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Allow the dounmount() to proceed even for doomed coveredvp.

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In dounmount(), before or while vn_lock(coveredvp) is called, coveredvp
vnode may be VI_DOOMED due to one of the following:
- other thread finished unmount and vput()ed it, and vnode was chosen
  for recycling, while vn_lock() slept;
- forced unmount of the coveredvp->v_mount fs.
In the first case, next check for changed v_mountedhere or mnt_gen counter
would be successfull. In the second case, the unmount shall be allowed.

Submitted by:	sobomax
MFC after:	2 weeks
This commit is contained in:
Konstantin Belousov 2007-04-26 08:56:56 +00:00
parent 64c43db51c
commit e5ea32c290
1 changed files with 1 additions and 3 deletions
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4
sys/kern/vfs_mount.c
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@ -1168,14 +1168,12 @@ dounmount(mp, flags, td)
mnt_gen_r = mp->mnt_gen;
VI_LOCK(coveredvp);
vholdl(coveredvp);
error = vn_lock(coveredvp, LK_EXCLUSIVE | LK_INTERLOCK, td);
vn_lock(coveredvp, LK_EXCLUSIVE | LK_INTERLOCK | LK_RETRY, td);
vdrop(coveredvp);
/*
* Check for mp being unmounted while waiting for the
* covered vnode lock.
*/
if (error)
return (error);
if (coveredvp->v_mountedhere != mp ||
coveredvp->v_mountedhere->mnt_gen != mnt_gen_r) {
VOP_UNLOCK(coveredvp, 0, td);