Commit 5f027a3b authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer
Browse files

dm thin: fix to consistently zero-fill reads to unprovisioned blocks

It was always intended that a read to an unprovisioned block will return
zeroes regardless of whether the pool is in read-only or read-write
mode.  thin_bio_map() was inconsistent with its handling of such reads
when the pool is in read-only mode, it now properly zero-fills the bios
it returns in response to unprovisioned block reads.

Eliminate thin_bio_map()'s special read-only mode handling of -ENODATA
and just allow the IO to be deferred to the worker which will result in
pool->process_bio() handling the IO (which already properly zero-fills
reads to unprovisioned blocks).
Reported-by: default avatarEric Sandeen <>
Signed-off-by: default avatarJoe Thornber <>
Signed-off-by: default avatarMike Snitzer <>
parent c517d838
......@@ -2358,17 +2358,6 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
case -ENODATA:
if (get_pool_mode(tc->pool) == PM_READ_ONLY) {
* This block isn't provisioned, and we have no way
* of doing so.
handle_unserviceable_bio(tc->pool, bio);
cell_defer_no_holder(tc, virt_cell);
/* fall through */
thin_defer_cell(tc, virt_cell);
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