On Sat 26-08-23 23:58:41, vk.en.mail@xxxxxxxxx wrote: > From: Vitaliy Kuznetsov <vk.en.mail@xxxxxxxxx> > > This patch introduces a mechanism to periodically check and update > the superblock within the ext4 file system. The main purpose of this > patch is to keep the disk superblock up to date. The update will be > performed if more than one hour has passed since the last update, and > if more than 16MB of data have been written to disk. > > This check and update is performed within the ext4_journal_commit_callback > function, ensuring that the superblock is written while the disk is > active, rather than based on a timer that may trigger during disk idle > periods. > > Discussion https://www.spinics.net/lists/linux-ext4/msg85865.html > > Signed-off-by: Vitaliy Kuznetsov <vk.en.mail@xxxxxxxxx> Looks good to me. Feel free to add: Reviewed-by: Jan Kara <jack@xxxxxxx> Honza > --- > fs/ext4/super.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 61 insertions(+), 1 deletion(-) > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index c94ebf704616..8bee05118c7a 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -433,6 +433,57 @@ static time64_t __ext4_get_tstamp(__le32 *lo, __u8 *hi) > #define ext4_get_tstamp(es, tstamp) \ > __ext4_get_tstamp(&(es)->tstamp, &(es)->tstamp ## _hi) > > +#define EXT4_SB_REFRESH_INTERVAL_SEC (3600) /* seconds (1 hour) */ > +#define EXT4_SB_REFRESH_INTERVAL_KB (16384) /* kilobytes (16MB) */ > + > +/* > + * The ext4_maybe_update_superblock() function checks and updates the > + * superblock if needed. > + * > + * This function is designed to update the on-disk superblock only under > + * certain conditions to prevent excessive disk writes and unnecessary > + * waking of the disk from sleep. The superblock will be updated if: > + * 1. More than an hour has passed since the last superblock update, and > + * 2. More than 16MB have been written since the last superblock update. > + * > + * @sb: The superblock > + */ > +static void ext4_maybe_update_superblock(struct super_block *sb) > +{ > + struct ext4_sb_info *sbi = EXT4_SB(sb); > + struct ext4_super_block *es = sbi->s_es; > + journal_t *journal = sbi->s_journal; > + time64_t now; > + __u64 last_update; > + __u64 lifetime_write_kbytes; > + __u64 diff_size; > + > + if (sb_rdonly(sb) || !(sb->s_flags & SB_ACTIVE) || > + !journal || (journal->j_flags & JBD2_UNMOUNT)) > + return; > + > + now = ktime_get_real_seconds(); > + last_update = ext4_get_tstamp(es, s_wtime); > + > + if (likely(now - last_update < EXT4_SB_REFRESH_INTERVAL_SEC)) > + return; > + > + lifetime_write_kbytes = sbi->s_kbytes_written + > + ((part_stat_read(sb->s_bdev, sectors[STAT_WRITE]) - > + sbi->s_sectors_written_start) >> 1); > + > + /* Get the number of kilobytes not written to disk to account > + * for statistics and compare with a multiple of 16 MB. This > + * is used to determine when the next superblock commit should > + * occur (i.e. not more often than once per 16MB if there was > + * less written in an hour). > + */ > + diff_size = lifetime_write_kbytes - le64_to_cpu(es->s_kbytes_written); > + > + if (diff_size > EXT4_SB_REFRESH_INTERVAL_KB) > + schedule_work(&EXT4_SB(sb)->s_error_work); > +} > + > /* > * The del_gendisk() function uninitializes the disk-specific data > * structures, including the bdi structure, without telling anyone > @@ -459,6 +510,7 @@ static void ext4_journal_commit_callback(journal_t *journal, transaction_t *txn) > BUG_ON(txn->t_state == T_FINISHED); > > ext4_process_freed_data(sb, txn->t_tid); > + ext4_maybe_update_superblock(sb); > > spin_lock(&sbi->s_md_lock); > while (!list_empty(&txn->t_private_list)) { > @@ -715,6 +767,7 @@ static void flush_stashed_error_work(struct work_struct *work) > */ > if (!sb_rdonly(sbi->s_sb) && journal) { > struct buffer_head *sbh = sbi->s_sbh; > + bool call_notify_err = false; > handle = jbd2_journal_start(journal, 1); > if (IS_ERR(handle)) > goto write_directly; > @@ -722,6 +775,10 @@ static void flush_stashed_error_work(struct work_struct *work) > jbd2_journal_stop(handle); > goto write_directly; > } > + > + if (sbi->s_add_error_count > 0) > + call_notify_err = true; > + > ext4_update_super(sbi->s_sb); > if (buffer_write_io_error(sbh) || !buffer_uptodate(sbh)) { > ext4_msg(sbi->s_sb, KERN_ERR, "previous I/O error to " > @@ -735,7 +792,10 @@ static void flush_stashed_error_work(struct work_struct *work) > goto write_directly; > } > jbd2_journal_stop(handle); > - ext4_notify_error_sysfs(sbi); > + > + if (call_notify_err) > + ext4_notify_error_sysfs(sbi); > + > return; > } > write_directly: > -- > 2.39.2 -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
