[RFC][PATCHSET] reduce messing with iovecs in cifs

[RFC][PATCHSET] reduce messing with iovecs in cifs

[Al Viro]

	Now that sendmsg/recvmsg do not mangle iovecs and are capable of
handling bvec-based ->msg_iter, we can seriously reduce the amount of PITA
in cifs.  The series below is completely untested, and I would appreciate
comments/review/testing/etc.

I'll post the individual patches in followups; for those who prefer to use
git it can be found in
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git sendmsg.cifs

1/6: [net] drop 'size' argument of sock_recvmsg()
	should go via net-next; does what it says.

2/6: cifs: merge the hash calculation helpers
	takes the common parts of {cifs,smb2,smb3}_calc_signature() into a
common helper.

3/6: cifs: quit playing games with draining iovecs
	Switch smb_send_kvec() to passing msghdr (and thus iov_iter) and
make it use sock_sendmsg() - that allows to avoid draining iovecs, since
->msg_iter will be advanced properly and all we need is to keep it around
between the calls of sock_sendmsg(), rather than reinitializing it on each
loop iteration.  The same thing allows to get rid of messing with kmap()
when sending the stuff in ->rq_pages[] - ITER_BVEC will do the right thing.

4/6: cifs: no need to wank with copying and advancing iovec on recvmsg side either
	Similar to the previous - use sock_recvmsg() in cifs_readv_from_socket()
and there's no need to modify iovecs, or allocate a copy especially for
such modifications, etc.

5/6: cifs_readv_receive: use cifs_read_from_socket()
	building a 1-element iovec array for cifs_readv_from_socket() is
an overkill - simple cifs_read_from_socket() will do just fine.

6/6: cifs: don't bother with kmap on read_pages side
	Similar to the other half of 3/6: we can use ITER_BVEC for
read-into-page case.  Just make cifs_readv_from_socket() take msghdr from
caller and use a helper that would feed it a bvec-backed ->msg_iter.

[PATCH 2/6] cifs: merge the hash calculation helpers

[Al Viro]

three practically identical copies...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/cifs/cifsencrypt.c   |  97 ++++++++++++++++++++++++-------------------
 fs/cifs/cifsproto.h     |   3 ++
 fs/cifs/smb2transport.c | 107 +++++-------------------------------------------
 3 files changed, 67 insertions(+), 140 deletions(-)

diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
index 4897dac..6aeb8d4 100644
--- a/fs/cifs/cifsencrypt.c
+++ b/fs/cifs/cifsencrypt.c
@@ -66,45 +66,15 @@ cifs_crypto_shash_md5_allocate(struct TCP_Server_Info *server)
 	return 0;
 }
 
-/*
- * Calculate and return the CIFS signature based on the mac key and SMB PDU.
- * The 16 byte signature must be allocated by the caller. Note we only use the
- * 1st eight bytes and that the smb header signature field on input contains
- * the sequence number before this function is called. Also, this function
- * should be called with the server->srv_mutex held.
- */
-static int cifs_calc_signature(struct smb_rqst *rqst,
-			struct TCP_Server_Info *server, char *signature)
+int __cifs_calc_signature(struct smb_rqst *rqst,
+			struct TCP_Server_Info *server, char *signature,
+			struct shash_desc *shash)
 {
 	int i;
 	int rc;
 	struct kvec *iov = rqst->rq_iov;
 	int n_vec = rqst->rq_nvec;
 
-	if (iov == NULL || signature == NULL || server == NULL)
-		return -EINVAL;
-
-	if (!server->secmech.sdescmd5) {
-		rc = cifs_crypto_shash_md5_allocate(server);
-		if (rc) {
-			cifs_dbg(VFS, "%s: Can't alloc md5 crypto\n", __func__);
-			return -1;
-		}
-	}
-
-	rc = crypto_shash_init(&server->secmech.sdescmd5->shash);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not init md5\n", __func__);
-		return rc;
-	}
-
-	rc = crypto_shash_update(&server->secmech.sdescmd5->shash,
-		server->session_key.response, server->session_key.len);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
-		return rc;
-	}
-
 	for (i = 0; i < n_vec; i++) {
 		if (iov[i].iov_len == 0)
 			continue;
@@ -117,12 +87,10 @@ static int cifs_calc_signature(struct smb_rqst *rqst,
 		if (i == 0) {
 			if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
 				break; /* nothing to sign or corrupt header */
-			rc =
-			crypto_shash_update(&server->secmech.sdescmd5->shash,
+			rc = crypto_shash_update(shash,
 				iov[i].iov_base + 4, iov[i].iov_len - 4);
 		} else {
-			rc =
-			crypto_shash_update(&server->secmech.sdescmd5->shash,
+			rc = crypto_shash_update(shash,
 				iov[i].iov_base, iov[i].iov_len);
 		}
 		if (rc) {
@@ -134,21 +102,64 @@ static int cifs_calc_signature(struct smb_rqst *rqst,
 
 	/* now hash over the rq_pages array */
 	for (i = 0; i < rqst->rq_npages; i++) {
-		struct kvec p_iov;
+		void *kaddr = kmap(rqst->rq_pages[i]);
+		size_t len = rqst->rq_pagesz;
+
+		if (i == rqst->rq_npages - 1)
+			len = rqst->rq_tailsz;
+
+		crypto_shash_update(shash, kaddr, len);
 
-		cifs_rqst_page_to_kvec(rqst, i, &p_iov);
-		crypto_shash_update(&server->secmech.sdescmd5->shash,
-					p_iov.iov_base, p_iov.iov_len);
 		kunmap(rqst->rq_pages[i]);
 	}
 
-	rc = crypto_shash_final(&server->secmech.sdescmd5->shash, signature);
+	rc = crypto_shash_final(shash, signature);
 	if (rc)
-		cifs_dbg(VFS, "%s: Could not generate md5 hash\n", __func__);
+		cifs_dbg(VFS, "%s: Could not generate hash\n", __func__);
 
 	return rc;
 }
 
+/*
+ * Calculate and return the CIFS signature based on the mac key and SMB PDU.
+ * The 16 byte signature must be allocated by the caller. Note we only use the
+ * 1st eight bytes and that the smb header signature field on input contains
+ * the sequence number before this function is called. Also, this function
+ * should be called with the server->srv_mutex held.
+ */
+static int cifs_calc_signature(struct smb_rqst *rqst,
+			struct TCP_Server_Info *server, char *signature)
+{
+	int rc;
+
+	if (!rqst->rq_iov || !signature || !server)
+		return -EINVAL;
+
+	if (!server->secmech.sdescmd5) {
+		rc = cifs_crypto_shash_md5_allocate(server);
+		if (rc) {
+			cifs_dbg(VFS, "%s: Can't alloc md5 crypto\n", __func__);
+			return -1;
+		}
+	}
+
+	rc = crypto_shash_init(&server->secmech.sdescmd5->shash);
+	if (rc) {
+		cifs_dbg(VFS, "%s: Could not init md5\n", __func__);
+		return rc;
+	}
+
+	rc = crypto_shash_update(&server->secmech.sdescmd5->shash,
+		server->session_key.response, server->session_key.len);
+	if (rc) {
+		cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
+		return rc;
+	}
+
+	return __cifs_calc_signature(rqst, server, signature,
+				     &server->secmech.sdescmd5->shash);
+}
+
 /* must be called with server->srv_mutex held */
 int cifs_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server,
 		   __u32 *pexpected_response_sequence_number)
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index eed7ff5..d9b4f44 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -512,4 +512,7 @@ int cifs_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
 			   struct cifs_sb_info *cifs_sb,
 			   const unsigned char *path, char *pbuf,
 			   unsigned int *pbytes_written);
+int __cifs_calc_signature(struct smb_rqst *rqst,
+			struct TCP_Server_Info *server, char *signature,
+			struct shash_desc *shash);
 #endif			/* _CIFSPROTO_H */
diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index 8732a43..bc9a7b6 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -135,11 +135,10 @@ smb2_find_smb_ses(struct smb2_hdr *smb2hdr, struct TCP_Server_Info *server)
 int
 smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 {
-	int i, rc;
+	int rc;
 	unsigned char smb2_signature[SMB2_HMACSHA256_SIZE];
 	unsigned char *sigptr = smb2_signature;
 	struct kvec *iov = rqst->rq_iov;
-	int n_vec = rqst->rq_nvec;
 	struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;
 	struct cifs_ses *ses;
 
@@ -171,53 +170,11 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 		return rc;
 	}
 
-	for (i = 0; i < n_vec; i++) {
-		if (iov[i].iov_len == 0)
-			continue;
-		if (iov[i].iov_base == NULL) {
-			cifs_dbg(VFS, "null iovec entry\n");
-			return -EIO;
-		}
-		/*
-		 * The first entry includes a length field (which does not get
-		 * signed that occupies the first 4 bytes before the header).
-		 */
-		if (i == 0) {
-			if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
-				break; /* nothing to sign or corrupt header */
-			rc =
-			crypto_shash_update(
-				&server->secmech.sdeschmacsha256->shash,
-				iov[i].iov_base + 4, iov[i].iov_len - 4);
-		} else {
-			rc =
-			crypto_shash_update(
-				&server->secmech.sdeschmacsha256->shash,
-				iov[i].iov_base, iov[i].iov_len);
-		}
-		if (rc) {
-			cifs_dbg(VFS, "%s: Could not update with payload\n",
-				 __func__);
-			return rc;
-		}
-	}
-
-	/* now hash over the rq_pages array */
-	for (i = 0; i < rqst->rq_npages; i++) {
-		struct kvec p_iov;
-
-		cifs_rqst_page_to_kvec(rqst, i, &p_iov);
-		crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
-					p_iov.iov_base, p_iov.iov_len);
-		kunmap(rqst->rq_pages[i]);
-	}
-
-	rc = crypto_shash_final(&server->secmech.sdeschmacsha256->shash,
-				sigptr);
-	if (rc)
-		cifs_dbg(VFS, "%s: Could not generate sha256 hash\n", __func__);
+	rc = __cifs_calc_signature(rqst, server, sigptr,
+		&server->secmech.sdeschmacsha256->shash);
 
-	memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
+	if (!rc)
+		memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
 
 	return rc;
 }
@@ -395,12 +352,10 @@ generate_smb311signingkey(struct cifs_ses *ses)
 int
 smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 {
-	int i;
 	int rc = 0;
 	unsigned char smb3_signature[SMB2_CMACAES_SIZE];
 	unsigned char *sigptr = smb3_signature;
 	struct kvec *iov = rqst->rq_iov;
-	int n_vec = rqst->rq_nvec;
 	struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;
 	struct cifs_ses *ses;
 
@@ -431,54 +386,12 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 		cifs_dbg(VFS, "%s: Could not init cmac aes\n", __func__);
 		return rc;
 	}
+	
+	rc = __cifs_calc_signature(rqst, server, sigptr,
+				   &server->secmech.sdesccmacaes->shash);
 
-	for (i = 0; i < n_vec; i++) {
-		if (iov[i].iov_len == 0)
-			continue;
-		if (iov[i].iov_base == NULL) {
-			cifs_dbg(VFS, "null iovec entry");
-			return -EIO;
-		}
-		/*
-		 * The first entry includes a length field (which does not get
-		 * signed that occupies the first 4 bytes before the header).
-		 */
-		if (i == 0) {
-			if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
-				break; /* nothing to sign or corrupt header */
-			rc =
-			crypto_shash_update(
-				&server->secmech.sdesccmacaes->shash,
-				iov[i].iov_base + 4, iov[i].iov_len - 4);
-		} else {
-			rc =
-			crypto_shash_update(
-				&server->secmech.sdesccmacaes->shash,
-				iov[i].iov_base, iov[i].iov_len);
-		}
-		if (rc) {
-			cifs_dbg(VFS, "%s: Couldn't update cmac aes with payload\n",
-							__func__);
-			return rc;
-		}
-	}
-
-	/* now hash over the rq_pages array */
-	for (i = 0; i < rqst->rq_npages; i++) {
-		struct kvec p_iov;
-
-		cifs_rqst_page_to_kvec(rqst, i, &p_iov);
-		crypto_shash_update(&server->secmech.sdesccmacaes->shash,
-					p_iov.iov_base, p_iov.iov_len);
-		kunmap(rqst->rq_pages[i]);
-	}
-
-	rc = crypto_shash_final(&server->secmech.sdesccmacaes->shash,
-						sigptr);
-	if (rc)
-		cifs_dbg(VFS, "%s: Could not generate cmac aes\n", __func__);
-
-	memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
+	if (!rc)
+		memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
 
 	return rc;
 }
-- 
2.8.0.rc3

Re: [PATCH 2/6] cifs: merge the hash calculation helpers

[Shirish Pargaonkar]

Looks correct.
Tested with -o vers=1.0, -o vers=2.0, and -o vers=2.1.
Will test using mount option vers=3.0 as soon as I find a server.

Reviewed-by: Shirish Pargaonkar <shirishpargaonkar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Tested-by: Shirish Pargaonkar <shirishpargaonkar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

On Sat, Apr 9, 2016 at 3:50 PM, Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org> wrote:
> three practically identical copies...
>
> Signed-off-by: Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
> ---
>  fs/cifs/cifsencrypt.c   |  97 ++++++++++++++++++++++++-------------------
>  fs/cifs/cifsproto.h     |   3 ++
>  fs/cifs/smb2transport.c | 107 +++++-------------------------------------------
>  3 files changed, 67 insertions(+), 140 deletions(-)
>
> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
> index 4897dac..6aeb8d4 100644
> --- a/fs/cifs/cifsencrypt.c
> +++ b/fs/cifs/cifsencrypt.c
> @@ -66,45 +66,15 @@ cifs_crypto_shash_md5_allocate(struct TCP_Server_Info *server)
>         return 0;
>  }
>
> -/*
> - * Calculate and return the CIFS signature based on the mac key and SMB PDU.
> - * The 16 byte signature must be allocated by the caller. Note we only use the
> - * 1st eight bytes and that the smb header signature field on input contains
> - * the sequence number before this function is called. Also, this function
> - * should be called with the server->srv_mutex held.
> - */
> -static int cifs_calc_signature(struct smb_rqst *rqst,
> -                       struct TCP_Server_Info *server, char *signature)
> +int __cifs_calc_signature(struct smb_rqst *rqst,
> +                       struct TCP_Server_Info *server, char *signature,
> +                       struct shash_desc *shash)
>  {
>         int i;
>         int rc;
>         struct kvec *iov = rqst->rq_iov;
>         int n_vec = rqst->rq_nvec;
>
> -       if (iov == NULL || signature == NULL || server == NULL)
> -               return -EINVAL;
> -
> -       if (!server->secmech.sdescmd5) {
> -               rc = cifs_crypto_shash_md5_allocate(server);
> -               if (rc) {
> -                       cifs_dbg(VFS, "%s: Can't alloc md5 crypto\n", __func__);
> -                       return -1;
> -               }
> -       }
> -
> -       rc = crypto_shash_init(&server->secmech.sdescmd5->shash);
> -       if (rc) {
> -               cifs_dbg(VFS, "%s: Could not init md5\n", __func__);
> -               return rc;
> -       }
> -
> -       rc = crypto_shash_update(&server->secmech.sdescmd5->shash,
> -               server->session_key.response, server->session_key.len);
> -       if (rc) {
> -               cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
> -               return rc;
> -       }
> -
>         for (i = 0; i < n_vec; i++) {
>                 if (iov[i].iov_len == 0)
>                         continue;
> @@ -117,12 +87,10 @@ static int cifs_calc_signature(struct smb_rqst *rqst,
>                 if (i == 0) {
>                         if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
>                                 break; /* nothing to sign or corrupt header */
> -                       rc =
> -                       crypto_shash_update(&server->secmech.sdescmd5->shash,
> +                       rc = crypto_shash_update(shash,
>                                 iov[i].iov_base + 4, iov[i].iov_len - 4);
>                 } else {
> -                       rc =
> -                       crypto_shash_update(&server->secmech.sdescmd5->shash,
> +                       rc = crypto_shash_update(shash,
>                                 iov[i].iov_base, iov[i].iov_len);
>                 }
>                 if (rc) {
> @@ -134,21 +102,64 @@ static int cifs_calc_signature(struct smb_rqst *rqst,
>
>         /* now hash over the rq_pages array */
>         for (i = 0; i < rqst->rq_npages; i++) {
> -               struct kvec p_iov;
> +               void *kaddr = kmap(rqst->rq_pages[i]);
> +               size_t len = rqst->rq_pagesz;
> +
> +               if (i == rqst->rq_npages - 1)
> +                       len = rqst->rq_tailsz;
> +
> +               crypto_shash_update(shash, kaddr, len);
>
> -               cifs_rqst_page_to_kvec(rqst, i, &p_iov);
> -               crypto_shash_update(&server->secmech.sdescmd5->shash,
> -                                       p_iov.iov_base, p_iov.iov_len);
>                 kunmap(rqst->rq_pages[i]);
>         }
>
> -       rc = crypto_shash_final(&server->secmech.sdescmd5->shash, signature);
> +       rc = crypto_shash_final(shash, signature);
>         if (rc)
> -               cifs_dbg(VFS, "%s: Could not generate md5 hash\n", __func__);
> +               cifs_dbg(VFS, "%s: Could not generate hash\n", __func__);
>
>         return rc;
>  }
>
> +/*
> + * Calculate and return the CIFS signature based on the mac key and SMB PDU.
> + * The 16 byte signature must be allocated by the caller. Note we only use the
> + * 1st eight bytes and that the smb header signature field on input contains
> + * the sequence number before this function is called. Also, this function
> + * should be called with the server->srv_mutex held.
> + */
> +static int cifs_calc_signature(struct smb_rqst *rqst,
> +                       struct TCP_Server_Info *server, char *signature)
> +{
> +       int rc;
> +
> +       if (!rqst->rq_iov || !signature || !server)
> +               return -EINVAL;
> +
> +       if (!server->secmech.sdescmd5) {
> +               rc = cifs_crypto_shash_md5_allocate(server);
> +               if (rc) {
> +                       cifs_dbg(VFS, "%s: Can't alloc md5 crypto\n", __func__);
> +                       return -1;
> +               }
> +       }
> +
> +       rc = crypto_shash_init(&server->secmech.sdescmd5->shash);
> +       if (rc) {
> +               cifs_dbg(VFS, "%s: Could not init md5\n", __func__);
> +               return rc;
> +       }
> +
> +       rc = crypto_shash_update(&server->secmech.sdescmd5->shash,
> +               server->session_key.response, server->session_key.len);
> +       if (rc) {
> +               cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
> +               return rc;
> +       }
> +
> +       return __cifs_calc_signature(rqst, server, signature,
> +                                    &server->secmech.sdescmd5->shash);
> +}
> +
>  /* must be called with server->srv_mutex held */
>  int cifs_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server,
>                    __u32 *pexpected_response_sequence_number)
> diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
> index eed7ff5..d9b4f44 100644
> --- a/fs/cifs/cifsproto.h
> +++ b/fs/cifs/cifsproto.h
> @@ -512,4 +512,7 @@ int cifs_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
>                            struct cifs_sb_info *cifs_sb,
>                            const unsigned char *path, char *pbuf,
>                            unsigned int *pbytes_written);
> +int __cifs_calc_signature(struct smb_rqst *rqst,
> +                       struct TCP_Server_Info *server, char *signature,
> +                       struct shash_desc *shash);
>  #endif                 /* _CIFSPROTO_H */
> diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
> index 8732a43..bc9a7b6 100644
> --- a/fs/cifs/smb2transport.c
> +++ b/fs/cifs/smb2transport.c
> @@ -135,11 +135,10 @@ smb2_find_smb_ses(struct smb2_hdr *smb2hdr, struct TCP_Server_Info *server)
>  int
>  smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
>  {
> -       int i, rc;
> +       int rc;
>         unsigned char smb2_signature[SMB2_HMACSHA256_SIZE];
>         unsigned char *sigptr = smb2_signature;
>         struct kvec *iov = rqst->rq_iov;
> -       int n_vec = rqst->rq_nvec;
>         struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;
>         struct cifs_ses *ses;
>
> @@ -171,53 +170,11 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
>                 return rc;
>         }
>
> -       for (i = 0; i < n_vec; i++) {
> -               if (iov[i].iov_len == 0)
> -                       continue;
> -               if (iov[i].iov_base == NULL) {
> -                       cifs_dbg(VFS, "null iovec entry\n");
> -                       return -EIO;
> -               }
> -               /*
> -                * The first entry includes a length field (which does not get
> -                * signed that occupies the first 4 bytes before the header).
> -                */
> -               if (i == 0) {
> -                       if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
> -                               break; /* nothing to sign or corrupt header */
> -                       rc =
> -                       crypto_shash_update(
> -                               &server->secmech.sdeschmacsha256->shash,
> -                               iov[i].iov_base + 4, iov[i].iov_len - 4);
> -               } else {
> -                       rc =
> -                       crypto_shash_update(
> -                               &server->secmech.sdeschmacsha256->shash,
> -                               iov[i].iov_base, iov[i].iov_len);
> -               }
> -               if (rc) {
> -                       cifs_dbg(VFS, "%s: Could not update with payload\n",
> -                                __func__);
> -                       return rc;
> -               }
> -       }
> -
> -       /* now hash over the rq_pages array */
> -       for (i = 0; i < rqst->rq_npages; i++) {
> -               struct kvec p_iov;
> -
> -               cifs_rqst_page_to_kvec(rqst, i, &p_iov);
> -               crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
> -                                       p_iov.iov_base, p_iov.iov_len);
> -               kunmap(rqst->rq_pages[i]);
> -       }
> -
> -       rc = crypto_shash_final(&server->secmech.sdeschmacsha256->shash,
> -                               sigptr);
> -       if (rc)
> -               cifs_dbg(VFS, "%s: Could not generate sha256 hash\n", __func__);
> +       rc = __cifs_calc_signature(rqst, server, sigptr,
> +               &server->secmech.sdeschmacsha256->shash);
>
> -       memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
> +       if (!rc)
> +               memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
>
>         return rc;
>  }
> @@ -395,12 +352,10 @@ generate_smb311signingkey(struct cifs_ses *ses)
>  int
>  smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
>  {
> -       int i;
>         int rc = 0;
>         unsigned char smb3_signature[SMB2_CMACAES_SIZE];
>         unsigned char *sigptr = smb3_signature;
>         struct kvec *iov = rqst->rq_iov;
> -       int n_vec = rqst->rq_nvec;
>         struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;
>         struct cifs_ses *ses;
>
> @@ -431,54 +386,12 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
>                 cifs_dbg(VFS, "%s: Could not init cmac aes\n", __func__);
>                 return rc;
>         }
> +
> +       rc = __cifs_calc_signature(rqst, server, sigptr,
> +                                  &server->secmech.sdesccmacaes->shash);
>
> -       for (i = 0; i < n_vec; i++) {
> -               if (iov[i].iov_len == 0)
> -                       continue;
> -               if (iov[i].iov_base == NULL) {
> -                       cifs_dbg(VFS, "null iovec entry");
> -                       return -EIO;
> -               }
> -               /*
> -                * The first entry includes a length field (which does not get
> -                * signed that occupies the first 4 bytes before the header).
> -                */
> -               if (i == 0) {
> -                       if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
> -                               break; /* nothing to sign or corrupt header */
> -                       rc =
> -                       crypto_shash_update(
> -                               &server->secmech.sdesccmacaes->shash,
> -                               iov[i].iov_base + 4, iov[i].iov_len - 4);
> -               } else {
> -                       rc =
> -                       crypto_shash_update(
> -                               &server->secmech.sdesccmacaes->shash,
> -                               iov[i].iov_base, iov[i].iov_len);
> -               }
> -               if (rc) {
> -                       cifs_dbg(VFS, "%s: Couldn't update cmac aes with payload\n",
> -                                                       __func__);
> -                       return rc;
> -               }
> -       }
> -
> -       /* now hash over the rq_pages array */
> -       for (i = 0; i < rqst->rq_npages; i++) {
> -               struct kvec p_iov;
> -
> -               cifs_rqst_page_to_kvec(rqst, i, &p_iov);
> -               crypto_shash_update(&server->secmech.sdesccmacaes->shash,
> -                                       p_iov.iov_base, p_iov.iov_len);
> -               kunmap(rqst->rq_pages[i]);
> -       }
> -
> -       rc = crypto_shash_final(&server->secmech.sdesccmacaes->shash,
> -                                               sigptr);
> -       if (rc)
> -               cifs_dbg(VFS, "%s: Could not generate cmac aes\n", __func__);
> -
> -       memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
> +       if (!rc)
> +               memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
>
>         return rc;
>  }
> --
> 2.8.0.rc3
>
> --
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> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
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Re: [PATCH 2/6] cifs: merge the hash calculation helpers

[Jeff Layton]

On Sat, 2016-04-09 at 21:50 +0100, Al Viro wrote:
> three practically identical copies...
> 
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> ---
>  fs/cifs/cifsencrypt.c   |  97 ++++++++++++++++++++++++-------------------
>  fs/cifs/cifsproto.h     |   3 ++
>  fs/cifs/smb2transport.c | 107 +++++-------------------------------------------
>  3 files changed, 67 insertions(+), 140 deletions(-)
> 
> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
> index 4897dac..6aeb8d4 100644
> --- a/fs/cifs/cifsencrypt.c
> +++ b/fs/cifs/cifsencrypt.c
> @@ -66,45 +66,15 @@ cifs_crypto_shash_md5_allocate(struct TCP_Server_Info *server)
>  	return 0;
>  }
>  
> -/*
> - * Calculate and return the CIFS signature based on the mac key and SMB PDU.
> - * The 16 byte signature must be allocated by the caller. Note we only use the
> - * 1st eight bytes and that the smb header signature field on input contains
> - * the sequence number before this function is called. Also, this function
> - * should be called with the server->srv_mutex held.
> - */
> -static int cifs_calc_signature(struct smb_rqst *rqst,
> -			struct TCP_Server_Info *server, char *signature)
> +int __cifs_calc_signature(struct smb_rqst *rqst,
> +			struct TCP_Server_Info *server, char *signature,
> +			struct shash_desc *shash)
>  {
>  	int i;
>  	int rc;
>  	struct kvec *iov = rqst->rq_iov;
>  	int n_vec = rqst->rq_nvec;
>  
> -	if (iov == NULL || signature == NULL || server == NULL)
> -		return -EINVAL;
> -
> -	if (!server->secmech.sdescmd5) {
> -		rc = cifs_crypto_shash_md5_allocate(server);
> -		if (rc) {
> -			cifs_dbg(VFS, "%s: Can't alloc md5 crypto\n", __func__);
> -			return -1;
> -		}
> -	}
> -
> -	rc = crypto_shash_init(&server->secmech.sdescmd5->shash);
> -	if (rc) {
> -		cifs_dbg(VFS, "%s: Could not init md5\n", __func__);
> -		return rc;
> -	}
> -
> -	rc = crypto_shash_update(&server->secmech.sdescmd5->shash,
> -		server->session_key.response, server->session_key.len);
> -	if (rc) {
> -		cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
> -		return rc;
> -	}
> -
>  	for (i = 0; i < n_vec; i++) {
>  		if (iov[i].iov_len == 0)
>  			continue;
> @@ -117,12 +87,10 @@ static int cifs_calc_signature(struct smb_rqst *rqst,
>  		if (i == 0) {
>  			if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
>  				break; /* nothing to sign or corrupt header */
> -			rc =
> -			crypto_shash_update(&server->secmech.sdescmd5->shash,
> +			rc = crypto_shash_update(shash,
>  				iov[i].iov_base + 4, iov[i].iov_len - 4);
>  		} else {
> -			rc =
> -			crypto_shash_update(&server->secmech.sdescmd5->shash,
> +			rc = crypto_shash_update(shash,
>  				iov[i].iov_base, iov[i].iov_len);
>  		}
>  		if (rc) {
> @@ -134,21 +102,64 @@ static int cifs_calc_signature(struct smb_rqst *rqst,
>  
>  	/* now hash over the rq_pages array */
>  	for (i = 0; i < rqst->rq_npages; i++) {
> -		struct kvec p_iov;
> +		void *kaddr = kmap(rqst->rq_pages[i]);
> +		size_t len = rqst->rq_pagesz;
> +
> +		if (i == rqst->rq_npages - 1)
> +			len = rqst->rq_tailsz;
> +
> +		crypto_shash_update(shash, kaddr, len);
>  
> -		cifs_rqst_page_to_kvec(rqst, i, &p_iov);
> -		crypto_shash_update(&server->secmech.sdescmd5->shash,
> -					p_iov.iov_base, p_iov.iov_len);
>  		kunmap(rqst->rq_pages[i]);
>  	}
>  
> -	rc = crypto_shash_final(&server->secmech.sdescmd5->shash, signature);
> +	rc = crypto_shash_final(shash, signature);
>  	if (rc)
> -		cifs_dbg(VFS, "%s: Could not generate md5 hash\n", __func__);
> +		cifs_dbg(VFS, "%s: Could not generate hash\n", __func__);
>  
>  	return rc;
>  }
>  
> +/*
> + * Calculate and return the CIFS signature based on the mac key and SMB PDU.
> + * The 16 byte signature must be allocated by the caller. Note we only use the
> + * 1st eight bytes and that the smb header signature field on input contains
> + * the sequence number before this function is called. Also, this function
> + * should be called with the server->srv_mutex held.
> + */
> +static int cifs_calc_signature(struct smb_rqst *rqst,
> +			struct TCP_Server_Info *server, char *signature)
> +{
> +	int rc;
> +
> +	if (!rqst->rq_iov || !signature || !server)
> +		return -EINVAL;
> +
> +	if (!server->secmech.sdescmd5) {
> +		rc = cifs_crypto_shash_md5_allocate(server);
> +		if (rc) {
> +			cifs_dbg(VFS, "%s: Can't alloc md5 crypto\n", __func__);
> +			return -1;
> +		}
> +	}
> +
> +	rc = crypto_shash_init(&server->secmech.sdescmd5->shash);
> +	if (rc) {
> +		cifs_dbg(VFS, "%s: Could not init md5\n", __func__);
> +		return rc;
> +	}
> +
> +	rc = crypto_shash_update(&server->secmech.sdescmd5->shash,
> +		server->session_key.response, server->session_key.len);
> +	if (rc) {
> +		cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
> +		return rc;
> +	}
> +
> +	return __cifs_calc_signature(rqst, server, signature,
> +				     &server->secmech.sdescmd5->shash);
> +}
> +
>  /* must be called with server->srv_mutex held */
>  int cifs_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server,
>  		   __u32 *pexpected_response_sequence_number)
> diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
> index eed7ff5..d9b4f44 100644
> --- a/fs/cifs/cifsproto.h
> +++ b/fs/cifs/cifsproto.h
> @@ -512,4 +512,7 @@ int cifs_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
>  			   struct cifs_sb_info *cifs_sb,
>  			   const unsigned char *path, char *pbuf,
>  			   unsigned int *pbytes_written);
> +int __cifs_calc_signature(struct smb_rqst *rqst,
> +			struct TCP_Server_Info *server, char *signature,
> +			struct shash_desc *shash);
>  #endif			/* _CIFSPROTO_H */
> diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
> index 8732a43..bc9a7b6 100644
> --- a/fs/cifs/smb2transport.c
> +++ b/fs/cifs/smb2transport.c
> @@ -135,11 +135,10 @@ smb2_find_smb_ses(struct smb2_hdr *smb2hdr, struct TCP_Server_Info *server)
>  int
>  smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
>  {
> -	int i, rc;
> +	int rc;
>  	unsigned char smb2_signature[SMB2_HMACSHA256_SIZE];
>  	unsigned char *sigptr = smb2_signature;
>  	struct kvec *iov = rqst->rq_iov;
> -	int n_vec = rqst->rq_nvec;
>  	struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;
>  	struct cifs_ses *ses;
>  
> @@ -171,53 +170,11 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
>  		return rc;
>  	}
>  
> -	for (i = 0; i < n_vec; i++) {
> -		if (iov[i].iov_len == 0)
> -			continue;
> -		if (iov[i].iov_base == NULL) {
> -			cifs_dbg(VFS, "null iovec entry\n");
> -			return -EIO;
> -		}
> -		/*
> -		 * The first entry includes a length field (which does not get
> -		 * signed that occupies the first 4 bytes before the header).
> -		 */
> -		if (i == 0) {
> -			if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
> -				break; /* nothing to sign or corrupt header */
> -			rc =
> -			crypto_shash_update(
> -				&server->secmech.sdeschmacsha256->shash,
> -				iov[i].iov_base + 4, iov[i].iov_len - 4);
> -		} else {
> -			rc =
> -			crypto_shash_update(
> -				&server->secmech.sdeschmacsha256->shash,
> -				iov[i].iov_base, iov[i].iov_len);
> -		}
> -		if (rc) {
> -			cifs_dbg(VFS, "%s: Could not update with payload\n",
> -				 __func__);
> -			return rc;
> -		}
> -	}
> -
> -	/* now hash over the rq_pages array */
> -	for (i = 0; i < rqst->rq_npages; i++) {
> -		struct kvec p_iov;
> -
> -		cifs_rqst_page_to_kvec(rqst, i, &p_iov);
> -		crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
> -					p_iov.iov_base, p_iov.iov_len);
> -		kunmap(rqst->rq_pages[i]);
> -	}
> -
> -	rc = crypto_shash_final(&server->secmech.sdeschmacsha256->shash,
> -				sigptr);
> -	if (rc)
> -		cifs_dbg(VFS, "%s: Could not generate sha256 hash\n", __func__);
> +	rc = __cifs_calc_signature(rqst, server, sigptr,
> +		&server->secmech.sdeschmacsha256->shash);
>  
> -	memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
> +	if (!rc)
> +		memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
>  
>  	return rc;
>  }
> @@ -395,12 +352,10 @@ generate_smb311signingkey(struct cifs_ses *ses)
>  int
>  smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
>  {
> -	int i;
>  	int rc = 0;
>  	unsigned char smb3_signature[SMB2_CMACAES_SIZE];
>  	unsigned char *sigptr = smb3_signature;
>  	struct kvec *iov = rqst->rq_iov;
> -	int n_vec = rqst->rq_nvec;
>  	struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;
>  	struct cifs_ses *ses;
>  
> @@ -431,54 +386,12 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
>  		cifs_dbg(VFS, "%s: Could not init cmac aes\n", __func__);
>  		return rc;
>  	}
> +	
> +	rc = __cifs_calc_signature(rqst, server, sigptr,
> +				   &server->secmech.sdesccmacaes->shash);
>  
> -	for (i = 0; i < n_vec; i++) {
> -		if (iov[i].iov_len == 0)
> -			continue;
> -		if (iov[i].iov_base == NULL) {
> -			cifs_dbg(VFS, "null iovec entry");
> -			return -EIO;
> -		}
> -		/*
> -		 * The first entry includes a length field (which does not get
> -		 * signed that occupies the first 4 bytes before the header).
> -		 */
> -		if (i == 0) {
> -			if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
> -				break; /* nothing to sign or corrupt header */
> -			rc =
> -			crypto_shash_update(
> -				&server->secmech.sdesccmacaes->shash,
> -				iov[i].iov_base + 4, iov[i].iov_len - 4);
> -		} else {
> -			rc =
> -			crypto_shash_update(
> -				&server->secmech.sdesccmacaes->shash,
> -				iov[i].iov_base, iov[i].iov_len);
> -		}
> -		if (rc) {
> -			cifs_dbg(VFS, "%s: Couldn't update cmac aes with payload\n",
> -							__func__);
> -			return rc;
> -		}
> -	}
> -
> -	/* now hash over the rq_pages array */
> -	for (i = 0; i < rqst->rq_npages; i++) {
> -		struct kvec p_iov;
> -
> -		cifs_rqst_page_to_kvec(rqst, i, &p_iov);
> -		crypto_shash_update(&server->secmech.sdesccmacaes->shash,
> -					p_iov.iov_base, p_iov.iov_len);
> -		kunmap(rqst->rq_pages[i]);
> -	}
> -
> -	rc = crypto_shash_final(&server->secmech.sdesccmacaes->shash,
> -						sigptr);
> -	if (rc)
> -		cifs_dbg(VFS, "%s: Could not generate cmac aes\n", __func__);
> -
> -	memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
> +	if (!rc)
> +		memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
>  
>  	return rc;
>  }

Nice. Long overdue cleanup.

Reviewed-by: Jeff Layton <jlayton@poochiereds.net>

[PATCH 1/6] [net] drop 'size' argument of sock_recvmsg()

[Al Viro]

all callers have it equal to msg_data_left(msg).

Signed-off-by: Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
---
 drivers/target/iscsi/iscsi_target_util.c |  5 ++---
 include/linux/net.h                      |  3 +--
 net/socket.c                             | 23 ++++++++++-------------
 3 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index 428b0d9..5772038 100644
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -1283,9 +1283,8 @@ static int iscsit_do_rx_data(
 	iov_iter_kvec(&msg.msg_iter, READ | ITER_KVEC,
 		      count->iov, count->iov_count, data);
 
-	while (total_rx < data) {
-		rx_loop = sock_recvmsg(conn->sock, &msg,
-				      (data - total_rx), MSG_WAITALL);
+	while (msg_data_left(&msg)) {
+		rx_loop = sock_recvmsg(conn->sock, &msg, MSG_WAITALL);
 		if (rx_loop <= 0) {
 			pr_debug("rx_loop: %d total_rx: %d\n",
 				rx_loop, total_rx);
diff --git a/include/linux/net.h b/include/linux/net.h
index 49175e4..72c1e06 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -218,8 +218,7 @@ int sock_create_lite(int family, int type, int proto, struct socket **res);
 struct socket *sock_alloc(void);
 void sock_release(struct socket *sock);
 int sock_sendmsg(struct socket *sock, struct msghdr *msg);
-int sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
-		 int flags);
+int sock_recvmsg(struct socket *sock, struct msghdr *msg, int flags);
 struct file *sock_alloc_file(struct socket *sock, int flags, const char *dname);
 struct socket *sockfd_lookup(int fd, int *err);
 struct socket *sock_from_file(struct file *file, int *err);
diff --git a/net/socket.c b/net/socket.c
index 5f77a8e..956426e3 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -709,17 +709,16 @@ void __sock_recv_ts_and_drops(struct msghdr *msg, struct sock *sk,
 EXPORT_SYMBOL_GPL(__sock_recv_ts_and_drops);
 
 static inline int sock_recvmsg_nosec(struct socket *sock, struct msghdr *msg,
-				     size_t size, int flags)
+				     int flags)
 {
-	return sock->ops->recvmsg(sock, msg, size, flags);
+	return sock->ops->recvmsg(sock, msg, msg_data_left(msg), flags);
 }
 
-int sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
-		 int flags)
+int sock_recvmsg(struct socket *sock, struct msghdr *msg, int flags)
 {
-	int err = security_socket_recvmsg(sock, msg, size, flags);
+	int err = security_socket_recvmsg(sock, msg, msg_data_left(msg), flags);
 
-	return err ?: sock_recvmsg_nosec(sock, msg, size, flags);
+	return err ?: sock_recvmsg_nosec(sock, msg, flags);
 }
 EXPORT_SYMBOL(sock_recvmsg);
 
@@ -746,7 +745,7 @@ int kernel_recvmsg(struct socket *sock, struct msghdr *msg,
 
 	iov_iter_kvec(&msg->msg_iter, READ | ITER_KVEC, vec, num, size);
 	set_fs(KERNEL_DS);
-	result = sock_recvmsg(sock, msg, size, flags);
+	result = sock_recvmsg(sock, msg, flags);
 	set_fs(oldfs);
 	return result;
 }
@@ -796,7 +795,7 @@ static ssize_t sock_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	if (!iov_iter_count(to))	/* Match SYS5 behaviour */
 		return 0;
 
-	res = sock_recvmsg(sock, &msg, iov_iter_count(to), msg.msg_flags);
+	res = sock_recvmsg(sock, &msg, msg.msg_flags);
 	*to = msg.msg_iter;
 	return res;
 }
@@ -1696,7 +1695,7 @@ SYSCALL_DEFINE6(recvfrom, int, fd, void __user *, ubuf, size_t, size,
 	msg.msg_iocb = NULL;
 	if (sock->file->f_flags & O_NONBLOCK)
 		flags |= MSG_DONTWAIT;
-	err = sock_recvmsg(sock, &msg, iov_iter_count(&msg.msg_iter), flags);
+	err = sock_recvmsg(sock, &msg, flags);
 
 	if (err >= 0 && addr != NULL) {
 		err2 = move_addr_to_user(&address,
@@ -2073,7 +2072,7 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg,
 	struct iovec iovstack[UIO_FASTIOV];
 	struct iovec *iov = iovstack;
 	unsigned long cmsg_ptr;
-	int total_len, len;
+	int len;
 	ssize_t err;
 
 	/* kernel mode address */
@@ -2091,7 +2090,6 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg,
 		err = copy_msghdr_from_user(msg_sys, msg, &uaddr, &iov);
 	if (err < 0)
 		return err;
-	total_len = iov_iter_count(&msg_sys->msg_iter);
 
 	cmsg_ptr = (unsigned long)msg_sys->msg_control;
 	msg_sys->msg_flags = flags & (MSG_CMSG_CLOEXEC|MSG_CMSG_COMPAT);
@@ -2101,8 +2099,7 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg,
 
 	if (sock->file->f_flags & O_NONBLOCK)
 		flags |= MSG_DONTWAIT;
-	err = (nosec ? sock_recvmsg_nosec : sock_recvmsg)(sock, msg_sys,
-							  total_len, flags);
+	err = (nosec ? sock_recvmsg_nosec : sock_recvmsg)(sock, msg_sys, flags);
 	if (err < 0)
 		goto out_freeiov;
 	len = err;
-- 
2.8.0.rc3

Re: [PATCH 1/6] [net] drop 'size' argument of sock_recvmsg()

[Jeff Layton]

On Sat, 2016-04-09 at 21:50 +0100, Al Viro wrote:
> all callers have it equal to msg_data_left(msg).
> 
> Signed-off-by: Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
> ---
>  drivers/target/iscsi/iscsi_target_util.c |  5 ++---
>  include/linux/net.h                      |  3 +--
>  net/socket.c                             | 23 ++++++++++-------------
>  3 files changed, 13 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
> index 428b0d9..5772038 100644
> --- a/drivers/target/iscsi/iscsi_target_util.c
> +++ b/drivers/target/iscsi/iscsi_target_util.c
> @@ -1283,9 +1283,8 @@ static int iscsit_do_rx_data(
>  	iov_iter_kvec(&msg.msg_iter, READ | ITER_KVEC,
>  		      count->iov, count->iov_count, data);
>  
> -	while (total_rx < data) {
> -		rx_loop = sock_recvmsg(conn->sock, &msg,
> -				      (data - total_rx), MSG_WAITALL);
> +	while (msg_data_left(&msg)) {
> +		rx_loop = sock_recvmsg(conn->sock, &msg, MSG_WAITALL);
>  		if (rx_loop <= 0) {
>  			pr_debug("rx_loop: %d total_rx: %d\n",
>  				rx_loop, total_rx);
> diff --git a/include/linux/net.h b/include/linux/net.h
> index 49175e4..72c1e06 100644
> --- a/include/linux/net.h
> +++ b/include/linux/net.h
> @@ -218,8 +218,7 @@ int sock_create_lite(int family, int type, int proto, struct socket **res);
>  struct socket *sock_alloc(void);
>  void sock_release(struct socket *sock);
>  int sock_sendmsg(struct socket *sock, struct msghdr *msg);
> -int sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
> -		 int flags);
> +int sock_recvmsg(struct socket *sock, struct msghdr *msg, int flags);
>  struct file *sock_alloc_file(struct socket *sock, int flags, const char *dname);
>  struct socket *sockfd_lookup(int fd, int *err);
>  struct socket *sock_from_file(struct file *file, int *err);
> diff --git a/net/socket.c b/net/socket.c
> index 5f77a8e..956426e3 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -709,17 +709,16 @@ void __sock_recv_ts_and_drops(struct msghdr *msg, struct sock *sk,
>  EXPORT_SYMBOL_GPL(__sock_recv_ts_and_drops);
>  
>  static inline int sock_recvmsg_nosec(struct socket *sock, struct msghdr *msg,
> -				     size_t size, int flags)
> +				     int flags)
>  {
> -	return sock->ops->recvmsg(sock, msg, size, flags);
> +	return sock->ops->recvmsg(sock, msg, msg_data_left(msg), flags);
>  }
>  
> -int sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
> -		 int flags)
> +int sock_recvmsg(struct socket *sock, struct msghdr *msg, int flags)
>  {
> -	int err = security_socket_recvmsg(sock, msg, size, flags);
> +	int err = security_socket_recvmsg(sock, msg, msg_data_left(msg), flags);
>  
> -	return err ?: sock_recvmsg_nosec(sock, msg, size, flags);
> +	return err ?: sock_recvmsg_nosec(sock, msg, flags);
>  }
>  EXPORT_SYMBOL(sock_recvmsg);
>  
> @@ -746,7 +745,7 @@ int kernel_recvmsg(struct socket *sock, struct msghdr *msg,
>  
>  	iov_iter_kvec(&msg->msg_iter, READ | ITER_KVEC, vec, num, size);
>  	set_fs(KERNEL_DS);
> -	result = sock_recvmsg(sock, msg, size, flags);
> +	result = sock_recvmsg(sock, msg, flags);
>  	set_fs(oldfs);
>  	return result;
>  }
> @@ -796,7 +795,7 @@ static ssize_t sock_read_iter(struct kiocb *iocb, struct iov_iter *to)
>  	if (!iov_iter_count(to))	/* Match SYS5 behaviour */
>  		return 0;
>  
> -	res = sock_recvmsg(sock, &msg, iov_iter_count(to), msg.msg_flags);
> +	res = sock_recvmsg(sock, &msg, msg.msg_flags);
>  	*to = msg.msg_iter;
>  	return res;
>  }
> @@ -1696,7 +1695,7 @@ SYSCALL_DEFINE6(recvfrom, int, fd, void __user *, ubuf, size_t, size,
>  	msg.msg_iocb = NULL;
>  	if (sock->file->f_flags & O_NONBLOCK)
>  		flags |= MSG_DONTWAIT;
> -	err = sock_recvmsg(sock, &msg, iov_iter_count(&msg.msg_iter), flags);
> +	err = sock_recvmsg(sock, &msg, flags);
>  
>  	if (err >= 0 && addr != NULL) {
>  		err2 = move_addr_to_user(&address,
> @@ -2073,7 +2072,7 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg,
>  	struct iovec iovstack[UIO_FASTIOV];
>  	struct iovec *iov = iovstack;
>  	unsigned long cmsg_ptr;
> -	int total_len, len;
> +	int len;
>  	ssize_t err;
>  
>  	/* kernel mode address */
> @@ -2091,7 +2090,6 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg,
>  		err = copy_msghdr_from_user(msg_sys, msg, &uaddr, &iov);
>  	if (err < 0)
>  		return err;
> -	total_len = iov_iter_count(&msg_sys->msg_iter);
>  
>  	cmsg_ptr = (unsigned long)msg_sys->msg_control;
>  	msg_sys->msg_flags = flags & (MSG_CMSG_CLOEXEC|MSG_CMSG_COMPAT);
> @@ -2101,8 +2099,7 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg,
>  
>  	if (sock->file->f_flags & O_NONBLOCK)
>  		flags |= MSG_DONTWAIT;
> -	err = (nosec ? sock_recvmsg_nosec : sock_recvmsg)(sock, msg_sys,
> -							  total_len, flags);
> +	err = (nosec ? sock_recvmsg_nosec : sock_recvmsg)(sock, msg_sys, flags);
>  	if (err < 0)
>  		goto out_freeiov;
>  	len = err;

Looks good. Assuming that the corresponding change to sock_recvmsg is
merged.

Reviewed-by: Jeff Layton <jlayton-vpEMnDpepFuMZCB2o+C8xQ@public.gmane.org>

[PATCH 3/6] cifs: quit playing games with draining iovecs

[Al Viro]

... and use ITER_BVEC for the page part of request to send

Signed-off-by: Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
---
 fs/cifs/cifsproto.h |   2 -
 fs/cifs/transport.c | 141 +++++++++++++++-------------------------------------
 2 files changed, 41 insertions(+), 102 deletions(-)

diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index d9b4f44..7d5f53a 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -37,8 +37,6 @@ extern void cifs_buf_release(void *);
 extern struct smb_hdr *cifs_small_buf_get(void);
 extern void cifs_small_buf_release(void *);
 extern void free_rsp_buf(int, void *);
-extern void cifs_rqst_page_to_kvec(struct smb_rqst *rqst, unsigned int idx,
-					struct kvec *iov);
 extern int smb_send(struct TCP_Server_Info *, struct smb_hdr *,
 			unsigned int /* length */);
 extern unsigned int _get_xid(void);
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 87abe8e..206a597 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -124,41 +124,32 @@ cifs_delete_mid(struct mid_q_entry *mid)
 /*
  * smb_send_kvec - send an array of kvecs to the server
  * @server:	Server to send the data to
- * @iov:	Pointer to array of kvecs
- * @n_vec:	length of kvec array
+ * @smb_msg:	Message to send
  * @sent:	amount of data sent on socket is stored here
  *
  * Our basic "send data to server" function. Should be called with srv_mutex
  * held. The caller is responsible for handling the results.
  */
 static int
-smb_send_kvec(struct TCP_Server_Info *server, struct kvec *iov, size_t n_vec,
-		size_t *sent)
+smb_send_kvec(struct TCP_Server_Info *server, struct msghdr *smb_msg,
+	      size_t *sent)
 {
 	int rc = 0;
-	int i = 0;
-	struct msghdr smb_msg;
-	unsigned int remaining;
-	size_t first_vec = 0;
+	int retries = 0;
 	struct socket *ssocket = server->ssocket;
 
 	*sent = 0;
 
-	smb_msg.msg_name = (struct sockaddr *) &server->dstaddr;
-	smb_msg.msg_namelen = sizeof(struct sockaddr);
-	smb_msg.msg_control = NULL;
-	smb_msg.msg_controllen = 0;
+	smb_msg->msg_name = (struct sockaddr *) &server->dstaddr;
+	smb_msg->msg_namelen = sizeof(struct sockaddr);
+	smb_msg->msg_control = NULL;
+	smb_msg->msg_controllen = 0;
 	if (server->noblocksnd)
-		smb_msg.msg_flags = MSG_DONTWAIT + MSG_NOSIGNAL;
+		smb_msg->msg_flags = MSG_DONTWAIT + MSG_NOSIGNAL;
 	else
-		smb_msg.msg_flags = MSG_NOSIGNAL;
-
-	remaining = 0;
-	for (i = 0; i < n_vec; i++)
-		remaining += iov[i].iov_len;
+		smb_msg->msg_flags = MSG_NOSIGNAL;
 
-	i = 0;
-	while (remaining) {
+	while (msg_data_left(smb_msg)) {
 		/*
 		 * If blocking send, we try 3 times, since each can block
 		 * for 5 seconds. For nonblocking  we have to try more
@@ -177,35 +168,21 @@ smb_send_kvec(struct TCP_Server_Info *server, struct kvec *iov, size_t n_vec,
 		 * after the retries we will kill the socket and
 		 * reconnect which may clear the network problem.
 		 */
-		rc = kernel_sendmsg(ssocket, &smb_msg, &iov[first_vec],
-				    n_vec - first_vec, remaining);
+		rc = sock_sendmsg(ssocket, smb_msg);
 		if (rc == -EAGAIN) {
-			i++;
-			if (i >= 14 || (!server->noblocksnd && (i > 2))) {
+			retries++;
+			if (retries >= 14 ||
+			    (!server->noblocksnd && (retries > 2))) {
 				cifs_dbg(VFS, "sends on sock %p stuck for 15 seconds\n",
 					 ssocket);
-				rc = -EAGAIN;
-				break;
+				return -EAGAIN;
 			}
-			msleep(1 << i);
+			msleep(1 << retries);
 			continue;
 		}
 
 		if (rc < 0)
-			break;
-
-		/* send was at least partially successful */
-		*sent += rc;
-
-		if (rc == remaining) {
-			remaining = 0;
-			break;
-		}
-
-		if (rc > remaining) {
-			cifs_dbg(VFS, "sent %d requested %d\n", rc, remaining);
-			break;
-		}
+			return rc;
 
 		if (rc == 0) {
 			/* should never happen, letting socket clear before
@@ -215,59 +192,11 @@ smb_send_kvec(struct TCP_Server_Info *server, struct kvec *iov, size_t n_vec,
 			continue;
 		}
 
-		remaining -= rc;
-
-		/* the line below resets i */
-		for (i = first_vec; i < n_vec; i++) {
-			if (iov[i].iov_len) {
-				if (rc > iov[i].iov_len) {
-					rc -= iov[i].iov_len;
-					iov[i].iov_len = 0;
-				} else {
-					iov[i].iov_base += rc;
-					iov[i].iov_len -= rc;
-					first_vec = i;
-					break;
-				}
-			}
-		}
-
-		i = 0; /* in case we get ENOSPC on the next send */
-		rc = 0;
+		/* send was at least partially successful */
+		*sent += rc;
+		retries = 0; /* in case we get ENOSPC on the next send */
 	}
-	return rc;
-}
-
-/**
- * rqst_page_to_kvec - Turn a slot in the smb_rqst page array into a kvec
- * @rqst: pointer to smb_rqst
- * @idx: index into the array of the page
- * @iov: pointer to struct kvec that will hold the result
- *
- * Helper function to convert a slot in the rqst->rq_pages array into a kvec.
- * The page will be kmapped and the address placed into iov_base. The length
- * will then be adjusted according to the ptailoff.
- */
-void
-cifs_rqst_page_to_kvec(struct smb_rqst *rqst, unsigned int idx,
-			struct kvec *iov)
-{
-	/*
-	 * FIXME: We could avoid this kmap altogether if we used
-	 * kernel_sendpage instead of kernel_sendmsg. That will only
-	 * work if signing is disabled though as sendpage inlines the
-	 * page directly into the fraglist. If userspace modifies the
-	 * page after we calculate the signature, then the server will
-	 * reject it and may break the connection. kernel_sendmsg does
-	 * an extra copy of the data and avoids that issue.
-	 */
-	iov->iov_base = kmap(rqst->rq_pages[idx]);
-
-	/* if last page, don't send beyond this offset into page */
-	if (idx == (rqst->rq_npages - 1))
-		iov->iov_len = rqst->rq_tailsz;
-	else
-		iov->iov_len = rqst->rq_pagesz;
+	return 0;
 }
 
 static unsigned long
@@ -299,8 +228,9 @@ smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst)
 	unsigned int smb_buf_length = get_rfc1002_length(iov[0].iov_base);
 	unsigned long send_length;
 	unsigned int i;
-	size_t total_len = 0, sent;
+	size_t total_len = 0, sent, size;
 	struct socket *ssocket = server->ssocket;
+	struct msghdr smb_msg;
 	int val = 1;
 
 	if (ssocket == NULL)
@@ -321,7 +251,13 @@ smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst)
 	kernel_setsockopt(ssocket, SOL_TCP, TCP_CORK,
 				(char *)&val, sizeof(val));
 
-	rc = smb_send_kvec(server, iov, n_vec, &sent);
+	size = 0;
+	for (i = 0; i < n_vec; i++)
+		size += iov[i].iov_len;
+
+	iov_iter_kvec(&smb_msg.msg_iter, WRITE | ITER_KVEC, iov, n_vec, size);
+
+	rc = smb_send_kvec(server, &smb_msg, &sent);
 	if (rc < 0)
 		goto uncork;
 
@@ -329,11 +265,16 @@ smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst)
 
 	/* now walk the page array and send each page in it */
 	for (i = 0; i < rqst->rq_npages; i++) {
-		struct kvec p_iov;
-
-		cifs_rqst_page_to_kvec(rqst, i, &p_iov);
-		rc = smb_send_kvec(server, &p_iov, 1, &sent);
-		kunmap(rqst->rq_pages[i]);
+		size_t len = i == rqst->rq_npages - 1
+				? rqst->rq_tailsz
+				: rqst->rq_pagesz;
+		struct bio_vec bvec = {
+			.bv_page = rqst->rq_pages[i],
+			.bv_len = len
+		};
+		iov_iter_bvec(&smb_msg.msg_iter, WRITE | ITER_BVEC,
+			      &bvec, 1, len);
+		rc = smb_send_kvec(server, &smb_msg, &sent);
 		if (rc < 0)
 			break;
 
-- 
2.8.0.rc3

Re: [PATCH 3/6] cifs: quit playing games with draining iovecs

[Jeff Layton]

On Sat, 2016-04-09 at 21:51 +0100, Al Viro wrote:
> ... and use ITER_BVEC for the page part of request to send
> 
> Signed-off-by: Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
> ---
>  fs/cifs/cifsproto.h |   2 -
>  fs/cifs/transport.c | 141 +++++++++++++++---------------------------
> ----------
>  2 files changed, 41 insertions(+), 102 deletions(-)
> 
> diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
> index d9b4f44..7d5f53a 100644
> --- a/fs/cifs/cifsproto.h
> +++ b/fs/cifs/cifsproto.h
> @@ -37,8 +37,6 @@ extern void cifs_buf_release(void *);
>  extern struct smb_hdr *cifs_small_buf_get(void);
>  extern void cifs_small_buf_release(void *);
>  extern void free_rsp_buf(int, void *);
> -extern void cifs_rqst_page_to_kvec(struct smb_rqst *rqst, unsigned
> int idx,
> -					struct kvec *iov);
>  extern int smb_send(struct TCP_Server_Info *, struct smb_hdr *,
>  			unsigned int /* length */);
>  extern unsigned int _get_xid(void);
> diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
> index 87abe8e..206a597 100644
> --- a/fs/cifs/transport.c
> +++ b/fs/cifs/transport.c
> @@ -124,41 +124,32 @@ cifs_delete_mid(struct mid_q_entry *mid)
>  /*
>   * smb_send_kvec - send an array of kvecs to the server
>   * @server:	Server to send the data to
> - * @iov:	Pointer to array of kvecs
> - * @n_vec:	length of kvec array
> + * @smb_msg:	Message to send
>   * @sent:	amount of data sent on socket is stored here
>   *
>   * Our basic "send data to server" function. Should be called with
> srv_mutex
>   * held. The caller is responsible for handling the results.
>   */
>  static int
> -smb_send_kvec(struct TCP_Server_Info *server, struct kvec *iov,
> size_t n_vec,
> -		size_t *sent)
> +smb_send_kvec(struct TCP_Server_Info *server, struct msghdr
> *smb_msg,
> +	      size_t *sent)
>  {
>  	int rc = 0;
> -	int i = 0;
> -	struct msghdr smb_msg;
> -	unsigned int remaining;
> -	size_t first_vec = 0;
> +	int retries = 0;
>  	struct socket *ssocket = server->ssocket;
>  
>  	*sent = 0;
>  
> -	smb_msg.msg_name = (struct sockaddr *) &server->dstaddr;
> -	smb_msg.msg_namelen = sizeof(struct sockaddr);
> -	smb_msg.msg_control = NULL;
> -	smb_msg.msg_controllen = 0;
> +	smb_msg->msg_name = (struct sockaddr *) &server->dstaddr;
> +	smb_msg->msg_namelen = sizeof(struct sockaddr);
> +	smb_msg->msg_control = NULL;
> +	smb_msg->msg_controllen = 0;
>  	if (server->noblocksnd)
> -		smb_msg.msg_flags = MSG_DONTWAIT + MSG_NOSIGNAL;
> +		smb_msg->msg_flags = MSG_DONTWAIT + MSG_NOSIGNAL;
>  	else
> -		smb_msg.msg_flags = MSG_NOSIGNAL;
> -
> -	remaining = 0;
> -	for (i = 0; i < n_vec; i++)
> -		remaining += iov[i].iov_len;
> +		smb_msg->msg_flags = MSG_NOSIGNAL;
>  
> -	i = 0;
> -	while (remaining) {
> +	while (msg_data_left(smb_msg)) {
>  		/*
>  		 * If blocking send, we try 3 times, since each can
> block
>  		 * for 5 seconds. For nonblocking  we have to try
> more
> @@ -177,35 +168,21 @@ smb_send_kvec(struct TCP_Server_Info *server,
> struct kvec *iov, size_t n_vec,
>  		 * after the retries we will kill the socket and
>  		 * reconnect which may clear the network problem.
>  		 */
> -		rc = kernel_sendmsg(ssocket, &smb_msg,
> &iov[first_vec],
> -				    n_vec - first_vec, remaining);
> +		rc = sock_sendmsg(ssocket, smb_msg);
>  		if (rc == -EAGAIN) {
> -			i++;
> -			if (i >= 14 || (!server->noblocksnd && (i >
> 2))) {
> +			retries++;
> +			if (retries >= 14 ||
> +			    (!server->noblocksnd && (retries > 2)))
> {
>  				cifs_dbg(VFS, "sends on sock %p
> stuck for 15 seconds\n",
>  					 ssocket);
> -				rc = -EAGAIN;
> -				break;
> +				return -EAGAIN;
>  			}
> -			msleep(1 << i);
> +			msleep(1 << retries);
>  			continue;
>  		}
>  
>  		if (rc < 0)
> -			break;
> -
> -		/* send was at least partially successful */
> -		*sent += rc;
> -
> -		if (rc == remaining) {
> -			remaining = 0;
> -			break;
> -		}
> -
> -		if (rc > remaining) {
> -			cifs_dbg(VFS, "sent %d requested %d\n", rc,
> remaining);
> -			break;
> -		}
> +			return rc;
>  
>  		if (rc == 0) {
>  			/* should never happen, letting socket clear
> before
> @@ -215,59 +192,11 @@ smb_send_kvec(struct TCP_Server_Info *server,
> struct kvec *iov, size_t n_vec,
>  			continue;
>  		}
>  
> -		remaining -= rc;
> -
> -		/* the line below resets i */
> -		for (i = first_vec; i < n_vec; i++) {
> -			if (iov[i].iov_len) {
> -				if (rc > iov[i].iov_len) {
> -					rc -= iov[i].iov_len;
> -					iov[i].iov_len = 0;
> -				} else {
> -					iov[i].iov_base += rc;
> -					iov[i].iov_len -= rc;
> -					first_vec = i;
> -					break;
> -				}
> -			}
> -		}
> -
> -		i = 0; /* in case we get ENOSPC on the next send */
> -		rc = 0;
> +		/* send was at least partially successful */
> +		*sent += rc;
> +		retries = 0; /* in case we get ENOSPC on the next
> send */
>  	}
> -	return rc;
> -}
> -
> -/**
> - * rqst_page_to_kvec - Turn a slot in the smb_rqst page array into a
> kvec
> - * @rqst: pointer to smb_rqst
> - * @idx: index into the array of the page
> - * @iov: pointer to struct kvec that will hold the result
> - *
> - * Helper function to convert a slot in the rqst->rq_pages array
> into a kvec.
> - * The page will be kmapped and the address placed into iov_base.
> The length
> - * will then be adjusted according to the ptailoff.
> - */
> -void
> -cifs_rqst_page_to_kvec(struct smb_rqst *rqst, unsigned int idx,
> -			struct kvec *iov)
> -{
> -	/*
> -	 * FIXME: We could avoid this kmap altogether if we used
> -	 * kernel_sendpage instead of kernel_sendmsg. That will only
> -	 * work if signing is disabled though as sendpage inlines
> the
> -	 * page directly into the fraglist. If userspace modifies
> the
> -	 * page after we calculate the signature, then the server
> will
> -	 * reject it and may break the connection. kernel_sendmsg
> does
> -	 * an extra copy of the data and avoids that issue.
> -	 */
> -	iov->iov_base = kmap(rqst->rq_pages[idx]);
> -
> -	/* if last page, don't send beyond this offset into page */
> -	if (idx == (rqst->rq_npages - 1))
> -		iov->iov_len = rqst->rq_tailsz;
> -	else
> -		iov->iov_len = rqst->rq_pagesz;
> +	return 0;
>  }
>  
>  static unsigned long
> @@ -299,8 +228,9 @@ smb_send_rqst(struct TCP_Server_Info *server,
> struct smb_rqst *rqst)
>  	unsigned int smb_buf_length =
> get_rfc1002_length(iov[0].iov_base);
>  	unsigned long send_length;
>  	unsigned int i;
> -	size_t total_len = 0, sent;
> +	size_t total_len = 0, sent, size;
>  	struct socket *ssocket = server->ssocket;
> +	struct msghdr smb_msg;
>  	int val = 1;
>  
>  	if (ssocket == NULL)
> @@ -321,7 +251,13 @@ smb_send_rqst(struct TCP_Server_Info *server,
> struct smb_rqst *rqst)
>  	kernel_setsockopt(ssocket, SOL_TCP, TCP_CORK,
>  				(char *)&val, sizeof(val));
>  
> -	rc = smb_send_kvec(server, iov, n_vec, &sent);
> +	size = 0;
> +	for (i = 0; i < n_vec; i++)
> +		size += iov[i].iov_len;
> +
> +	iov_iter_kvec(&smb_msg.msg_iter, WRITE | ITER_KVEC, iov,
> n_vec, size);
> +
> +	rc = smb_send_kvec(server, &smb_msg, &sent);
>  	if (rc < 0)
>  		goto uncork;
>  
> @@ -329,11 +265,16 @@ smb_send_rqst(struct TCP_Server_Info *server,
> struct smb_rqst *rqst)
>  
>  	/* now walk the page array and send each page in it */
>  	for (i = 0; i < rqst->rq_npages; i++) {
> -		struct kvec p_iov;
> -
> -		cifs_rqst_page_to_kvec(rqst, i, &p_iov);
> -		rc = smb_send_kvec(server, &p_iov, 1, &sent);
> -		kunmap(rqst->rq_pages[i]);
> +		size_t len = i == rqst->rq_npages - 1
> +				? rqst->rq_tailsz
> +				: rqst->rq_pagesz;
> +		struct bio_vec bvec = {
> +			.bv_page = rqst->rq_pages[i],
> +			.bv_len = len
> +		};
> +		iov_iter_bvec(&smb_msg.msg_iter, WRITE | ITER_BVEC,
> +			      &bvec, 1, len);
> +		rc = smb_send_kvec(server, &smb_msg, &sent);
>  		if (rc < 0)
>  			break;
>  

What's the advantage of using iov_iter_bvec over iov_iter_kvec ?

That said...

Acked-by: Jeff Layton <jlayton-vpEMnDpepFuMZCB2o+C8xQ@public.gmane.org>

Re: [PATCH 3/6] cifs: quit playing games with draining iovecs

[Al Viro]

On Tue, Apr 19, 2016 at 01:53:17PM -0400, Jeff Layton wrote:

> What's the advantage of using iov_iter_bvec over iov_iter_kvec ?

No need to screw with kmap() in the caller; moreover, when it comes to actual
copying it gets away with kmap_atomic() just around the memcpy(), which is
considerably cheaper.

[PATCH 4/6] cifs: no need to wank with copying and advancing iovec on recvmsg side either

[Al Viro]

Signed-off-by: Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
---
 fs/cifs/cifsglob.h |  2 --
 fs/cifs/connect.c  | 72 ++++--------------------------------------------------
 2 files changed, 5 insertions(+), 69 deletions(-)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index d21da9f..df03c5e 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -615,8 +615,6 @@ struct TCP_Server_Info {
 	bool	sec_mskerberos;		/* supports legacy MS Kerberos */
 	bool	large_buf;		/* is current buffer large? */
 	struct delayed_work	echo; /* echo ping workqueue job */
-	struct kvec *iov;	/* reusable kvec array for receives */
-	unsigned int nr_iov;	/* number of kvecs in array */
 	char	*smallbuf;	/* pointer to current "small" buffer */
 	char	*bigbuf;	/* pointer to current "big" buffer */
 	unsigned int total_read; /* total amount of data read in this pass */
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index a763cd3..eb42665 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -501,77 +501,20 @@ server_unresponsive(struct TCP_Server_Info *server)
 	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 struct kvec *
-get_server_iovec(struct TCP_Server_Info *server, unsigned int nr_segs)
-{
-	struct kvec *new_iov;
-
-	if (server->iov && nr_segs <= server->nr_iov)
-		return server->iov;
-
-	/* not big enough -- allocate a new one and release the old */
-	new_iov = kmalloc(sizeof(*new_iov) * nr_segs, GFP_NOFS);
-	if (new_iov) {
-		kfree(server->iov);
-		server->iov = new_iov;
-		server->nr_iov = nr_segs;
-	}
-	return new_iov;
-}
-
 int
 cifs_readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,
 		       unsigned int nr_segs, unsigned int to_read)
 {
 	int length = 0;
 	int total_read;
-	unsigned int segs;
 	struct msghdr smb_msg;
-	struct kvec *iov;
-
-	iov = get_server_iovec(server, nr_segs);
-	if (!iov)
-		return -ENOMEM;
 
 	smb_msg.msg_control = NULL;
 	smb_msg.msg_controllen = 0;
+	iov_iter_kvec(&smb_msg.msg_iter, READ | ITER_KVEC,
+		      iov_orig, nr_segs, to_read);
 
-	for (total_read = 0; to_read; total_read += length, to_read -= length) {
+	for (total_read = 0; msg_data_left(&smb_msg); total_read += length) {
 		try_to_freeze();
 
 		if (server_unresponsive(server)) {
@@ -579,10 +522,7 @@ cifs_readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,
 			break;
 		}
 
-		segs = kvec_array_init(iov, iov_orig, nr_segs, total_read);
-
-		length = kernel_recvmsg(server->ssocket, &smb_msg,
-					iov, segs, to_read, 0);
+		length = sock_recvmsg(server->ssocket, &smb_msg, 0);
 
 		if (server->tcpStatus == CifsExiting) {
 			total_read = -ESHUTDOWN;
@@ -603,8 +543,7 @@ cifs_readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,
 			length = 0;
 			continue;
 		} else if (length <= 0) {
-			cifs_dbg(FYI, "Received no data or error: expecting %d\n"
-				 "got %d", to_read, length);
+			cifs_dbg(FYI, "Received no data or error: %d\n", length);
 			cifs_reconnect(server);
 			total_read = -ECONNABORTED;
 			break;
@@ -783,7 +722,6 @@ static void clean_demultiplex_info(struct TCP_Server_Info *server)
 	}
 
 	kfree(server->hostname);
-	kfree(server->iov);
 	kfree(server);
 
 	length = atomic_dec_return(&tcpSesAllocCount);
-- 
2.8.0.rc3

Re: [PATCH 4/6] cifs: no need to wank with copying and advancing iovec on recvmsg side either

[Jeff Layton]

On Sat, 2016-04-09 at 21:52 +0100, Al Viro wrote:
> Signed-off-by: Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
> ---
>  fs/cifs/cifsglob.h |  2 --
>  fs/cifs/connect.c  | 72 ++++--------------------------------------------------
>  2 files changed, 5 insertions(+), 69 deletions(-)
> 
> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> index d21da9f..df03c5e 100644
> --- a/fs/cifs/cifsglob.h
> +++ b/fs/cifs/cifsglob.h
> @@ -615,8 +615,6 @@ struct TCP_Server_Info {
>  	bool	sec_mskerberos;		/* supports legacy MS Kerberos */
>  	bool	large_buf;		/* is current buffer large? */
>  	struct delayed_work	echo; /* echo ping workqueue job */
> -	struct kvec *iov;	/* reusable kvec array for receives */
> -	unsigned int nr_iov;	/* number of kvecs in array */
>  	char	*smallbuf;	/* pointer to current "small" buffer */
>  	char	*bigbuf;	/* pointer to current "big" buffer */
>  	unsigned int total_read; /* total amount of data read in this pass */
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index a763cd3..eb42665 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -501,77 +501,20 @@ server_unresponsive(struct TCP_Server_Info *server)
>  	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 struct kvec *
> -get_server_iovec(struct TCP_Server_Info *server, unsigned int nr_segs)
> -{
> -	struct kvec *new_iov;
> -
> -	if (server->iov && nr_segs <= server->nr_iov)
> -		return server->iov;
> -
> -	/* not big enough -- allocate a new one and release the old */
> -	new_iov = kmalloc(sizeof(*new_iov) * nr_segs, GFP_NOFS);
> -	if (new_iov) {
> -		kfree(server->iov);
> -		server->iov = new_iov;
> -		server->nr_iov = nr_segs;
> -	}
> -	return new_iov;
> -}
> -
>  int
>  cifs_readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,
>  		       unsigned int nr_segs, unsigned int to_read)
>  {
>  	int length = 0;
>  	int total_read;
> -	unsigned int segs;
>  	struct msghdr smb_msg;
> -	struct kvec *iov;
> -
> -	iov = get_server_iovec(server, nr_segs);
> -	if (!iov)
> -		return -ENOMEM;
>  
>  	smb_msg.msg_control = NULL;
>  	smb_msg.msg_controllen = 0;
> +	iov_iter_kvec(&smb_msg.msg_iter, READ | ITER_KVEC,
> +		      iov_orig, nr_segs, to_read);
>  
> -	for (total_read = 0; to_read; total_read += length, to_read -= length) {
> +	for (total_read = 0; msg_data_left(&smb_msg); total_read += length) {
>  		try_to_freeze();
>  
>  		if (server_unresponsive(server)) {
> @@ -579,10 +522,7 @@ cifs_readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,
>  			break;
>  		}
>  
> -		segs = kvec_array_init(iov, iov_orig, nr_segs, total_read);
> -
> -		length = kernel_recvmsg(server->ssocket, &smb_msg,
> -					iov, segs, to_read, 0);
> +		length = sock_recvmsg(server->ssocket, &smb_msg, 0);
>  
>  		if (server->tcpStatus == CifsExiting) {
>  			total_read = -ESHUTDOWN;
> @@ -603,8 +543,7 @@ cifs_readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,
>  			length = 0;
>  			continue;
>  		} else if (length <= 0) {
> -			cifs_dbg(FYI, "Received no data or error: expecting %d\n"
> -				 "got %d", to_read, length);
> +			cifs_dbg(FYI, "Received no data or error: %d\n", length);
>  			cifs_reconnect(server);
>  			total_read = -ECONNABORTED;
>  			break;
> @@ -783,7 +722,6 @@ static void clean_demultiplex_info(struct TCP_Server_Info *server)
>  	}
>  
>  	kfree(server->hostname);
> -	kfree(server->iov);
>  	kfree(server);
>  
>  	length = atomic_dec_return(&tcpSesAllocCount);

Good riddance.

Reviewed-by: Jeff Layton <jlayton-vpEMnDpepFuMZCB2o+C8xQ@public.gmane.org>

[PATCH 5/6] cifs_readv_receive: use cifs_read_from_socket()

[Al Viro]

Signed-off-by: Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
---
 fs/cifs/cifssmb.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 76fcb50..3da077a 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -1447,10 +1447,8 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
 	len = min_t(unsigned int, buflen, server->vals->read_rsp_size) -
 							HEADER_SIZE(server) + 1;
 
-	rdata->iov.iov_base = buf + HEADER_SIZE(server) - 1;
-	rdata->iov.iov_len = len;
-
-	length = cifs_readv_from_socket(server, &rdata->iov, 1, len);
+	length = cifs_read_from_socket(server,
+				       buf + HEADER_SIZE(server) - 1, len);
 	if (length < 0)
 		return length;
 	server->total_read += length;
@@ -1502,9 +1500,8 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
 	len = data_offset - server->total_read;
 	if (len > 0) {
 		/* read any junk before data into the rest of smallbuf */
-		rdata->iov.iov_base = buf + server->total_read;
-		rdata->iov.iov_len = len;
-		length = cifs_readv_from_socket(server, &rdata->iov, 1, len);
+		length = cifs_read_from_socket(server,
+					       buf + server->total_read, len);
 		if (length < 0)
 			return length;
 		server->total_read += length;
-- 
2.8.0.rc3

Re: [PATCH 5/6] cifs_readv_receive: use cifs_read_from_socket()

[Jeff Layton]

On Sat, 2016-04-09 at 21:52 +0100, Al Viro wrote:
> Signed-off-by: Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
> ---
>  fs/cifs/cifssmb.c | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
> index 76fcb50..3da077a 100644
> --- a/fs/cifs/cifssmb.c
> +++ b/fs/cifs/cifssmb.c
> @@ -1447,10 +1447,8 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
>  	len = min_t(unsigned int, buflen, server->vals->read_rsp_size) -
>  							HEADER_SIZE(server) + 1;
>  
> -	rdata->iov.iov_base = buf + HEADER_SIZE(server) - 1;
> -	rdata->iov.iov_len = len;
> -
> -	length = cifs_readv_from_socket(server, &rdata->iov, 1, len);
> +	length = cifs_read_from_socket(server,
> +				       buf + HEADER_SIZE(server) - 1, len);
>  	if (length < 0)
>  		return length;
>  	server->total_read += length;
> @@ -1502,9 +1500,8 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
>  	len = data_offset - server->total_read;
>  	if (len > 0) {
>  		/* read any junk before data into the rest of smallbuf */
> -		rdata->iov.iov_base = buf + server->total_read;
> -		rdata->iov.iov_len = len;
> -		length = cifs_readv_from_socket(server, &rdata->iov, 1, len);
> +		length = cifs_read_from_socket(server,
> +					       buf + server->total_read, len);
>  		if (length < 0)
>  			return length;
>  		server->total_read += length;

This one is orthogonal to the rest. Looks good though.

Reviewed-by: Jeff Layton <jlayton-vpEMnDpepFuMZCB2o+C8xQ@public.gmane.org>

[PATCH 6/6] cifs: don't bother with kmap on read_pages side

[Al Viro]

just do ITER_BVEC recvmsg

Signed-off-by: Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
---
 fs/cifs/cifsproto.h |  7 +++---
 fs/cifs/connect.c   | 65 ++++++++++++++++++++++++++++-------------------------
 fs/cifs/file.c      | 53 ++++++++++++++-----------------------------
 3 files changed, 55 insertions(+), 70 deletions(-)

diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 7d5f53a..0f9a6bc 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -179,10 +179,9 @@ extern int set_cifs_acl(struct cifs_ntsd *, __u32, struct inode *,
 
 extern void dequeue_mid(struct mid_q_entry *mid, bool malformed);
 extern int cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
-		     unsigned int to_read);
-extern int cifs_readv_from_socket(struct TCP_Server_Info *server,
-		struct kvec *iov_orig, unsigned int nr_segs,
-		unsigned int to_read);
+			         unsigned int to_read);
+extern int cifs_read_page_from_socket(struct TCP_Server_Info *server,
+				      struct page *page, unsigned int to_read);
 extern void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
 			       struct cifs_sb_info *cifs_sb);
 extern int cifs_match_super(struct super_block *, void *);
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index eb42665..e33c5e0 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -501,39 +501,34 @@ server_unresponsive(struct TCP_Server_Info *server)
 	return false;
 }
 
-int
-cifs_readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,
-		       unsigned int nr_segs, unsigned int to_read)
+static int
+cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg)
 {
 	int length = 0;
 	int total_read;
-	struct msghdr smb_msg;
 
-	smb_msg.msg_control = NULL;
-	smb_msg.msg_controllen = 0;
-	iov_iter_kvec(&smb_msg.msg_iter, READ | ITER_KVEC,
-		      iov_orig, nr_segs, to_read);
+	smb_msg->msg_control = NULL;
+	smb_msg->msg_controllen = 0;
 
-	for (total_read = 0; msg_data_left(&smb_msg); total_read += length) {
+	for (total_read = 0; msg_data_left(smb_msg); total_read += length) {
 		try_to_freeze();
 
-		if (server_unresponsive(server)) {
-			total_read = -ECONNABORTED;
-			break;
-		}
+		if (server_unresponsive(server))
+			return -ECONNABORTED;
 
-		length = sock_recvmsg(server->ssocket, &smb_msg, 0);
+		length = sock_recvmsg(server->ssocket, smb_msg, 0);
 
-		if (server->tcpStatus == CifsExiting) {
-			total_read = -ESHUTDOWN;
-			break;
-		} else if (server->tcpStatus == CifsNeedReconnect) {
+		if (server->tcpStatus == CifsExiting)
+			return -ESHUTDOWN;
+
+		if (server->tcpStatus == CifsNeedReconnect) {
 			cifs_reconnect(server);
-			total_read = -ECONNABORTED;
-			break;
-		} else if (length == -ERESTARTSYS ||
-			   length == -EAGAIN ||
-			   length == -EINTR) {
+			return -ECONNABORTED;
+		}
+
+		if (length == -ERESTARTSYS ||
+		    length == -EAGAIN ||
+		    length == -EINTR) {
 			/*
 			 * Minimum sleep to prevent looping, allowing socket
 			 * to clear and app threads to set tcpStatus
@@ -542,11 +537,12 @@ cifs_readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,
 			usleep_range(1000, 2000);
 			length = 0;
 			continue;
-		} else if (length <= 0) {
+		}
+
+		if (length <= 0) {
 			cifs_dbg(FYI, "Received no data or error: %d\n", length);
 			cifs_reconnect(server);
-			total_read = -ECONNABORTED;
-			break;
+			return -ECONNABORTED;
 		}
 	}
 	return total_read;
@@ -556,12 +552,21 @@ int
 cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
 		      unsigned int to_read)
 {
-	struct kvec iov;
+	struct msghdr smb_msg;
+	struct kvec iov = {.iov_base = buf, .iov_len = to_read};
+	iov_iter_kvec(&smb_msg.msg_iter, READ | ITER_KVEC, &iov, 1, to_read);
 
-	iov.iov_base = buf;
-	iov.iov_len = to_read;
+	return cifs_readv_from_socket(server, &smb_msg);
+}
 
-	return cifs_readv_from_socket(server, &iov, 1, to_read);
+int
+cifs_read_page_from_socket(struct TCP_Server_Info *server, struct page *page,
+		      unsigned int to_read)
+{
+	struct msghdr smb_msg;
+	struct bio_vec bv = {.bv_page = page, .bv_len = to_read};
+	iov_iter_bvec(&smb_msg.msg_iter, READ | ITER_BVEC, &bv, 1, to_read);
+	return cifs_readv_from_socket(server, &smb_msg);
 }
 
 static bool
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index ff882ae..0f71867 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2855,39 +2855,31 @@ cifs_uncached_read_into_pages(struct TCP_Server_Info *server,
 	int result = 0;
 	unsigned int i;
 	unsigned int nr_pages = rdata->nr_pages;
-	struct kvec iov;
 
 	rdata->got_bytes = 0;
 	rdata->tailsz = PAGE_SIZE;
 	for (i = 0; i < nr_pages; i++) {
 		struct page *page = rdata->pages[i];
+		size_t n;
 
-		if (len >= PAGE_SIZE) {
-			/* enough data to fill the page */
-			iov.iov_base = kmap(page);
-			iov.iov_len = PAGE_SIZE;
-			cifs_dbg(FYI, "%u: iov_base=%p iov_len=%zu\n",
-				 i, iov.iov_base, iov.iov_len);
-			len -= PAGE_SIZE;
-		} else if (len > 0) {
-			/* enough for partial page, fill and zero the rest */
-			iov.iov_base = kmap(page);
-			iov.iov_len = len;
-			cifs_dbg(FYI, "%u: iov_base=%p iov_len=%zu\n",
-				 i, iov.iov_base, iov.iov_len);
-			memset(iov.iov_base + len, '\0', PAGE_SIZE - len);
-			rdata->tailsz = len;
-			len = 0;
-		} else {
+		if (len <= 0) {
 			/* no need to hold page hostage */
 			rdata->pages[i] = NULL;
 			rdata->nr_pages--;
 			put_page(page);
 			continue;
 		}
-
-		result = cifs_readv_from_socket(server, &iov, 1, iov.iov_len);
-		kunmap(page);
+		n = len;
+		if (len >= PAGE_SIZE) {
+			/* enough data to fill the page */
+			n = PAGE_SIZE;
+			len -= n;
+		} else {
+			zero_user(page, len, PAGE_SIZE - len);
+			rdata->tailsz = len;
+			len = 0;
+		}
+		result = cifs_read_page_from_socket(server, page, n);
 		if (result < 0)
 			break;
 
@@ -3303,7 +3295,6 @@ cifs_readpages_read_into_pages(struct TCP_Server_Info *server,
 	u64 eof;
 	pgoff_t eof_index;
 	unsigned int nr_pages = rdata->nr_pages;
-	struct kvec iov;
 
 	/* determine the eof that the server (probably) has */
 	eof = CIFS_I(rdata->mapping->host)->server_eof;
@@ -3314,23 +3305,14 @@ cifs_readpages_read_into_pages(struct TCP_Server_Info *server,
 	rdata->tailsz = PAGE_CACHE_SIZE;
 	for (i = 0; i < nr_pages; i++) {
 		struct page *page = rdata->pages[i];
+		size_t n = PAGE_CACHE_SIZE;
 
 		if (len >= PAGE_CACHE_SIZE) {
-			/* enough data to fill the page */
-			iov.iov_base = kmap(page);
-			iov.iov_len = PAGE_CACHE_SIZE;
-			cifs_dbg(FYI, "%u: idx=%lu iov_base=%p iov_len=%zu\n",
-				 i, page->index, iov.iov_base, iov.iov_len);
 			len -= PAGE_CACHE_SIZE;
 		} else if (len > 0) {
 			/* enough for partial page, fill and zero the rest */
-			iov.iov_base = kmap(page);
-			iov.iov_len = len;
-			cifs_dbg(FYI, "%u: idx=%lu iov_base=%p iov_len=%zu\n",
-				 i, page->index, iov.iov_base, iov.iov_len);
-			memset(iov.iov_base + len,
-				'\0', PAGE_CACHE_SIZE - len);
-			rdata->tailsz = len;
+			zero_user(page, len, PAGE_CACHE_SIZE - len);
+			n = rdata->tailsz = len;
 			len = 0;
 		} else if (page->index > eof_index) {
 			/*
@@ -3360,8 +3342,7 @@ cifs_readpages_read_into_pages(struct TCP_Server_Info *server,
 			continue;
 		}
 
-		result = cifs_readv_from_socket(server, &iov, 1, iov.iov_len);
-		kunmap(page);
+		result = cifs_read_page_from_socket(server, page, n);
 		if (result < 0)
 			break;
 
-- 
2.8.0.rc3

Re: [PATCH 6/6] cifs: don't bother with kmap on read_pages side

[Jeff Layton]

On Sat, 2016-04-09 at 21:53 +0100, Al Viro wrote:
> just do ITER_BVEC recvmsg
> 
> Signed-off-by: Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
> ---
>  fs/cifs/cifsproto.h |  7 +++---
>  fs/cifs/connect.c   | 65 ++++++++++++++++++++++++++++-------------------------
>  fs/cifs/file.c      | 53 ++++++++++++++-----------------------------
>  3 files changed, 55 insertions(+), 70 deletions(-)
> 
> diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
> index 7d5f53a..0f9a6bc 100644
> --- a/fs/cifs/cifsproto.h
> +++ b/fs/cifs/cifsproto.h
> @@ -179,10 +179,9 @@ extern int set_cifs_acl(struct cifs_ntsd *, __u32, struct inode *,
>  
>  extern void dequeue_mid(struct mid_q_entry *mid, bool malformed);
>  extern int cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
> -		     unsigned int to_read);
> -extern int cifs_readv_from_socket(struct TCP_Server_Info *server,
> -		struct kvec *iov_orig, unsigned int nr_segs,
> -		unsigned int to_read);
> +			         unsigned int to_read);
> +extern int cifs_read_page_from_socket(struct TCP_Server_Info *server,
> +				      struct page *page, unsigned int to_read);
>  extern void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
>  			       struct cifs_sb_info *cifs_sb);
>  extern int cifs_match_super(struct super_block *, void *);
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index eb42665..e33c5e0 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -501,39 +501,34 @@ server_unresponsive(struct TCP_Server_Info *server)
>  	return false;
>  }
>  
> -int
> -cifs_readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,
> -		       unsigned int nr_segs, unsigned int to_read)
> +static int
> +cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg)
>  {
>  	int length = 0;
>  	int total_read;
> -	struct msghdr smb_msg;
>  
> -	smb_msg.msg_control = NULL;
> -	smb_msg.msg_controllen = 0;
> -	iov_iter_kvec(&smb_msg.msg_iter, READ | ITER_KVEC,
> -		      iov_orig, nr_segs, to_read);
> +	smb_msg->msg_control = NULL;
> +	smb_msg->msg_controllen = 0;
>  
> -	for (total_read = 0; msg_data_left(&smb_msg); total_read += length) {
> +	for (total_read = 0; msg_data_left(smb_msg); total_read += length) {
>  		try_to_freeze();
>  
> -		if (server_unresponsive(server)) {
> -			total_read = -ECONNABORTED;
> -			break;
> -		}
> +		if (server_unresponsive(server))
> +			return -ECONNABORTED;
>  
> -		length = sock_recvmsg(server->ssocket, &smb_msg, 0);
> +		length = sock_recvmsg(server->ssocket, smb_msg, 0);
>  
> -		if (server->tcpStatus == CifsExiting) {
> -			total_read = -ESHUTDOWN;
> -			break;
> -		} else if (server->tcpStatus == CifsNeedReconnect) {
> +		if (server->tcpStatus == CifsExiting)
> +			return -ESHUTDOWN;
> +
> +		if (server->tcpStatus == CifsNeedReconnect) {
>  			cifs_reconnect(server);
> -			total_read = -ECONNABORTED;
> -			break;
> -		} else if (length == -ERESTARTSYS ||
> -			   length == -EAGAIN ||
> -			   length == -EINTR) {
> +			return -ECONNABORTED;
> +		}
> +
> +		if (length == -ERESTARTSYS ||
> +		    length == -EAGAIN ||
> +		    length == -EINTR) {
>  			/*
>  			 * Minimum sleep to prevent looping, allowing socket
>  			 * to clear and app threads to set tcpStatus
> @@ -542,11 +537,12 @@ cifs_readv_from_socket(struct TCP_Server_Info *server, struct kvec *iov_orig,
>  			usleep_range(1000, 2000);
>  			length = 0;
>  			continue;
> -		} else if (length <= 0) {
> +		}
> +
> +		if (length <= 0) {
>  			cifs_dbg(FYI, "Received no data or error: %d\n", length);
>  			cifs_reconnect(server);
> -			total_read = -ECONNABORTED;
> -			break;
> +			return -ECONNABORTED;
>  		}
>  	}
>  	return total_read;
> @@ -556,12 +552,21 @@ int
>  cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
>  		      unsigned int to_read)
>  {
> -	struct kvec iov;
> +	struct msghdr smb_msg;
> +	struct kvec iov = {.iov_base = buf, .iov_len = to_read};
> +	iov_iter_kvec(&smb_msg.msg_iter, READ | ITER_KVEC, &iov, 1, to_read);
>  
> -	iov.iov_base = buf;
> -	iov.iov_len = to_read;
> +	return cifs_readv_from_socket(server, &smb_msg);
> +}
>  
> -	return cifs_readv_from_socket(server, &iov, 1, to_read);
> +int
> +cifs_read_page_from_socket(struct TCP_Server_Info *server, struct page *page,
> +		      unsigned int to_read)
> +{
> +	struct msghdr smb_msg;
> +	struct bio_vec bv = {.bv_page = page, .bv_len = to_read};
> +	iov_iter_bvec(&smb_msg.msg_iter, READ | ITER_BVEC, &bv, 1, to_read);
> +	return cifs_readv_from_socket(server, &smb_msg);
>  }
>  
>  static bool
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index ff882ae..0f71867 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -2855,39 +2855,31 @@ cifs_uncached_read_into_pages(struct TCP_Server_Info *server,
>  	int result = 0;
>  	unsigned int i;
>  	unsigned int nr_pages = rdata->nr_pages;
> -	struct kvec iov;
>  
>  	rdata->got_bytes = 0;
>  	rdata->tailsz = PAGE_SIZE;
>  	for (i = 0; i < nr_pages; i++) {
>  		struct page *page = rdata->pages[i];
> +		size_t n;
>  
> -		if (len >= PAGE_SIZE) {
> -			/* enough data to fill the page */
> -			iov.iov_base = kmap(page);
> -			iov.iov_len = PAGE_SIZE;
> -			cifs_dbg(FYI, "%u: iov_base=%p iov_len=%zu\n",
> -				 i, iov.iov_base, iov.iov_len);
> -			len -= PAGE_SIZE;
> -		} else if (len > 0) {
> -			/* enough for partial page, fill and zero the rest */
> -			iov.iov_base = kmap(page);
> -			iov.iov_len = len;
> -			cifs_dbg(FYI, "%u: iov_base=%p iov_len=%zu\n",
> -				 i, iov.iov_base, iov.iov_len);
> -			memset(iov.iov_base + len, '\0', PAGE_SIZE - len);
> -			rdata->tailsz = len;
> -			len = 0;
> -		} else {
> +		if (len <= 0) {
>  			/* no need to hold page hostage */
>  			rdata->pages[i] = NULL;
>  			rdata->nr_pages--;
>  			put_page(page);
>  			continue;
>  		}
> -
> -		result = cifs_readv_from_socket(server, &iov, 1, iov.iov_len);
> -		kunmap(page);
> +		n = len;
> +		if (len >= PAGE_SIZE) {
> +			/* enough data to fill the page */
> +			n = PAGE_SIZE;
> +			len -= n;
> +		} else {
> +			zero_user(page, len, PAGE_SIZE - len);
> +			rdata->tailsz = len;
> +			len = 0;
> +		}
> +		result = cifs_read_page_from_socket(server, page, n);
>  		if (result < 0)
>  			break;
>  
> @@ -3303,7 +3295,6 @@ cifs_readpages_read_into_pages(struct TCP_Server_Info *server,
>  	u64 eof;
>  	pgoff_t eof_index;
>  	unsigned int nr_pages = rdata->nr_pages;
> -	struct kvec iov;
>  
>  	/* determine the eof that the server (probably) has */
>  	eof = CIFS_I(rdata->mapping->host)->server_eof;
> @@ -3314,23 +3305,14 @@ cifs_readpages_read_into_pages(struct TCP_Server_Info *server,
>  	rdata->tailsz = PAGE_CACHE_SIZE;
>  	for (i = 0; i < nr_pages; i++) {
>  		struct page *page = rdata->pages[i];
> +		size_t n = PAGE_CACHE_SIZE;
>  
>  		if (len >= PAGE_CACHE_SIZE) {
> -			/* enough data to fill the page */
> -			iov.iov_base = kmap(page);
> -			iov.iov_len = PAGE_CACHE_SIZE;
> -			cifs_dbg(FYI, "%u: idx=%lu iov_base=%p iov_len=%zu\n",
> -				 i, page->index, iov.iov_base, iov.iov_len);
>  			len -= PAGE_CACHE_SIZE;
>  		} else if (len > 0) {
>  			/* enough for partial page, fill and zero the rest */
> -			iov.iov_base = kmap(page);
> -			iov.iov_len = len;
> -			cifs_dbg(FYI, "%u: idx=%lu iov_base=%p iov_len=%zu\n",
> -				 i, page->index, iov.iov_base, iov.iov_len);
> -			memset(iov.iov_base + len,
> -				'\0', PAGE_CACHE_SIZE - len);
> -			rdata->tailsz = len;
> +			zero_user(page, len, PAGE_CACHE_SIZE - len);
> +			n = rdata->tailsz = len;
>  			len = 0;
>  		} else if (page->index > eof_index) {
>  			/*
> @@ -3360,8 +3342,7 @@ cifs_readpages_read_into_pages(struct TCP_Server_Info *server,
>  			continue;
>  		}
>  
> -		result = cifs_readv_from_socket(server, &iov, 1, iov.iov_len);
> -		kunmap(page);
> +		result = cifs_read_page_from_socket(server, page, n);
>  		if (result < 0)
>  			break;
>  

Reviewed-by: Jeff Layton <jlayton-vpEMnDpepFuMZCB2o+C8xQ@public.gmane.org>

Re: [RFC][PATCHSET] reduce messing with iovecs in cifs

[Shirish Pargaonkar]

Looking at the series. I briefly looked at 2/6 and looks correct but
would add tested-by once I test that patch
against a SMB server.

On Sat, Apr 9, 2016 at 3:43 PM, Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org> wrote:
>         Now that sendmsg/recvmsg do not mangle iovecs and are capable of
> handling bvec-based ->msg_iter, we can seriously reduce the amount of PITA
> in cifs.  The series below is completely untested, and I would appreciate
> comments/review/testing/etc.
>
> I'll post the individual patches in followups; for those who prefer to use
> git it can be found in
> git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git sendmsg.cifs
>
> 1/6: [net] drop 'size' argument of sock_recvmsg()
>         should go via net-next; does what it says.
>
> 2/6: cifs: merge the hash calculation helpers
>         takes the common parts of {cifs,smb2,smb3}_calc_signature() into a
> common helper.
>
> 3/6: cifs: quit playing games with draining iovecs
>         Switch smb_send_kvec() to passing msghdr (and thus iov_iter) and
> make it use sock_sendmsg() - that allows to avoid draining iovecs, since
> ->msg_iter will be advanced properly and all we need is to keep it around
> between the calls of sock_sendmsg(), rather than reinitializing it on each
> loop iteration.  The same thing allows to get rid of messing with kmap()
> when sending the stuff in ->rq_pages[] - ITER_BVEC will do the right thing.
>
> 4/6: cifs: no need to wank with copying and advancing iovec on recvmsg side either
>         Similar to the previous - use sock_recvmsg() in cifs_readv_from_socket()
> and there's no need to modify iovecs, or allocate a copy especially for
> such modifications, etc.
>
> 5/6: cifs_readv_receive: use cifs_read_from_socket()
>         building a 1-element iovec array for cifs_readv_from_socket() is
> an overkill - simple cifs_read_from_socket() will do just fine.
>
> 6/6: cifs: don't bother with kmap on read_pages side
>         Similar to the other half of 3/6: we can use ITER_BVEC for
> read-into-page case.  Just make cifs_readv_from_socket() take msghdr from
> caller and use a helper that would feed it a bvec-backed ->msg_iter.
> --
> To unsubscribe from this list: send the line "unsubscribe linux-cifs" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [RFC][PATCHSET] reduce messing with iovecs in cifs

[Steve French]

Reviewed-by: Steve French <steve.french-7I+n7zu2hftEKMMhf/gKZA@public.gmane.org>

Let me know if you want any of them to go in via the cifs tree or
prefer going in through your tree (other than patch 1 which could go
in the net-next tree are you indicated)

On Sat, Apr 9, 2016 at 3:43 PM, Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org> wrote:
>         Now that sendmsg/recvmsg do not mangle iovecs and are capable of
> handling bvec-based ->msg_iter, we can seriously reduce the amount of PITA
> in cifs.  The series below is completely untested, and I would appreciate
> comments/review/testing/etc.
>
> I'll post the individual patches in followups; for those who prefer to use
> git it can be found in
> git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git sendmsg.cifs
>
> 1/6: [net] drop 'size' argument of sock_recvmsg()
>         should go via net-next; does what it says.
>
> 2/6: cifs: merge the hash calculation helpers
>         takes the common parts of {cifs,smb2,smb3}_calc_signature() into a
> common helper.
>
> 3/6: cifs: quit playing games with draining iovecs
>         Switch smb_send_kvec() to passing msghdr (and thus iov_iter) and
> make it use sock_sendmsg() - that allows to avoid draining iovecs, since
> ->msg_iter will be advanced properly and all we need is to keep it around
> between the calls of sock_sendmsg(), rather than reinitializing it on each
> loop iteration.  The same thing allows to get rid of messing with kmap()
> when sending the stuff in ->rq_pages[] - ITER_BVEC will do the right thing.
>
> 4/6: cifs: no need to wank with copying and advancing iovec on recvmsg side either
>         Similar to the previous - use sock_recvmsg() in cifs_readv_from_socket()
> and there's no need to modify iovecs, or allocate a copy especially for
> such modifications, etc.
>
> 5/6: cifs_readv_receive: use cifs_read_from_socket()
>         building a 1-element iovec array for cifs_readv_from_socket() is
> an overkill - simple cifs_read_from_socket() will do just fine.
>
> 6/6: cifs: don't bother with kmap on read_pages side
>         Similar to the other half of 3/6: we can use ITER_BVEC for
> read-into-page case.  Just make cifs_readv_from_socket() take msghdr from
> caller and use a helper that would feed it a bvec-backed ->msg_iter.
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-- 
Thanks,

Steve