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cifs: do not share tcp sessions of dfs connections

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Make sure that we do not share tcp sessions of dfs mounts when
mounting regular shares that connect to same server.  DFS connections
rely on a single instance of tcp in order to do failover properly in
cifs_reconnect().

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Paulo Alcantara 2021-07-15 21:53:53 -03:00 committed by Steve French
parent 4511d7c8f4
commit cdc3363065
2 changed files with 38 additions and 3 deletions
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3
fs/cifs/cifsglob.h
View File

@ -693,6 +693,9 @@ struct TCP_Server_Info {
bool use_swn_dstaddr;
struct sockaddr_storage swn_dstaddr;
#endif
#ifdef CONFIG_CIFS_DFS_UPCALL
bool is_dfs_conn; /* if a dfs connection */
#endif
};
struct cifs_credits {

38
fs/cifs/connect.c
View File

@ -1268,6 +1268,16 @@ cifs_find_tcp_session(struct smb3_fs_context *ctx)
spin_lock(&cifs_tcp_ses_lock);
list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
#ifdef CONFIG_CIFS_DFS_UPCALL
/*
* DFS failover implementation in cifs_reconnect() requires unique tcp sessions for
* DFS connections to do failover properly, so avoid sharing them with regular
* shares or even links that may connect to same server but having completely
* different failover targets.
*/
if (server->is_dfs_conn)
continue;
#endif
/*
* Skip ses channels since they're only handled in lower layers
* (e.g. cifs_send_recv).
@ -2968,6 +2978,23 @@ static int mount_setup_tlink(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses,
}
#ifdef CONFIG_CIFS_DFS_UPCALL
static int mount_get_dfs_conns(struct smb3_fs_context *ctx, struct cifs_sb_info *cifs_sb,
unsigned int *xid, struct TCP_Server_Info **nserver,
struct cifs_ses **nses, struct cifs_tcon **ntcon)
{
int rc;
ctx->nosharesock = true;
rc = mount_get_conns(ctx, cifs_sb, xid, nserver, nses, ntcon);
if (*nserver) {
cifs_dbg(FYI, "%s: marking tcp session as a dfs connection\n", __func__);
spin_lock(&cifs_tcp_ses_lock);
(*nserver)->is_dfs_conn = true;
spin_unlock(&cifs_tcp_ses_lock);
}
return rc;
}
/*
* cifs_build_path_to_root returns full path to root when we do not have an
* existing connection (tcon)
@ -3163,7 +3190,7 @@ static int do_dfs_failover(const char *path, const char *full_path, struct cifs_
tmp_ctx.prepath);
mount_put_conns(cifs_sb, *xid, *server, *ses, *tcon);
rc = mount_get_conns(&tmp_ctx, cifs_sb, xid, server, ses, tcon);
rc = mount_get_dfs_conns(&tmp_ctx, cifs_sb, xid, server, ses, tcon);
if (!rc || (*server && *ses)) {
/*
* We were able to connect to new target server. Update current context with
@ -3462,7 +3489,12 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx)
goto error;
}
ctx->nosharesock = true;
mount_put_conns(cifs_sb, xid, server, ses, tcon);
/*
* Ignore error check here because we may failover to other targets from cached a
* referral.
*/
(void)mount_get_dfs_conns(ctx, cifs_sb, &xid, &server, &ses, &tcon);
/* Get path of DFS root */
ref_path = build_unc_path_to_root(ctx, cifs_sb, false);
@ -3491,7 +3523,7 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx)
/* Connect to new DFS target only if we were redirected */
if (oldmnt != cifs_sb->ctx->mount_options) {
mount_put_conns(cifs_sb, xid, server, ses, tcon);
rc = mount_get_conns(ctx, cifs_sb, &xid, &server, &ses, &tcon);
rc = mount_get_dfs_conns(ctx, cifs_sb, &xid, &server, &ses, &tcon);
}
if (rc && !server && !ses) {
/* Failed to connect. Try to connect to other targets in the referral. */