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cifs: use discard iterator to discard unneeded network data more efficiently

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[ Upstream commit cf0604a686b11175d8beae60281c4ccc95aaa5c2 ]

The iterator, ITER_DISCARD, that can only be used in READ mode and
just discards any data copied to it, was added to allow a network
filesystem to discard any unwanted data sent by a server.
Convert cifs_discard_from_socket() to use this.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Stable-dep-of: bedc8f76b353 ("cifs: always initialize struct msghdr smb_msg completely")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
David Howells
2021-02-04 00:15:21 -06:00
committed by Greg Kroah-Hartman
parent 09867977fc
commit 877231b0e6
3 changed files with 22 additions and 3 deletions
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2
fs/cifs/cifsproto.h
View File

@@ -230,6 +230,8 @@ extern unsigned int setup_special_user_owner_ACE(struct cifs_ace *pace);
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 ssize_t cifs_discard_from_socket(struct TCP_Server_Info *server,
size_t to_read);
extern int cifs_read_page_from_socket(struct TCP_Server_Info *server,
struct page *page,
unsigned int page_offset,

4
fs/cifs/cifssmb.c
View File

@@ -1451,8 +1451,8 @@ cifs_discard_remaining_data(struct TCP_Server_Info *server)
while (remaining > 0) {
int length;
length = cifs_read_from_socket(server, server->bigbuf,
min_t(unsigned int, remaining,
length = cifs_discard_from_socket(server,
min_t(size_t, remaining,
CIFSMaxBufSize + MAX_HEADER_SIZE(server)));
if (length < 0)
return length;

17
fs/cifs/connect.c
View File

@@ -755,6 +755,23 @@ cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
return cifs_readv_from_socket(server, &smb_msg);
}
ssize_t
cifs_discard_from_socket(struct TCP_Server_Info *server, size_t to_read)
{
struct msghdr smb_msg;
/*
* iov_iter_discard already sets smb_msg.type and count and iov_offset
* and cifs_readv_from_socket sets msg_control and msg_controllen
* so little to initialize in struct msghdr
*/
smb_msg.msg_name = NULL;
smb_msg.msg_namelen = 0;
iov_iter_discard(&smb_msg.msg_iter, READ, to_read);
return cifs_readv_from_socket(server, &smb_msg);
}
int
cifs_read_page_from_socket(struct TCP_Server_Info *server, struct page *page,
unsigned int page_offset, unsigned int to_read)