cvs commit: src/sys/kern vfs_bio.c

[Matthew Dillon]

dillon      2005/01/29 11:17:06 PST

DragonFly src repository

  Modified files:
    sys/kern             vfs_bio.c 
  Log:
  getblk() has an old crufty API in which the logical block size is not a
  well known quantity.  Device drivers standardize on using DEV_BSIZE (512),
  while file ops are supposed to use mount->mnt_stat.f_iosize.
  
  The existing code was testing for a non-NULL vnode->v_mountedhere field
  but this field is part of a union and only valid for VDIR types.  It was being
  improperly tested on non-VDIR vnode types.  In particular, if vn_isdisk()
  fails due to the disk device being ripped out from under a filesystem,
  the code would fall through and try to use v_mountedhere, leading to a
  crash.  It also makes no sense to use the target mount to calculate the
  block size for the underlying mount point's vnode, so this test has been
  removed entirely.  The vn_isdisk() test has been replaced with an explicit
  VBLK/VCHR test.
  
  Finally, note that filesystems like UFS use varying buffer cache buffer
  sizes for different areas of the same block device (e.g. bitmap areas,
  inode area, file data areas, superblock), which is why DEV_BSIZE is being
  used here.  What really needs to happen is for b_blkno to be entirely
  removed in favor of a 64 bit offset.
  
  Crash-Reported-by: Vyacheslav Bocharov <list at xxxxxxxxxx>
  
  Revision  Changes    Path
  1.33      +16 -3     src/sys/kern/vfs_bio.c


http://www.dragonflybsd.org/cvsweb/src/sys/kern/vfs_bio.c.diff?r1=1.32&r2=1.33&f=u