Re: [RFC V4] md/raid5: optimize Scattered Address Space and Thread-Level Parallelism to improve RAID5 performance

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Thanks Paul for testing the patch! Here are some detailed data and test setup mentioned in the patch changelog to improve performance.

"increased overall storage throughput by 89.4%": Set the iodepth to 32 and employ libaio. Configure the I/O size as 4 KB with sequential write and 16 threads. In RAID5 consist of 2+1 1TB Samsung 980Pro SSDs, throughput went from 5218MB/s to 9884MB/s when apply this patch.

"decrease the 99.99th percentile I/O latency by 85.4%": Set the iodepth to 32 and employ libaio. Configure the I/O size as 4 KB with sequential write. In RAID5 consist of 4+1 1TB Samsung 980Pro SSDs, 99.99th tail latency went from 6325us to 922us when apply this patch.

On Wed, 24 Apr 2024, 14:48
Paul E Luse <paul.e.luse@xxxxxxxxxxxxxxx> wrote:

> Thanks Shushu! Apprecaite the continued follow-ups for sure.  Wrt the
> performance claims below can you provide the full details on test setup
> and results?
> 
> Within the next few days I should have a chance to run this again on
> latest Xeon with gen5 Samsungs.
> 
> -Paul
> 
> On Tue, 16 Apr 2024 13:22:53 +0800
> Shushu Yi <teddyxym@xxxxxxxxxxx> wrote:
> 
> > Optimize scattered address space. Achieves significant improvements in
> > both throughput and latency.
> >
> > Maximize thread-level parallelism and reduce CPU suspension time
> > caused by lock contention. Achieve increased overall storage
> > throughput by 89.4% and decrease the 99.99th percentile I/O latency
> > by 85.4% on a system with four PCIe 4.0 SSDs.
> >
> > Note: Publish this work as a paper and provide the URL
> > (https://www.hotstorage.org/2022/camera-ready/hotstorage22-5/pdf/
> > hotstorage22-5.pdf).
> >
> > Co-developed-by: Yiming Xu <teddyxym@xxxxxxxxxxx>
> > Signed-off-by: Yiming Xu <teddyxym@xxxxxxxxxxx>
> > Signed-off-by: Shushu Yi <firnyee@xxxxxxxxx>
> > Tested-by: Paul Luse <paul.e.luse@xxxxxxxxx>
> > ---
> > V1 -> V2: Cleaned up coding style and divided into 2 patches (HemiRAID
> > and ScalaRAID corresponding to the paper mentioned above). ScalaRAID
> > equipped every counter with a counter lock and employ our D-Block.
> > HemiRAID increased the number of stripe locks to 128
> > V2 -> V3: Adjusted the language used in the subject and changelog.
> > Since patch 1/2 in V2 cannot be used independently and does not
> > encompass all of our work, it has been merged into a single patch.
> > V3 -> V4: Fixed incorrect sending address and changelog format.
> >
> >  drivers/md/md-bitmap.c | 197
> > ++++++++++++++++++++++++++++++----------- drivers/md/md-bitmap.h |
> > 12 ++- 2 files changed, 154 insertions(+), 55 deletions(-)
> >
> > diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
> > index 059afc24c08b..5ed5fe810b2f 100644
> > --- a/drivers/md/md-bitmap.c
> > +++ b/drivers/md/md-bitmap.c
> > @@ -47,10 +47,12 @@ static inline char *bmname(struct bitmap *bitmap)
> >   * if we find our page, we increment the page's refcount so that it
> > stays
> >   * allocated while we're using it
> >   */
> > -static int md_bitmap_checkpage(struct bitmap_counts *bitmap,
> > -                            unsigned long page, int create, int
> > no_hijack) -__releases(bitmap->lock)
> > -__acquires(bitmap->lock)
> > +static int md_bitmap_checkpage(struct bitmap_counts *bitmap,
> > unsigned long page,
> > +                            int create, int no_hijack, spinlock_t
> > *bmclock, int locktype) +__releases(bmclock)
> > +__acquires(bmclock)
> > +__releases(bitmap->mlock)
> > +__acquires(bitmap->mlock)
> >  {
> >       unsigned char *mappage;
> >
> > @@ -65,8 +67,10 @@ __acquires(bitmap->lock)
> >               return -ENOENT;
> >
> >       /* this page has not been allocated yet */
> > -
> > -     spin_unlock_irq(&bitmap->lock);
> > +     if (locktype)
> > +             spin_unlock_irq(bmclock);
> > +     else
> > +             write_unlock_irq(&bitmap->mlock);
> >       /* It is possible that this is being called inside a
> >        * prepare_to_wait/finish_wait loop from
> > raid5c:make_request().
> >        * In general it is not permitted to sleep in that context
> > as it @@ -81,7 +85,11 @@ __acquires(bitmap->lock)
> >        */
> >       sched_annotate_sleep();
> >       mappage = kzalloc(PAGE_SIZE, GFP_NOIO);
> > -     spin_lock_irq(&bitmap->lock);
> > +
> > +     if (locktype)
> > +             spin_lock_irq(bmclock);
> > +     else
> > +             write_lock_irq(&bitmap->mlock);
> >
> >       if (mappage == NULL) {
> >               pr_debug("md/bitmap: map page allocation failed,
> > hijacking\n"); @@ -399,7 +407,7 @@ static int read_file_page(struct
> > file *file, unsigned long index, }
> >
> >       wait_event(bitmap->write_wait,
> > -                atomic_read(&bitmap->pending_writes)==0);
> > +                atomic_read(&bitmap->pending_writes) == 0);
> >       if (test_bit(BITMAP_WRITE_ERROR, &bitmap->flags))
> >               ret = -EIO;
> >  out:
> > @@ -458,7 +466,7 @@ static void md_bitmap_wait_writes(struct bitmap
> > *bitmap) {
> >       if (bitmap->storage.file)
> >               wait_event(bitmap->write_wait,
> > -                        atomic_read(&bitmap->pending_writes)==0);
> > +                        atomic_read(&bitmap->pending_writes) ==
> > 0); else
> >               /* Note that we ignore the return value.  The writes
> >                * might have failed, but that would just mean that
> > @@ -1248,16 +1256,28 @@ void md_bitmap_write_all(struct bitmap
> > *bitmap) static void md_bitmap_count_page(struct bitmap_counts
> > *bitmap, sector_t offset, int inc)
> >  {
> > -     sector_t chunk = offset >> bitmap->chunkshift;
> > -     unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
> > +     sector_t blockno = offset >> (PAGE_SHIFT - SECTOR_SHIFT);
> > +     sector_t totblocks = bitmap->chunks << (bitmap->chunkshift -
> > (PAGE_SHIFT - SECTOR_SHIFT));
> > +     unsigned long bits = totblocks ? fls((totblocks - 1)) : 0;
> > +     unsigned long mask = ULONG_MAX << bits | ~(ULONG_MAX <<
> > +                                     (bits - (bitmap->chunkshift
> > + SECTOR_SHIFT - PAGE_SHIFT)));
> > +     unsigned long cntid = blockno & mask;
> > +     unsigned long page = cntid >> PAGE_COUNTER_SHIFT;
> > +
> >       bitmap->bp[page].count += inc;
> >       md_bitmap_checkfree(bitmap, page);
> >  }
> >
> >  static void md_bitmap_set_pending(struct bitmap_counts *bitmap,
> > sector_t offset) {
> > -     sector_t chunk = offset >> bitmap->chunkshift;
> > -     unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
> > +     sector_t blockno = offset >> (PAGE_SHIFT - SECTOR_SHIFT);
> > +     sector_t totblocks = bitmap->chunks << (bitmap->chunkshift -
> > (PAGE_SHIFT - SECTOR_SHIFT));
> > +     unsigned long bits = totblocks ? fls((totblocks - 1)) : 0;
> > +     unsigned long mask = ULONG_MAX << bits | ~(ULONG_MAX <<
> > +                                     (bits - (bitmap->chunkshift
> > + SECTOR_SHIFT - PAGE_SHIFT)));
> > +     unsigned long cntid = blockno & mask;
> > +     unsigned long page = cntid >> PAGE_COUNTER_SHIFT;
> > +
> >       struct bitmap_page *bp = &bitmap->bp[page];
> >
> >       if (!bp->pending)
> > @@ -1266,7 +1286,7 @@ static void md_bitmap_set_pending(struct
> > bitmap_counts *bitmap, sector_t offset)
> >  static bitmap_counter_t *md_bitmap_get_counter(struct bitmap_counts
> > *bitmap, sector_t offset, sector_t *blocks,
> > -                                            int create);
> > +                                            int create,
> > spinlock_t *bmclock, int locktype);
> >  static void mddev_set_timeout(struct mddev *mddev, unsigned long
> > timeout, bool force)
> > @@ -1349,7 +1369,7 @@ void md_bitmap_daemon_work(struct mddev *mddev)
> >        * decrement and handle accordingly.
> >        */
> >       counts = &bitmap->counts;
> > -     spin_lock_irq(&counts->lock);
> > +     write_lock_irq(&counts->mlock);
> >       nextpage = 0;
> >       for (j = 0; j < counts->chunks; j++) {
> >               bitmap_counter_t *bmc;
> > @@ -1364,7 +1384,7 @@ void md_bitmap_daemon_work(struct mddev *mddev)
> >                       counts->bp[j >> PAGE_COUNTER_SHIFT].pending
> > = 0; }
> >
> > -             bmc = md_bitmap_get_counter(counts, block, &blocks,
> > 0);
> > +             bmc = md_bitmap_get_counter(counts, block, &blocks,
> > 0, 0, 0); if (!bmc) {
> >                       j |= PAGE_COUNTER_MASK;
> >                       continue;
> > @@ -1380,7 +1400,7 @@ void md_bitmap_daemon_work(struct mddev *mddev)
> >                       bitmap->allclean = 0;
> >               }
> >       }
> > -     spin_unlock_irq(&counts->lock);
> > +     write_unlock_irq(&counts->mlock);
> >
> >       md_bitmap_wait_writes(bitmap);
> >       /* Now start writeout on any page in NEEDWRITE that isn't
> > DIRTY. @@ -1413,17 +1433,25 @@ void md_bitmap_daemon_work(struct
> > mddev *mddev)
> >  static bitmap_counter_t *md_bitmap_get_counter(struct bitmap_counts
> > *bitmap, sector_t offset, sector_t *blocks,
> > -                                            int create)
> > -__releases(bitmap->lock)
> > -__acquires(bitmap->lock)
> > +                                            int create,
> > spinlock_t *bmclock, int locktype) +__releases(bmclock)
> > +__acquires(bmclock)
> > +__releases(bitmap->mlock)
> > +__acquires(bitmap->mlock)
> >  {
> >       /* If 'create', we might release the lock and reclaim it.
> >        * The lock must have been taken with interrupts enabled.
> >        * If !create, we don't release the lock.
> >        */
> > -     sector_t chunk = offset >> bitmap->chunkshift;
> > -     unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
> > -     unsigned long pageoff = (chunk & PAGE_COUNTER_MASK) <<
> > COUNTER_BYTE_SHIFT;
> > +     sector_t blockno = offset >> (PAGE_SHIFT - SECTOR_SHIFT);
> > +     sector_t totblocks = bitmap->chunks << (bitmap->chunkshift -
> > (PAGE_SHIFT - SECTOR_SHIFT));
> > +     unsigned long bits = totblocks ? fls((totblocks - 1)) : 0;
> > +     unsigned long mask = ULONG_MAX << bits | ~(ULONG_MAX <<
> > +                                     (bits - (bitmap->chunkshift
> > + SECTOR_SHIFT - PAGE_SHIFT)));
> > +     unsigned long cntid = blockno & mask;
> > +     unsigned long page = cntid >> PAGE_COUNTER_SHIFT;
> > +     unsigned long pageoff = (cntid & PAGE_COUNTER_MASK) <<
> > COUNTER_BYTE_SHIFT; +
> >       sector_t csize;
> >       int err;
> >
> > @@ -1435,7 +1463,7 @@ __acquires(bitmap->lock)
> >                */
> >               return NULL;
> >       }
> > -     err = md_bitmap_checkpage(bitmap, page, create, 0);
> > +     err = md_bitmap_checkpage(bitmap, page, create, 0, bmclock,
> > 1);
> >       if (bitmap->bp[page].hijacked ||
> >           bitmap->bp[page].map == NULL)
> > @@ -1461,6 +1489,28 @@ __acquires(bitmap->lock)
> >                       &(bitmap->bp[page].map[pageoff]);
> >  }
> >
> > +/* set-association */
> > +static spinlock_t *md_bitmap_get_bmclock(struct bitmap_counts
> > *bitmap, sector_t offset); +
> > +static spinlock_t *md_bitmap_get_bmclock(struct bitmap_counts
> > *bitmap, sector_t offset) +{
> > +     sector_t blockno = offset >> (PAGE_SHIFT - SECTOR_SHIFT);
> > +     sector_t totblocks = bitmap->chunks << (bitmap->chunkshift -
> > (PAGE_SHIFT - SECTOR_SHIFT));
> > +     unsigned long bitscnt = totblocks ? fls((totblocks - 1)) : 0;
> > +     unsigned long maskcnt = ULONG_MAX << bitscnt | ~(ULONG_MAX
> > << (bitscnt -
> > +                                     (bitmap->chunkshift +
> > SECTOR_SHIFT - PAGE_SHIFT)));
> > +     unsigned long cntid = blockno & maskcnt;
> > +
> > +     unsigned long totcnts = bitmap->chunks;
> > +     unsigned long bitslock = totcnts ? fls((totcnts - 1)) : 0;
> > +     unsigned long masklock = ULONG_MAX << bitslock | ~(ULONG_MAX
> > <<
> > +                                     (bitslock -
> > BITMAP_COUNTER_LOCK_RATIO_SHIFT));
> > +     unsigned long lockid = cntid & masklock;
> > +
> > +     spinlock_t *bmclock = &(bitmap->bmclocks[lockid]);
> > +     return bmclock;
> > +}
> > +
> >  int md_bitmap_startwrite(struct bitmap *bitmap, sector_t offset,
> > unsigned long sectors, int behind) {
> >       if (!bitmap)
> > @@ -1480,11 +1530,15 @@ int md_bitmap_startwrite(struct bitmap
> > *bitmap, sector_t offset, unsigned long s while (sectors) {
> >               sector_t blocks;
> >               bitmap_counter_t *bmc;
> > +             spinlock_t *bmclock;
> >
> > -             spin_lock_irq(&bitmap->counts.lock);
> > -             bmc = md_bitmap_get_counter(&bitmap->counts, offset,
> > &blocks, 1);
> > +             bmclock = md_bitmap_get_bmclock(&bitmap->counts,
> > offset);
> > +             read_lock(&bitmap->counts.mlock);
> > +             spin_lock_irq(bmclock);
> > +             bmc = md_bitmap_get_counter(&bitmap->counts, offset,
> > &blocks, 1, bmclock, 1); if (!bmc) {
> > -                     spin_unlock_irq(&bitmap->counts.lock);
> > +                     spin_unlock_irq(bmclock);
> > +                     read_unlock(&bitmap->counts.mlock);
> >                       return 0;
> >               }
> >
> > @@ -1496,7 +1550,8 @@ int md_bitmap_startwrite(struct bitmap *bitmap,
> > sector_t offset, unsigned long s */
> >                       prepare_to_wait(&bitmap->overflow_wait,
> > &__wait, TASK_UNINTERRUPTIBLE);
> > -                     spin_unlock_irq(&bitmap->counts.lock);
> > +                     spin_unlock_irq(bmclock);
> > +                     read_unlock(&bitmap->counts.mlock);
> >                       schedule();
> >                       finish_wait(&bitmap->overflow_wait, &__wait);
> >                       continue;
> > @@ -1513,7 +1568,8 @@ int md_bitmap_startwrite(struct bitmap *bitmap,
> > sector_t offset, unsigned long s
> >               (*bmc)++;
> >
> > -             spin_unlock_irq(&bitmap->counts.lock);
> > +             spin_unlock_irq(bmclock);
> > +             read_unlock(&bitmap->counts.mlock);
> >
> >               offset += blocks;
> >               if (sectors > blocks)
> > @@ -1542,11 +1598,15 @@ void md_bitmap_endwrite(struct bitmap
> > *bitmap, sector_t offset, sector_t blocks;
> >               unsigned long flags;
> >               bitmap_counter_t *bmc;
> > +             spinlock_t *bmclock;
> >
> > -             spin_lock_irqsave(&bitmap->counts.lock, flags);
> > -             bmc = md_bitmap_get_counter(&bitmap->counts, offset,
> > &blocks, 0);
> > +             bmclock = md_bitmap_get_bmclock(&bitmap->counts,
> > offset);
> > +             read_lock(&bitmap->counts.mlock);
> > +             spin_lock_irqsave(bmclock, flags);
> > +             bmc = md_bitmap_get_counter(&bitmap->counts, offset,
> > &blocks, 0, bmclock, 1); if (!bmc) {
> > -                     spin_unlock_irqrestore(&bitmap->counts.lock,
> > flags);
> > +                     spin_unlock_irqrestore(bmclock, flags);
> > +                     read_unlock(&bitmap->counts.mlock);
> >                       return;
> >               }
> >
> > @@ -1568,7 +1628,8 @@ void md_bitmap_endwrite(struct bitmap *bitmap,
> > sector_t offset, md_bitmap_set_pending(&bitmap->counts, offset);
> >                       bitmap->allclean = 0;
> >               }
> > -             spin_unlock_irqrestore(&bitmap->counts.lock, flags);
> > +             spin_unlock_irqrestore(bmclock, flags);
> > +             read_unlock(&bitmap->counts.mlock);
> >               offset += blocks;
> >               if (sectors > blocks)
> >                       sectors -= blocks;
> > @@ -1582,13 +1643,16 @@ static int __bitmap_start_sync(struct bitmap
> > *bitmap, sector_t offset, sector_t int degraded)
> >  {
> >       bitmap_counter_t *bmc;
> > +     spinlock_t *bmclock;
> >       int rv;
> >       if (bitmap == NULL) {/* FIXME or bitmap set as 'failed' */
> >               *blocks = 1024;
> >               return 1; /* always resync if no bitmap */
> >       }
> > -     spin_lock_irq(&bitmap->counts.lock);
> > -     bmc = md_bitmap_get_counter(&bitmap->counts, offset, blocks,
> > 0);
> > +     bmclock = md_bitmap_get_bmclock(&bitmap->counts, offset);
> > +     read_lock(&bitmap->counts.mlock);
> > +     spin_lock_irq(bmclock);
> > +     bmc = md_bitmap_get_counter(&bitmap->counts, offset, blocks,
> > 0, bmclock, 1); rv = 0;
> >       if (bmc) {
> >               /* locked */
> > @@ -1602,7 +1666,8 @@ static int __bitmap_start_sync(struct bitmap
> > *bitmap, sector_t offset, sector_t }
> >               }
> >       }
> > -     spin_unlock_irq(&bitmap->counts.lock);
> > +     spin_unlock_irq(bmclock);
> > +     read_unlock(&bitmap->counts.mlock);
> >       return rv;
> >  }
> >
> > @@ -1634,13 +1699,16 @@ void md_bitmap_end_sync(struct bitmap
> > *bitmap, sector_t offset, sector_t *blocks {
> >       bitmap_counter_t *bmc;
> >       unsigned long flags;
> > +     spinlock_t *bmclock;
> >
> >       if (bitmap == NULL) {
> >               *blocks = 1024;
> >               return;
> >       }
> > -     spin_lock_irqsave(&bitmap->counts.lock, flags);
> > -     bmc = md_bitmap_get_counter(&bitmap->counts, offset, blocks,
> > 0);
> > +     bmclock = md_bitmap_get_bmclock(&bitmap->counts, offset);
> > +     read_lock(&bitmap->counts.mlock);
> > +     spin_lock_irqsave(bmclock, flags);
> > +     bmc = md_bitmap_get_counter(&bitmap->counts, offset, blocks,
> > 0, bmclock, 1); if (bmc == NULL)
> >               goto unlock;
> >       /* locked */
> > @@ -1657,7 +1725,8 @@ void md_bitmap_end_sync(struct bitmap *bitmap,
> > sector_t offset, sector_t *blocks }
> >       }
> >   unlock:
> > -     spin_unlock_irqrestore(&bitmap->counts.lock, flags);
> > +     spin_unlock_irqrestore(bmclock, flags);
> > +     read_unlock(&bitmap->counts.mlock);
> >  }
> >  EXPORT_SYMBOL(md_bitmap_end_sync);
> >
> > @@ -1738,10 +1807,15 @@ static void md_bitmap_set_memory_bits(struct
> > bitmap *bitmap, sector_t offset, in
> >       sector_t secs;
> >       bitmap_counter_t *bmc;
> > -     spin_lock_irq(&bitmap->counts.lock);
> > -     bmc = md_bitmap_get_counter(&bitmap->counts, offset, &secs,
> > 1);
> > +     spinlock_t *bmclock;
> > +
> > +     bmclock = md_bitmap_get_bmclock(&bitmap->counts, offset);
> > +     read_lock(&bitmap->counts.mlock);
> > +     spin_lock_irq(bmclock);
> > +     bmc = md_bitmap_get_counter(&bitmap->counts, offset, &secs,
> > 1, bmclock, 1); if (!bmc) {
> > -             spin_unlock_irq(&bitmap->counts.lock);
> > +             spin_unlock_irq(bmclock);
> > +             read_unlock(&bitmap->counts.mlock);
> >               return;
> >       }
> >       if (!*bmc) {
> > @@ -1752,7 +1826,8 @@ static void md_bitmap_set_memory_bits(struct
> > bitmap *bitmap, sector_t offset, in }
> >       if (needed)
> >               *bmc |= NEEDED_MASK;
> > -     spin_unlock_irq(&bitmap->counts.lock);
> > +     spin_unlock_irq(bmclock);
> > +     read_unlock(&bitmap->counts.mlock);
> >  }
> >
> >  /* dirty the memory and file bits for bitmap chunks "s" to "e" */
> > @@ -1806,6 +1881,7 @@ void md_bitmap_free(struct bitmap *bitmap)
> >  {
> >       unsigned long k, pages;
> >       struct bitmap_page *bp;
> > +     spinlock_t *bmclocks;
> >
> >       if (!bitmap) /* there was no bitmap */
> >               return;
> > @@ -1826,6 +1902,7 @@ void md_bitmap_free(struct bitmap *bitmap)
> >
> >       bp = bitmap->counts.bp;
> >       pages = bitmap->counts.pages;
> > +     bmclocks = bitmap->counts.bmclocks;
> >
> >       /* free all allocated memory */
> >
> > @@ -1834,6 +1911,7 @@ void md_bitmap_free(struct bitmap *bitmap)
> >                       if (bp[k].map && !bp[k].hijacked)
> >                               kfree(bp[k].map);
> >       kfree(bp);
> > +     kfree(bmclocks);
> >       kfree(bitmap);
> >  }
> >  EXPORT_SYMBOL(md_bitmap_free);
> > @@ -1900,7 +1978,9 @@ struct bitmap *md_bitmap_create(struct mddev
> > *mddev, int slot) if (!bitmap)
> >               return ERR_PTR(-ENOMEM);
> >
> > -     spin_lock_init(&bitmap->counts.lock);
> > +     /* initialize metadata lock */
> > +     rwlock_init(&bitmap->counts.mlock);
> > +
> >       atomic_set(&bitmap->pending_writes, 0);
> >       init_waitqueue_head(&bitmap->write_wait);
> >       init_waitqueue_head(&bitmap->overflow_wait);
> > @@ -2143,6 +2223,8 @@ int md_bitmap_resize(struct bitmap *bitmap,
> > sector_t blocks, int ret = 0;
> >       long pages;
> >       struct bitmap_page *new_bp;
> > +     spinlock_t *new_bmclocks;
> > +     int num_bmclocks, i;
> >
> >       if (bitmap->storage.file && !init) {
> >               pr_info("md: cannot resize file-based bitmap\n");
> > @@ -2211,7 +2293,7 @@ int md_bitmap_resize(struct bitmap *bitmap,
> > sector_t blocks, memcpy(page_address(store.sb_page),
> >                      page_address(bitmap->storage.sb_page),
> >                      sizeof(bitmap_super_t));
> > -     spin_lock_irq(&bitmap->counts.lock);
> > +     write_lock_irq(&bitmap->counts.mlock);
> >       md_bitmap_file_unmap(&bitmap->storage);
> >       bitmap->storage = store;
> >
> > @@ -2227,18 +2309,28 @@ int md_bitmap_resize(struct bitmap *bitmap,
> > sector_t blocks, blocks = min(old_counts.chunks <<
> > old_counts.chunkshift, chunks << chunkshift);
> >
> > +     /* initialize bmc locks */
> > +     num_bmclocks = DIV_ROUND_UP(chunks,
> > BITMAP_COUNTER_LOCK_RATIO); +
> > +     new_bmclocks = kvcalloc(num_bmclocks, sizeof(*new_bmclocks),
> > GFP_KERNEL);
> > +     bitmap->counts.bmclocks = new_bmclocks;
> > +     for (i = 0; i < num_bmclocks; ++i) {
> > +             spinlock_t *bmclock = &(bitmap->counts.bmclocks)[i];
> > +
> > +             spin_lock_init(bmclock);
> > +     }
> > +
> >       /* For cluster raid, need to pre-allocate bitmap */
> >       if (mddev_is_clustered(bitmap->mddev)) {
> >               unsigned long page;
> >               for (page = 0; page < pages; page++) {
> > -                     ret = md_bitmap_checkpage(&bitmap->counts,
> > page, 1, 1);
> > +                     ret = md_bitmap_checkpage(&bitmap->counts,
> > page, 1, 1, 0, 0); if (ret) {
> >                               unsigned long k;
> >
> >                               /* deallocate the page memory */
> > -                             for (k = 0; k < page; k++) {
> > +                             for (k = 0; k < page; k++)
> >                                       kfree(new_bp[k].map);
> > -                             }
> >                               kfree(new_bp);
> >
> >                               /* restore some fields from
> > old_counts */ @@ -2261,11 +2353,12 @@ int md_bitmap_resize(struct
> > bitmap *bitmap, sector_t blocks, bitmap_counter_t *bmc_old, *bmc_new;
> >               int set;
> >
> > -             bmc_old = md_bitmap_get_counter(&old_counts, block,
> > &old_blocks, 0);
> > +             bmc_old = md_bitmap_get_counter(&old_counts, block,
> > &old_blocks, 0, 0, 0); set = bmc_old && NEEDED(*bmc_old);
> >
> >               if (set) {
> > -                     bmc_new =
> > md_bitmap_get_counter(&bitmap->counts, block, &new_blocks, 1);
> > +                     bmc_new =
> > md_bitmap_get_counter(&bitmap->counts, block, &new_blocks,
> > +
> >               1, 0, 0); if (bmc_new) {
> >                               if (*bmc_new == 0) {
> >                                       /* need to set on-disk bits
> > too. */ @@ -2301,7 +2394,7 @@ int md_bitmap_resize(struct bitmap
> > *bitmap, sector_t blocks, int i;
> >               while (block < (chunks << chunkshift)) {
> >                       bitmap_counter_t *bmc;
> > -                     bmc = md_bitmap_get_counter(&bitmap->counts,
> > block, &new_blocks, 1);
> > +                     bmc = md_bitmap_get_counter(&bitmap->counts,
> > block, &new_blocks, 1, 0, 0); if (bmc) {
> >                               /* new space.  It needs to be
> > resynced, so
> >                                * we set NEEDED_MASK.
> > @@ -2317,7 +2410,7 @@ int md_bitmap_resize(struct bitmap *bitmap,
> > sector_t blocks, for (i = 0; i < bitmap->storage.file_pages; i++)
> >                       set_page_attr(bitmap, i, BITMAP_PAGE_DIRTY);
> >       }
> > -     spin_unlock_irq(&bitmap->counts.lock);
> > +     write_unlock_irq(&bitmap->counts.mlock);
> >
> >       if (!init) {
> >               md_bitmap_unplug(bitmap);
> > diff --git a/drivers/md/md-bitmap.h b/drivers/md/md-bitmap.h
> > index bb9eb418780a..1b9c36bb73ed 100644
> > --- a/drivers/md/md-bitmap.h
> > +++ b/drivers/md/md-bitmap.h
> > @@ -2,7 +2,9 @@
> >  /*
> >   * bitmap.h: Copyright (C) Peter T. Breuer (ptb@xxxxxxxxxx) 2003
> >   *
> > - * additions: Copyright (C) 2003-2004, Paul Clements, SteelEye
> > Technology, Inc.
> > + * additions:
> > + *           Copyright (C) 2003-2004, Paul Clements, SteelEye
> > Technology, Inc.
> > + *           Copyright (C) 2022-2023, Shushu Yi
> > (firnyee@xxxxxxxxx) */
> >  #ifndef BITMAP_H
> >  #define BITMAP_H 1
> > @@ -103,6 +105,9 @@ typedef __u16 bitmap_counter_t;
> >  #define PAGE_COUNTER_MASK  (PAGE_COUNTER_RATIO - 1)
> >
> >  #define BITMAP_BLOCK_SHIFT 9
> > +/* how many counters share the same bmclock? */
> > +#define BITMAP_COUNTER_LOCK_RATIO_SHIFT 0
> > +#define BITMAP_COUNTER_LOCK_RATIO (1 <<
> > BITMAP_COUNTER_LOCK_RATIO_SHIFT)
> >  #endif
> >
> > @@ -116,7 +121,7 @@ typedef __u16 bitmap_counter_t;
> >  enum bitmap_state {
> >       BITMAP_STALE       = 1,  /* the bitmap file is out of
> > date or had -EIO */ BITMAP_WRITE_ERROR = 2, /* A write error has
> > occurred */
> > -     BITMAP_HOSTENDIAN  =15,
> > +     BITMAP_HOSTENDIAN  = 15,
> >  };
> >
> >  /* the superblock at the front of the bitmap file -- little endian */
> > @@ -180,7 +185,8 @@ struct bitmap_page {
> >  struct bitmap {
> >
> >       struct bitmap_counts {
> > -             spinlock_t lock;
> > +             rwlock_t mlock;                         /*
> > lock for metadata */
> > +             spinlock_t *bmclocks;           /* locks for
> > bmc */ struct bitmap_page *bp;
> >               unsigned long pages;            /* total number
> > of pages
> >                                                * in the bitmap */






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