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authorJiri Kosina <jkosina@suse.cz>2018-04-26 22:40:04 +0200
committerJiri Kosina <jkosina@suse.cz>2018-04-26 22:40:04 +0200
commit100c95890a03f4de10d27ea920caff283ec67f62 (patch)
treec15d1e21bea8a857b608e7e212a773ec273b5a0c
parentadd140690663c0319071e7c8ad577fc6b3f7c3da (diff)
parent3c4b9ba15599e5ee522a1c92bfdd1c542b26f794 (diff)
Merge remote-tracking branch 'origin/users/jeffm/SLE15/for-next' into SLE15
Pull btrfs qgroups rescan race condition fix from Jeff Mahoney Conflicts: series.conf
-rw-r--r--patches.suse/btrfs-qgroups-fix-rescan-worker-running-races.patch140
-rw-r--r--series.conf1
2 files changed, 141 insertions, 0 deletions
diff --git a/patches.suse/btrfs-qgroups-fix-rescan-worker-running-races.patch b/patches.suse/btrfs-qgroups-fix-rescan-worker-running-races.patch
new file mode 100644
index 0000000000..b2193448d8
--- /dev/null
+++ b/patches.suse/btrfs-qgroups-fix-rescan-worker-running-races.patch
@@ -0,0 +1,140 @@
+From: Jeff Mahoney <jeffm@suse.com>
+Subject: btrfs: qgroups, fix rescan worker running races
+Patch-mainline: Submitted, linux-btrfs@vger.kernel.org, 26 Apr 2018
+References: bsc#1091101
+
+Commit d2c609b834d6 (Btrfs: fix qgroup rescan worker initialization)
+fixed the issue with BTRFS_IOC_QUOTA_RESCAN_WAIT being racy, but
+ended up reintroducing the hang-on-unmount bug that the commit it
+intended to fix addressed.
+
+The race this time is between qgroup_rescan_init setting
+->qgroup_rescan_running = true and the worker starting. There are
+many scenarios where we initialize the worker and never start it. The
+completion btrfs_ioctl_quota_rescan_wait waits for will never come.
+This can happen even without involving error handling, since mounting
+the file system read-only returns between initializing the worker and
+queueing it.
+
+The right place to do it is when we're queuing the worker. The flag
+really just means that btrfs_ioctl_quota_rescan_wait should wait for
+a completion.
+
+This patch introduces a new helper, queue_rescan_worker, that handles
+the ->qgroup_rescan_running flag, including any races with umount.
+
+While we're at it, ->qgroup_rescan_running is protected only by the
+->qgroup_rescan_mutex. btrfs_ioctl_quota_rescan_wait doesn't need
+to take the spinlock too.
+
+Fixes: d2c609b834d6 (Btrfs: fix qgroup rescan worker initialization)
+Signed-off-by: Jeff Mahoney <jeffm@suse.com>
+---
+ fs/btrfs/ctree.h | 1 +
+ fs/btrfs/qgroup.c | 40 ++++++++++++++++++++++++++++------------
+ 2 files changed, 29 insertions(+), 12 deletions(-)
+
+diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
+index da308774b8a4..dbba615f4d0f 100644
+--- a/fs/btrfs/ctree.h
++++ b/fs/btrfs/ctree.h
+@@ -1045,6 +1045,7 @@ struct btrfs_fs_info {
+ struct btrfs_workqueue *qgroup_rescan_workers;
+ struct completion qgroup_rescan_completion;
+ struct btrfs_work qgroup_rescan_work;
++ /* qgroup rescan worker is running or queued to run */
+ bool qgroup_rescan_running; /* protected by qgroup_rescan_lock */
+
+ /* relocation recovery items */
+diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
+index aa259d6986e1..be491b6c020a 100644
+--- a/fs/btrfs/qgroup.c
++++ b/fs/btrfs/qgroup.c
+@@ -2072,6 +2072,30 @@ int btrfs_qgroup_account_extents(struct btrfs_trans_handle *trans,
+ return ret;
+ }
+
++static void queue_rescan_worker(struct btrfs_fs_info *fs_info)
++{
++ mutex_lock(&fs_info->qgroup_rescan_lock);
++ if (btrfs_fs_closing(fs_info)) {
++ mutex_unlock(&fs_info->qgroup_rescan_lock);
++ return;
++ }
++ if (WARN_ON(fs_info->qgroup_rescan_running)) {
++ btrfs_warn(fs_info, "rescan worker already queued");
++ mutex_unlock(&fs_info->qgroup_rescan_lock);
++ return;
++ }
++
++ /*
++ * Being queued is enough for btrfs_qgroup_wait_for_completion
++ * to need to wait.
++ */
++ fs_info->qgroup_rescan_running = true;
++ mutex_unlock(&fs_info->qgroup_rescan_lock);
++
++ btrfs_queue_work(fs_info->qgroup_rescan_workers,
++ &fs_info->qgroup_rescan_work);
++}
++
+ /*
+ * called from commit_transaction. Writes all changed qgroups to disk.
+ */
+@@ -2123,8 +2147,7 @@ int btrfs_run_qgroups(struct btrfs_trans_handle *trans,
+ ret = qgroup_rescan_init(fs_info, 0, 1);
+ if (!ret) {
+ qgroup_rescan_zero_tracking(fs_info);
+- btrfs_queue_work(fs_info->qgroup_rescan_workers,
+- &fs_info->qgroup_rescan_work);
++ queue_rescan_worker(fs_info);
+ }
+ ret = 0;
+ }
+@@ -2713,7 +2736,6 @@ qgroup_rescan_init(struct btrfs_fs_info *fs_info, u64 progress_objectid,
+ sizeof(fs_info->qgroup_rescan_progress));
+ fs_info->qgroup_rescan_progress.objectid = progress_objectid;
+ init_completion(&fs_info->qgroup_rescan_completion);
+- fs_info->qgroup_rescan_running = true;
+
+ spin_unlock(&fs_info->qgroup_lock);
+ mutex_unlock(&fs_info->qgroup_rescan_lock);
+@@ -2785,9 +2807,7 @@ btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info)
+
+ qgroup_rescan_zero_tracking(fs_info);
+
+- btrfs_queue_work(fs_info->qgroup_rescan_workers,
+- &fs_info->qgroup_rescan_work);
+-
++ queue_rescan_worker(fs_info);
+ return 0;
+ }
+
+@@ -2798,9 +2818,7 @@ int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info,
+ int ret = 0;
+
+ mutex_lock(&fs_info->qgroup_rescan_lock);
+- spin_lock(&fs_info->qgroup_lock);
+ running = fs_info->qgroup_rescan_running;
+- spin_unlock(&fs_info->qgroup_lock);
+ mutex_unlock(&fs_info->qgroup_rescan_lock);
+
+ if (!running)
+@@ -2819,12 +2837,10 @@ int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info,
+ * this is only called from open_ctree where we're still single threaded, thus
+ * locking is omitted here.
+ */
+-void
+-btrfs_qgroup_rescan_resume(struct btrfs_fs_info *fs_info)
++void btrfs_qgroup_rescan_resume(struct btrfs_fs_info *fs_info)
+ {
+ if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN)
+- btrfs_queue_work(fs_info->qgroup_rescan_workers,
+- &fs_info->qgroup_rescan_work);
++ queue_rescan_worker(fs_info);
+ }
+
+ /*
+--
+2.12.3
+
diff --git a/series.conf b/series.conf
index 15486595fb..5f5cc5e3ff 100644
--- a/series.conf
+++ b/series.conf
@@ -12112,6 +12112,7 @@
patches.suse/btrfs-use-spinlock-to-protect--caching_block_groups-list.patch
patches.suse/0001-btrfs-Validate-child-tree-block-s-level-and-first-ke.patch
patches.suse/0001-btrfs-Only-check-first-key-for-committed-tree-blocks.patch
+ patches.suse/btrfs-qgroups-fix-rescan-worker-running-races.patch
########################################################
# NFS