• Zygo Blaxell's avatar
    btrfs: avoid blocking open_ctree from cleaner_kthread · 90c711ab
    Zygo Blaxell authored
    This fixes a problem introduced in commit 2f3165ec
    "btrfs: don't force mounts to wait for cleaner_kthread to delete one or more subvolumes".
    open_ctree eventually calls btrfs_replay_log which in turn calls
    btrfs_commit_super which tries to lock the cleaner_mutex, causing a
    recursive mutex deadlock during mount.
    Instead of playing whack-a-mole trying to keep up with all the
    functions that may want to lock cleaner_mutex, put all the cleaner_mutex
    lockers back where they were, and attack the problem more directly:
    keep cleaner_kthread asleep until the filesystem is mounted.
    When filesystems are mounted read-only and later remounted read-write,
    open_ctree did not set fs_info->open and neither does anything else.
    Set this flag in btrfs_remount so that neither btrfs_delete_unused_bgs
    nor cleaner_kthread get confused by the common case of "/" filesystem
    read-only mount followed by read-write remount.
    Signed-off-by: default avatarZygo Blaxell <ce3g8jdj@umail.furryterror.org>
    Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
    Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
super.c 64.7 KB