raid5: lockless access raid5 overrided bi_phys_segments
Raid5 overrides bio->bi_phys_segments, accessing it is with device_lock hold, which is unnecessary, We can make it lockless actually. Signed-off-by: Shaohua Li <shli@fusionio.com> Signed-off-by: NeilBrown <neilb@suse.de>hifive-unleashed-5.1
Shaohua Li
NeilBrown
parent
4eb788df67
commit
e7836bd6f6
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@ -99,34 +99,40 @@ static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector)
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* We maintain a biased count of active stripes in the bottom 16 bits of
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* bi_phys_segments, and a count of processed stripes in the upper 16 bits
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*/
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static inline int raid5_bi_phys_segments(struct bio *bio)
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static inline int raid5_bi_processed_stripes(struct bio *bio)
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{
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return bio->bi_phys_segments & 0xffff;
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atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
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return (atomic_read(segments) >> 16) & 0xffff;
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}
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static inline int raid5_bi_hw_segments(struct bio *bio)
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static inline int raid5_dec_bi_active_stripes(struct bio *bio)
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{
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return (bio->bi_phys_segments >> 16) & 0xffff;
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atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
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return atomic_sub_return(1, segments) & 0xffff;
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}
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static inline int raid5_dec_bi_phys_segments(struct bio *bio)
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static inline void raid5_inc_bi_active_stripes(struct bio *bio)
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{
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--bio->bi_phys_segments;
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return raid5_bi_phys_segments(bio);
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atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
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atomic_inc(segments);
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}
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static inline int raid5_dec_bi_hw_segments(struct bio *bio)
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static inline void raid5_set_bi_processed_stripes(struct bio *bio,
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unsigned int cnt)
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{
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unsigned short val = raid5_bi_hw_segments(bio);
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atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
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int old, new;
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--val;
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bio->bi_phys_segments = (val << 16) | raid5_bi_phys_segments(bio);
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return val;
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do {
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old = atomic_read(segments);
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new = (old & 0xffff) | (cnt << 16);
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} while (atomic_cmpxchg(segments, old, new) != old);
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}
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static inline void raid5_set_bi_hw_segments(struct bio *bio, unsigned int cnt)
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static inline void raid5_set_bi_stripes(struct bio *bio, unsigned int cnt)
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{
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bio->bi_phys_segments = raid5_bi_phys_segments(bio) | (cnt << 16);
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atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
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atomic_set(segments, cnt);
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}
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/* Find first data disk in a raid6 stripe */
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@ -781,7 +787,7 @@ static void ops_complete_biofill(void *stripe_head_ref)
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while (rbi && rbi->bi_sector <
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dev->sector + STRIPE_SECTORS) {
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rbi2 = r5_next_bio(rbi, dev->sector);
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if (!raid5_dec_bi_phys_segments(rbi)) {
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if (!raid5_dec_bi_active_stripes(rbi)) {
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rbi->bi_next = return_bi;
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return_bi = rbi;
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}
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@ -2367,7 +2373,7 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
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if (*bip)
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bi->bi_next = *bip;
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*bip = bi;
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bi->bi_phys_segments++;
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raid5_inc_bi_active_stripes(bi);
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if (forwrite) {
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/* check if page is covered */
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@ -2464,7 +2470,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
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sh->dev[i].sector + STRIPE_SECTORS) {
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struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
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clear_bit(BIO_UPTODATE, &bi->bi_flags);
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if (!raid5_dec_bi_phys_segments(bi)) {
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if (!raid5_dec_bi_active_stripes(bi)) {
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md_write_end(conf->mddev);
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bi->bi_next = *return_bi;
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*return_bi = bi;
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@ -2479,7 +2485,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
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sh->dev[i].sector + STRIPE_SECTORS) {
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struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
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clear_bit(BIO_UPTODATE, &bi->bi_flags);
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if (!raid5_dec_bi_phys_segments(bi)) {
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if (!raid5_dec_bi_active_stripes(bi)) {
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md_write_end(conf->mddev);
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bi->bi_next = *return_bi;
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*return_bi = bi;
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@ -2503,7 +2509,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
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struct bio *nextbi =
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r5_next_bio(bi, sh->dev[i].sector);
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clear_bit(BIO_UPTODATE, &bi->bi_flags);
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if (!raid5_dec_bi_phys_segments(bi)) {
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if (!raid5_dec_bi_active_stripes(bi)) {
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bi->bi_next = *return_bi;
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*return_bi = bi;
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}
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@ -2722,7 +2728,7 @@ static void handle_stripe_clean_event(struct r5conf *conf,
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while (wbi && wbi->bi_sector <
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dev->sector + STRIPE_SECTORS) {
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wbi2 = r5_next_bio(wbi, dev->sector);
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if (!raid5_dec_bi_phys_segments(wbi)) {
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if (!raid5_dec_bi_active_stripes(wbi)) {
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md_write_end(conf->mddev);
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wbi->bi_next = *return_bi;
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*return_bi = wbi;
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@ -3798,7 +3804,7 @@ static struct bio *remove_bio_from_retry(struct r5conf *conf)
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* this sets the active strip count to 1 and the processed
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* strip count to zero (upper 8 bits)
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*/
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bi->bi_phys_segments = 1; /* biased count of active stripes */
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raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
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}
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return bi;
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@ -4133,9 +4139,7 @@ static void make_request(struct mddev *mddev, struct bio * bi)
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}
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}
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spin_lock_irq(&conf->device_lock);
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remaining = raid5_dec_bi_phys_segments(bi);
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spin_unlock_irq(&conf->device_lock);
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remaining = raid5_dec_bi_active_stripes(bi);
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if (remaining == 0) {
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if ( rw == WRITE )
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@ -4491,7 +4495,7 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
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sector += STRIPE_SECTORS,
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scnt++) {
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if (scnt < raid5_bi_hw_segments(raid_bio))
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if (scnt < raid5_bi_processed_stripes(raid_bio))
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/* already done this stripe */
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continue;
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@ -4499,14 +4503,14 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
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if (!sh) {
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/* failed to get a stripe - must wait */
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raid5_set_bi_hw_segments(raid_bio, scnt);
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raid5_set_bi_processed_stripes(raid_bio, scnt);
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conf->retry_read_aligned = raid_bio;
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return handled;
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}
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if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
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release_stripe(sh);
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raid5_set_bi_hw_segments(raid_bio, scnt);
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raid5_set_bi_processed_stripes(raid_bio, scnt);
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conf->retry_read_aligned = raid_bio;
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return handled;
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}
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@ -4515,9 +4519,7 @@ static int retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
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release_stripe(sh);
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handled++;
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}
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spin_lock_irq(&conf->device_lock);
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remaining = raid5_dec_bi_phys_segments(raid_bio);
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spin_unlock_irq(&conf->device_lock);
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remaining = raid5_dec_bi_active_stripes(raid_bio);
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if (remaining == 0)
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bio_endio(raid_bio, 0);
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if (atomic_dec_and_test(&conf->active_aligned_reads))
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