On Tue, Mar 06, 2018 at 11:47:47AM +0100, David Sterba wrote:
> On Fri, Mar 02, 2018 at 04:10:37PM -0700, Liu Bo wrote:
> > In case of raid56, writes and rebuilds always take BTRFS_STRIPE_LEN(64K)
> > as unit, however, scrub_extent() sets blocksize as unit, so rebuild
> > process may be triggered on every block on a same stripe.
> >
> > A typical example would be that when we're replacing a disappeared disk,
> > all reads on the disks get -EIO, every block (size is 4K if blocksize is
> > 4K) would go thru these,
> >
> > scrub_handle_errored_block
> > scrub_recheck_block # re-read pages one by one
> > scrub_recheck_block # rebuild by calling raid56_parity_recover()
> > page by page
> >
> > Although with raid56 stripe cache most of reads during rebuild can be
> > avoided, the parity recover calculation(xor or raid6 algorithms) needs to
> > be done $(BTRFS_STRIPE_LEN / blocksize) times.
> >
> > This makes it less stupid by doing raid56 scrub/replace on stripe length.
>
> missing s-o-b
>
I'm surprised that checkpatch.pl didn't complain.
> > ---
> > fs/btrfs/scrub.c | 78
> > +++++++++++++++++++++++++++++++++++++++++++-------------
> > 1 file changed, 60 insertions(+), 18 deletions(-)
> >
> > diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
> > index 9882513..e3203a1 100644
> > --- a/fs/btrfs/scrub.c
> > +++ b/fs/btrfs/scrub.c
> > @@ -1718,6 +1718,44 @@ static int scrub_submit_raid56_bio_wait(struct
> > btrfs_fs_info *fs_info,
> > return blk_status_to_errno(bio->bi_status);
> > }
> >
> > +static void scrub_recheck_block_on_raid56(struct btrfs_fs_info *fs_info,
> > + struct scrub_block *sblock)
> > +{
> > + struct scrub_page *first_page = sblock->pagev[0];
> > + struct bio *bio = btrfs_io_bio_alloc(BIO_MAX_PAGES);
>
> nontrivial initializations (variable to variable) are better put into
> the statement section.
>
OK.
> > + int page_num;
> > +
> > + /* All pages in sblock belongs to the same stripe on the same device. */
> > + ASSERT(first_page->dev);
> > + if (first_page->dev->bdev == NULL)
> > + goto out;
> > +
> > + bio_set_dev(bio, first_page->dev->bdev);
> > +
> > + for (page_num = 0; page_num < sblock->page_count; page_num++) {
> > + struct scrub_page *page = sblock->pagev[page_num];
> > +
> > + WARN_ON(!page->page);
> > + bio_add_page(bio, page->page, PAGE_SIZE, 0);
> > + }
> > +
> > + if (scrub_submit_raid56_bio_wait(fs_info, bio, first_page)) {
> > + bio_put(bio);
> > + goto out;
> > + }
> > +
> > + bio_put(bio);
> > +
> > + scrub_recheck_block_checksum(sblock);
> > +
> > + return;
> > +out:
> > + for (page_num = 0; page_num < sblock->page_count; page_num++)
> > + sblock->pagev[page_num]->io_error = 1;
> > +
> > + sblock->no_io_error_seen = 0;
> > +}
> > +
> > /*
> > * this function will check the on disk data for checksum errors, header
> > * errors and read I/O errors. If any I/O errors happen, the exact pages
> > @@ -1733,6 +1771,10 @@ static void scrub_recheck_block(struct btrfs_fs_info
> > *fs_info,
> >
> > sblock->no_io_error_seen = 1;
> >
> > + /* short cut for raid56 */
> > + if (!retry_failed_mirror && scrub_is_page_on_raid56(sblock->pagev[0]))
> > + return scrub_recheck_block_on_raid56(fs_info, sblock);
> > +
> > for (page_num = 0; page_num < sblock->page_count; page_num++) {
> > struct bio *bio;
> > struct scrub_page *page = sblock->pagev[page_num];
> > @@ -1748,19 +1790,12 @@ static void scrub_recheck_block(struct
> > btrfs_fs_info *fs_info,
> > bio_set_dev(bio, page->dev->bdev);
> >
> > bio_add_page(bio, page->page, PAGE_SIZE, 0);
> > - if (!retry_failed_mirror && scrub_is_page_on_raid56(page)) {
> > - if (scrub_submit_raid56_bio_wait(fs_info, bio, page)) {
> > - page->io_error = 1;
> > - sblock->no_io_error_seen = 0;
> > - }
> > - } else {
> > - bio->bi_iter.bi_sector = page->physical >> 9;
> > - bio_set_op_attrs(bio, REQ_OP_READ, 0);
> > + bio->bi_iter.bi_sector = page->physical >> 9;
> > + bio_set_op_attrs(bio, REQ_OP_READ, 0);
>
> https://elixir.bootlin.com/linux/latest/source/include/linux/blk_types.h#L270
>
> bio_set_op_attrs should not be used
OK.
Thanks,
-liubo
>
> >
> > - if (btrfsic_submit_bio_wait(bio)) {
> > - page->io_error = 1;
> > - sblock->no_io_error_seen = 0;
> > - }
> > + if (btrfsic_submit_bio_wait(bio)) {
> > + page->io_error = 1;
> > + sblock->no_io_error_seen = 0;
> > }
> >
> > bio_put(bio);
> > @@ -2728,7 +2763,8 @@ static int scrub_find_csum(struct scrub_ctx *sctx,
> > u64 logical, u8 *csum)
> > }
> >
> > /* scrub extent tries to collect up to 64 kB for each bio */
> > -static int scrub_extent(struct scrub_ctx *sctx, u64 logical, u64 len,
> > +static int scrub_extent(struct scrub_ctx *sctx, struct map_lookup *map,
> > + u64 logical, u64 len,
> > u64 physical, struct btrfs_device *dev, u64 flags,
> > u64 gen, int mirror_num, u64 physical_for_dev_replace)
> > {
> > @@ -2737,13 +2773,19 @@ static int scrub_extent(struct scrub_ctx *sctx, u64
> > logical, u64 len,
> > u32 blocksize;
> >
> > if (flags & BTRFS_EXTENT_FLAG_DATA) {
> > - blocksize = sctx->fs_info->sectorsize;
> > + if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
> > + blocksize = map->stripe_len;
> > + else
> > + blocksize = sctx->fs_info->sectorsize;
> > spin_lock(&sctx->stat_lock);
> > sctx->stat.data_extents_scrubbed++;
> > sctx->stat.data_bytes_scrubbed += len;
> > spin_unlock(&sctx->stat_lock);
> > } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
> > - blocksize = sctx->fs_info->nodesize;
> > + if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
> > + blocksize = map->stripe_len;
> > + else
> > + blocksize = sctx->fs_info->nodesize;
> > spin_lock(&sctx->stat_lock);
> > sctx->stat.tree_extents_scrubbed++;
> > sctx->stat.tree_bytes_scrubbed += len;
> > @@ -2883,9 +2925,9 @@ static int scrub_extent_for_parity(struct
> > scrub_parity *sparity,
> > }
> >
> > if (flags & BTRFS_EXTENT_FLAG_DATA) {
> > - blocksize = sctx->fs_info->sectorsize;
> > + blocksize = sparity->stripe_len;
> > } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
> > - blocksize = sctx->fs_info->nodesize;
> > + blocksize = sparity->stripe_len;
> > } else {
> > blocksize = sctx->fs_info->sectorsize;
> > WARN_ON(1);
> > @@ -3595,7 +3637,7 @@ static noinline_for_stack int scrub_stripe(struct
> > scrub_ctx *sctx,
> > if (ret)
> > goto out;
> >
> > - ret = scrub_extent(sctx, extent_logical, extent_len,
> > + ret = scrub_extent(sctx, map, extent_logical,
> > extent_len,
> > extent_physical, extent_dev, flags,
> > generation, extent_mirror_num,
> > extent_logical - logical + physical);
> > --
> > 2.9.4
> >
> > --
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