diff options
| author | Aleix Roca Nonell <aleix.rocanonell@bsc.es> | 2019-08-15 14:03:22 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-08-15 11:03:38 -0600 |
| commit | 99c79f6692ccdc42e04deea8a36e22bb48168a62 (patch) | |
| tree | d665a31392cb938848e7a17e21d7fe2b034ed862 /fs/io_uring.c | |
| parent | ae78ca3cf3d9e9f914bfcd0bc5c389ff18b9c2e0 (diff) | |
| download | lwn-99c79f6692ccdc42e04deea8a36e22bb48168a62.tar.gz lwn-99c79f6692ccdc42e04deea8a36e22bb48168a62.zip | |
io_uring: fix manual setup of iov_iter for fixed buffers
Commit bd11b3a391e3 ("io_uring: don't use iov_iter_advance() for fixed
buffers") introduced an optimization to avoid using the slow
iov_iter_advance by manually populating the iov_iter iterator in some
cases.
However, the computation of the iterator count field was erroneous: The
first bvec was always accounted for an extent of page size even if the
bvec length was smaller.
In consequence, some I/O operations on fixed buffers were unable to
operate on the full extent of the buffer, consistently skipping some
bytes at the end of it.
Fixes: bd11b3a391e3 ("io_uring: don't use iov_iter_advance() for fixed buffers")
Cc: stable@vger.kernel.org
Signed-off-by: Aleix Roca Nonell <aleix.rocanonell@bsc.es>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io_uring.c')
| -rw-r--r-- | fs/io_uring.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index d542f1cf4428..aa25b5bbd4ae 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1097,10 +1097,8 @@ static int io_import_fixed(struct io_ring_ctx *ctx, int rw, iter->bvec = bvec + seg_skip; iter->nr_segs -= seg_skip; - iter->count -= (seg_skip << PAGE_SHIFT); + iter->count -= bvec->bv_len + offset; iter->iov_offset = offset & ~PAGE_MASK; - if (iter->iov_offset) - iter->count -= iter->iov_offset; } } |