HEADSUP: UFS on GEOM now.

This is hopefully a no-op for all purposes than the increased access
flexibility.

I am very interested if anybody can measure the performance difference
better than I could myself:  1.7% +/- 0.5%.

Poul-Henning

phk         2004-10-29 10:15:56 UTC

  FreeBSD src repository

  Modified files:
    sys/ufs/ffs          ffs_alloc.c ffs_extern.h ffs_rawread.c 
                         ffs_snapshot.c ffs_softdep.c ffs_vfsops.c 
                         ffs_vnops.c 
    sys/ufs/ufs          inode.h ufs_vnops.c ufsmount.h 
  Log:
  Move UFS from DEVFS backing to GEOM backing.
  
  This eliminates a bunch of vnode overhead (approx 1-2 % speed
  improvement) and gives us more control over the access to the storage
  device.
  
  Access counts on the underlying device are not correctly tracked and
  therefore it is possible to read-only mount the same disk device multiple
  times:
          syv# mount -p
          /dev/md0        /var    ufs rw  2 2
          /dev/ad0        /mnt    ufs ro  1 1
          /dev/ad0        /mnt2   ufs ro  1 1
          /dev/ad0        /mnt3   ufs ro  1 1
  
  Since UFS/FFS is not a synchrousely consistent filesystem (ie: it caches
  things in RAM) this is not possible with read-write mounts, and the system
  will correctly reject this.
  
  Details:
  
          Add a geom consumer and a bufobj pointer to ufsmount.
  
          Eliminate the vnode argument from softdep_disk_prewrite().
          Pick the vnode out of bp->b_vp for now.  Eventually we
          should find it through bp->b_bufobj->b_private.
  
          In the mountcode, use g_vfs_open() once we have used
          VOP_ACCESS() to check permissions.
  
          When upgrading and downgrading between r/o and r/w do the
          right thing with GEOM access counts.  Remove all the
          workarounds for not being able to do this with VOP_OPEN().
  
          If we are the root mount, drop the exclusive access count
          until we upgrade to r/w.  This allows fsck of the root
          filesystem and the MNT_RELOAD to work correctly.
  
          Set bo_private to the GEOM consumer on the device bufobj.
  
          Change the ffs_ops->strategy function to call g_vfs_strategy()
  
          In ufs_strategy() directly call the strategy on the disk
          bufobj.  Same in rawread.
  
          In ffs_fsync() we will no longer see VCHR device nodes, so
          remove code which synced the filesystem mounted on it, in
          case we came there.  I'm not sure this code made sense in
          the first place since we would have taken the specfs route
          on such a vnode.
  
          Redo the highly bogus readblock() function in the snapshot
          code to something slightly less bogus: Constructing an uio
          and using physio was really quite a detour.  Instead just
          fill in a bio and ship it down.
  
  Revision  Changes    Path
  1.126     +0 -3      src/sys/ufs/ffs/ffs_alloc.c
  1.61      +1 -1      src/sys/ufs/ffs/ffs_extern.h
  1.18      +1 -5      src/sys/ufs/ffs/ffs_rawread.c
  1.89      +17 -13    src/sys/ufs/ffs/ffs_snapshot.c
  1.163     +6 -24     src/sys/ufs/ffs/ffs_softdep.c
  1.250     +63 -60    src/sys/ufs/ffs/ffs_vfsops.c
  1.141     +2 -11     src/sys/ufs/ffs/ffs_vnops.c
  1.47      +1 -0      src/sys/ufs/ufs/inode.h
  1.249     +3 -7      src/sys/ufs/ufs/ufs_vnops.c
  1.32      +2 -0      src/sys/ufs/ufs/ufsmount.h


------- End of Forwarded Message