[CIFS] Avoid extra large buffer allocation (and memcpy) in cifs_readpages
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 3565d3b..1620991 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -958,21 +958,19 @@
return rc;
}
-/* If no buffer passed in, then caller wants to do the copy
- as in the case of readpages so the SMB buffer must be
- freed by the caller */
-
int
CIFSSMBRead(const int xid, struct cifsTconInfo *tcon,
- const int netfid, const unsigned int count,
- const __u64 lseek, unsigned int *nbytes, char **buf)
+ const int netfid, const unsigned int count,
+ const __u64 lseek, unsigned int *nbytes, char **buf,
+ int * pbuf_type)
{
int rc = -EACCES;
READ_REQ *pSMB = NULL;
READ_RSP *pSMBr = NULL;
char *pReadData = NULL;
- int bytes_returned;
int wct;
+ int resp_buf_type = 0;
+ struct kvec iov[1];
cFYI(1,("Reading %d bytes on fid %d",count,netfid));
if(tcon->ses->capabilities & CAP_LARGE_FILES)
@@ -981,8 +979,7 @@
wct = 10; /* old style read */
*nbytes = 0;
- rc = smb_init(SMB_COM_READ_ANDX, wct, tcon, (void **) &pSMB,
- (void **) &pSMBr);
+ rc = small_smb_init(SMB_COM_READ_ANDX, wct, tcon, (void **) &pSMB);
if (rc)
return rc;
@@ -990,13 +987,13 @@
if (tcon->ses->server == NULL)
return -ECONNABORTED;
- pSMB->AndXCommand = 0xFF; /* none */
+ pSMB->AndXCommand = 0xFF; /* none */
pSMB->Fid = netfid;
pSMB->OffsetLow = cpu_to_le32(lseek & 0xFFFFFFFF);
if(wct == 12)
pSMB->OffsetHigh = cpu_to_le32(lseek >> 32);
- else if((lseek >> 32) > 0) /* can not handle this big offset for old */
- return -EIO;
+ else if((lseek >> 32) > 0) /* can not handle this big offset for old */
+ return -EIO;
pSMB->Remaining = 0;
pSMB->MaxCount = cpu_to_le16(count & 0xFFFF);
@@ -1005,14 +1002,18 @@
pSMB->ByteCount = 0; /* no need to do le conversion since 0 */
else {
/* old style read */
- struct smb_com_readx_req * pSMBW =
+ struct smb_com_readx_req * pSMBW =
(struct smb_com_readx_req *)pSMB;
- pSMBW->ByteCount = 0;
+ pSMBW->ByteCount = 0;
}
-
- rc = SendReceive(xid, tcon->ses, (struct smb_hdr *) pSMB,
- (struct smb_hdr *) pSMBr, &bytes_returned, 0);
+
+ iov[0].iov_base = (char *)pSMB;
+ iov[0].iov_len = pSMB->hdr.smb_buf_length + 4;
+ rc = SendReceive2(xid, tcon->ses, iov,
+ 1 /* num iovecs */,
+ &resp_buf_type, 0);
cifs_stats_inc(&tcon->num_reads);
+ pSMBr = (READ_RSP *)iov[0].iov_base;
if (rc) {
cERROR(1, ("Send error in read = %d", rc));
} else {
@@ -1022,33 +1023,43 @@
*nbytes = data_length;
/*check that DataLength would not go beyond end of SMB */
- if ((data_length > CIFSMaxBufSize)
+ if ((data_length > CIFSMaxBufSize)
|| (data_length > count)) {
cFYI(1,("bad length %d for count %d",data_length,count));
rc = -EIO;
*nbytes = 0;
} else {
- pReadData =
- (char *) (&pSMBr->hdr.Protocol) +
+ pReadData = (char *) (&pSMBr->hdr.Protocol) +
le16_to_cpu(pSMBr->DataOffset);
-/* if(rc = copy_to_user(buf, pReadData, data_length)) {
- cERROR(1,("Faulting on read rc = %d",rc));
- rc = -EFAULT;
- }*/ /* can not use copy_to_user when using page cache*/
+/* if(rc = copy_to_user(buf, pReadData, data_length)) {
+ cERROR(1,("Faulting on read rc = %d",rc));
+ rc = -EFAULT;
+ }*/ /* can not use copy_to_user when using page cache*/
if(*buf)
- memcpy(*buf,pReadData,data_length);
+ memcpy(*buf,pReadData,data_length);
}
}
- if(*buf)
- cifs_buf_release(pSMB);
- else
- *buf = (char *)pSMB;
- /* Note: On -EAGAIN error only caller can retry on handle based calls
+ cifs_small_buf_release(pSMB);
+ if(*buf) {
+ if(resp_buf_type == CIFS_SMALL_BUFFER)
+ cifs_small_buf_release(iov[0].iov_base);
+ else if(resp_buf_type == CIFS_LARGE_BUFFER)
+ cifs_buf_release(iov[0].iov_base);
+ } else /* return buffer to caller to free */ /* BB FIXME how do we tell caller if it is not a large buffer */ {
+ *buf = iov[0].iov_base;
+ if(resp_buf_type == CIFS_SMALL_BUFFER)
+ *pbuf_type = CIFS_SMALL_BUFFER;
+ else if(resp_buf_type == CIFS_LARGE_BUFFER)
+ *pbuf_type = CIFS_LARGE_BUFFER;
+ }
+
+ /* Note: On -EAGAIN error only caller can retry on handle based calls
since file handle passed in no longer valid */
return rc;
}
+
int
CIFSSMBWrite(const int xid, struct cifsTconInfo *tcon,
const int netfid, const unsigned int count,
@@ -1163,10 +1174,10 @@
{
int rc = -EACCES;
WRITE_REQ *pSMB = NULL;
- int bytes_returned, wct;
+ int wct;
int smb_hdr_len;
+ int resp_buf_type = 0;
- /* BB removeme BB */
cFYI(1,("write2 at %lld %d bytes", (long long)offset, count));
if(tcon->ses->capabilities & CAP_LARGE_FILES)
@@ -1209,22 +1220,34 @@
pSMBW->ByteCount = cpu_to_le16(count + 5);
}
iov[0].iov_base = pSMB;
- iov[0].iov_len = smb_hdr_len + 4;
+ if(wct == 14)
+ iov[0].iov_len = smb_hdr_len + 4;
+ else /* wct == 12 pad bigger by four bytes */
+ iov[0].iov_len = smb_hdr_len + 8;
+
- rc = SendReceive2(xid, tcon->ses, iov, n_vec + 1, &bytes_returned,
+ rc = SendReceive2(xid, tcon->ses, iov, n_vec + 1, &resp_buf_type,
long_op);
cifs_stats_inc(&tcon->num_writes);
if (rc) {
cFYI(1, ("Send error Write2 = %d", rc));
*nbytes = 0;
+ } else if(resp_buf_type == 0) {
+ /* presumably this can not happen, but best to be safe */
+ rc = -EIO;
+ *nbytes = 0;
} else {
- WRITE_RSP * pSMBr = (WRITE_RSP *)pSMB;
+ WRITE_RSP * pSMBr = (WRITE_RSP *)iov[0].iov_base;
*nbytes = le16_to_cpu(pSMBr->CountHigh);
*nbytes = (*nbytes) << 16;
*nbytes += le16_to_cpu(pSMBr->Count);
}
cifs_small_buf_release(pSMB);
+ if(resp_buf_type == CIFS_SMALL_BUFFER)
+ cifs_small_buf_release(iov[0].iov_base);
+ else if(resp_buf_type == CIFS_LARGE_BUFFER)
+ cifs_buf_release(iov[0].iov_base);
/* Note: On -EAGAIN error only caller can retry on handle based calls
since file handle passed in no longer valid */