Drop path prefix workaround

Canonicalization, the source of the trouble, was disabled in 9000a9f.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Sterling Jensen <[email protected]>
Closes #11295

Author: sterlingjensen

cmd/mount_zfs/mount_zfs.c

@@ -43,53 +43,30 @@
 libzfs_handle_t *g_zfs;
 
 /*
- * Return the pool/dataset to mount given the name passed to mount.  This
- * is expected to be of the form pool/dataset, however may also refer to
- * a block device if that device contains a valid zfs label.
+ * Opportunistically convert a target string into a pool name. If the
+ * string does not represent a block device with a valid zfs label
+ * then it is passed through without modification.
  */
 static void
 parse_dataset(const char *target, char **dataset)
 {
-	/*
-	 * We expect a pool/dataset to be provided, however if we're
-	 * given a device which is a member of a zpool we attempt to
-	 * extract the pool name stored in the label.  Given the pool
-	 * name we can mount the root dataset.
-	 */
-	int fd = open(target, O_RDONLY);
-	if (fd >= 0) {
-		nvlist_t *config = NULL;
-		if (zpool_read_label(fd, &config, NULL) != 0)
-			config = NULL;
-		if (close(fd))
-			perror("close");
-
-		if (config) {
-			char *name = NULL;
-			if (!nvlist_lookup_string(config,
-			    ZPOOL_CONFIG_POOL_NAME, &name))
-				(void) strlcpy(*dataset, name, PATH_MAX);
-			nvlist_free(config);
-			if (name)
-				return;
-		}
-	}
+	/* Assume pool/dataset is more likely */
+	strlcpy(*dataset, target, PATH_MAX);
 
-	/*
-	 * If a file or directory in your current working directory is
-	 * named 'dataset' then mount(8) will prepend your current working
-	 * directory to the dataset.  There is no way to prevent this
-	 * behavior so we simply check for it and strip the prepended
-	 * patch when it is added.
-	 */
-	char cwd[PATH_MAX];
-	if (getcwd(cwd, PATH_MAX) != NULL) {
-		int len = strlen(cwd);
-		/* Do not add one when cwd already ends in a trailing '/' */
-		if (strncmp(cwd, target, len) == 0)
-			target += len + (cwd[len-1] != '/');
+	int fd = open(target, O_RDONLY | O_CLOEXEC);
+	if (fd < 0)
+		return;
+
+	nvlist_t *cfg = NULL;
+	if (zpool_read_label(fd, &cfg, NULL) == 0) {
+		char *nm = NULL;
+		if (!nvlist_lookup_string(cfg, ZPOOL_CONFIG_POOL_NAME, &nm))
+			strlcpy(*dataset, nm, PATH_MAX);
+		nvlist_free(cfg);
 	}
-	strlcpy(*dataset, target, PATH_MAX);
+
+	if (close(fd))
+		perror("close");
 }
 
 /*

tests/zfs-tests/tests/functional/cli_root/zfs_mount/zfs_mount_013_pos.ksh

@@ -25,34 +25,37 @@
 verify_runnable "both"
 
 set -A vdevs $(get_disklist_fullpath $TESTPOOL)
-vdev=${vdevs[0]}
-mntpoint=$TESTDIR/$TESTPOOL
-helper="mount.zfs -o zfsutil"
-fs=$TESTPOOL/$TESTFS
+typeset -r mntpoint=$(get_prop mountpoint $TESTPOOL)
+typeset -r helper="mount.zfs -o zfsutil"
+typeset -r fs=$TESTPOOL/$TESTFS
 
 function cleanup
 {
-    log_must force_unmount $vdev
-    [[ -d $mntpoint ]] && log_must rm -rf $mntpoint
+	cd $STF_SUITE
+	[[ -d $TESTDIR/$$ ]] && (rm -rf $TESTDIR/$$ || log_fail)
+	mounted && zfs $mountcmd $TESTPOOL
 	return 0
 }
 log_onexit cleanup
 
 log_note "Verify zfs mount helper functions for both devices and pools"
 
 # Ensure that the ZFS filesystem is unmounted
-force_unmount $fs
-log_must mkdir -p $mntpoint
+force_unmount $TESTPOOL
 
 log_note "Verify '<dataset> <path>'"
 log_must $helper $fs $mntpoint
 log_must ismounted $fs
 force_unmount $fs
 
-log_note "Verify '\$PWD/<pool> <path>' prefix workaround"
-log_must $helper $PWD/$fs $mntpoint
-log_must ismounted $fs
-force_unmount $fs
+log_note "Verify mount(8) does not canonicalize before calling helper"
+# Canonicalization is confused by files in PWD matching [device|mountpoint]
+mkdir -p $TESTDIR/$$/$TESTPOOL && cd $TESTDIR/$$ || log_fail
+# The env flag directs zfs to exec /bin/mount, which then calls helper
+log_must eval ZFS_MOUNT_HELPER=1 zfs $mountcmd -v $TESTPOOL
+# mount (2.35.2) still suffers from a cosmetic PWD prefix bug
+log_must mounted $TESTPOOL
+force_unmount $TESTPOOL
 
 log_note "Verify '-f <dataset> <path>' fakemount"
 log_must $helper -f $fs $mntpoint
@@ -63,14 +66,13 @@ log_must ${helper},ro -v $fs $mntpoint
 log_must ismounted $fs
 force_unmount $fs
 
-log_note "Verify '<device> <path>'"
-log_must $helper $vdev $mntpoint
-log_must ismounted $mntpoint
-log_must umount $TESTPOOL
-
 log_note "Verify '-o abc -s <device> <path>' sloppy option"
-log_must ${helper},abc -s $vdev $mntpoint
-log_must ismounted $mntpoint
-log_must umount $TESTPOOL
+log_must ${helper},abc -s ${vdevs[0]} $mntpoint
+log_must mounted $mntpoint
+force_unmount $TESTPOOL
+
+log_note "Verify '<device> <path>'"
+log_must $helper ${vdevs[0]} $mntpoint
+log_must mounted $mntpoint
 
 log_pass "zfs mount helper correctly handles both device and pool strings"