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author | Yu Kuai <yukuai3@huawei.com> | 2023-09-27 14:12:41 +0800 |
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committer | Song Liu <song@kernel.org> | 2023-09-27 13:54:26 -0700 |
commit | cf1b6d4441fffd0ba8ae4ced6a12f578c95ca049 (patch) | |
tree | ea69d822457495a10c3ff2ec463422cceebdaae8 /drivers/md/md.c | |
parent | 3d8d32873c7b6d9cec5b40c2ddb8c7c55961694f (diff) | |
download | lwn-cf1b6d4441fffd0ba8ae4ced6a12f578c95ca049.tar.gz lwn-cf1b6d4441fffd0ba8ae4ced6a12f578c95ca049.zip |
md: simplify md_seq_ops
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
Diffstat (limited to 'drivers/md/md.c')
-rw-r--r-- | drivers/md/md.c | 100 |
1 files changed, 22 insertions, 78 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index aad91cd72a06..38a6767c65b1 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8213,105 +8213,46 @@ 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), @@ -8382,6 +8323,9 @@ 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; } |