Commit 9d002df4 authored by Jeff Layton's avatar Jeff Layton Committed by Steve French
Browse files

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: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarSteve French <sfrench@us.ibm.com>
parent c9928f70

fs/cifs/cifs_fs_sb.h

+5 −2
Original line number Diff line number Diff line
@@ -15,6 +15,8 @@ 
 *   the GNU Lesser General Public License for more details.

 *

 */

#include <linux/radix-tree.h>



#ifndef _CIFS_FS_SB_H

#define _CIFS_FS_SB_H
@@ -40,8 +42,9 @@ 
#define CIFS_MOUNT_MULTIUSER	0x20000 /* multiuser mount */



struct cifs_sb_info {

	struct cifsTconInfo *ptcon;	/* primary mount */

	struct list_head nested_tcon_q;

	struct radix_tree_root tlink_tree;

#define CIFS_TLINK_MASTER_TAG		0	/* is "master" (mount) tcon */

	spinlock_t tlink_tree_lock;

	struct nls_table *local_nls;

	unsigned int rsize;

	unsigned int wsize;

fs/cifs/cifsglob.h

+13 −19
Original line number Diff line number Diff line
@@ -317,42 +317,36 @@ struct cifsTconInfo { 
 * "get" on the container.

 */

struct tcon_link {

	spinlock_t		tl_lock;

	u32			tl_count;

	u64			tl_time;

	unsigned long		tl_index;

	unsigned long		tl_flags;

#define TCON_LINK_MASTER	0

#define TCON_LINK_PENDING	1

#define TCON_LINK_IN_TREE	2

	unsigned long		tl_time;

	atomic_t		tl_count;

	struct cifsTconInfo	*tl_tcon;

};



static inline struct tcon_link *

cifs_sb_tlink(struct cifs_sb_info *cifs_sb)

{

	return (struct tcon_link *)cifs_sb->ptcon;

}

extern struct tcon_link *cifs_sb_tlink(struct cifs_sb_info *cifs_sb);



static inline struct cifsTconInfo *

tlink_tcon(struct tcon_link *tlink)

{

	return (struct cifsTconInfo *)tlink;

	return tlink->tl_tcon;

}



static inline void

cifs_put_tlink(struct tcon_link *tlink)

{

	return;

}

extern void cifs_put_tlink(struct tcon_link *tlink);



static inline struct tcon_link *

cifs_get_tlink(struct tcon_link *tlink)

{

	if (tlink && !IS_ERR(tlink))

		atomic_inc(&tlink->tl_count);

	return tlink;

}



/* This function is always expected to succeed */

static inline struct cifsTconInfo *

cifs_sb_master_tcon(struct cifs_sb_info *cifs_sb)

{

	return cifs_sb->ptcon;

}

extern struct cifsTconInfo *cifs_sb_master_tcon(struct cifs_sb_info *cifs_sb);



/*

 * This info hangs off the cifsFileInfo structure, pointed to by llist.

fs/cifs/connect.c

+261 −7
Original line number Diff line number Diff line
@@ -109,6 +109,9 @@ struct smb_vol { 
	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 @@ out_fail: 
	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 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb, 
	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 @@ try_mount_again: 
	pSesInfo = NULL;

	srvTcp = NULL;

	full_path = NULL;

	tlink = NULL;



	xid = GetXid();
@@ -2727,8 +2749,6 @@ try_mount_again: 
		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 @@ remote_path_check: 
#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 @@ CIFSTCon(unsigned int xid, struct cifsSesInfo *ses, 
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);



	cifs_put_tcon(tcon);

	struct tcon_link *tlink[8];

	unsigned long index = 0;



	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);



		for (i = 0; i < ret; i++)

			cifs_put_tlink(tlink[i]);

	} while (ret != 0);



	cifs_sb->ptcon = NULL;

	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 @@ int cifs_setup_session(unsigned int xid, struct cifsSesInfo *ses, 
	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;

}

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