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>
This commit is contained in:
Jeff Layton
Steve French
Родитель
c9928f7040
Коммит
9d002df492
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@ -15,6 +15,8 @@
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* the GNU Lesser General Public License for more details.
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*
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*/
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#include <linux/radix-tree.h>
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#ifndef _CIFS_FS_SB_H
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#define _CIFS_FS_SB_H
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@ -40,8 +42,9 @@
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#define CIFS_MOUNT_MULTIUSER 0x20000 /* multiuser mount */
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struct cifs_sb_info {
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struct cifsTconInfo *ptcon; /* primary mount */
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struct list_head nested_tcon_q;
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struct radix_tree_root tlink_tree;
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#define CIFS_TLINK_MASTER_TAG 0 /* is "master" (mount) tcon */
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spinlock_t tlink_tree_lock;
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struct nls_table *local_nls;
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unsigned int rsize;
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unsigned int wsize;
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@ -317,42 +317,36 @@ struct cifsTconInfo {
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* "get" on the container.
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*/
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struct tcon_link {
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spinlock_t tl_lock;
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u32 tl_count;
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u64 tl_time;
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unsigned long tl_index;
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unsigned long tl_flags;
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#define TCON_LINK_MASTER 0
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#define TCON_LINK_PENDING 1
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#define TCON_LINK_IN_TREE 2
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unsigned long tl_time;
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atomic_t tl_count;
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struct cifsTconInfo *tl_tcon;
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};
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static inline struct tcon_link *
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cifs_sb_tlink(struct cifs_sb_info *cifs_sb)
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{
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return (struct tcon_link *)cifs_sb->ptcon;
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}
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extern struct tcon_link *cifs_sb_tlink(struct cifs_sb_info *cifs_sb);
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static inline struct cifsTconInfo *
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tlink_tcon(struct tcon_link *tlink)
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{
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return (struct cifsTconInfo *)tlink;
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return tlink->tl_tcon;
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}
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static inline void
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cifs_put_tlink(struct tcon_link *tlink)
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{
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return;
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}
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extern void cifs_put_tlink(struct tcon_link *tlink);
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static inline struct tcon_link *
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cifs_get_tlink(struct tcon_link *tlink)
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{
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if (tlink && !IS_ERR(tlink))
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atomic_inc(&tlink->tl_count);
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return tlink;
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}
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/* This function is always expected to succeed */
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static inline struct cifsTconInfo *
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cifs_sb_master_tcon(struct cifs_sb_info *cifs_sb)
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{
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return cifs_sb->ptcon;
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}
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extern struct cifsTconInfo *cifs_sb_master_tcon(struct cifs_sb_info *cifs_sb);
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/*
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* This info hangs off the cifsFileInfo structure, pointed to by llist.
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@ -109,6 +109,9 @@ struct smb_vol {
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struct nls_table *local_nls;
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};
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#define TLINK_ERROR_EXPIRE (1 * HZ)
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static int ipv4_connect(struct TCP_Server_Info *server);
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static int ipv6_connect(struct TCP_Server_Info *server);
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@ -1959,6 +1962,23 @@ out_fail:
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return ERR_PTR(rc);
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}
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void
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cifs_put_tlink(struct tcon_link *tlink)
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{
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if (!tlink || IS_ERR(tlink))
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return;
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if (!atomic_dec_and_test(&tlink->tl_count) ||
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test_bit(TCON_LINK_IN_TREE, &tlink->tl_flags)) {
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tlink->tl_time = jiffies;
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return;
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}
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if (!IS_ERR(tlink_tcon(tlink)))
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cifs_put_tcon(tlink_tcon(tlink));
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kfree(tlink);
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return;
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}
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int
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get_dfs_path(int xid, struct cifsSesInfo *pSesInfo, const char *old_path,
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@ -2641,6 +2661,7 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
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struct TCP_Server_Info *srvTcp;
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char *full_path;
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char *mount_data = mount_data_global;
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struct tcon_link *tlink;
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#ifdef CONFIG_CIFS_DFS_UPCALL
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struct dfs_info3_param *referrals = NULL;
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unsigned int num_referrals = 0;
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@ -2652,6 +2673,7 @@ try_mount_again:
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pSesInfo = NULL;
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srvTcp = NULL;
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full_path = NULL;
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tlink = NULL;
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xid = GetXid();
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@ -2727,8 +2749,6 @@ try_mount_again:
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goto remote_path_check;
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}
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cifs_sb->ptcon = tcon;
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/* do not care if following two calls succeed - informational */
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if (!tcon->ipc) {
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CIFSSMBQFSDeviceInfo(xid, tcon);
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@ -2837,6 +2857,35 @@ remote_path_check:
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#endif
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}
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if (rc)
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goto mount_fail_check;
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/* now, hang the tcon off of the superblock */
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tlink = kzalloc(sizeof *tlink, GFP_KERNEL);
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if (tlink == NULL) {
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rc = -ENOMEM;
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goto mount_fail_check;
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}
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tlink->tl_index = pSesInfo->linux_uid;
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tlink->tl_tcon = tcon;
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tlink->tl_time = jiffies;
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set_bit(TCON_LINK_MASTER, &tlink->tl_flags);
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set_bit(TCON_LINK_IN_TREE, &tlink->tl_flags);
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rc = radix_tree_preload(GFP_KERNEL);
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if (rc == -ENOMEM) {
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kfree(tlink);
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goto mount_fail_check;
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}
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spin_lock(&cifs_sb->tlink_tree_lock);
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radix_tree_insert(&cifs_sb->tlink_tree, pSesInfo->linux_uid, tlink);
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radix_tree_tag_set(&cifs_sb->tlink_tree, pSesInfo->linux_uid,
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CIFS_TLINK_MASTER_TAG);
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spin_unlock(&cifs_sb->tlink_tree_lock);
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radix_tree_preload_end();
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mount_fail_check:
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/* on error free sesinfo and tcon struct if needed */
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if (rc) {
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@ -3023,19 +3072,37 @@ CIFSTCon(unsigned int xid, struct cifsSesInfo *ses,
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int
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cifs_umount(struct super_block *sb, struct cifs_sb_info *cifs_sb)
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{
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int rc = 0;
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int i, ret;
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char *tmp;
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struct cifsTconInfo *tcon = cifs_sb_master_tcon(cifs_sb);
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struct tcon_link *tlink[8];
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unsigned long index = 0;
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cifs_put_tcon(tcon);
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do {
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spin_lock(&cifs_sb->tlink_tree_lock);
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ret = radix_tree_gang_lookup(&cifs_sb->tlink_tree,
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(void **)tlink, index,
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ARRAY_SIZE(tlink));
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/* increment index for next pass */
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if (ret > 0)
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index = tlink[ret - 1]->tl_index + 1;
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for (i = 0; i < ret; i++) {
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cifs_get_tlink(tlink[i]);
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clear_bit(TCON_LINK_IN_TREE, &tlink[i]->tl_flags);
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radix_tree_delete(&cifs_sb->tlink_tree,
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tlink[i]->tl_index);
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}
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spin_unlock(&cifs_sb->tlink_tree_lock);
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for (i = 0; i < ret; i++)
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cifs_put_tlink(tlink[i]);
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} while (ret != 0);
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cifs_sb->ptcon = NULL;
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tmp = cifs_sb->prepath;
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cifs_sb->prepathlen = 0;
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cifs_sb->prepath = NULL;
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kfree(tmp);
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return rc;
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return 0;
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}
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int cifs_negotiate_protocol(unsigned int xid, struct cifsSesInfo *ses)
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@ -3096,3 +3163,190 @@ int cifs_setup_session(unsigned int xid, struct cifsSesInfo *ses,
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return rc;
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}
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struct cifsTconInfo *
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cifs_construct_tcon(struct cifs_sb_info *cifs_sb, uid_t fsuid)
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{
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struct cifsTconInfo *master_tcon = cifs_sb_master_tcon(cifs_sb);
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struct cifsSesInfo *ses;
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struct cifsTconInfo *tcon = NULL;
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struct smb_vol *vol_info;
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char username[MAX_USERNAME_SIZE + 1];
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vol_info = kzalloc(sizeof(*vol_info), GFP_KERNEL);
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if (vol_info == NULL) {
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tcon = ERR_PTR(-ENOMEM);
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goto out;
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}
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snprintf(username, MAX_USERNAME_SIZE, "krb50x%x", fsuid);
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vol_info->username = username;
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vol_info->local_nls = cifs_sb->local_nls;
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vol_info->linux_uid = fsuid;
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vol_info->cred_uid = fsuid;
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vol_info->UNC = master_tcon->treeName;
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vol_info->retry = master_tcon->retry;
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vol_info->nocase = master_tcon->nocase;
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vol_info->local_lease = master_tcon->local_lease;
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vol_info->no_linux_ext = !master_tcon->unix_ext;
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/* FIXME: allow for other secFlg settings */
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vol_info->secFlg = CIFSSEC_MUST_KRB5;
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/* get a reference for the same TCP session */
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write_lock(&cifs_tcp_ses_lock);
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++master_tcon->ses->server->srv_count;
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write_unlock(&cifs_tcp_ses_lock);
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ses = cifs_get_smb_ses(master_tcon->ses->server, vol_info);
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if (IS_ERR(ses)) {
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tcon = (struct cifsTconInfo *)ses;
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cifs_put_tcp_session(master_tcon->ses->server);
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goto out;
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}
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tcon = cifs_get_tcon(ses, vol_info);
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if (IS_ERR(tcon)) {
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cifs_put_smb_ses(ses);
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goto out;
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}
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if (ses->capabilities & CAP_UNIX)
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reset_cifs_unix_caps(0, tcon, NULL, vol_info);
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out:
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kfree(vol_info);
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return tcon;
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}
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static struct tcon_link *
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cifs_sb_master_tlink(struct cifs_sb_info *cifs_sb)
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{
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struct tcon_link *tlink;
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unsigned int ret;
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spin_lock(&cifs_sb->tlink_tree_lock);
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ret = radix_tree_gang_lookup_tag(&cifs_sb->tlink_tree, (void **)&tlink,
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0, 1, CIFS_TLINK_MASTER_TAG);
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spin_unlock(&cifs_sb->tlink_tree_lock);
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/* the master tcon should always be present */
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if (ret == 0)
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BUG();
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return tlink;
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}
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struct cifsTconInfo *
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cifs_sb_master_tcon(struct cifs_sb_info *cifs_sb)
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{
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return tlink_tcon(cifs_sb_master_tlink(cifs_sb));
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}
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static int
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cifs_sb_tcon_pending_wait(void *unused)
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{
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schedule();
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return signal_pending(current) ? -ERESTARTSYS : 0;
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}
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/*
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* Find or construct an appropriate tcon given a cifs_sb and the fsuid of the
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* current task.
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*
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* If the superblock doesn't refer to a multiuser mount, then just return
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* the master tcon for the mount.
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*
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* First, search the radix tree for an existing tcon for this fsuid. If one
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* exists, then check to see if it's pending construction. If it is then wait
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* for construction to complete. Once it's no longer pending, check to see if
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* it failed and either return an error or retry construction, depending on
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* the timeout.
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*
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* If one doesn't exist then insert a new tcon_link struct into the tree and
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* try to construct a new one.
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*/
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struct tcon_link *
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cifs_sb_tlink(struct cifs_sb_info *cifs_sb)
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{
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int ret;
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unsigned long fsuid = (unsigned long) current_fsuid();
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struct tcon_link *tlink, *newtlink;
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if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
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return cifs_get_tlink(cifs_sb_master_tlink(cifs_sb));
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spin_lock(&cifs_sb->tlink_tree_lock);
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tlink = radix_tree_lookup(&cifs_sb->tlink_tree, fsuid);
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if (tlink)
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cifs_get_tlink(tlink);
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spin_unlock(&cifs_sb->tlink_tree_lock);
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if (tlink == NULL) {
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newtlink = kzalloc(sizeof(*tlink), GFP_KERNEL);
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if (newtlink == NULL)
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return ERR_PTR(-ENOMEM);
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newtlink->tl_index = fsuid;
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newtlink->tl_tcon = ERR_PTR(-EACCES);
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set_bit(TCON_LINK_PENDING, &newtlink->tl_flags);
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set_bit(TCON_LINK_IN_TREE, &newtlink->tl_flags);
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cifs_get_tlink(newtlink);
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ret = radix_tree_preload(GFP_KERNEL);
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if (ret != 0) {
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kfree(newtlink);
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return ERR_PTR(ret);
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}
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spin_lock(&cifs_sb->tlink_tree_lock);
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/* was one inserted after previous search? */
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tlink = radix_tree_lookup(&cifs_sb->tlink_tree, fsuid);
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if (tlink) {
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cifs_get_tlink(tlink);
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spin_unlock(&cifs_sb->tlink_tree_lock);
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radix_tree_preload_end();
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kfree(newtlink);
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goto wait_for_construction;
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}
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ret = radix_tree_insert(&cifs_sb->tlink_tree, fsuid, newtlink);
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spin_unlock(&cifs_sb->tlink_tree_lock);
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radix_tree_preload_end();
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if (ret) {
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kfree(newtlink);
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return ERR_PTR(ret);
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}
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tlink = newtlink;
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} else {
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wait_for_construction:
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ret = wait_on_bit(&tlink->tl_flags, TCON_LINK_PENDING,
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cifs_sb_tcon_pending_wait,
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TASK_INTERRUPTIBLE);
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if (ret) {
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cifs_put_tlink(tlink);
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return ERR_PTR(ret);
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}
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/* if it's good, return it */
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if (!IS_ERR(tlink->tl_tcon))
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return tlink;
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/* return error if we tried this already recently */
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if (time_before(jiffies, tlink->tl_time + TLINK_ERROR_EXPIRE)) {
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cifs_put_tlink(tlink);
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return ERR_PTR(-EACCES);
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}
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if (test_and_set_bit(TCON_LINK_PENDING, &tlink->tl_flags))
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goto wait_for_construction;
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}
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tlink->tl_tcon = cifs_construct_tcon(cifs_sb, fsuid);
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clear_bit(TCON_LINK_PENDING, &tlink->tl_flags);
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wake_up_bit(&tlink->tl_flags, TCON_LINK_PENDING);
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if (IS_ERR(tlink->tl_tcon)) {
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cifs_put_tlink(tlink);
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return ERR_PTR(-EACCES);
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}
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return tlink;
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}
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