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SubjectRe: [PATCH 1/6] f2fs: support issuing/waiting discard in range
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Hi Jaegeuk,

On 2017/10/4 4:16, Jaegeuk Kim wrote:
> On 09/19, Chao Yu wrote:
>> From: Chao Yu <yuchao0@huawei.com>
>>
>> Fstrim intends to trim invalid blocks of filesystem only with specified
>> range and granularity, but actually, it will issue all previous cached
>> discard commands which may be out-of-range and be with unmatched
>> granularity, it's unneeded.
>>
>> In order to fix above issues, this patch introduces new helps to support
>> to issue and wait discard in range and adds a new fstrim_list for tracking
>> in-flight discard from ->fstrim.
>>
>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>> ---
>> fs/f2fs/f2fs.h | 1 +
>> fs/f2fs/segment.c | 125 +++++++++++++++++++++++++++++++++++++++++++++---------
>> 2 files changed, 106 insertions(+), 20 deletions(-)
>>
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 89b4927dcd79..cb13c7df6971 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -249,6 +249,7 @@ struct discard_cmd_control {
>> struct list_head pend_list[MAX_PLIST_NUM];/* store pending entries */
>> unsigned char pend_list_tag[MAX_PLIST_NUM];/* tag for pending entries */
>> struct list_head wait_list; /* store on-flushing entries */
>> + struct list_head fstrim_list; /* in-flight discard from fstrim */
>> wait_queue_head_t discard_wait_queue; /* waiting queue for wake-up */
>> unsigned int discard_wake; /* to wake up discard thread */
>> struct mutex cmd_lock;
>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>> index dedf0209d820..088936c61905 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -845,9 +845,11 @@ void __check_sit_bitmap(struct f2fs_sb_info *sbi,
>>
>> /* this function is copied from blkdev_issue_discard from block/blk-lib.c */
>> static void __submit_discard_cmd(struct f2fs_sb_info *sbi,
>> - struct discard_cmd *dc)
>> + struct discard_cmd *dc, bool fstrim)
>> {
>> struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
>> + struct list_head *wait_list = fstrim ? &(dcc->fstrim_list) :
>> + &(dcc->wait_list);
>> struct bio *bio = NULL;
>>
>> if (dc->state != D_PREP)
>> @@ -869,7 +871,7 @@ static void __submit_discard_cmd(struct f2fs_sb_info *sbi,
>> bio->bi_end_io = f2fs_submit_discard_endio;
>> bio->bi_opf |= REQ_SYNC;
>> submit_bio(bio);
>> - list_move_tail(&dc->list, &dcc->wait_list);
>> + list_move_tail(&dc->list, wait_list);
>> __check_sit_bitmap(sbi, dc->start, dc->start + dc->len);
>>
>> f2fs_update_iostat(sbi, FS_DISCARD, 1);
>> @@ -1054,6 +1056,68 @@ static int __queue_discard_cmd(struct f2fs_sb_info *sbi,
>> return 0;
>> }
>>
>> +static void __issue_discard_cmd_range(struct f2fs_sb_info *sbi,
>> + unsigned int start, unsigned int end,
>> + unsigned int granularity)
>> +{
>> + struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
>> + struct discard_cmd *prev_dc = NULL, *next_dc = NULL;
>> + struct rb_node **insert_p = NULL, *insert_parent = NULL;
>> + struct discard_cmd *dc;
>> + struct blk_plug plug;
>> + int issued;
>> +
>> +next:
>> + issued = 0;
>> +
>> + mutex_lock(&dcc->cmd_lock);
>> + f2fs_bug_on(sbi, !__check_rb_tree_consistence(sbi, &dcc->root));
>> +
>> + dc = (struct discard_cmd *)__lookup_rb_tree_ret(&dcc->root,
>> + NULL, start,
>> + (struct rb_entry **)&prev_dc,
>> + (struct rb_entry **)&next_dc,
>> + &insert_p, &insert_parent, true);
>> + if (!dc)
>> + dc = next_dc;
>> +
>> + blk_start_plug(&plug);
>> +
>> + while (dc && dc->lstart <= end) {
>> + struct rb_node *node;
>> +
>> + if (dc->len < granularity)
>> + goto skip;
>> +
>> + if (dc->state != D_PREP) {
>> + list_move_tail(&dc->list, &dcc->fstrim_list);
>> + goto skip;
>> + }
>> +
>> + __submit_discard_cmd(sbi, dc, true);
>> +
>> + if (++issued >= DISCARD_ISSUE_RATE) {
>> + start = dc->lstart + dc->len;
>> +
>> + blk_finish_plug(&plug);
>> + mutex_unlock(&dcc->cmd_lock);
>> +
>> + schedule();
>> +
>> + goto next;
>> + }
>> +skip:
>> + node = rb_next(&dc->rb_node);
>> + dc = rb_entry_safe(node, struct discard_cmd, rb_node);
>> +
>> + if (fatal_signal_pending(current))
>> + break;
>> + }
>> +
>> + blk_finish_plug(&plug);
>> + mutex_unlock(&dcc->cmd_lock);
>> +}
>> +
>> static int __issue_discard_cmd(struct f2fs_sb_info *sbi, bool issue_cond)
>> {
>> struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
>> @@ -1076,22 +1140,19 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi, bool issue_cond)
>>
>> /* Hurry up to finish fstrim */
>> if (dcc->pend_list_tag[i] & P_TRIM) {
>> - __submit_discard_cmd(sbi, dc);
>> + __submit_discard_cmd(sbi, dc, false);
>> issued++;
>> -
>> - if (fatal_signal_pending(current))
>> - break;
>> continue;
>> }
>>
>> if (!issue_cond) {
>> - __submit_discard_cmd(sbi, dc);
>> + __submit_discard_cmd(sbi, dc, false);
>> issued++;
>> continue;
>> }
>>
>> if (is_idle(sbi)) {
>> - __submit_discard_cmd(sbi, dc);
>> + __submit_discard_cmd(sbi, dc, false);
>> issued++;
>> } else {
>> io_interrupted = true;
>> @@ -1145,10 +1206,14 @@ static void __wait_one_discard_bio(struct f2fs_sb_info *sbi,
>> mutex_unlock(&dcc->cmd_lock);
>> }
>>
>> -static void __wait_discard_cmd(struct f2fs_sb_info *sbi, bool wait_cond)
>> +static void __wait_discard_cmd_range(struct f2fs_sb_info *sbi, bool wait_cond,
>> + block_t start, block_t end,
>> + unsigned int granularity,
>> + bool fstrim)
>> {
>> struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
>> - struct list_head *wait_list = &(dcc->wait_list);
>> + struct list_head *wait_list = fstrim ? &(dcc->fstrim_list) :
>> + &(dcc->wait_list);
>> struct discard_cmd *dc, *tmp;
>> bool need_wait;
>>
>> @@ -1157,6 +1222,10 @@ static void __wait_discard_cmd(struct f2fs_sb_info *sbi, bool wait_cond)
>>
>> mutex_lock(&dcc->cmd_lock);
>> list_for_each_entry_safe(dc, tmp, wait_list, list) {
>> + if (dc->lstart + dc->len <= start || end <= dc->lstart)
>> + continue;
>> + if (dc->len < granularity)
>> + continue;
>> if (!wait_cond || (dc->state == D_DONE && !dc->ref)) {
>> wait_for_completion_io(&dc->wait);
>> __remove_discard_cmd(sbi, dc);
>
> So, we need to add this on top of the patch that fixes the bug reported
> by Juhyung, right?
>
> if (fstrim)
> need_wait = true;

+ __wait_discard_cmd_range(sbi, false, start_block, end_block,
+ cpc.trim_minlen, true);

We can control wait_cond through the parameter in __wait_discard_cmd_range,
let me fix that wrong parameter passed from f2fs_trim_fs. :)

Thanks,

>
> Thanks,
>
>> @@ -1174,6 +1243,11 @@ static void __wait_discard_cmd(struct f2fs_sb_info *sbi, bool wait_cond)
>> }
>> }
>>
>> +static void __wait_all_discard_cmd(struct f2fs_sb_info *sbi, bool wait_cond)
>> +{
>> + __wait_discard_cmd_range(sbi, wait_cond, 0, UINT_MAX, 1, false);
>> +}
>> +
>> /* This should be covered by global mutex, &sit_i->sentry_lock */
>> void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi, block_t blkaddr)
>> {
>> @@ -1209,12 +1283,12 @@ void stop_discard_thread(struct f2fs_sb_info *sbi)
>> }
>> }
>>
>> -/* This comes from f2fs_put_super and f2fs_trim_fs */
>> +/* This comes from f2fs_put_super */
>> void f2fs_wait_discard_bios(struct f2fs_sb_info *sbi)
>> {
>> __issue_discard_cmd(sbi, false);
>> __drop_discard_cmd(sbi);
>> - __wait_discard_cmd(sbi, false);
>> + __wait_all_discard_cmd(sbi, false);
>> }
>>
>> static void mark_discard_range_all(struct f2fs_sb_info *sbi)
>> @@ -1258,7 +1332,7 @@ static int issue_discard_thread(void *data)
>>
>> issued = __issue_discard_cmd(sbi, true);
>> if (issued) {
>> - __wait_discard_cmd(sbi, true);
>> + __wait_all_discard_cmd(sbi, true);
>> wait_ms = DEF_MIN_DISCARD_ISSUE_TIME;
>> } else {
>> wait_ms = DEF_MAX_DISCARD_ISSUE_TIME;
>> @@ -1569,6 +1643,7 @@ static int create_discard_cmd_control(struct f2fs_sb_info *sbi)
>> dcc->pend_list_tag[i] |= P_ACTIVE;
>> }
>> INIT_LIST_HEAD(&dcc->wait_list);
>> + INIT_LIST_HEAD(&dcc->fstrim_list);
>> mutex_init(&dcc->cmd_lock);
>> atomic_set(&dcc->issued_discard, 0);
>> atomic_set(&dcc->issing_discard, 0);
>> @@ -2196,7 +2271,8 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
>> {
>> __u64 start = F2FS_BYTES_TO_BLK(range->start);
>> __u64 end = start + F2FS_BYTES_TO_BLK(range->len) - 1;
>> - unsigned int start_segno, end_segno;
>> + unsigned int start_segno, end_segno, cur_segno;
>> + block_t start_block, end_block;
>> struct cp_control cpc;
>> int err = 0;
>>
>> @@ -2217,12 +2293,17 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
>> start_segno = (start <= MAIN_BLKADDR(sbi)) ? 0 : GET_SEGNO(sbi, start);
>> end_segno = (end >= MAX_BLKADDR(sbi)) ? MAIN_SEGS(sbi) - 1 :
>> GET_SEGNO(sbi, end);
>> +
>> + start_block = START_BLOCK(sbi, start_segno);
>> + end_block = START_BLOCK(sbi, end_segno + 1);
>> +
>> cpc.reason = CP_DISCARD;
>> cpc.trim_minlen = max_t(__u64, 1, F2FS_BYTES_TO_BLK(range->minlen));
>>
>> /* do checkpoint to issue discard commands safely */
>> - for (; start_segno <= end_segno; start_segno = cpc.trim_end + 1) {
>> - cpc.trim_start = start_segno;
>> + for (cur_segno = start_segno; cur_segno <= end_segno;
>> + cur_segno = cpc.trim_end + 1) {
>> + cpc.trim_start = cur_segno;
>>
>> if (sbi->discard_blks == 0)
>> break;
>> @@ -2230,7 +2311,7 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
>> cpc.trim_end = end_segno;
>> else
>> cpc.trim_end = min_t(unsigned int,
>> - rounddown(start_segno +
>> + rounddown(cur_segno +
>> BATCHED_TRIM_SEGMENTS(sbi),
>> sbi->segs_per_sec) - 1, end_segno);
>>
>> @@ -2242,9 +2323,13 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
>>
>> schedule();
>> }
>> - /* It's time to issue all the filed discards */
>> - mark_discard_range_all(sbi);
>> - f2fs_wait_discard_bios(sbi);
>> +
>> + start_block = START_BLOCK(sbi, start_segno);
>> + end_block = START_BLOCK(sbi, min(cur_segno, end_segno) + 1);
>> +
>> + __issue_discard_cmd_range(sbi, start_block, end_block, cpc.trim_minlen);
>> + __wait_discard_cmd_range(sbi, false, start_block, end_block,
>> + cpc.trim_minlen, true);
>> out:
>> range->len = F2FS_BLK_TO_BYTES(cpc.trimmed);
>> return err;
>> --
>> 2.14.1.145.gb3622a4ee

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