From: Jeff Mahoney Date: Mon, 15 Aug 2016 16:10:33 +0000 (-0400) Subject: btrfs: properly track when rescan worker is running X-Git-Tag: v4.8-rc4~11^2~15 X-Git-Url: http://git.cascardo.eti.br/?p=cascardo%2Flinux.git;a=commitdiff_plain;h=d2c609b834d62f1e91f1635a27dca29f7806d3d6 btrfs: properly track when rescan worker is running The qgroup_flags field is overloaded such that it reflects the on-disk status of qgroups and the runtime state. The BTRFS_QGROUP_STATUS_FLAG_RESCAN flag is used to indicate that a rescan operation is in progress, but if the file system is unmounted while a rescan is running, the rescan operation is paused. If the file system is then mounted read-only, the flag will still be present but the rescan operation will not have been resumed. When we go to umount, btrfs_qgroup_wait_for_completion will see the flag and interpret it to mean that the rescan worker is still running and will wait for a completion that will never come. This patch uses a separate flag to indicate when the worker is running. The locking and state surrounding the qgroup rescan worker needs a lot of attention beyond this patch but this is enough to avoid a hung umount. Cc: # v4.4+ Signed-off-by; Jeff Mahoney Reviewed-by: Qu Wenruo Signed-off-by: David Sterba Signed-off-by: Chris Mason --- diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index f66a0ba9a2a9..acc6850a118f 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1028,6 +1028,7 @@ struct btrfs_fs_info { struct btrfs_workqueue *qgroup_rescan_workers; struct completion qgroup_rescan_completion; struct btrfs_work qgroup_rescan_work; + bool qgroup_rescan_running; /* protected by qgroup_rescan_lock */ /* filesystem state */ unsigned long fs_state; diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 4a34c9fcc1a7..f5b2a7fb4575 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2304,6 +2304,7 @@ static void btrfs_init_qgroup(struct btrfs_fs_info *fs_info) fs_info->quota_enabled = 0; fs_info->pending_quota_state = 0; fs_info->qgroup_ulist = NULL; + fs_info->qgroup_rescan_running = false; mutex_init(&fs_info->qgroup_rescan_lock); } diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 93ee1c18ef9d..3fe295e2c84a 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -2303,6 +2303,10 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work) int err = -ENOMEM; int ret = 0; + mutex_lock(&fs_info->qgroup_rescan_lock); + fs_info->qgroup_rescan_running = true; + mutex_unlock(&fs_info->qgroup_rescan_lock); + path = btrfs_alloc_path(); if (!path) goto out; @@ -2369,6 +2373,9 @@ out: } done: + mutex_lock(&fs_info->qgroup_rescan_lock); + fs_info->qgroup_rescan_running = false; + mutex_unlock(&fs_info->qgroup_rescan_lock); complete_all(&fs_info->qgroup_rescan_completion); } @@ -2494,7 +2501,7 @@ int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info) mutex_lock(&fs_info->qgroup_rescan_lock); spin_lock(&fs_info->qgroup_lock); - running = fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN; + running = fs_info->qgroup_rescan_running; spin_unlock(&fs_info->qgroup_lock); mutex_unlock(&fs_info->qgroup_rescan_lock);