5.10-stable patches

added patches:
	f2fs-quota-fix-potential-deadlock.patch

diff --git a/queue-5.10/f2fs-quota-fix-potential-deadlock.patch b/queue-5.10/f2fs-quota-fix-potential-deadlock.patch
new file mode 100644 (file)
index 0000000..318e104
--- /dev/null
+++ b/queue-5.10/f2fs-quota-fix-potential-deadlock.patch
@@ -0,0 +1,60 @@
+From a5c0042200b28fff3bde6fa128ddeaef97990f8d Mon Sep 17 00:00:00 2001
+From: Chao Yu <chao@kernel.org>
+Date: Fri, 3 Sep 2021 10:38:11 +0800
+Subject: f2fs: quota: fix potential deadlock
+
+From: Chao Yu <chao@kernel.org>
+
+commit a5c0042200b28fff3bde6fa128ddeaef97990f8d upstream.
+
+As Yi Zhuang reported in bugzilla:
+
+https://bugzilla.kernel.org/show_bug.cgi?id=214299
+
+There is potential deadlock during quota data flush as below:
+
+Thread A:                      Thread B:
+f2fs_dquot_acquire
+down_read(&sbi->quota_sem)
+                               f2fs_write_checkpoint
+                               block_operations
+                               f2fs_look_all
+                               down_write(&sbi->cp_rwsem)
+f2fs_quota_write
+f2fs_write_begin
+__do_map_lock
+f2fs_lock_op
+down_read(&sbi->cp_rwsem)
+                               __need_flush_qutoa
+                               down_write(&sbi->quota_sem)
+
+This patch changes block_operations() to use trylock, if it fails,
+it means there is potential quota data updater, in this condition,
+let's flush quota data first and then trylock again to check dirty
+status of quota data.
+
+The side effect is: in heavy race condition (e.g. multi quota data
+upaters vs quota data flusher), it may decrease the probability of
+synchronizing quota data successfully in checkpoint() due to limited
+retry time of quota flush.
+
+Reported-by: Yi Zhuang <zhuangyi1@huawei.com>
+Signed-off-by: Chao Yu <chao@kernel.org>
+Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ fs/f2fs/checkpoint.c |    3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+--- a/fs/f2fs/checkpoint.c
++++ b/fs/f2fs/checkpoint.c
+@@ -1147,7 +1147,8 @@ static bool __need_flush_quota(struct f2
+       if (!is_journalled_quota(sbi))
+               return false;
+ 
+-      down_write(&sbi->quota_sem);
++      if (!down_write_trylock(&sbi->quota_sem))
++              return true;
+       if (is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH)) {
+               ret = false;
+       } else if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR)) {

diff --git a/queue-5.10/series b/queue-5.10/series
new file mode 100644 (file)
index 0000000..a73b51d
--- /dev/null
+++ b/queue-5.10/series
@@ -0,0 +1 @@
+f2fs-quota-fix-potential-deadlock.patch