libspl/mnttab: remove struct extmnttab

The two additional fields are never used by calling code, and we can
replace their sole internal use with an extra stack param.

Sponsored-by: TrueNAS
Reviewed-by: Ameer Hamza <ahamza@ixsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <rob.norris@truenas.com>
Closes #18296

cmd/zfs/zfs_main.c

@@ -7694,15 +7694,11 @@ unshare_unmount_path(int op, char *path, int flags, boolean_t is_manual)
 	zfs_handle_t *zhp;
 	int ret = 0;
 	struct stat64 statbuf;
-	struct extmnttab entry;
+	struct mnttab entry;
 	const char *cmdname = (op == OP_SHARE) ? "unshare" : "unmount";
 	ino_t path_inode;
 	char *zfs_mntpnt, *entry_mntpnt;
 
-	/*
-	 * Search for the given (major,minor) pair in the mount table.
-	 */
-
 	if (getextmntent(path, &entry, &statbuf) != 0) {
 		if (op == OP_SHARE) {
 			(void) fprintf(stderr, gettext("cannot %s '%s': not "

cmd/zinject/translate.c

@@ -85,7 +85,7 @@ static int
 parse_pathname(const char *inpath, char *dataset, char *relpath,
     struct stat64 *statbuf)
 {
-	struct extmnttab mp;
+	struct mnttab mp;
 	const char *rel;
 	char fullpath[MAXPATHLEN];
 

lib/libspl/include/os/freebsd/sys/mnttab.h

@@ -57,26 +57,11 @@ struct mnttab {
 	char *mnt_mntopts;
 };
 
-/*
- * NOTE: fields in extmnttab should match struct mnttab till new fields
- * are encountered, this allows hasmntopt to work properly when its arg is
- * a pointer to an extmnttab struct cast to a mnttab struct pointer.
- */
-
-struct extmnttab {
-	char *mnt_special;
-	char *mnt_mountp;
-	char *mnt_fstype;
-	char *mnt_mntopts;
-	uint_t mnt_major;
-	uint_t mnt_minor;
-};
-
 struct stat64;
 struct statfs;
 
 extern int _sol_getmntent(FILE *fp, struct mnttab *mp);
-extern int getextmntent(const char *path, struct extmnttab *entry,
+extern int getextmntent(const char *path, struct mnttab *entry,
     struct stat64 *statbuf);
 extern void statfs2mnttab(struct statfs *sfs, struct mnttab *mp);
 extern char *hasmntopt(struct mnttab *mnt, const char *opt);

lib/libspl/include/os/linux/sys/mnttab.h

@@ -54,25 +54,10 @@ struct mnttab {
 	char *mnt_mntopts;
 };
 
-/*
- * NOTE: fields in extmnttab should match struct mnttab till new fields
- * are encountered, this allows hasmntopt to work properly when its arg is
- * a pointer to an extmnttab struct cast to a mnttab struct pointer.
- */
-
-struct extmnttab {
-	char *mnt_special;
-	char *mnt_mountp;
-	char *mnt_fstype;
-	char *mnt_mntopts;
-	uint_t mnt_major;
-	uint_t mnt_minor;
-};
-
 struct statfs;
 
 extern int _sol_getmntent(FILE *fp, struct mnttab *mp);
-extern int getextmntent(const char *path, struct extmnttab *mp,
+extern int getextmntent(const char *path, struct mnttab *mp,
     struct stat64 *statbuf);
 static inline char *_sol_hasmntopt(struct mnttab *mnt, const char *opt)
 {

lib/libspl/os/freebsd/getextmntent.c

@@ -40,7 +40,7 @@
 #include <libzutil.h>
 
 int
-getextmntent(const char *path, struct extmnttab *entry, struct stat64 *statbuf)
+getextmntent(const char *path, struct mnttab *entry, struct stat64 *statbuf)
 {
 	struct statfs sfs;
 
@@ -60,6 +60,6 @@ getextmntent(const char *path, struct extmnttab *entry, struct stat64 *statbuf)
 		    zfs_strerror(errno));
 		return (-1);
 	}
-	statfs2mnttab(&sfs, (struct mnttab *)entry);
+	statfs2mnttab(&sfs, entry);
 	return (0);
 }

lib/libspl/os/linux/mnttab.c

@@ -68,7 +68,7 @@ _sol_getmntent(FILE *fp, struct mnttab *mgetp)
 }
 
 static int
-getextmntent_impl(FILE *fp, struct extmnttab *mp, uint64_t *mnt_id)
+getextmntent_impl(FILE *fp, struct mnttab *mp, uint64_t *mnt_id, dev_t *dev)
 {
 	int ret;
 	struct stat64 st;
@@ -84,19 +84,17 @@ getextmntent_impl(FILE *fp, struct extmnttab *mp, uint64_t *mnt_id)
 			*mnt_id = stx.stx_mnt_id;
 #endif
 		if (stat64(mp->mnt_mountp, &st) != 0) {
-			mp->mnt_major = 0;
+			*dev = 0;
-			mp->mnt_minor = 0;
 			return (ret);
 		}
-		mp->mnt_major = major(st.st_dev);
+		*dev = st.st_dev;
-		mp->mnt_minor = minor(st.st_dev);
 	}
 
 	return (ret);
 }
 
 int
-getextmntent(const char *path, struct extmnttab *entry, struct stat64 *statbuf)
+getextmntent(const char *path, struct mnttab *entry, struct stat64 *statbuf)
 {
 	struct stat64 st;
 	FILE *fp;
@@ -104,6 +102,7 @@ getextmntent(const char *path, struct extmnttab *entry, struct stat64 *statbuf)
 	boolean_t have_mnt_id = B_FALSE;
 	uint64_t target_mnt_id = 0;
 	uint64_t entry_mnt_id;
+	dev_t dev;
 #ifdef HAVE_STATX_MNT_ID
 	struct statx stx;
 #endif
@@ -143,12 +142,11 @@ getextmntent(const char *path, struct extmnttab *entry, struct stat64 *statbuf)
 	 */
 
 	match = 0;
-	while (getextmntent_impl(fp, entry, &entry_mnt_id) == 0) {
+	while (getextmntent_impl(fp, entry, &entry_mnt_id, &dev) == 0) {
 		if (have_mnt_id) {
 			match = (entry_mnt_id == target_mnt_id);
 		} else {
-			match = makedev(entry->mnt_major, entry->mnt_minor) ==
+			match = (dev == statbuf->st_dev);
-			    statbuf->st_dev;
 		}
 		if (match)
 			break;
@@ -161,11 +159,8 @@ getextmntent(const char *path, struct extmnttab *entry, struct stat64 *statbuf)
 		return (-1);
 	}
 
-	if (stat64(entry->mnt_mountp, &st) != 0) {
+	if (stat64(entry->mnt_mountp, &st) != 0)
-		entry->mnt_major = 0;
-		entry->mnt_minor = 0;
 		return (-1);
-	}
 
 	return (0);
 }

lib/libzfs/libzfs_util.c

@@ -1171,7 +1171,7 @@ zfs_handle_t *
 zfs_path_to_zhandle(libzfs_handle_t *hdl, const char *path, zfs_type_t argtype)
 {
 	struct stat64 statbuf;
-	struct extmnttab entry;
+	struct mnttab entry;
 
 	if (path[0] != '/' && strncmp(path, "./", strlen("./")) != 0) {
 		/*