[PATCH v2 2/2] ext4: protect ext4_release_dquot against freezing

Ojaswin Mujoo
2024-11-21T12:39:14Z

Protect ext4_release_dquot against freezing so that we
don't try to start a transaction when FS is frozen, leading
to warnings.

Further, avoid taking the freeze protection if a transaction
is already running so that we don't need end up in a deadlock
as described in

46e294efc355 ext4: fix deadlock with fs freezing and EA inodes

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
---
fs/ext4/super.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 16a4ce704460..f7437a592359 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -6887,12 +6887,25 @@ static int ext4_release_dquot(struct dquot *dquot)
{
int ret, err;
handle_t *handle;
+ bool freeze_protected = false;
+
+ /*
+ * Trying to sb_start_intwrite() in a running transaction
+ * can result in a deadlock. Further, running transactions
+ * are already protected from freezing.
+ */
+ if (!ext4_journal_current_handle()) {
+ sb_start_intwrite(dquot->dq_sb);
+ freeze_protected = true;
+ }

handle = ext4_journal_start(dquot_to_inode(dquot), EXT4_HT_QUOTA,
EXT4_QUOTA_DEL_BLOCKS(dquot->dq_sb));
if (IS_ERR(handle)) {
/* Release dquot anyway to avoid endless cycle in dqput() */
dquot_release(dquot);
+ if (freeze_protected)
+ sb_end_intwrite(dquot->dq_sb);
return PTR_ERR(handle);
}
ret = dquot_release(dquot);
@@ -6903,6 +6916,10 @@ static int ext4_release_dquot(struct dquot *dquot)
err = ext4_journal_stop(handle);
if (!ret)
ret = err;
+
+ if (freeze_protected)
+ sb_end_intwrite(dquot->dq_sb);
+
return ret;
}

--
2.43.5