[PATCH 4/4] ext4: fix incorrect tid assumption in ext4_fc_mark_ineligible()

Luis Henriques (SUSE)
2024-07-23T15:44:28Z

Function jbd2_journal_shrink_checkpoint_list() assumes that '0' is not a
valid value for transaction IDs, which is incorrect.

Furthermore, the sbi->s_fc_ineligible_tid handling also makes the same
assumption by being initialised to '0'. Fortunately, the sb flag
EXT4_MF_FC_INELIGIBLE can be used to check whether sbi->s_fc_ineligible_tid
has been previously set instead of comparing it with '0'.

Signed-off-by: Luis Henriques (SUSE) <luis.henriques@linux.dev>
---
fs/ext4/fast_commit.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
index 3926a05eceee..3e0793cfea38 100644
--- a/fs/ext4/fast_commit.c
+++ b/fs/ext4/fast_commit.c
@@ -339,22 +339,29 @@ void ext4_fc_mark_ineligible(struct super_block *sb, int reason, handle_t *handl
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
tid_t tid;
+ bool has_transaction = true;
+ bool is_ineligible;

if (ext4_fc_disabled(sb))
return;

- ext4_set_mount_flag(sb, EXT4_MF_FC_INELIGIBLE);
if (handle && !IS_ERR(handle))
tid = handle->h_transaction->t_tid;
else {
read_lock(&sbi->s_journal->j_state_lock);
- tid = sbi->s_journal->j_running_transaction ?
- sbi->s_journal->j_running_transaction->t_tid : 0;
+ if (sbi->s_journal->j_running_transaction)
+ tid = sbi->s_journal->j_running_transaction->t_tid;
+ else
+ has_transaction = false;
read_unlock(&sbi->s_journal->j_state_lock);
}
spin_lock(&sbi->s_fc_lock);
- if (tid_gt(tid, sbi->s_fc_ineligible_tid))
+ is_ineligible = ext4_test_mount_flag(sb, EXT4_MF_FC_INELIGIBLE);
+ if (has_transaction &&
+ ((!is_ineligible) ||
+ (is_ineligible && tid_gt(tid, sbi->s_fc_ineligible_tid))))
sbi->s_fc_ineligible_tid = tid;
+ ext4_set_mount_flag(sb, EXT4_MF_FC_INELIGIBLE);
spin_unlock(&sbi->s_fc_lock);
WARN_ON(reason >= EXT4_FC_REASON_MAX);
sbi->s_fc_stats.fc_ineligible_reason_count[reason]++;