diff options
author | NeilBrown <neilb@suse.com> | 2019-03-29 10:46:16 -0700 |
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committer | Jens Axboe <axboe@kernel.dk> | 2019-04-01 12:11:48 -0600 |
commit | 4bc034d35377196c854236133b07730a777c4aba (patch) | |
tree | 58b75009263777beb5fdf4a058af5f6ba2a3d1be /block/bio.c | |
parent | 4f4fd7c5798bbdd5a03a60f6269cf1177fbd11ef (diff) |
Revert "MD: fix lock contention for flush bios"
This reverts commit 5a409b4f56d50b212334f338cb8465d65550cd85.
This patch has two problems.
1/ it make multiple calls to submit_bio() from inside a make_request_fn.
The bios thus submitted will be queued on current->bio_list and not
submitted immediately. As the bios are allocated from a mempool,
this can theoretically result in a deadlock - all the pool of requests
could be in various ->bio_list queues and a subsequent mempool_alloc
could block waiting for one of them to be released.
2/ It aims to handle a case when there are many concurrent flush requests.
It handles this by submitting many requests in parallel - all of which
are identical and so most of which do nothing useful.
It would be more efficient to just send one lower-level request, but
allow that to satisfy multiple upper-level requests.
Fixes: 5a409b4f56d5 ("MD: fix lock contention for flush bios")
Cc: <stable@vger.kernel.org> # v4.19+
Tested-by: Xiao Ni <xni@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/bio.c')
0 files changed, 0 insertions, 0 deletions