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devmnt: handle rpc buffer exhaustion on mntflushalloc()

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this bug happens when the kernel runs out of mount rpc
buffers when allocating a flush rpc. in this case, mntflushalloc()
will errorjump out of mountio() leaving the currently in
flight rpc in the mount. the caller of mountrpc()/mountio()
frees the rpc thats still queued in the mount leaving
to interesting results.

for the fix, we add a waserror() arround mntflushalloc() and
handle the error case like a mount rpc failure which will
properly dequeue the rpc's in flight.
This commit is contained in:
cinap_lenrek 2015-01-27 22:14:26 +01:00
parent 72be22cd3a
commit e823ddb3b0
1 changed files with 2 additions and 1 deletions
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3
sys/src/9/port/devmnt.c
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@ -774,7 +774,7 @@ mountio(Mnt *m, Mntrpc *r)
while(waserror()) {
if(m->rip == up)
mntgate(m);
if(strcmp(up->errstr, Eintr) != 0){
if(strcmp(up->errstr, Eintr) != 0 || waserror()){
r = mntflushfree(m, r);
switch(r->request.type){
case Tremove:
@ -786,6 +786,7 @@ mountio(Mnt *m, Mntrpc *r)
nexterror();
}
r = mntflushalloc(r, m->msize);
poperror();
}
lock(m);