From: Eric Wong <e@80x24.org>
To: cmogstored-public@yhbt.net
Subject: [RFC] dev.c: emit usage for devices with unknown mount point
Date: Mon, 20 Jul 2020 08:51:19 +0000 [thread overview]
Message-ID: <20200720085119.11067-1-e@80x24.org> (raw)
LUKS + btrfs on Linux gives an .st_rdev value of `0', so we
can't reliably figure out what the "device:" field in
/devXX/usage should be without parsing /proc/partitions.
Since MogileFS::Worker::Monitor only cares about the "used:" and
"total:" fields, we'll just emit "(?)" in the device field. The
effort of parsing /proc/partitions to correctly display a field
that our only known consumer won't use is a waste of our time.
---
cmogstored.h | 1 +
dev.c | 91 ++++++++++++++++++++++++++--------------------------
2 files changed, 47 insertions(+), 45 deletions(-)
diff --git a/cmogstored.h b/cmogstored.h
index 081ffbf..35ddc73 100644
--- a/cmogstored.h
+++ b/cmogstored.h
@@ -108,6 +108,7 @@ struct mog_ioq {
struct mog_wbuf;
struct mog_dev {
dev_t st_dev;
+ unsigned no_me_warned : 1;
uint32_t devid;
pthread_mutex_t usage_lock; /* protects usage_txt */
unsigned usage_len;
diff --git a/dev.c b/dev.c
index b149619..c120736 100644
--- a/dev.c
+++ b/dev.c
@@ -33,6 +33,7 @@ static struct mog_dev *mog_dev_new(struct mog_svc *svc, uint32_t mog_devid)
dev->st_dev = sb.st_dev;
mog_ioq_init(&dev->fsckq, svc, 1);
mog_ioq_init(&dev->ioq, svc, svc->thr_per_dev);
+ dev->no_me_warned = 0;
dev->usage_txt = 0;
dev->usage_len = 0;
dev->usage_mtime = 0;
@@ -122,6 +123,15 @@ emit_usage(struct mog_dev *dev, struct mog_svc *svc, int fd, struct statvfs *v)
long long now = (long long)time(NULL);
long double mb = v->f_frsize / (long double)1024.0;
const struct mount_entry *me;
+ char *usage_txt;
+ static const char usage_fmt[] =
+ "available: %llu\n"
+ "device: %s\n"
+ "disk: %s/dev%u\n"
+ "time: %lld\n"
+ "total: %llu\n"
+ "use: %u%%\n"
+ "used: %llu\n";
available *= mb;
total *= mb;
@@ -131,53 +141,44 @@ emit_usage(struct mog_dev *dev, struct mog_svc *svc, int fd, struct statvfs *v)
use = 100;
me = mog_mnt_acquire(dev->st_dev);
- if (me) {
- char *usage_txt;
- static const char usage_fmt[] =
- "available: %llu\n"
- "device: %s\n"
- "disk: %s/dev%u\n"
- "time: %lld\n"
- "total: %llu\n"
- "use: %u%%\n"
- "used: %llu\n";
-
- errno = 0;
- rc = asprintf(&usage_txt, usage_fmt,
- available, me->me_devname, svc->docroot,
- (unsigned)dev->devid, now, total, use, used);
- if (rc > 0) {
- char *old_usage;
-
- CHECK(int, 0, pthread_mutex_lock(&dev->usage_lock));
- old_usage = dev->usage_txt;
- dev->usage_txt = usage_txt;
- dev->usage_len = rc;
- dev->usage_mtime = (time_t)now;
- CHECK(int, 0, pthread_mutex_unlock(&dev->usage_lock));
-
- free(old_usage);
- if (fd >= 0) {
- ssize_t w = write(fd, usage_txt, rc);
-
- if (w >= 0 && w != rc)
- errno = ENOSPC;
- else if (w < 0)
- rc = -1;
- }
- }
-
- PRESERVE_ERRNO( mog_mnt_release(me) );
- if (rc < 0 || errno == ENOSPC) {
- PRESERVE_ERRNO(do {
- syslog(LOG_ERR, "write(%s/dev%u/usage): %m",
- svc->docroot, (unsigned)dev->devid);
- } while (0));
- }
- } else {
+ if (!me && !dev->no_me_warned) {
syslog(LOG_ERR, "mount entry not found for %s/dev%u",
svc->docroot, (unsigned)dev->devid);
- errno = ENODEV;
+ dev->no_me_warned = 1;
+ }
+ errno = 0;
+ rc = asprintf(&usage_txt, usage_fmt, available,
+ /* device:, MogileFS::Worker::Monitor doesn't care: */
+ me ? me->me_devname : "(?)",
+ svc->docroot,
+ (unsigned)dev->devid, now, total, use, used);
+ if (rc > 0) {
+ char *old_usage;
+
+ CHECK(int, 0, pthread_mutex_lock(&dev->usage_lock));
+ old_usage = dev->usage_txt;
+ dev->usage_txt = usage_txt;
+ dev->usage_len = rc;
+ dev->usage_mtime = (time_t)now;
+ CHECK(int, 0, pthread_mutex_unlock(&dev->usage_lock));
+
+ free(old_usage);
+ if (fd >= 0) {
+ ssize_t w = write(fd, usage_txt, rc);
+
+ if (w >= 0 && w != rc)
+ errno = ENOSPC;
+ else if (w < 0)
+ rc = -1;
+ }
+ }
+ if (me)
+ PRESERVE_ERRNO( mog_mnt_release(me) );
+ if (rc < 0 || errno == ENOSPC) {
+ PRESERVE_ERRNO(do {
+ syslog(LOG_ERR, "write(%s/dev%u/usage): %m",
+ svc->docroot, (unsigned)dev->devid);
+ } while (0));
}
return rc;
reply other threads:[~2020-07-20 8:51 UTC|newest]
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