orangefs: copy Orangefs-sized blocks into the pagecache if possible.

->readpage looks in file->private_data to try and find out how the
userspace program set "count" in read(2) or with "dd bs=" or whatever.

->readpage uses "count" and inode->i_size to calculate how much
data Orangefs should deposit in the Orangefs shared buffer, and
remembers which slot the data is in.

After copying data from the Orangefs shared buffer slot into
"the page", readpage tries to increment through the pagecache index
and fill as many pages as it can from the extra data in the shared
buffer. Hopefully these extra pages will soon be needed by the vfs,
and they'll be in the pagecache already.

Signed-off-by: Mike Marshall <hubcap@omnibond.com>
Signed-off-by: Martin Brandenburg <martin@omnibond.com>

1 files changed, 32 insertions, 5 deletions

diff --git a/fs/orangefs/file.c b/fs/orangefs/file.c
index 68ba5ae7ef5d..a35c17017210 100644
--- a/fs/orangefs/file.c
+++ b/fs/orangefs/file.c
@@ -54,6 +54,7 @@ ssize_t wait_for_direct_io(enum ORANGEFS_io_type type, struct inode *inode,
 	struct orangefs_kernel_op_s *new_op = NULL;
 	int buffer_index = -1;
 	ssize_t ret;
+	size_t copy_amount;
 
 	new_op = op_alloc(ORANGEFS_VFS_OP_FILE_IO);
 	if (!new_op)
@@ -212,8 +213,25 @@ populate_shared_memory:
 		 *       can futher be kernel-space or user-space addresses.
 		 *       or it can pointers to struct page's
 		 */
+
+		/*
+		 * When reading, readahead_size will only be zero when
+		 * we're doing O_DIRECT, otherwise we got here from
+		 * orangefs_readpage.
+		 *
+		 * If we got here from orangefs_readpage we want to
+		 * copy either a page or the whole file into the io
+		 * vector, whichever is smaller.
+		 */
+		if (readahead_size)
+			copy_amount =
+				min(new_op->downcall.resp.io.amt_complete,
+					(__s64)PAGE_SIZE);
+		else
+			copy_amount = new_op->downcall.resp.io.amt_complete;
+
 		ret = orangefs_bufmap_copy_to_iovec(iter, buffer_index,
-		    new_op->downcall.resp.io.amt_complete);
+			copy_amount);
 		if (ret < 0) {
 			gossip_err("%s: Failed to copy-out buffers. Please make sure that the pvfs2-client is running (%ld)\n",
 			    __func__, (long)ret);
@@ -231,10 +249,19 @@ populate_shared_memory:
 
 out:
 	if (buffer_index >= 0) {
-		orangefs_bufmap_put(buffer_index);
-		gossip_debug(GOSSIP_FILE_DEBUG,
-			     "%s(%pU): PUT buffer_index %d\n",
-			     __func__, handle, buffer_index);
+		if ((readahead_size) && (type == ORANGEFS_IO_READ)) {
+			/* readpage */
+			*index_return = buffer_index;
+			gossip_debug(GOSSIP_FILE_DEBUG,
+				"%s: hold on to buffer_index :%d:\n",
+				__func__, buffer_index);
+		} else {
+			/* O_DIRECT */
+			orangefs_bufmap_put(buffer_index);
+			gossip_debug(GOSSIP_FILE_DEBUG,
+				"%s(%pU): PUT buffer_index %d\n",
+				__func__, handle, buffer_index);
+		}
 		buffer_index = -1;
 	}
 	op_release(new_op);