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authorJeffle Xu2020-11-04 11:57:56 +0800
committerMike Snitzer2020-12-04 18:04:35 -0500
commit985eabdcfe3aad1aea6fc195dafff503f303aa3a (patch)
tree563e26950b3471f537ab1abb2e10fe4d902ca87e /drivers/md
parent65f33b35722952fa076811d5686bfd8a611a80fa (diff)
dm: remove unnecessary current->bio_list check when submitting split bio
The depth-first splitting is introduced in commit 18a25da84354 ("dm: ensure bio submission follows a depth-first tree walk"), which is used to fix the potential deadlock in case of the misordering handling of bios caused by bio_list. There're two paths submitting split bios, dm_wq_work() from worker thread and submit_bio() from application. Back upon that time, dm_wq_work() thread calls __split_and_process_bio() directly and thus will not trigger this issue since bio_list doesn't exist here. So this issue will only be triggered from application calling submit_bio(), and the fix has to check if current->bio_list is non-NULL to distinguish this case. However since commit 0c2915b8c6db1 ("dm: fix missing imposition of queue_limits from dm_wq_work() thread"), dm_wq_work() thread calls submit_bio_noacct() and thus also uses bio_list. Since then all entries into __split_and_process_bio() are under protection of bio_list, and thus the checking of current->bio_list when determinning if the depth-first principle should be used, seems kind of nonsense. After all the checking always succeeds now. Fixes: 0c2915b8c6db1 ("dm: fix missing imposition of queue_limits from dm_wq_work() thread") Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 4e0cbfe3f14d..9408df43ba75 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1590,7 +1590,7 @@ static blk_qc_t __split_and_process_bio(struct mapped_device *md,
ci.sector_count = bio_sectors(bio);
while (ci.sector_count && !error) {
error = __split_and_process_non_flush(&ci);
- if (current->bio_list && ci.sector_count && !error) {
+ if (ci.sector_count && !error) {
/*
* Remainder must be passed to submit_bio_noacct()
* so that it gets handled *after* bios already submitted