orangefs: don't bother with splitting iovecs

copy_page_{to,from}_iter() advances it just fine *and* it has no
problem with partially consumed segments.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NMike Marshall <hubcap@omnibond.com>

fs/orangefs/file.c

@@ -256,168 +256,6 @@ static ssize_t wait_for_direct_io(enum PVFS_io_type type, struct inode *inode,
 	return ret;
 }
 
-/*
- * The reason we need to do this is to be able to support readv and writev
- * that are larger than (pvfs_bufmap_size_query()) Default is
- * PVFS2_BUFMAP_DEFAULT_DESC_SIZE MB. What that means is that we will
- * create a new io vec descriptor for those memory addresses that
- * go beyond the limit. Return value for this routine is negative in case
- * of errors and 0 in case of success.
- *
- * Further, the new_nr_segs pointer is updated to hold the new value
- * of number of iovecs, the new_vec pointer is updated to hold the pointer
- * to the new split iovec, and the size array is an array of integers holding
- * the number of iovecs that straddle pvfs_bufmap_size_query().
- * The max_new_nr_segs value is computed by the caller and returned.
- * (It will be (count of all iov_len/ block_size) + 1).
- */
-static int split_iovecs(unsigned long max_new_nr_segs,		/* IN */
-			unsigned long nr_segs,			/* IN */
-			const struct iovec *original_iovec,	/* IN */
-			unsigned long *new_nr_segs,		/* OUT */
-			struct iovec **new_vec,			/* OUT */
-			unsigned long *seg_count,		/* OUT */
-			unsigned long **seg_array)		/* OUT */
-{
-	unsigned long seg;
-	unsigned long count = 0;
-	unsigned long begin_seg;
-	unsigned long tmpnew_nr_segs = 0;
-	struct iovec *new_iovec = NULL;
-	struct iovec *orig_iovec;
-	unsigned long *sizes = NULL;
-	unsigned long sizes_count = 0;
-
-	if (nr_segs <= 0 ||
-	    original_iovec == NULL ||
-	    new_nr_segs == NULL ||
-	    new_vec == NULL ||
-	    seg_count == NULL ||
-	    seg_array == NULL ||
-	    max_new_nr_segs <= 0) {
-		gossip_err("Invalid parameters to split_iovecs\n");
-		return -EINVAL;
-	}
-	*new_nr_segs = 0;
-	*new_vec = NULL;
-	*seg_count = 0;
-	*seg_array = NULL;
-	/* copy the passed in iovec descriptor to a temp structure */
-	orig_iovec = kmalloc_array(nr_segs,
-				   sizeof(*orig_iovec),
-				   PVFS2_BUFMAP_GFP_FLAGS);
-	if (orig_iovec == NULL) {
-		gossip_err(
-		    "split_iovecs: Could not allocate memory for %lu bytes!\n",
-		    (unsigned long)(nr_segs * sizeof(*orig_iovec)));
-		return -ENOMEM;
-	}
-	new_iovec = kcalloc(max_new_nr_segs,
-			    sizeof(*new_iovec),
-			    PVFS2_BUFMAP_GFP_FLAGS);
-	if (new_iovec == NULL) {
-		kfree(orig_iovec);
-		gossip_err(
-		    "split_iovecs: Could not allocate memory for %lu bytes!\n",
-		    (unsigned long)(max_new_nr_segs * sizeof(*new_iovec)));
-		return -ENOMEM;
-	}
-	sizes = kcalloc(max_new_nr_segs,
-			sizeof(*sizes),
-			PVFS2_BUFMAP_GFP_FLAGS);
-	if (sizes == NULL) {
-		kfree(new_iovec);
-		kfree(orig_iovec);
-		gossip_err(
-		    "split_iovecs: Could not allocate memory for %lu bytes!\n",
-		    (unsigned long)(max_new_nr_segs * sizeof(*sizes)));
-		return -ENOMEM;
-	}
-	/* copy the passed in iovec to a temp structure */
-	memcpy(orig_iovec, original_iovec, nr_segs * sizeof(*orig_iovec));
-	begin_seg = 0;
-repeat:
-	for (seg = begin_seg; seg < nr_segs; seg++) {
-		if (tmpnew_nr_segs >= max_new_nr_segs ||
-		    sizes_count >= max_new_nr_segs) {
-			kfree(sizes);
-			kfree(orig_iovec);
-			kfree(new_iovec);
-			gossip_err
-			    ("split_iovecs: exceeded the index limit (%lu)\n",
-			    tmpnew_nr_segs);
-			return -EINVAL;
-		}
-		if (count + orig_iovec[seg].iov_len <
-		    pvfs_bufmap_size_query()) {
-			count += orig_iovec[seg].iov_len;
-			memcpy(&new_iovec[tmpnew_nr_segs],
-			       &orig_iovec[seg],
-			       sizeof(*new_iovec));
-			tmpnew_nr_segs++;
-			sizes[sizes_count]++;
-		} else {
-			new_iovec[tmpnew_nr_segs].iov_base =
-			    orig_iovec[seg].iov_base;
-			new_iovec[tmpnew_nr_segs].iov_len =
-			    (pvfs_bufmap_size_query() - count);
-			tmpnew_nr_segs++;
-			sizes[sizes_count]++;
-			sizes_count++;
-			begin_seg = seg;
-			orig_iovec[seg].iov_base +=
-			    (pvfs_bufmap_size_query() - count);
-			orig_iovec[seg].iov_len -=
-			    (pvfs_bufmap_size_query() - count);
-			count = 0;
-			break;
-		}
-	}
-	if (seg != nr_segs)
-		goto repeat;
-	else
-		sizes_count++;
-
-	*new_nr_segs = tmpnew_nr_segs;
-	/* new_iovec is freed by the caller */
-	*new_vec = new_iovec;
-	*seg_count = sizes_count;
-	/* seg_array is also freed by the caller */
-	*seg_array = sizes;
-	kfree(orig_iovec);
-	return 0;
-}
-
-static long bound_max_iovecs(const struct iovec *curr, unsigned long nr_segs,
-			     ssize_t *total_count)
-{
-	unsigned long i;
-	long max_nr_iovecs;
-	ssize_t total;
-	ssize_t count;
-
-	total = 0;
-	count = 0;
-	max_nr_iovecs = 0;
-	for (i = 0; i < nr_segs; i++) {
-		const struct iovec *iv = &curr[i];
-
-		count += iv->iov_len;
-		if (unlikely((ssize_t) (count | iv->iov_len) < 0))
-			return -EINVAL;
-		if (total + iv->iov_len < pvfs_bufmap_size_query()) {
-			total += iv->iov_len;
-			max_nr_iovecs++;
-		} else {
-			total =
-			    (total + iv->iov_len - pvfs_bufmap_size_query());
-			max_nr_iovecs += (total / pvfs_bufmap_size_query() + 2);
-		}
-	}
-	*total_count = count;
-	return max_nr_iovecs;
-}
-
 /*
  * Common entry point for read/write/readv/writev
  * This function will dispatch it to either the direct I/O
@@ -431,25 +269,10 @@ static ssize_t do_readv_writev(enum PVFS_io_type type, struct file *file,
 	struct inode *inode = file->f_mapping->host;
 	struct pvfs2_inode_s *pvfs2_inode = PVFS2_I(inode);
 	struct pvfs2_khandle *handle = &pvfs2_inode->refn.khandle;
-	ssize_t ret;
-	ssize_t total_count;
-	unsigned int to_free;
-	size_t count;
-	unsigned long seg;
-	unsigned long new_nr_segs;
-	unsigned long max_new_nr_segs;
-	unsigned long seg_count;
-	unsigned long *seg_array;
-	struct iovec *iovecptr;
-	struct iovec *ptr;
-
-	total_count = 0;
-	ret = -EINVAL;
-	count = 0;
-	to_free = 0;
-
-	/* Compute total and max number of segments after split */
-	max_new_nr_segs = bound_max_iovecs(iov, nr_segs, &count);
+	struct iov_iter iter;
+	size_t count = iov_length(iov, nr_segs);
+	ssize_t total_count = 0;
+	ssize_t ret = -EINVAL;
 
 	gossip_debug(GOSSIP_FILE_DEBUG,
 		"%s-BEGIN(%pU): count(%d) after estimate_max_iovecs.\n",
@@ -472,93 +295,10 @@ static ssize_t do_readv_writev(enum PVFS_io_type type, struct file *file,
 		goto out;
 	}
 
-	/*
-	 * if the total size of data transfer requested is greater than
-	 * the kernel-set blocksize of PVFS2, then we split the iovecs
-	 * such that no iovec description straddles a block size limit
-	 */
-
-	gossip_debug(GOSSIP_FILE_DEBUG,
-		     "%s: pvfs_bufmap_size:%d\n",
-		     __func__,
-		     pvfs_bufmap_size_query());
-
-	if (count > pvfs_bufmap_size_query()) {
-		/*
-		 * Split up the given iovec description such that
-		 * no iovec descriptor straddles over the block-size limitation.
-		 * This makes us our job easier to stage the I/O.
-		 * In addition, this function will also compute an array
-		 * with seg_count entries that will store the number of
-		 * segments that straddle the block-size boundaries.
-		 */
-		ret = split_iovecs(max_new_nr_segs,	/* IN */
-				   nr_segs,		/* IN */
-				   iov,			/* IN */
-				   &new_nr_segs,	/* OUT */
-				   &iovecptr,		/* OUT */
-				   &seg_count,		/* OUT */
-				   &seg_array);		/* OUT */
-		if (ret < 0) {
-			gossip_err("%s: Failed to split iovecs to satisfy larger than blocksize readv/writev request %zd\n",
-				__func__,
-				ret);
-			goto out;
-		}
-		gossip_debug(GOSSIP_FILE_DEBUG,
-			     "%s: Splitting iovecs from %lu to %lu"
-			     " [max_new %lu]\n",
-			     __func__,
-			     nr_segs,
-			     new_nr_segs,
-			     max_new_nr_segs);
-		/* We must free seg_array and iovecptr */
-		to_free = 1;
-	} else {
-		new_nr_segs = nr_segs;
-		/* use the given iovec description */
-		iovecptr = (struct iovec *)iov;
-		/* There is only 1 element in the seg_array */
-		seg_count = 1;
-		/* and its value is the number of segments passed in */
-		seg_array = &nr_segs;
-		/* We dont have to free up anything */
-		to_free = 0;
-	}
-	ptr = iovecptr;
-
-	gossip_debug(GOSSIP_FILE_DEBUG,
-		     "%s(%pU) %zd@%llu\n",
-		     __func__,
-		     handle,
-		     count,
-		     llu(*offset));
-	gossip_debug(GOSSIP_FILE_DEBUG,
-		     "%s(%pU): new_nr_segs: %lu, seg_count: %lu\n",
-		     __func__,
-		     handle,
-		     new_nr_segs, seg_count);
+	iov_iter_init(&iter, type == PVFS_IO_READ ? READ : WRITE,
+			      iov, nr_segs, count);
 
-/* PVFS2_KERNEL_DEBUG is a CFLAGS define. */
-#ifdef PVFS2_KERNEL_DEBUG
-	for (seg = 0; seg < new_nr_segs; seg++)
-		gossip_debug(GOSSIP_FILE_DEBUG,
-			     "%s: %d) %p to %p [%d bytes]\n",
-			     __func__,
-			     (int)seg + 1,
-			     iovecptr[seg].iov_base,
-			     iovecptr[seg].iov_base + iovecptr[seg].iov_len,
-			     (int)iovecptr[seg].iov_len);
-	for (seg = 0; seg < seg_count; seg++)
-		gossip_debug(GOSSIP_FILE_DEBUG,
-			     "%s: %zd) %lu\n",
-			     __func__,
-			     seg + 1,
-			     seg_array[seg]);
-#endif
-	seg = 0;
 	while (total_count < count) {
-		struct iov_iter iter;
 		size_t each_count;
 		size_t amt_complete;
 
@@ -579,9 +319,6 @@ static ssize_t do_readv_writev(enum PVFS_io_type type, struct file *file,
 			     handle,
 			     (int)*offset);
 
-		iov_iter_init(&iter, type == PVFS_IO_READ ? READ : WRITE,
-			      ptr, seg_array[seg], each_count);
-
 		ret = wait_for_direct_io(type, inode, offset, &iter,
 				each_count, 0);
 		gossip_debug(GOSSIP_FILE_DEBUG,
@@ -593,9 +330,6 @@ static ssize_t do_readv_writev(enum PVFS_io_type type, struct file *file,
 		if (ret < 0)
 			goto out;
 
-		/* advance the iovec pointer */
-		ptr += seg_array[seg];
-		seg++;
 		*offset += ret;
 		total_count += ret;
 		amt_complete = ret;
@@ -617,10 +351,6 @@ static ssize_t do_readv_writev(enum PVFS_io_type type, struct file *file,
 	if (total_count > 0)
 		ret = total_count;
 out:
-	if (to_free) {
-		kfree(iovecptr);
-		kfree(seg_array);
-	}
 	if (ret > 0) {
 		if (type == PVFS_IO_READ) {
 			file_accessed(file);