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

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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: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
This commit is contained in:
Ronnie Sahlberg 2017-11-21 15:08:07 +11:00 committed by Steve French
parent 305428acf0
commit 3cecf4865c
1 changed files with 23 additions and 10 deletions
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33
fs/cifs/transport.c
View File

@ -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 (!new_iov)
return -ENOMEM;
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));
@ -823,7 +830,8 @@ 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);
kfree(new_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 (!new_iov)
return -ENOMEM;
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));
@ -861,7 +873,8 @@ 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);
kfree(new_iov);
if (n_vec + 1 > CIFS_MAX_IOV_SIZE)
kfree(new_iov);
return rc;
}