Let zfs mount all tolerate in-progress mounts

The zfs-mount service can unexpectedly fail to start when zfs
encounters a mount that is in progress. This service uses
zfs mount -a, which has a window between the time it checks if
the dataset was mounted and when the actual mount (via mount.zfs
binary) occurs.

The reason for the racing mounts is that both zfs-mount.target
and zfs-share.target are allowed to execute concurrently after
the import.  This is more of an issue with the relatively recent
addition of parallel mounting, and we should consider serializing
the mount and share targets.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Allan Jude <allanjude@freebsd.org>
Signed-off-by: Don Brady <don.brady@delphix.com>
Closes #8881
This commit is contained in:
Don Brady 2019-06-22 16:41:21 -07:00 committed by Tony Hutter
parent d053481523
commit 95fcb04215
1 changed files with 18 additions and 1 deletions

View File

@ -6446,8 +6446,25 @@ share_mount_one(zfs_handle_t *zhp, int op, int flags, char *protocol,
return (1);
}
if (zfs_mount(zhp, options, flags) != 0)
if (zfs_mount(zhp, options, flags) != 0) {
/*
* Check if a mount sneaked in after we checked
*/
if (!explicit &&
libzfs_errno(g_zfs) == EZFS_MOUNTFAILED) {
usleep(10 * MILLISEC);
libzfs_mnttab_cache(g_zfs, B_FALSE);
if (zfs_is_mounted(zhp, NULL)) {
(void) fprintf(stderr, gettext(
"Ignoring previous 'already "
"mounted' error for '%s'\n"),
zfs_get_name(zhp));
return (0);
}
}
return (1);
}
break;
}