On 01/25/2012 02:09 PM, Jeff Layton wrote:
> On Wed, 25 Jan 2012 13:16:24 -0500
> Steve Dickson <SteveD@xxxxxxxxxx> wrote:
>
>> Hey Jeff,
>>
>> Commit inline...
>>
>> On 01/23/2012 03:02 PM, Jeff Layton wrote:
>>> This can happen if nfsd is shut down and restarted. If that occurs,
>>> then reopen the pipe so we're not waiting for data on the defunct
>>> pipe.
>>>
>>> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
>>> ---
>>> utils/nfsdcld/nfsdcld.c | 84 +++++++++++++++++++++++++++++++++++++++++-----
>>> 1 files changed, 74 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/utils/nfsdcld/nfsdcld.c b/utils/nfsdcld/nfsdcld.c
>>> index b0c08e2..0dc5b37 100644
>>> --- a/utils/nfsdcld/nfsdcld.c
>>> +++ b/utils/nfsdcld/nfsdcld.c
>>> @@ -57,6 +57,8 @@ struct cld_client {
>>>
>>> /* global variables */
>>> static char *pipepath = DEFAULT_CLD_PATH;
>>> +static int inotify_fd = -1;
>>> +static struct event pipedir_event;
>>>
>>> static struct option longopts[] =
>>> {
>>> @@ -68,8 +70,10 @@ static struct option longopts[] =
>>> { NULL, 0, 0, 0 },
>>> };
>>>
>>> +
>>> /* forward declarations */
>>> static void cldcb(int UNUSED(fd), short which, void *data);
>>> +static void cld_pipe_reopen(struct cld_client *clnt);
>>>
>>> static void
>>> usage(char *progname)
>>> @@ -80,10 +84,62 @@ usage(char *progname)
>>>
>>> #define INOTIFY_EVENT_MAX (sizeof(struct inotify_event) + NAME_MAX)
>>>
>>> +static void
>>> +cld_inotify_cb(int UNUSED(fd), short which, void *data)
>>> +{
>>> + int ret, oldfd;
>>> + char evbuf[INOTIFY_EVENT_MAX];
>>> + char *dirc = NULL, *pname;
>>> + struct inotify_event *event = (struct inotify_event *)evbuf;
>>> + struct cld_client *clnt = data;
>>> +
>>> + if (which != EV_READ)
>>> + return;
>>> +
>>> + dirc = strndup(pipepath, PATH_MAX);
>>> + if (!dirc) {
>>> + xlog_err("%s: unable to allocate memory", __func__);
>>> + goto out;
>>> + }
>>> +
>>> + ret = read(inotify_fd, evbuf, INOTIFY_EVENT_MAX);
>>> + if (ret < 0) {
>>> + xlog_err("%s: read from inotify fd failed: %m", __func__);
>>> + goto out;
>>> + }
>>> +
>>> + /* check to see if we have a filename in the evbuf */
>>> + if (!event->len)
>>> + goto out;
>>> +
>>> + pname = basename(dirc);
>>> +
>>> + /* does the filename match our pipe? */
>>> + if (strncmp(pname, event->name, event->len))
>>> + goto out;
>>> +
>>> + /*
>>> + * reopen the pipe. The old fd is not closed until the new one is
>>> + * opened, so we know they should be different if the reopen is
>>> + * successful.
>>> + */
>>> + oldfd = clnt->cl_fd;
>>> + do {
>>> + cld_pipe_reopen(clnt);
>>> + } while (oldfd == clnt->cl_fd);
>> Doesn't this have a potential for an infinite loop?
>>
>> steved.
>
>
> Yes. If reopening the new pipe continually fails then it will loop
> forever.
Would it be more accurate to say it would be spinning forever?
Since there is no sleep or delay in cld_pipe_reopen, what's
going to stop the daemon from spinning in a CPU bound loop?
steved.
>
>>> +
>>> + /* readd the event for the cl_event pipe */
>>> + event_add(&clnt->cl_event, NULL);
>>> +
>>> +out:
>>> + event_add(&pipedir_event, NULL);
>>> + free(dirc);
>>> +}
>>> +
>>> static int
>>> cld_pipe_open(struct cld_client *clnt)
>>> {
>>> - int ifd, wat;
>>> + int wat;
>>> ssize_t ret;
>>> char *dirc, *dname;
>>> char event[INOTIFY_EVENT_MAX];
>>> @@ -97,16 +153,16 @@ cld_pipe_open(struct cld_client *clnt)
>>>
>>> dname = dirname(dirc);
>>>
>>> - ifd = inotify_init();
>>> - if (ifd < 0) {
>>> + inotify_fd = inotify_init();
>>> + if (inotify_fd < 0) {
>>> xlog_err("%s: inotify_init failed: %m", __func__);
>>> goto out_free;
>>> }
>>>
>>> - wat = inotify_add_watch(ifd, dname, IN_CREATE);
>>> + wat = inotify_add_watch(inotify_fd, dname, IN_CREATE);
>>> if (wat < 0) {
>>> xlog_err("%s: inotify_add_watch failed: %m", __func__);
>>> - goto out;
>>> + goto out_err;
>>> }
>>>
>>> for (;;) {
>>> @@ -117,24 +173,31 @@ cld_pipe_open(struct cld_client *clnt)
>>> else if (errno != ENOENT) {
>>> xlog_err("%s: unable to open %s: %m", __func__,
>>> pipepath);
>>> - goto out;
>>> + goto out_err;
>>> }
>>> - ret = read(ifd, event, INOTIFY_EVENT_MAX);
>>> + ret = read(inotify_fd, event, INOTIFY_EVENT_MAX);
>>> if (ret < 0) {
>>> xlog_err("%s: read from inotify fd failed: %m",
>>> __func__);
>>> - goto out;
>>> + goto out_err;
>>> }
>>> }
>>>
>>> + /* set event for the pipe reads */
>>> event_set(&clnt->cl_event, clnt->cl_fd, EV_READ, cldcb, clnt);
>>> event_add(&clnt->cl_event, NULL);
>>>
>>> -out:
>>> - close(ifd);
>>> + /* another event for inotify read */
>>> + event_set(&pipedir_event, inotify_fd, EV_READ, cld_inotify_cb, clnt);
>>> + event_add(&pipedir_event, NULL);
>>> +
>>> out_free:
>>> free(dirc);
>>> return clnt->cl_fd;
>>> +
>>> +out_err:
>>> + close(inotify_fd);
>>> + goto out_free;
>>> }
>>>
>>> static void
>>> @@ -142,6 +205,7 @@ cld_pipe_reopen(struct cld_client *clnt)
>>> {
>>> int fd;
>>>
>>> + xlog(D_GENERAL, "%s: reopening pipe", __func__);
>>> fd = open(pipepath, O_RDWR, 0);
>>> if (fd < 0) {
>>> xlog_warn("%s: Re-opening of %s failed: %m",
>>> -- 1.7.7.5
>
>
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