| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.19 61/75] dm thin: fix to consistently zero-fill reads to unprovisioned blocks | Date | Fri, 10 Apr 2015 15:19:27 +0200 |
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3.19-stable review patch. If anyone has any objections, please let me know.
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From: Joe Thornber <ejt@redhat.com>
commit 5f027a3bf184d1d36e68745f7cd3718a8b879cc0 upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/md/dm-thin.c | 11 ----------- 1 file changed, 11 deletions(-)
--- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -2357,17 +2357,6 @@ static int thin_bio_map(struct dm_target return DM_MAPIO_REMAPPED; 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); - return DM_MAPIO_SUBMITTED; - } - /* fall through */ - case -EWOULDBLOCK: thin_defer_cell(tc, virt_cell); return DM_MAPIO_SUBMITTED;
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