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.
---
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);
+ 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);
- 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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