Commit 3cecf486 authored by Ronnie Sahlberg's avatar Ronnie Sahlberg Committed by Steve French
Browse files

cifs: avoid a kmalloc in smb2_send_recv/SendReceive2 for the common case 



In both functions, use an array of 8 (arbitrary but should be big enough
for all current uses) iov and avoid having to kmalloc the array
for the common case.

If 8 is too small, then fall back to the original behaviour and use
kmalloc/kfree.

This should not change any behaviour but should save us a tiny amount of
cpu cycles.

Signed-off-by: default avatarRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: default avatarSteve French <smfrench@gmail.com>
Reviewed-by: default avatarPavel Shilovsky <pshilov@microsoft.com>
parent 305428ac

fs/cifs/transport.c

+23 −10
Original line number Diff line number Diff line
@@ -38,6 +38,9 @@ 
#include "cifsproto.h"

#include "cifs_debug.h"



/* Max number of iovectors we can use off the stack when sending requests. */

#define CIFS_MAX_IOV_SIZE 8



void

cifs_wake_up_task(struct mid_q_entry *mid)

{
@@ -803,12 +806,16 @@ SendReceive2(const unsigned int xid, struct cifs_ses *ses, 
	     const int flags, struct kvec *resp_iov)

{

	struct smb_rqst rqst;

	struct kvec *new_iov;

	struct kvec s_iov[CIFS_MAX_IOV_SIZE], *new_iov;

	int rc;



	new_iov = kmalloc(sizeof(struct kvec) * (n_vec + 1), GFP_KERNEL);

	if (n_vec + 1 > CIFS_MAX_IOV_SIZE) {

		new_iov = kmalloc(sizeof(struct kvec) * (n_vec + 1),

				  GFP_KERNEL);

		if (!new_iov)

			return -ENOMEM;

	} else

		new_iov = s_iov;



	/* 1st iov is a RFC1001 length followed by the rest of the packet */

	memcpy(new_iov + 1, iov, (sizeof(struct kvec) * n_vec));
@@ -823,6 +830,7 @@ SendReceive2(const unsigned int xid, struct cifs_ses *ses, 
	rqst.rq_nvec = n_vec + 1;



	rc = cifs_send_recv(xid, ses, &rqst, resp_buf_type, flags, resp_iov);

	if (n_vec + 1 > CIFS_MAX_IOV_SIZE)

		kfree(new_iov);

	return rc;

}
@@ -834,15 +842,19 @@ smb2_send_recv(const unsigned int xid, struct cifs_ses *ses, 
	       const int flags, struct kvec *resp_iov)

{

	struct smb_rqst rqst;

	struct kvec *new_iov;

	struct kvec s_iov[CIFS_MAX_IOV_SIZE], *new_iov;

	int rc;

	int i;

	__u32 count;

	__be32 rfc1002_marker;



	new_iov = kmalloc(sizeof(struct kvec) * (n_vec + 1), GFP_KERNEL);

	if (n_vec + 1 > CIFS_MAX_IOV_SIZE) {

		new_iov = kmalloc(sizeof(struct kvec) * (n_vec + 1),

				  GFP_KERNEL);

		if (!new_iov)

			return -ENOMEM;

	} else

		new_iov = s_iov;



	/* 1st iov is an RFC1002 Session Message length */

	memcpy(new_iov + 1, iov, (sizeof(struct kvec) * n_vec));
@@ -861,6 +873,7 @@ smb2_send_recv(const unsigned int xid, struct cifs_ses *ses, 
	rqst.rq_nvec = n_vec + 1;



	rc = cifs_send_recv(xid, ses, &rqst, resp_buf_type, flags, resp_iov);

	if (n_vec + 1 > CIFS_MAX_IOV_SIZE)

		kfree(new_iov);

	return rc;

}

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