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cifs: turn read_from_socket into a wrapper around a vectorized version

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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: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
This commit is contained in:
Jeff Layton
2011-10-19 15:28:17 -04:00
parent 7748dd6eab
commit 42c4dfc213
1 changed files with 61 additions and 7 deletions
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68
fs/cifs/connect.c
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@@ -375,14 +375,54 @@ server_unresponsive(struct TCP_Server_Info *server)
return false; 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 static int
read_from_socket(struct TCP_Server_Info *server, char *buf, readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,
unsigned int to_read) unsigned int nr_segs, unsigned int to_read)
{ {
int length = 0; int length = 0;
int total_read; int total_read;
unsigned int segs;
struct msghdr smb_msg; 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_control = NULL;
smb_msg.msg_controllen = 0; smb_msg.msg_controllen = 0;
@@ -393,10 +433,11 @@ read_from_socket(struct TCP_Server_Info *server, char *buf,
break; break;
} }
iov.iov_base = buf + total_read; segs = kvec_array_init(iov, iov_orig, nr_segs, total_read);
iov.iov_len = to_read;
length = kernel_recvmsg(server->ssocket, &smb_msg, &iov, 1, length = kernel_recvmsg(server->ssocket, &smb_msg,
to_read, 0); iov, segs, to_read, 0);
if (server->tcpStatus == CifsExiting) { if (server->tcpStatus == CifsExiting) {
total_read = -ESHUTDOWN; total_read = -ESHUTDOWN;
break; break;
@@ -423,9 +464,22 @@ read_from_socket(struct TCP_Server_Info *server, char *buf,
break; break;
} }
} }
kfree(iov);
return total_read; 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 static bool
is_smb_response(struct TCP_Server_Info *server, unsigned char type) is_smb_response(struct TCP_Server_Info *server, unsigned char type)
{ {