cifs: add routines to build sessions and tcons on the fly
This patch is rather large, but it's a bit difficult to do piecemeal...
For non-multiuser mounts, everything will basically work as it does
today. A call to cifs_sb_tlink will return the "master" tcon link.
Turn the tcon pointer in the cifs_sb into a radix tree that uses the
fsuid of the process as a key. The value is a new "tcon_link" struct
that contains info about a tcon that's under construction.
When a new process needs a tcon, it'll call cifs_sb_tcon. That will
then look up the tcon_link in the radix tree. If it exists and is
valid, it's returned.
If it doesn't exist, then we stuff a new tcon_link into the tree and
mark it as pending and then go and try to build the session/tcon.
If that works, the tcon pointer in the tcon_link is updated and the
pending flag is cleared.
If the construction fails, then we set the tcon pointer to an ERR_PTR
and clear the pending flag.
If the radix tree is searched and the tcon_link is marked pending
then we go to sleep and wait for the pending flag to be cleared.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index f6a3091..3156a9d 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -109,6 +109,9 @@
struct nls_table *local_nls;
};
+#define TLINK_ERROR_EXPIRE (1 * HZ)
+
+
static int ipv4_connect(struct TCP_Server_Info *server);
static int ipv6_connect(struct TCP_Server_Info *server);
@@ -1959,6 +1962,23 @@
return ERR_PTR(rc);
}
+void
+cifs_put_tlink(struct tcon_link *tlink)
+{
+ if (!tlink || IS_ERR(tlink))
+ return;
+
+ if (!atomic_dec_and_test(&tlink->tl_count) ||
+ test_bit(TCON_LINK_IN_TREE, &tlink->tl_flags)) {
+ tlink->tl_time = jiffies;
+ return;
+ }
+
+ if (!IS_ERR(tlink_tcon(tlink)))
+ cifs_put_tcon(tlink_tcon(tlink));
+ kfree(tlink);
+ return;
+}
int
get_dfs_path(int xid, struct cifsSesInfo *pSesInfo, const char *old_path,
@@ -2641,6 +2661,7 @@
struct TCP_Server_Info *srvTcp;
char *full_path;
char *mount_data = mount_data_global;
+ struct tcon_link *tlink;
#ifdef CONFIG_CIFS_DFS_UPCALL
struct dfs_info3_param *referrals = NULL;
unsigned int num_referrals = 0;
@@ -2652,6 +2673,7 @@
pSesInfo = NULL;
srvTcp = NULL;
full_path = NULL;
+ tlink = NULL;
xid = GetXid();
@@ -2727,8 +2749,6 @@
goto remote_path_check;
}
- cifs_sb->ptcon = tcon;
-
/* do not care if following two calls succeed - informational */
if (!tcon->ipc) {
CIFSSMBQFSDeviceInfo(xid, tcon);
@@ -2837,6 +2857,35 @@
#endif
}
+ if (rc)
+ goto mount_fail_check;
+
+ /* now, hang the tcon off of the superblock */
+ tlink = kzalloc(sizeof *tlink, GFP_KERNEL);
+ if (tlink == NULL) {
+ rc = -ENOMEM;
+ goto mount_fail_check;
+ }
+
+ tlink->tl_index = pSesInfo->linux_uid;
+ tlink->tl_tcon = tcon;
+ tlink->tl_time = jiffies;
+ set_bit(TCON_LINK_MASTER, &tlink->tl_flags);
+ set_bit(TCON_LINK_IN_TREE, &tlink->tl_flags);
+
+ rc = radix_tree_preload(GFP_KERNEL);
+ if (rc == -ENOMEM) {
+ kfree(tlink);
+ goto mount_fail_check;
+ }
+
+ spin_lock(&cifs_sb->tlink_tree_lock);
+ radix_tree_insert(&cifs_sb->tlink_tree, pSesInfo->linux_uid, tlink);
+ radix_tree_tag_set(&cifs_sb->tlink_tree, pSesInfo->linux_uid,
+ CIFS_TLINK_MASTER_TAG);
+ spin_unlock(&cifs_sb->tlink_tree_lock);
+ radix_tree_preload_end();
+
mount_fail_check:
/* on error free sesinfo and tcon struct if needed */
if (rc) {
@@ -3023,19 +3072,37 @@
int
cifs_umount(struct super_block *sb, struct cifs_sb_info *cifs_sb)
{
- int rc = 0;
+ int i, ret;
char *tmp;
- struct cifsTconInfo *tcon = cifs_sb_master_tcon(cifs_sb);
+ struct tcon_link *tlink[8];
+ unsigned long index = 0;
- cifs_put_tcon(tcon);
+ do {
+ spin_lock(&cifs_sb->tlink_tree_lock);
+ ret = radix_tree_gang_lookup(&cifs_sb->tlink_tree,
+ (void **)tlink, index,
+ ARRAY_SIZE(tlink));
+ /* increment index for next pass */
+ if (ret > 0)
+ index = tlink[ret - 1]->tl_index + 1;
+ for (i = 0; i < ret; i++) {
+ cifs_get_tlink(tlink[i]);
+ clear_bit(TCON_LINK_IN_TREE, &tlink[i]->tl_flags);
+ radix_tree_delete(&cifs_sb->tlink_tree,
+ tlink[i]->tl_index);
+ }
+ spin_unlock(&cifs_sb->tlink_tree_lock);
- cifs_sb->ptcon = NULL;
+ for (i = 0; i < ret; i++)
+ cifs_put_tlink(tlink[i]);
+ } while (ret != 0);
+
tmp = cifs_sb->prepath;
cifs_sb->prepathlen = 0;
cifs_sb->prepath = NULL;
kfree(tmp);
- return rc;
+ return 0;
}
int cifs_negotiate_protocol(unsigned int xid, struct cifsSesInfo *ses)
@@ -3096,3 +3163,190 @@
return rc;
}
+struct cifsTconInfo *
+cifs_construct_tcon(struct cifs_sb_info *cifs_sb, uid_t fsuid)
+{
+ struct cifsTconInfo *master_tcon = cifs_sb_master_tcon(cifs_sb);
+ struct cifsSesInfo *ses;
+ struct cifsTconInfo *tcon = NULL;
+ struct smb_vol *vol_info;
+ char username[MAX_USERNAME_SIZE + 1];
+
+ vol_info = kzalloc(sizeof(*vol_info), GFP_KERNEL);
+ if (vol_info == NULL) {
+ tcon = ERR_PTR(-ENOMEM);
+ goto out;
+ }
+
+ snprintf(username, MAX_USERNAME_SIZE, "krb50x%x", fsuid);
+ vol_info->username = username;
+ vol_info->local_nls = cifs_sb->local_nls;
+ vol_info->linux_uid = fsuid;
+ vol_info->cred_uid = fsuid;
+ vol_info->UNC = master_tcon->treeName;
+ vol_info->retry = master_tcon->retry;
+ vol_info->nocase = master_tcon->nocase;
+ vol_info->local_lease = master_tcon->local_lease;
+ vol_info->no_linux_ext = !master_tcon->unix_ext;
+
+ /* FIXME: allow for other secFlg settings */
+ vol_info->secFlg = CIFSSEC_MUST_KRB5;
+
+ /* get a reference for the same TCP session */
+ write_lock(&cifs_tcp_ses_lock);
+ ++master_tcon->ses->server->srv_count;
+ write_unlock(&cifs_tcp_ses_lock);
+
+ ses = cifs_get_smb_ses(master_tcon->ses->server, vol_info);
+ if (IS_ERR(ses)) {
+ tcon = (struct cifsTconInfo *)ses;
+ cifs_put_tcp_session(master_tcon->ses->server);
+ goto out;
+ }
+
+ tcon = cifs_get_tcon(ses, vol_info);
+ if (IS_ERR(tcon)) {
+ cifs_put_smb_ses(ses);
+ goto out;
+ }
+
+ if (ses->capabilities & CAP_UNIX)
+ reset_cifs_unix_caps(0, tcon, NULL, vol_info);
+out:
+ kfree(vol_info);
+
+ return tcon;
+}
+
+static struct tcon_link *
+cifs_sb_master_tlink(struct cifs_sb_info *cifs_sb)
+{
+ struct tcon_link *tlink;
+ unsigned int ret;
+
+ spin_lock(&cifs_sb->tlink_tree_lock);
+ ret = radix_tree_gang_lookup_tag(&cifs_sb->tlink_tree, (void **)&tlink,
+ 0, 1, CIFS_TLINK_MASTER_TAG);
+ spin_unlock(&cifs_sb->tlink_tree_lock);
+
+ /* the master tcon should always be present */
+ if (ret == 0)
+ BUG();
+
+ return tlink;
+}
+
+struct cifsTconInfo *
+cifs_sb_master_tcon(struct cifs_sb_info *cifs_sb)
+{
+ return tlink_tcon(cifs_sb_master_tlink(cifs_sb));
+}
+
+static int
+cifs_sb_tcon_pending_wait(void *unused)
+{
+ schedule();
+ return signal_pending(current) ? -ERESTARTSYS : 0;
+}
+
+/*
+ * Find or construct an appropriate tcon given a cifs_sb and the fsuid of the
+ * current task.
+ *
+ * If the superblock doesn't refer to a multiuser mount, then just return
+ * the master tcon for the mount.
+ *
+ * First, search the radix tree for an existing tcon for this fsuid. If one
+ * exists, then check to see if it's pending construction. If it is then wait
+ * for construction to complete. Once it's no longer pending, check to see if
+ * it failed and either return an error or retry construction, depending on
+ * the timeout.
+ *
+ * If one doesn't exist then insert a new tcon_link struct into the tree and
+ * try to construct a new one.
+ */
+struct tcon_link *
+cifs_sb_tlink(struct cifs_sb_info *cifs_sb)
+{
+ int ret;
+ unsigned long fsuid = (unsigned long) current_fsuid();
+ struct tcon_link *tlink, *newtlink;
+
+ if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
+ return cifs_get_tlink(cifs_sb_master_tlink(cifs_sb));
+
+ spin_lock(&cifs_sb->tlink_tree_lock);
+ tlink = radix_tree_lookup(&cifs_sb->tlink_tree, fsuid);
+ if (tlink)
+ cifs_get_tlink(tlink);
+ spin_unlock(&cifs_sb->tlink_tree_lock);
+
+ if (tlink == NULL) {
+ newtlink = kzalloc(sizeof(*tlink), GFP_KERNEL);
+ if (newtlink == NULL)
+ return ERR_PTR(-ENOMEM);
+ newtlink->tl_index = fsuid;
+ newtlink->tl_tcon = ERR_PTR(-EACCES);
+ set_bit(TCON_LINK_PENDING, &newtlink->tl_flags);
+ set_bit(TCON_LINK_IN_TREE, &newtlink->tl_flags);
+ cifs_get_tlink(newtlink);
+
+ ret = radix_tree_preload(GFP_KERNEL);
+ if (ret != 0) {
+ kfree(newtlink);
+ return ERR_PTR(ret);
+ }
+
+ spin_lock(&cifs_sb->tlink_tree_lock);
+ /* was one inserted after previous search? */
+ tlink = radix_tree_lookup(&cifs_sb->tlink_tree, fsuid);
+ if (tlink) {
+ cifs_get_tlink(tlink);
+ spin_unlock(&cifs_sb->tlink_tree_lock);
+ radix_tree_preload_end();
+ kfree(newtlink);
+ goto wait_for_construction;
+ }
+ ret = radix_tree_insert(&cifs_sb->tlink_tree, fsuid, newtlink);
+ spin_unlock(&cifs_sb->tlink_tree_lock);
+ radix_tree_preload_end();
+ if (ret) {
+ kfree(newtlink);
+ return ERR_PTR(ret);
+ }
+ tlink = newtlink;
+ } else {
+wait_for_construction:
+ ret = wait_on_bit(&tlink->tl_flags, TCON_LINK_PENDING,
+ cifs_sb_tcon_pending_wait,
+ TASK_INTERRUPTIBLE);
+ if (ret) {
+ cifs_put_tlink(tlink);
+ return ERR_PTR(ret);
+ }
+
+ /* if it's good, return it */
+ if (!IS_ERR(tlink->tl_tcon))
+ return tlink;
+
+ /* return error if we tried this already recently */
+ if (time_before(jiffies, tlink->tl_time + TLINK_ERROR_EXPIRE)) {
+ cifs_put_tlink(tlink);
+ return ERR_PTR(-EACCES);
+ }
+
+ if (test_and_set_bit(TCON_LINK_PENDING, &tlink->tl_flags))
+ goto wait_for_construction;
+ }
+
+ tlink->tl_tcon = cifs_construct_tcon(cifs_sb, fsuid);
+ clear_bit(TCON_LINK_PENDING, &tlink->tl_flags);
+ wake_up_bit(&tlink->tl_flags, TCON_LINK_PENDING);
+
+ if (IS_ERR(tlink->tl_tcon)) {
+ cifs_put_tlink(tlink);
+ return ERR_PTR(-EACCES);
+ }
+
+ return tlink;
+}