2024-05-29 09:21:22

by Luis Henriques

Subject: [PATCH v3 2/2] ext4: fix possible tid_t sequence overflows

In the fast commit code there are a few places where tid_t variables are
being compared without taking into account the fact that these sequence
numbers may wrap. Fix this issue by using the helper functions tid_gt()
and tid_geq().

Signed-off-by: Luis Henriques (SUSE) <[email protected]>
---
fs/ext4/fast_commit.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
index 088bd509b116..30d312e16916 100644
--- a/fs/ext4/fast_commit.c
+++ b/fs/ext4/fast_commit.c
@@ -353,7 +353,7 @@ void ext4_fc_mark_ineligible(struct super_block *sb, int reason, handle_t *handl
read_unlock(&sbi->s_journal->j_state_lock);
}
spin_lock(&sbi->s_fc_lock);
- if (sbi->s_fc_ineligible_tid < tid)
+ if (tid_gt(tid, sbi->s_fc_ineligible_tid))
sbi->s_fc_ineligible_tid = tid;
spin_unlock(&sbi->s_fc_lock);
WARN_ON(reason >= EXT4_FC_REASON_MAX);
@@ -1207,7 +1207,7 @@ int ext4_fc_commit(journal_t *journal, tid_t commit_tid)
if (ret == -EALREADY) {
/* There was an ongoing commit, check if we need to restart */
if (atomic_read(&sbi->s_fc_subtid) <= subtid &&
- commit_tid > journal->j_commit_sequence)
+ tid_gt(commit_tid, journal->j_commit_sequence))
goto restart_fc;
ext4_fc_update_stats(sb, EXT4_FC_STATUS_SKIPPED, 0, 0,
commit_tid);
@@ -1282,7 +1282,7 @@ static void ext4_fc_cleanup(journal_t *journal, int full, tid_t tid)
list_del_init(&iter->i_fc_list);
ext4_clear_inode_state(&iter->vfs_inode,
EXT4_STATE_FC_COMMITTING);
- if (iter->i_sync_tid <= tid) {
+ if (tid_geq(tid, iter->i_sync_tid)) {
ext4_fc_reset_inode(&iter->vfs_inode);
} else {
/*
@@ -1322,7 +1322,7 @@ static void ext4_fc_cleanup(journal_t *journal, int full, tid_t tid)
list_splice_init(&sbi->s_fc_q[FC_Q_STAGING],
&sbi->s_fc_q[FC_Q_MAIN]);

- if (tid >= sbi->s_fc_ineligible_tid) {
+ if (tid_geq(tid, sbi->s_fc_ineligible_tid)) {
sbi->s_fc_ineligible_tid = 0;
ext4_clear_mount_flag(sb, EXT4_MF_FC_INELIGIBLE);
}

2024-05-29 09:53:19

by Jan Kara

Subject: Re: [PATCH v3 2/2] ext4: fix possible tid_t sequence overflows

On Wed 29-05-24 10:20:30, Luis Henriques (SUSE) wrote:
> In the fast commit code there are a few places where tid_t variables are
> being compared without taking into account the fact that these sequence
> numbers may wrap. Fix this issue by using the helper functions tid_gt()
> and tid_geq().
>
> Signed-off-by: Luis Henriques (SUSE) <[email protected]>

Thanks! Feel free to add:

Reviewed-by: Jan Kara <[email protected]>

Honza

> ---
> fs/ext4/fast_commit.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
> index 088bd509b116..30d312e16916 100644
> --- a/fs/ext4/fast_commit.c
> +++ b/fs/ext4/fast_commit.c
> @@ -353,7 +353,7 @@ void ext4_fc_mark_ineligible(struct super_block *sb, int reason, handle_t *handl
> read_unlock(&sbi->s_journal->j_state_lock);
> }
> spin_lock(&sbi->s_fc_lock);
> - if (sbi->s_fc_ineligible_tid < tid)
> + if (tid_gt(tid, sbi->s_fc_ineligible_tid))
> sbi->s_fc_ineligible_tid = tid;
> spin_unlock(&sbi->s_fc_lock);
> WARN_ON(reason >= EXT4_FC_REASON_MAX);
> @@ -1207,7 +1207,7 @@ int ext4_fc_commit(journal_t *journal, tid_t commit_tid)
> if (ret == -EALREADY) {
> /* There was an ongoing commit, check if we need to restart */
> if (atomic_read(&sbi->s_fc_subtid) <= subtid &&
> - commit_tid > journal->j_commit_sequence)
> + tid_gt(commit_tid, journal->j_commit_sequence))
> goto restart_fc;
> ext4_fc_update_stats(sb, EXT4_FC_STATUS_SKIPPED, 0, 0,
> commit_tid);
> @@ -1282,7 +1282,7 @@ static void ext4_fc_cleanup(journal_t *journal, int full, tid_t tid)
> list_del_init(&iter->i_fc_list);
> ext4_clear_inode_state(&iter->vfs_inode,
> EXT4_STATE_FC_COMMITTING);
> - if (iter->i_sync_tid <= tid) {
> + if (tid_geq(tid, iter->i_sync_tid)) {
> ext4_fc_reset_inode(&iter->vfs_inode);
> } else {
> /*
> @@ -1322,7 +1322,7 @@ static void ext4_fc_cleanup(journal_t *journal, int full, tid_t tid)
> list_splice_init(&sbi->s_fc_q[FC_Q_STAGING],
> &sbi->s_fc_q[FC_Q_MAIN]);
>
> - if (tid >= sbi->s_fc_ineligible_tid) {
> + if (tid_geq(tid, sbi->s_fc_ineligible_tid)) {
> sbi->s_fc_ineligible_tid = 0;
> ext4_clear_mount_flag(sb, EXT4_MF_FC_INELIGIBLE);
> }
>
--
Jan Kara <[email protected]>
SUSE Labs, CR