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libgeom: Avoid fixed remappings of the devstat device

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libgeom maintains a quasi-private mapping of /dev/devstat, which might
grow over time if new devices appear.  When the mapping needs to be
expanded, the old mapping is passed as a hint, but this appears to be
unnecessary.

Simplify and improve things a bit:
- stop passing a hint when remapping,
- don't creat a mapping in geom_stats_open(), as geom_stats_resync() will
  create it for us,
- check for errors from munmap().

Reviewed by:	imp, asomers
Tested by:	asomers
MFC after:	2 weeks
Sponsored by:	Innovate UK
Differential Revision:	https://reviews.freebsd.org/D46294
This commit is contained in:
Mark Johnston 2024-08-19 16:02:26 +00:00
parent 22a632c366
commit d06fe346ec
1 changed files with 12 additions and 22 deletions
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26
lib/libgeom/geom_stats.c
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@ -54,8 +54,11 @@ geom_stats_close(void)
{
if (statsfd == -1)
return;
munmap(statp, npages * pagesize);
if (statp != NULL) {
if (munmap(statp, npages * pagesize) != 0)
err(1, "munmap");
statp = NULL;
}
close(statsfd);
statsfd = -1;
}
@ -73,22 +76,18 @@ geom_stats_resync(void)
if (error)
err(1, "DIOCGMEDIASIZE(" _PATH_DEV DEVSTAT_DEVICE_NAME ")");
munmap(statp, npages * pagesize);
p = mmap(statp, mediasize, PROT_READ, MAP_SHARED, statsfd, 0);
if (statp != NULL && munmap(statp, npages * pagesize) != 0)
err(1, "munmap");
p = mmap(NULL, mediasize, PROT_READ, MAP_SHARED, statsfd, 0);
if (p == MAP_FAILED)
err(1, "mmap(/dev/devstat):");
else {
err(1, "mmap(/dev/devstat)");
statp = p;
npages = mediasize / pagesize;
}
}
int
geom_stats_open(void)
{
int error;
void *p;
if (statsfd != -1)
return (EBUSY);
statsfd = open(_PATH_DEV DEVSTAT_DEVICE_NAME, O_RDONLY);
@ -96,15 +95,6 @@ geom_stats_open(void)
return (errno);
pagesize = getpagesize();
spp = pagesize / sizeof(struct devstat);
p = mmap(NULL, pagesize, PROT_READ, MAP_SHARED, statsfd, 0);
if (p == MAP_FAILED) {
error = errno;
close(statsfd);
statsfd = -1;
errno = error;
return (error);
}
statp = p;
npages = 1;
geom_stats_resync();
return (0);