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| author | Ross Lagerwall <ross.lagerwall@citrix.com> | 2023-04-26 17:40:05 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-06-21 15:39:57 +0200 |
| commit | 2540c662d846c522fb4ed3f1af0f80ec95d532fc (patch) | |
| tree | ade60f548ec2e3b73029ab22a5ca74d080619c3d | |
| parent | 793092e8002cc567f428dcd8d6a8bc2297f0e865 (diff) | |
| download | linux-2540c662d846c522fb4ed3f1af0f80ec95d532fc.tar.gz linux-2540c662d846c522fb4ed3f1af0f80ec95d532fc.tar.bz2 linux-2540c662d846c522fb4ed3f1af0f80ec95d532fc.zip | |
xen/blkfront: Only check REQ_FUA for writes
[ Upstream commit b6ebaa8100090092aa602530d7e8316816d0c98d ]
The existing code silently converts read operations with the
REQ_FUA bit set into write-barrier operations. This results in data
loss as the backend scribbles zeroes over the data instead of returning
it.
While the REQ_FUA bit doesn't make sense on a read operation, at least
one well-known out-of-tree kernel module does set it and since it
results in data loss, let's be safe here and only look at REQ_FUA for
writes.
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Acked-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20230426164005.2213139-1-ross.lagerwall@citrix.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | drivers/block/xen-blkfront.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 7ee618ab1567..b4807d12ef29 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -779,7 +779,8 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri ring_req->u.rw.handle = info->handle; ring_req->operation = rq_data_dir(req) ? BLKIF_OP_WRITE : BLKIF_OP_READ; - if (req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA) { + if (req_op(req) == REQ_OP_FLUSH || + (req_op(req) == REQ_OP_WRITE && (req->cmd_flags & REQ_FUA))) { /* * Ideally we can do an unordered flush-to-disk. * In case the backend onlysupports barriers, use that. |