CVS commit: src/sys/kern

[Manuel Bouyer <bouyer%netbsd.org@localhost>]

Module Name:    src
Committed By:   bouyer
Date:           Sat Nov 28 10:10:18 UTC 2009

Modified Files:
        src/sys/kern: vfs_subr.c

Log Message:
Previous did cause a deadlock with layered FS: the vrele thread
can sleep on the vnode lock, while vget is sleeping on the
VI_INACTNOW flag (or the vget caller is looping on vget returning failure
because of the VI_INACTNOW flag). With layered FSes, the upper and lower
vnodes share the same lock, so the vget() caller above can be already
holding the vnode lock.

Fix by dropping VI_INACTNOW before sleeping on the vnode lock in
vrelel(), and check the ref count again once we have the lock. If the
vnode has more than one reference, donc VOP_INACTIVE it.
Fix PR kern/42318 and PR kern/42377
patch tested by Hisashi T Fujinaka, Joachim König, Stephen Borrill and
Matthias Scheler.


To generate a diff of this commit:
cvs rdiff -u -r1.391 -r1.392 src/sys/kern/vfs_subr.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.