From: Lars Ellenberg <lars.ellenberg@xxxxxxxxxx>
We usually do all our bitmap IO in units of PAGE_SIZE.
With very small or oddly sized external meta data, or with
PAGE_SIZE != 4k, it can happen that our last on-disk bitmap page
is not fully PAGE_SIZE aligned, so we may need to adjust the size
of the IO.
We used to do that with
min_t(unsigned int, PAGE_SIZE,
last_allowed_sector - current_offset);
And for just the right diff, (unsigned int)(diff) will result in 0.
A bio of length 0 will correctly be rejected with an IO error
(and some scary WARN_ON_ONCE()) by the scsi layer.
Do the calculation properly.
Signed-off-by: Lars Ellenberg <lars.ellenberg@xxxxxxxxxx>
Signed-off-by: Christoph Böhmwalder <christoph.boehmwalder@xxxxxxxxxx>
---
drivers/block/drbd/drbd_bitmap.c | 49 +++++++++++++++++++++++++++-----
1 file changed, 42 insertions(+), 7 deletions(-)
diff --git a/drivers/block/drbd/drbd_bitmap.c b/drivers/block/drbd/drbd_bitmap.c
index 9e060e49b3f8..bd2133ef6e0a 100644
--- a/drivers/block/drbd/drbd_bitmap.c
+++ b/drivers/block/drbd/drbd_bitmap.c
@@ -974,25 +974,58 @@ static void drbd_bm_endio(struct bio *bio)
}
}
+/* For the layout, see comment above drbd_md_set_sector_offsets(). */
+static inline sector_t drbd_md_last_bitmap_sector(struct drbd_backing_dev *bdev)
+{
+ switch (bdev->md.meta_dev_idx) {
+ case DRBD_MD_INDEX_INTERNAL:
+ case DRBD_MD_INDEX_FLEX_INT:
+ return bdev->md.md_offset + bdev->md.al_offset -1;
+ case DRBD_MD_INDEX_FLEX_EXT:
+ default:
+ return bdev->md.md_offset + bdev->md.md_size_sect -1;
+ }
+}
+
static void bm_page_io_async(struct drbd_bm_aio_ctx *ctx, int page_nr) __must_hold(local)
{
struct drbd_device *device = ctx->device;
unsigned int op = (ctx->flags & BM_AIO_READ) ? REQ_OP_READ : REQ_OP_WRITE;
- struct bio *bio = bio_alloc_bioset(device->ldev->md_bdev, 1, op,
- GFP_NOIO, &drbd_md_io_bio_set);
struct drbd_bitmap *b = device->bitmap;
+ struct bio *bio;
struct page *page;
+ sector_t last_bm_sect;
+ sector_t first_bm_sect;
+ sector_t on_disk_sector;
unsigned int len;
- sector_t on_disk_sector =
- device->ldev->md.md_offset + device->ldev->md.bm_offset;
- on_disk_sector += ((sector_t)page_nr) << (PAGE_SHIFT-9);
+ first_bm_sect = device->ldev->md.md_offset + device->ldev->md.bm_offset;
+ on_disk_sector = first_bm_sect + (((sector_t)page_nr) << (PAGE_SHIFT-SECTOR_SHIFT));
/* this might happen with very small
* flexible external meta data device,
* or with PAGE_SIZE > 4k */
- len = min_t(unsigned int, PAGE_SIZE,
- (drbd_md_last_sector(device->ldev) - on_disk_sector + 1)<<9);
+ last_bm_sect = drbd_md_last_bitmap_sector(device->ldev);
+ if (first_bm_sect <= on_disk_sector && last_bm_sect >= on_disk_sector) {
+ sector_t len_sect = last_bm_sect - on_disk_sector + 1;
+ if (len_sect < PAGE_SIZE/SECTOR_SIZE)
+ len = (unsigned int)len_sect*SECTOR_SIZE;
+ else
+ len = PAGE_SIZE;
+ } else {
+ if (__ratelimit(&drbd_ratelimit_state)) {
+ drbd_err(device, "Invalid offset during on-disk bitmap access: "
+ "page idx %u, sector %llu\n", page_nr, on_disk_sector);
+ }
+ ctx->error = -EIO;
+ bm_set_page_io_err(b->bm_pages[page_nr]);
+ if (atomic_dec_and_test(&ctx->in_flight)) {
+ ctx->done = 1;
+ wake_up(&device->misc_wait);
+ kref_put(&ctx->kref, &drbd_bm_aio_ctx_destroy);
+ }
+ return;
+ }
/* serialize IO on this page */
bm_page_lock_io(device, page_nr);
@@ -1007,6 +1040,8 @@ static void bm_page_io_async(struct drbd_bm_aio_ctx *ctx, int page_nr) __must_ho
bm_store_page_idx(page, page_nr);
} else
page = b->bm_pages[page_nr];
+ bio = bio_alloc_bioset(device->ldev->md_bdev, 1, op, GFP_NOIO,
+ &drbd_md_io_bio_set);
bio->bi_iter.bi_sector = on_disk_sector;
/* bio_add_page of a single page to an empty bio will always succeed,
* according to api. Do we want to assert that? */
--
2.36.1
