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: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
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@ -2358,17 +2358,6 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
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return DM_MAPIO_REMAPPED;
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case -ENODATA:
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if (get_pool_mode(tc->pool) == PM_READ_ONLY) {
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/*
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* This block isn't provisioned, and we have no way
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* of doing so.
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*/
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handle_unserviceable_bio(tc->pool, bio);
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cell_defer_no_holder(tc, virt_cell);
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return DM_MAPIO_SUBMITTED;
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}
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/* fall through */
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case -EWOULDBLOCK:
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thin_defer_cell(tc, virt_cell);
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return DM_MAPIO_SUBMITTED;
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