From cf0604a686b11175d8beae60281c4ccc95aaa5c2 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 4 Feb 2021 00:15:21 -0600 Subject: [PATCH] cifs: use discard iterator to discard unneeded network data more efficiently 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 Signed-off-by: Steve French --- fs/cifs/cifsproto.h | 2 ++ fs/cifs/cifssmb.c | 6 +++--- fs/cifs/connect.c | 17 +++++++++++++++++ 3 files changed, 22 insertions(+), 3 deletions(-) diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h index 32f7a01..75ce6f7 100644 --- a/fs/cifs/cifsproto.h +++ b/fs/cifs/cifsproto.h @@ -232,6 +232,8 @@ 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, diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c index 0496934..c279527 100644 --- a/fs/cifs/cifssmb.c +++ b/fs/cifs/cifssmb.c @@ -1451,9 +1451,9 @@ 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, - CIFSMaxBufSize + MAX_HEADER_SIZE(server))); + length = cifs_discard_from_socket(server, + min_t(size_t, remaining, + CIFSMaxBufSize + MAX_HEADER_SIZE(server))); if (length < 0) return length; server->total_read += length; diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index b2447ce..1126923 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -564,6 +564,23 @@ 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) -- 2.7.4