
+			cFYI(1, "%u: idx=%lu iov_base=%p iov_len=%zu",
+				rdata->nr_iov, page->index,
+				rdata->iov[rdata->nr_iov].iov_base,
+				rdata->iov[rdata->nr_iov].iov_len);
+			++rdata->nr_iov;
+			len += PAGE_SIZE;
+			remaining -= PAGE_SIZE;
+		} else if (remaining > 0) {
+			/* enough for partial page, fill and zero the rest */
+			rdata->iov[rdata->nr_iov].iov_base = kmap(page);
+			rdata->iov[rdata->nr_iov].iov_len = remaining;
+			cFYI(1, "%u: idx=%lu iov_base=%p iov_len=%zu",
+				rdata->nr_iov, page->index,
+				rdata->iov[rdata->nr_iov].iov_base,
+				rdata->iov[rdata->nr_iov].iov_len);
+			memset(rdata->iov[rdata->nr_iov].iov_base + remaining,
+				'\0', PAGE_SIZE - remaining);
+			++rdata->nr_iov;
+			len += remaining;
+			remaining = 0;
+		} else {
+			/* no need to hold page hostage */
+			list_del(&page->lru);
+			put_page(page);
+		}
+	}
+
+	return len;
+}
+
 static ssize_t
 cifs_iovec_read(struct file *file, const struct iovec *iov,
 		 unsigned long nr_segs, loff_t *poffset)
 {
-	int rc;
-	int xid;
-	ssize_t total_read;
-	unsigned int bytes_read = 0;
+	ssize_t rc;
 	size_t len, cur_len;
-	int iov_offset = 0;
+	ssize_t total_read = 0;
+	loff_t offset = *poffset;
+	unsigned int npages;
 	struct cifs_sb_info *cifs_sb;
-	struct cifs_tcon *pTcon;
+	struct cifs_tcon *tcon;
 	struct cifsFileInfo *open_file;
-	struct smb_com_read_rsp *pSMBr;
-	struct cifs_io_parms io_parms;
-	char *read_data;
-	unsigned int rsize;
-	__u32 pid;
+	struct cifs_readdata *rdata, *tmp;
+	struct list_head rdata_list;
+	pid_t pid;
 
 	if (!nr_segs)
 		return 0;
@@ -2409,14 +2565,10 @@ cifs_iovec_read(struct file *file, const struct iovec *iov,
 	if (!len)
 		return 0;
 
-	xid = GetXid();
+	INIT_LIST_HEAD(&rdata_list);
 	cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
-
-	/* FIXME: set up handlers for larger reads and/or convert to async */
-	rsize = min_t(unsigned int, cifs_sb->rsize, CIFSMaxBufSize);
-
 	open_file = file->private_data;
-	pTcon = tlink_tcon(open_file->tlink);
+	tcon = tlink_tcon(open_file->tlink);
 
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
 		pid = open_file->pid;
@@ -2426,56 +2578,78 @@ cifs_iovec_read(struct file *file, const struct iovec *iov,
 	if ((file->f_flags & O_ACCMODE) == O_WRONLY)
 		cFYI(1, "attempting read on write only file instance");
 
-	for (total_read = 0; total_read < len; total_read += bytes_read) {
-		cur_len = min_t(const size_t, len - total_read, rsize);
-		rc = -EAGAIN;
-		read_data = NULL;
+	do {
+		cur_len = min_t(const size_t, len - total_read, cifs_sb->rsize);
+		npages = DIV_ROUND_UP(cur_len, PAGE_SIZE);
 
-		while (rc == -EAGAIN) {
-			int buf_type = CIFS_NO_BUFFER;
-			if (open_file->invalidHandle) {
-				rc = cifs_reopen_file(open_file, true);
-				if (rc != 0)
-					break;
-			}
-			io_parms.netfid = open_file->netfid;
-			io_parms.pid = pid;
-			io_parms.tcon = pTcon;
-			io_parms.offset = *poffset;
-			io_parms.length = cur_len;
-			rc = CIFSSMBRead(xid, &io_parms, &bytes_read,
-					 &read_data, &buf_type);
-			pSMBr = (struct smb_com_read_rsp *)read_data;
-			if (read_data) {
-				char *data_offset = read_data + 4 +
-						le16_to_cpu(pSMBr->DataOffset);
-				if (memcpy_toiovecend(iov, data_offset,
-						      iov_offset, bytes_read))
-					rc = -EFAULT;
-				if (buf_type == CIFS_SMALL_BUFFER)
-					cifs_small_buf_release(read_data);
-				else if (buf_type == CIFS_LARGE_BUFFER)
-					cifs_buf_release(read_data);
-				read_data = NULL;
-				iov_offset += bytes_read;
-			}
+		/* allocate a readdata struct */
+		rdata = cifs_readdata_alloc(npages,
+					    cifs_uncached_readv_complete);
+		if (!rdata) {
+			rc = -ENOMEM;
+			goto error;
 		}
 
-		if (rc || (bytes_read == 0)) {
-			if (total_read) {
-				break;
-			} else {
-				FreeXid(xid);
-				return rc;
+		rc = cifs_read_allocate_pages(&rdata->pages, npages);
+		if (rc)
+			goto error;
+
+		rdata->cfile = cifsFileInfo_get(open_file);
+		rdata->offset = offset;
+		rdata->bytes = cur_len;
+		rdata->pid = pid;
+		rdata->marshal_iov = cifs_uncached_read_marshal_iov;
+
+		rc = cifs_retry_async_readv(rdata);
+error:
+		if (rc) {
+			kref_put(&rdata->refcount,
+				 cifs_uncached_readdata_release);
+			break;
+		}
+
+		list_add_tail(&rdata->list, &rdata_list);
+		offset += cur_len;
+		len -= cur_len;
+	} while (len > 0);
+
+	/* if at least one read request send succeeded, then reset rc */
+	if (!list_empty(&rdata_list))
+		rc = 0;
+
+	/* the loop below should proceed in the order of increasing offsets */
+restart_loop:
+	list_for_each_entry_safe(rdata, tmp, &rdata_list, list) {
+		if (!rc) {
+			ssize_t copied;
+
+			/* FIXME: freezable sleep too? */
+			rc = wait_for_completion_killable(&rdata->done);
+			if (rc)
+				rc = -EINTR;
+			else if (rdata->result)
+				rc = rdata->result;
+			else {
+				rc = cifs_readdata_to_iov(rdata, iov,
+							nr_segs, *poffset,
+							&copied);
+				total_read += copied;
+			}
+
+			/* resend call if it's a retryable error */
+			if (rc == -EAGAIN) {
+				rc = cifs_retry_async_readv(rdata);
+				goto restart_loop;
 			}
-		} else {
-			cifs_stats_bytes_read(pTcon, bytes_read);
-			*poffset += bytes_read;
 		}
+		list_del_init(&rdata->list);
+		kref_put(&rdata->refcount, cifs_uncached_readdata_release);
 	}
 
-	FreeXid(xid);
-	return total_read;
+	cifs_stats_bytes_read(tcon, total_read);
+	*poffset += total_read;
+
+	return total_read ? total_read : rc;
 }
 
 ssize_t cifs_user_readv(struct kiocb *iocb, const struct iovec *iov,