d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

vfs: release the interlock after failing to set VHOLD_NO_SMR

Browse Source 
While here add more comments.

Diagnosed by:	markj
Reported by:	pho
Fixes:	r362827 ("vfs: protect vnodes with smr")
This commit is contained in:
Mateusz Guzik 2020-08-07 19:36:08 +00:00
parent 21673cf0bd
commit 1ff80a3400
1 changed files with 11 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
sys/kern/vfs_subr.c
View File

@ -3683,19 +3683,24 @@ vdropl(struct vnode *vp)
}
if (!VN_IS_DOOMED(vp)) {
vdrop_deactivate(vp);
/*
* Also unlocks the interlock. We can't assert on it as we
* released our hold and by now the vnode might have been
* freed.
*/
return;
}
/*
* We may be racing against vhold_smr.
* Set the VHOLD_NO_SMR flag.
*
* If they win we can just pretend we never got this far, they will
* vdrop later.
* We may be racing against vhold_smr. If they win we can just pretend
* we never got this far, they will vdrop later.
*/
if (!atomic_cmpset_int(&vp->v_holdcnt, 0, VHOLD_NO_SMR)) {
VI_UNLOCK(vp);
/*
* We lost the aforementioned race. Note that any subsequent
* access is invalid as they might have managed to vdropl on
* their own.
* We lost the aforementioned race. Any subsequent access is
* invalid as they might have managed to vdropl on their own.
*/
return;
}