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Commit 42c4dfc2 authored by Jeff Layton's avatar Jeff Layton
Browse files

cifs: turn read_from_socket into a wrapper around a vectorized version 



Eventually we'll want to allow cifsd to read data directly into the
pagecache. In order to do that we'll need a routine that can take a
kvec array and pass that directly to kernel_recvmsg.

Unfortunately though, the kernel's recvmsg routines modify the kvec
array that gets passed in, so we need to use a copy of the kvec array
and refresh that copy on each pass through the loop.

Reviewed-and-Tested-by: default avatarPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
parent 7748dd6e

fs/cifs/connect.c

+61 −7
Original line number Diff line number Diff line
@@ -375,14 +375,54 @@ server_unresponsive(struct TCP_Server_Info *server) 
	return false;

}



/*

 * kvec_array_init - clone a kvec array, and advance into it

 * @new:	pointer to memory for cloned array

 * @iov:	pointer to original array

 * @nr_segs:	number of members in original array

 * @bytes:	number of bytes to advance into the cloned array

 *

 * This function will copy the array provided in iov to a section of memory

 * and advance the specified number of bytes into the new array. It returns

 * the number of segments in the new array. "new" must be at least as big as

 * the original iov array.

 */

static unsigned int

kvec_array_init(struct kvec *new, struct kvec *iov, unsigned int nr_segs,

		size_t bytes)

{

	size_t base = 0;



	while (bytes || !iov->iov_len) {

		int copy = min(bytes, iov->iov_len);



		bytes -= copy;

		base += copy;

		if (iov->iov_len == base) {

			iov++;

			nr_segs--;

			base = 0;

		}

	}

	memcpy(new, iov, sizeof(*iov) * nr_segs);

	new->iov_base += base;

	new->iov_len -= base;

	return nr_segs;

}



static int

read_from_socket(struct TCP_Server_Info *server, char *buf,

		 unsigned int to_read)

readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,

		  unsigned int nr_segs, unsigned int to_read)

{

	int length = 0;

	int total_read;

	unsigned int segs;

	struct msghdr smb_msg;

	struct kvec iov;

	struct kvec *iov;



	iov = kmalloc(sizeof(*iov_orig) * nr_segs, GFP_NOFS);

	if (!iov)

		return -ENOMEM;



	smb_msg.msg_control = NULL;

	smb_msg.msg_controllen = 0;
@@ -393,10 +433,11 @@ read_from_socket(struct TCP_Server_Info *server, char *buf, 
			break;

		}



		iov.iov_base = buf + total_read;

		iov.iov_len = to_read;

		length = kernel_recvmsg(server->ssocket, &smb_msg, &iov, 1,

					to_read, 0);

		segs = kvec_array_init(iov, iov_orig, nr_segs, total_read);



		length = kernel_recvmsg(server->ssocket, &smb_msg,

					iov, segs, to_read, 0);



		if (server->tcpStatus == CifsExiting) {

			total_read = -ESHUTDOWN;

			break;
@@ -423,9 +464,22 @@ read_from_socket(struct TCP_Server_Info *server, char *buf, 
			break;

		}

	}

	kfree(iov);

	return total_read;

}



static int

read_from_socket(struct TCP_Server_Info *server, char *buf,

		 unsigned int to_read)

{

	struct kvec iov;



	iov.iov_base = buf;

	iov.iov_len = to_read;



	return readv_from_socket(server, &iov, 1, to_read);

}



static bool

is_smb_response(struct TCP_Server_Info *server, unsigned char type)

{