From: Yu Kuai yukuai3@huawei.com
mainline inclusion from mainline-v6.7-rc1 commit cf1b6d4441fffd0ba8ae4ced6a12f578c95ca049 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8T02O
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
--------------------------------
Before this patch, the implementation is hacky and hard to understand:
1) md_seq_start set pos to 1; 2) md_seq_show found pos is 1, then print Personalities; 3) md_seq_next found pos is 1, then it update pos to the first mddev; 4) md_seq_show found pos is not 1 or 2, show mddev; 5) md_seq_next found pos is not 1 or 2, update pos to next mddev; 6) loop 4-5 until the last mddev, then md_seq_next update pos to 2; 7) md_seq_show found pos is 2, then print unused devices; 8) md_seq_next found pos is 2, stop;
This patch remove the magic value and use seq_list_start/next/stop() directly, and move printing "Personalities" to md_seq_start(), "unsed devices" to md_seq_stop():
1) md_seq_start print Personalities, and then set pos to first mddev; 2) md_seq_show show mddev; 3) md_seq_next update pos to next mddev; 4) loop 2-3 until the last mddev; 5) md_seq_stop print unsed devices;
Signed-off-by: Yu Kuai yukuai3@huawei.com Signed-off-by: Song Liu song@kernel.org Link: https://lore.kernel.org/r/20230927061241.1552837-3-yukuai1@huaweicloud.com Signed-off-by: Li Nan linan122@huawei.com --- drivers/md/md.c | 100 +++++++++++------------------------------------- 1 file changed, 22 insertions(+), 78 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c index 9dd3bd65ce9e..548dd9befb6e 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8206,105 +8206,46 @@ static int status_resync(struct seq_file *seq, struct mddev *mddev) }
static void *md_seq_start(struct seq_file *seq, loff_t *pos) + __acquires(&all_mddevs_lock) { - struct list_head *tmp; - loff_t l = *pos; - struct mddev *mddev; + struct md_personality *pers;
- if (l == 0x10000) { - ++*pos; - return (void *)2; - } - if (l > 0x10000) - return NULL; - if (!l--) - /* header */ - return (void*)1; + seq_puts(seq, "Personalities : "); + spin_lock(&pers_lock); + list_for_each_entry(pers, &pers_list, list) + seq_printf(seq, "[%s] ", pers->name); + + spin_unlock(&pers_lock); + seq_puts(seq, "\n"); + seq->poll_event = atomic_read(&md_event_count);
spin_lock(&all_mddevs_lock); - list_for_each(tmp,&all_mddevs) - if (!l--) { - mddev = list_entry(tmp, struct mddev, all_mddevs); - if (!mddev_get(mddev)) - continue; - spin_unlock(&all_mddevs_lock); - return mddev; - } - spin_unlock(&all_mddevs_lock); - if (!l--) - return (void*)2;/* tail */ - return NULL; + + return seq_list_start(&all_mddevs, *pos); }
static void *md_seq_next(struct seq_file *seq, void *v, loff_t *pos) { - struct list_head *tmp; - struct mddev *next_mddev, *mddev = v; - struct mddev *to_put = NULL; - - ++*pos; - if (v == (void*)2) - return NULL; - - spin_lock(&all_mddevs_lock); - if (v == (void*)1) { - tmp = all_mddevs.next; - } else { - to_put = mddev; - tmp = mddev->all_mddevs.next; - } - - for (;;) { - if (tmp == &all_mddevs) { - next_mddev = (void*)2; - *pos = 0x10000; - break; - } - next_mddev = list_entry(tmp, struct mddev, all_mddevs); - if (mddev_get(next_mddev)) - break; - mddev = next_mddev; - tmp = mddev->all_mddevs.next; - } - spin_unlock(&all_mddevs_lock); - - if (to_put) - mddev_put(to_put); - return next_mddev; - + return seq_list_next(v, &all_mddevs, pos); }
static void md_seq_stop(struct seq_file *seq, void *v) + __releases(&all_mddevs_lock) { - struct mddev *mddev = v; - - if (mddev && v != (void*)1 && v != (void*)2) - mddev_put(mddev); + status_unused(seq); + spin_unlock(&all_mddevs_lock); }
static int md_seq_show(struct seq_file *seq, void *v) { - struct mddev *mddev = v; + struct mddev *mddev = list_entry(v, struct mddev, all_mddevs); sector_t sectors; struct md_rdev *rdev;
- if (v == (void*)1) { - struct md_personality *pers; - seq_printf(seq, "Personalities : "); - spin_lock(&pers_lock); - list_for_each_entry(pers, &pers_list, list) - seq_printf(seq, "[%s] ", pers->name); - - spin_unlock(&pers_lock); - seq_printf(seq, "\n"); - seq->poll_event = atomic_read(&md_event_count); + if (!mddev_get(mddev)) return 0; - } - if (v == (void*)2) { - status_unused(seq); - return 0; - }
+ spin_unlock(&all_mddevs_lock); spin_lock(&mddev->lock); if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) { seq_printf(seq, "%s : %sactive", mdname(mddev), @@ -8375,6 +8316,9 @@ static int md_seq_show(struct seq_file *seq, void *v) seq_printf(seq, "\n"); } spin_unlock(&mddev->lock); + spin_lock(&all_mddevs_lock); + if (atomic_dec_and_test(&mddev->active)) + __mddev_put(mddev);
return 0; }