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cifs: avoid parallel session setups on same channel

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After allowing channels to reconnect in parallel, it now
becomes important to take care that multiple processes do not
call negotiate/session setup in parallel on the same channel.

This change avoids that by marking a channel as "in_reconnect".
During session setup if the channel in question has this flag
set, we return immediately.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Shyam Prasad N 2022-04-08 13:31:37 +00:00 committed by Steve French
parent dd3cd8709e
commit 5752bf645f
5 changed files with 65 additions and 7 deletions
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4
fs/cifs/cifs_debug.c
View file

@ -419,6 +419,8 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
spin_lock(&ses->chan_lock);
if (CIFS_CHAN_NEEDS_RECONNECT(ses, 0))
seq_puts(m, "\tPrimary channel: DISCONNECTED ");
if (CIFS_CHAN_IN_RECONNECT(ses, 0))
seq_puts(m, "\t[RECONNECTING] ");
if (ses->chan_count > 1) {
seq_printf(m, "\n\n\tExtra Channels: %zu ",
@ -427,6 +429,8 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
cifs_dump_channel(m, j, &ses->chans[j]);
if (CIFS_CHAN_NEEDS_RECONNECT(ses, j))
seq_puts(m, "\tDISCONNECTED ");
if (CIFS_CHAN_IN_RECONNECT(ses, j))
seq_puts(m, "\t[RECONNECTING] ");
}
}
spin_unlock(&ses->chan_lock);

5
fs/cifs/cifsglob.h
View file

@ -922,6 +922,7 @@ struct cifs_server_iface {
};
struct cifs_chan {
unsigned int in_reconnect : 1; /* if session setup in progress for this channel */
struct TCP_Server_Info *server;
__u8 signkey[SMB3_SIGN_KEY_SIZE];
};
@ -984,12 +985,16 @@ struct cifs_ses {
#define CIFS_MAX_CHANNELS 16
#define CIFS_ALL_CHANNELS_SET(ses) \
((1UL << (ses)->chan_count) - 1)
#define CIFS_ALL_CHANS_GOOD(ses) \
(!(ses)->chans_need_reconnect)
#define CIFS_ALL_CHANS_NEED_RECONNECT(ses) \
((ses)->chans_need_reconnect == CIFS_ALL_CHANNELS_SET(ses))
#define CIFS_SET_ALL_CHANS_NEED_RECONNECT(ses) \
((ses)->chans_need_reconnect = CIFS_ALL_CHANNELS_SET(ses))
#define CIFS_CHAN_NEEDS_RECONNECT(ses, index) \
test_bit((index), &(ses)->chans_need_reconnect)
#define CIFS_CHAN_IN_RECONNECT(ses, index) \
((ses)->chans[(index)].in_reconnect)
struct cifs_chan chans[CIFS_MAX_CHANNELS];
size_t chan_count;

9
fs/cifs/cifsproto.h
View file

@ -619,6 +619,15 @@ unsigned int
cifs_ses_get_chan_index(struct cifs_ses *ses,
struct TCP_Server_Info *server);
void
cifs_chan_set_in_reconnect(struct cifs_ses *ses,
struct TCP_Server_Info *server);
void
cifs_chan_clear_in_reconnect(struct cifs_ses *ses,
struct TCP_Server_Info *server);
bool
cifs_chan_in_reconnect(struct cifs_ses *ses,
struct TCP_Server_Info *server);
void
cifs_chan_set_need_reconnect(struct cifs_ses *ses,
struct TCP_Server_Info *server);
void

27
fs/cifs/connect.c
View file

@ -3995,17 +3995,27 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
int rc = -ENOSYS;
bool is_binding = false;
/* only send once per connect */
spin_lock(&ses->chan_lock);
is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses);
spin_unlock(&ses->chan_lock);
spin_lock(&cifs_tcp_ses_lock);
if (ses->ses_status == SES_EXITING) {
if (ses->ses_status != SES_GOOD &&
ses->ses_status != SES_NEW &&
ses->ses_status != SES_NEED_RECON) {
spin_unlock(&cifs_tcp_ses_lock);
return 0;
}
/* only send once per connect */
spin_lock(&ses->chan_lock);
if (CIFS_ALL_CHANS_GOOD(ses) ||
cifs_chan_in_reconnect(ses, server)) {
spin_unlock(&ses->chan_lock);
spin_unlock(&cifs_tcp_ses_lock);
return 0;
}
is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses);
cifs_chan_set_in_reconnect(ses, server);
spin_unlock(&ses->chan_lock);
if (!is_binding)
ses->ses_status = SES_IN_SETUP;
spin_unlock(&cifs_tcp_ses_lock);
@ -4035,16 +4045,19 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
spin_lock(&cifs_tcp_ses_lock);
if (ses->ses_status == SES_IN_SETUP)
ses->ses_status = SES_NEED_RECON;
spin_lock(&ses->chan_lock);
cifs_chan_clear_in_reconnect(ses, server);
spin_unlock(&ses->chan_lock);
spin_unlock(&cifs_tcp_ses_lock);
} else {
spin_lock(&cifs_tcp_ses_lock);
if (ses->ses_status == SES_IN_SETUP)
ses->ses_status = SES_GOOD;
spin_unlock(&cifs_tcp_ses_lock);
spin_lock(&ses->chan_lock);
cifs_chan_clear_in_reconnect(ses, server);
cifs_chan_clear_need_reconnect(ses, server);
spin_unlock(&ses->chan_lock);
spin_unlock(&cifs_tcp_ses_lock);
}
return rc;

27
fs/cifs/sess.c
View file

@ -85,6 +85,33 @@ cifs_ses_get_chan_index(struct cifs_ses *ses,
return 0;
}
void
cifs_chan_set_in_reconnect(struct cifs_ses *ses,
struct TCP_Server_Info *server)
{
unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
ses->chans[chan_index].in_reconnect = true;
}
void
cifs_chan_clear_in_reconnect(struct cifs_ses *ses,
struct TCP_Server_Info *server)
{
unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
ses->chans[chan_index].in_reconnect = false;
}
bool
cifs_chan_in_reconnect(struct cifs_ses *ses,
struct TCP_Server_Info *server)
{
unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
return CIFS_CHAN_IN_RECONNECT(ses, chan_index);
}
void
cifs_chan_set_need_reconnect(struct cifs_ses *ses,
struct TCP_Server_Info *server)