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: Pavel Shilovsky <piastry@etersoft.ru> Signed-off-by: Jeff Layton <jlayton@redhat.com>
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@ -375,14 +375,54 @@ server_unresponsive(struct TCP_Server_Info *server)
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return false;
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}
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/*
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* kvec_array_init - clone a kvec array, and advance into it
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* @new: pointer to memory for cloned array
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* @iov: pointer to original array
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* @nr_segs: number of members in original array
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* @bytes: number of bytes to advance into the cloned array
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*
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* This function will copy the array provided in iov to a section of memory
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* and advance the specified number of bytes into the new array. It returns
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* the number of segments in the new array. "new" must be at least as big as
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* the original iov array.
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*/
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static unsigned int
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kvec_array_init(struct kvec *new, struct kvec *iov, unsigned int nr_segs,
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size_t bytes)
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{
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size_t base = 0;
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while (bytes || !iov->iov_len) {
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int copy = min(bytes, iov->iov_len);
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bytes -= copy;
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base += copy;
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if (iov->iov_len == base) {
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iov++;
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nr_segs--;
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base = 0;
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}
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}
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memcpy(new, iov, sizeof(*iov) * nr_segs);
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new->iov_base += base;
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new->iov_len -= base;
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return nr_segs;
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}
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static int
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read_from_socket(struct TCP_Server_Info *server, char *buf,
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unsigned int to_read)
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readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,
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unsigned int nr_segs, unsigned int to_read)
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{
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int length = 0;
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int total_read;
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unsigned int segs;
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struct msghdr smb_msg;
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struct kvec iov;
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struct kvec *iov;
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iov = kmalloc(sizeof(*iov_orig) * nr_segs, GFP_NOFS);
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if (!iov)
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return -ENOMEM;
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smb_msg.msg_control = NULL;
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smb_msg.msg_controllen = 0;
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@ -393,10 +433,11 @@ read_from_socket(struct TCP_Server_Info *server, char *buf,
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break;
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}
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iov.iov_base = buf + total_read;
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iov.iov_len = to_read;
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length = kernel_recvmsg(server->ssocket, &smb_msg, &iov, 1,
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to_read, 0);
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segs = kvec_array_init(iov, iov_orig, nr_segs, total_read);
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length = kernel_recvmsg(server->ssocket, &smb_msg,
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iov, segs, to_read, 0);
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if (server->tcpStatus == CifsExiting) {
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total_read = -ESHUTDOWN;
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break;
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@ -423,9 +464,22 @@ read_from_socket(struct TCP_Server_Info *server, char *buf,
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break;
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}
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}
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kfree(iov);
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return total_read;
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}
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static int
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read_from_socket(struct TCP_Server_Info *server, char *buf,
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unsigned int to_read)
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{
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struct kvec iov;
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iov.iov_base = buf;
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iov.iov_len = to_read;
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return readv_from_socket(server, &iov, 1, to_read);
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}
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static bool
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is_smb_response(struct TCP_Server_Info *server, unsigned char type)
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{
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