cifs: add refcounted and timestamped container for holding tcons

Eventually, we'll need to track the use of tcons on a per-sb basis, so that
we know when it's ok to tear them down. Begin this conversion by adding a
new "tcon_link" struct and accessors that get it. For now, the core data
structures are untouched -- cifs_sb still just points to a single tcon and
the pointers are just cast to deal with the accessor functions. A later
patch will flesh this out.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 58 insertions, 29 deletions

diff --git a/fs/cifs/link.c b/fs/cifs/link.c
index 66db2d61fa43..b38fe6704ad2 100644
--- a/fs/cifs/link.c
+++ b/fs/cifs/link.c
@@ -249,7 +249,8 @@ CIFSCheckMFSymlink(struct cifs_fattr *fattr,
         int rc;
         int oplock = 0;
         __u16 netfid = 0;
-        struct cifsTconInfo *pTcon = cifs_sb_tcon(cifs_sb);
+        struct tcon_link *tlink;
+        struct cifsTconInfo *pTcon;
         u8 *buf;
         char *pbuf;
         unsigned int bytes_read = 0;
@@ -261,23 +262,30 @@ CIFSCheckMFSymlink(struct cifs_fattr *fattr,
                 /* it's not a symlink */
                 return 0;
 
+        tlink = cifs_sb_tlink(cifs_sb);
+        if (IS_ERR(tlink))
+                return PTR_ERR(tlink);
+        pTcon = tlink_tcon(tlink);
+
         rc = CIFSSMBOpen(xid, pTcon, path, FILE_OPEN, GENERIC_READ,
                          CREATE_NOT_DIR, &netfid, &oplock, &file_info,
                          cifs_sb->local_nls,
                          cifs_sb->mnt_cifs_flags &
                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
         if (rc != 0)
-                return rc;
+                goto out;
 
         if (file_info.EndOfFile != CIFS_MF_SYMLINK_FILE_SIZE) {
                 CIFSSMBClose(xid, pTcon, netfid);
                 /* it's not a symlink */
-                return 0;
+                goto out;
         }
 
         buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
-        if (!buf)
-                return -ENOMEM;
+        if (!buf) {
+                rc = -ENOMEM;
+                goto out;
+        }
         pbuf = buf;
 
         rc = CIFSSMBRead(xid, pTcon, netfid,
@@ -287,23 +295,28 @@ CIFSCheckMFSymlink(struct cifs_fattr *fattr,
         CIFSSMBClose(xid, pTcon, netfid);
         if (rc != 0) {
                 kfree(buf);
-                return rc;
+                goto out;
         }
 
         rc = CIFSParseMFSymlink(buf, bytes_read, &link_len, NULL);
         kfree(buf);
-        if (rc == -EINVAL)
+        if (rc == -EINVAL) {
                 /* it's not a symlink */
-                return 0;
+                rc = 0;
+                goto out;
+        }
+
         if (rc != 0)
-                return rc;
+                goto out;
 
         /* it is a symlink */
         fattr->cf_eof = link_len;
         fattr->cf_mode &= ~S_IFMT;
         fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
         fattr->cf_dtype = DT_LNK;
-        return 0;
+out:
+        cifs_put_tlink(tlink);
+        return rc;
 }
 
 int
@@ -314,17 +327,17 @@ cifs_hardlink(struct dentry *old_file, struct inode *inode,
         int xid;
         char *fromName = NULL;
         char *toName = NULL;
-        struct cifs_sb_info *cifs_sb_target;
+        struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
+        struct tcon_link *tlink;
         struct cifsTconInfo *pTcon;
         struct cifsInodeInfo *cifsInode;
 
-        xid = GetXid();
-
-        cifs_sb_target = CIFS_SB(inode->i_sb);
-        pTcon = cifs_sb_tcon(cifs_sb_target);
+        tlink = cifs_sb_tlink(cifs_sb);
+        if (IS_ERR(tlink))
+                return PTR_ERR(tlink);
+        pTcon = tlink_tcon(tlink);
 
-/* No need to check for cross device links since server will do that
-   BB note DFS case in future though (when we may have to check) */
+        xid = GetXid();
 
         fromName = build_path_from_dentry(old_file);
         toName = build_path_from_dentry(direntry);
@@ -336,13 +349,13 @@ cifs_hardlink(struct dentry *old_file, struct inode *inode,
 /*      if (cifs_sb_target->tcon->ses->capabilities & CAP_UNIX)*/
         if (pTcon->unix_ext)
                 rc = CIFSUnixCreateHardLink(xid, pTcon, fromName, toName,
-                                            cifs_sb_target->local_nls,
-                                            cifs_sb_target->mnt_cifs_flags &
+                                            cifs_sb->local_nls,
+                                            cifs_sb->mnt_cifs_flags &
                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
         else {
                 rc = CIFSCreateHardLink(xid, pTcon, fromName, toName,
-                                        cifs_sb_target->local_nls,
-                                        cifs_sb_target->mnt_cifs_flags &
+                                        cifs_sb->local_nls,
+                                        cifs_sb->mnt_cifs_flags &
                                                 CIFS_MOUNT_MAP_SPECIAL_CHR);
                 if ((rc == -EIO) || (rc == -EINVAL))
                         rc = -EOPNOTSUPP;
@@ -378,6 +391,7 @@ cifs_hl_exit:
         kfree(fromName);
         kfree(toName);
         FreeXid(xid);
+        cifs_put_tlink(tlink);
         return rc;
 }
 
@@ -390,10 +404,19 @@ cifs_follow_link(struct dentry *direntry, struct nameidata *nd)
         char *full_path = NULL;
         char *target_path = NULL;
         struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
-        struct cifsTconInfo *tcon = cifs_sb_tcon(cifs_sb);
+        struct tcon_link *tlink = NULL;
+        struct cifsTconInfo *tcon;
 
         xid = GetXid();
 
+        tlink = cifs_sb_tlink(cifs_sb);
+        if (IS_ERR(tlink)) {
+                rc = PTR_ERR(tlink);
+                tlink = NULL;
+                goto out;
+        }
+        tcon = tlink_tcon(tlink);
+
         /*
          * For now, we just handle symlinks with unix extensions enabled.
          * Eventually we should handle NTFS reparse points, and MacOS
@@ -442,6 +465,8 @@ out:
         }
 
         FreeXid(xid);
+        if (tlink)
+                cifs_put_tlink(tlink);
         nd_set_link(nd, target_path);
         return NULL;
 }
@@ -451,22 +476,25 @@ cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
 {
         int rc = -EOPNOTSUPP;
         int xid;
-        struct cifs_sb_info *cifs_sb;
+        struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
+        struct tcon_link *tlink;
         struct cifsTconInfo *pTcon;
         char *full_path = NULL;
         struct inode *newinode = NULL;
 
         xid = GetXid();
 
-        cifs_sb = CIFS_SB(inode->i_sb);
-        pTcon = cifs_sb_tcon(cifs_sb);
+        tlink = cifs_sb_tlink(cifs_sb);
+        if (IS_ERR(tlink)) {
+                rc = PTR_ERR(tlink);
+                goto symlink_exit;
+        }
+        pTcon = tlink_tcon(tlink);
 
         full_path = build_path_from_dentry(direntry);
-
         if (full_path == NULL) {
                 rc = -ENOMEM;
-                FreeXid(xid);
-                return rc;
+                goto symlink_exit;
         }
 
         cFYI(1, "Full path: %s", full_path);
@@ -504,8 +532,9 @@ cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
                         d_instantiate(direntry, newinode);
                 }
         }
-
+symlink_exit:
         kfree(full_path);
+        cifs_put_tlink(tlink);
         FreeXid(xid);
         return rc;
 }