7178 tmpfs incorrectly calculates amount of free space
Reviewed by: Alexander Stetsenko <astetsenko@racktopsystems.com>

*** 19,28 ****
--- 19,29 ----
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 1990, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright (c) 2011, Joyent, Inc. All rights reserved.
+  * Copyright 2016 RackTop Systems.
   */
  
  #include <sys/types.h>
  #include <sys/param.h>
  #include <sys/sysmacros.h>
*** 584,597 ****
          ASSERT(k_anoninfo.ani_max >= k_anoninfo.ani_phys_resv);
          blocks = (ulong_t)CURRENT_TOTAL_AVAILABLE_SWAP;
          mutex_exit(&anoninfo_lock);
  
          /*
!          * If tm_anonmax for this mount is less than the available swap space
!          * (minus the amount tmpfs can't use), use that instead
!          */
!         if (blocks > tmpfs_minfree)
                  sbp->f_bfree = MIN(blocks - tmpfs_minfree,
                      tm->tm_anonmax - tm->tm_anonmem);
          else
                  sbp->f_bfree = 0;
  
--- 585,601 ----
          ASSERT(k_anoninfo.ani_max >= k_anoninfo.ani_phys_resv);
          blocks = (ulong_t)CURRENT_TOTAL_AVAILABLE_SWAP;
          mutex_exit(&anoninfo_lock);
  
          /*
!          * Compare the amount of space that should be free to this mount
!          * (which may be limited by tm_anonmax) with the amount of space
!          * that's actually free to all tmpfs and use the lowest value.
!          */
!         if (tm->tm_anonmax == ULONG_MAX)
!                 sbp->f_bfree = MAX(blocks - tmpfs_minfree, 0);
!         else if (blocks > tmpfs_minfree && tm->tm_anonmax > tm->tm_anonmem)
                  sbp->f_bfree = MIN(blocks - tmpfs_minfree,
                      tm->tm_anonmax - tm->tm_anonmem);
          else
                  sbp->f_bfree = 0;
  
*** 624,644 ****
                  sbp->f_blocks = MIN(pgcap, sbp->f_blocks);
          }
  
          /*
           * The maximum number of files available is approximately the number
!          * of tmpnodes we can allocate from the remaining kernel memory
!          * available to tmpfs.  This is fairly inaccurate since it doesn't
!          * take into account the names stored in the directory entries.
           */
!         if (tmpfs_maxkmem > tmp_kmemspace)
!                 sbp->f_ffree = (tmpfs_maxkmem - tmp_kmemspace) /
                      (sizeof (struct tmpnode) + sizeof (struct tdirent));
!         else
!                 sbp->f_ffree = 0;
! 
!         sbp->f_files = tmpfs_maxkmem /
              (sizeof (struct tmpnode) + sizeof (struct tdirent));
          sbp->f_favail = (fsfilcnt64_t)(sbp->f_ffree);
          (void) cmpldev(&d32, vfsp->vfs_dev);
          sbp->f_fsid = d32;
          (void) strcpy(sbp->f_basetype, vfssw[tmpfsfstype].vsw_name);
--- 628,644 ----
                  sbp->f_blocks = MIN(pgcap, sbp->f_blocks);
          }
  
          /*
           * The maximum number of files available is approximately the number
!          * of tmpnodes we can allocate from the number of blocks available
!          * to this mount.  This is fairly inaccurate since it doesn't take
!          * into account the names stored in the directory entries.
           */
!         sbp->f_ffree = sbp->f_bfree == 0 ? 0 : sbp->f_bfree /
              (sizeof (struct tmpnode) + sizeof (struct tdirent));
!         sbp->f_files = sbp->f_blocks == 0 ? 0 : sbp->f_blocks /
              (sizeof (struct tmpnode) + sizeof (struct tdirent));
          sbp->f_favail = (fsfilcnt64_t)(sbp->f_ffree);
          (void) cmpldev(&d32, vfsp->vfs_dev);
          sbp->f_fsid = d32;
          (void) strcpy(sbp->f_basetype, vfssw[tmpfsfstype].vsw_name);