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FreeBSD: libspl: Add locking around statfs globals 

Makes getmntent and getmntany thread-safe for external consumers of
libzfs zpool_disable_datasets, zfs_iter_mounted, libzfs_mnttab_update,
libzfs_mnttab_find.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <freqlabs@FreeBSD.org>
Closes #13484
This commit is contained in:
Ryan Moeller 2022-05-24 12:40:20 -04:00 committed by Brian Behlendorf
parent ed16dd7635
commit fde66e583d
1 changed files with 15 additions and 1 deletions
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16
lib/libspl/os/freebsd/mnttab.c
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@ -39,6 +39,7 @@ __FBSDID("$FreeBSD$");
#include <ctype.h> #include <ctype.h>
#include <errno.h> #include <errno.h>
#include <pthread.h>
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
#include <string.h> #include <string.h>
@ -136,6 +137,7 @@ statfs2mnttab(struct statfs *sfs, struct mnttab *mp)
mp->mnt_mntopts = gmntopts; mp->mnt_mntopts = gmntopts;
} }
static pthread_rwlock_t gsfs_lock = PTHREAD_RWLOCK_INITIALIZER;
static struct statfs *gsfs = NULL; static struct statfs *gsfs = NULL;
static int allfs = 0; static int allfs = 0;
@ -145,6 +147,8 @@ statfs_init(void)
struct statfs *sfs; struct statfs *sfs;
int error; int error;
(void) pthread_rwlock_wrlock(&gsfs_lock);
if (gsfs != NULL) { if (gsfs != NULL) {
free(gsfs); free(gsfs);
gsfs = NULL; gsfs = NULL;
@ -162,6 +166,7 @@ statfs_init(void)
sfs = realloc(gsfs, allfs * sizeof (gsfs[0])); sfs = realloc(gsfs, allfs * sizeof (gsfs[0]));
if (sfs != NULL) if (sfs != NULL)
gsfs = sfs; gsfs = sfs;
(void) pthread_rwlock_unlock(&gsfs_lock);
return (0); return (0);
fail: fail:
error = errno; error = errno;
@ -169,6 +174,7 @@ fail:
free(gsfs); free(gsfs);
gsfs = NULL; gsfs = NULL;
allfs = 0; allfs = 0;
(void) pthread_rwlock_unlock(&gsfs_lock);
return (error); return (error);
} }
@ -181,6 +187,8 @@ getmntany(FILE *fd __unused, struct mnttab *mgetp, struct mnttab *mrefp)
if (error != 0) if (error != 0)
return (error); return (error);
(void) pthread_rwlock_rdlock(&gsfs_lock);
for (i = 0; i < allfs; i++) { for (i = 0; i < allfs; i++) {
if (mrefp->mnt_special != NULL && if (mrefp->mnt_special != NULL &&
strcmp(mrefp->mnt_special, gsfs[i].f_mntfromname) != 0) { strcmp(mrefp->mnt_special, gsfs[i].f_mntfromname) != 0) {
@ -195,8 +203,10 @@ getmntany(FILE *fd __unused, struct mnttab *mgetp, struct mnttab *mrefp)
continue; continue;
} }
statfs2mnttab(&gsfs[i], mgetp); statfs2mnttab(&gsfs[i], mgetp);
(void) pthread_rwlock_unlock(&gsfs_lock);
return (0); return (0);
} }
(void) pthread_rwlock_unlock(&gsfs_lock);
return (-1); return (-1);
} }
@ -214,9 +224,13 @@ getmntent(FILE *fp, struct mnttab *mp)
if (error != 0) if (error != 0)
return (error); return (error);
} }
if (nfs >= allfs) (void) pthread_rwlock_rdlock(&gsfs_lock);
if (nfs >= allfs) {
(void) pthread_rwlock_unlock(&gsfs_lock);
return (-1); return (-1);
}
statfs2mnttab(&gsfs[nfs], mp); statfs2mnttab(&gsfs[nfs], mp);
(void) pthread_rwlock_unlock(&gsfs_lock);
if (lseek(fileno(fp), 1, SEEK_CUR) == -1) if (lseek(fileno(fp), 1, SEEK_CUR) == -1)
return (errno); return (errno);
return (0); return (0);