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SubjectRe: [PATCH 1/6] f2fs: support issuing/waiting discard in range
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;

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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