diff options
| author | Jens Axboe <axboe@kernel.dk> | 2019-02-27 13:05:25 -0700 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-03-18 10:44:48 -0600 |
| commit | 875f1d0769cdcfe1596ff0ca609b453359e42ec9 (patch) | |
| tree | 7a62a8236e2412bc136376e0c22114b5e631f98a /fs/io_uring.c | |
| parent | bf33a7699e992b12d4c7d39dc3f0b61f6b26c5c2 (diff) | |
iov_iter: add ITER_BVEC_FLAG_NO_REF flag
For ITER_BVEC, if we're holding on to kernel pages, the caller
doesn't need to grab a reference to the bvec pages, and drop that
same reference on IO completion. This is essentially safe for any
ITER_BVEC, but some use cases end up reusing pages and uncondtionally
dropping a page reference on completion. And example of that is
sendfile(2), that ends up being a splice_in + splice_out on the
pipe pages.
Add a flag that tells us it's fine to not grab a page reference
to the bvec pages, since that caller knows not to drop a reference
when it's done with the pages.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io_uring.c')
| -rw-r--r-- | fs/io_uring.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 4c6a5e60ddbe..c592a0933b0d 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -855,6 +855,9 @@ static int io_import_fixed(struct io_ring_ctx *ctx, int rw, iov_iter_bvec(iter, rw, imu->bvec, imu->nr_bvecs, offset + len); if (offset) iov_iter_advance(iter, offset); + + /* don't drop a reference to these pages */ + iter->type |= ITER_BVEC_FLAG_NO_REF; return 0; } |