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authorDamien Le Moal2019-08-01 19:21:51 +0900
committerJens Axboe2019-08-01 13:51:18 -0600
commit0eb6ddfb865c7d7ec05cb330050671363515e67f (patch)
tree154f2d35d99a33fb052046358f9e6e1586b6e8f6
parent3d0b63c5dfa8a912ac2d5026a24826b99b20ecc9 (diff)
block: Fix __blkdev_direct_IO() for bio fragments
The recent fix to properly handle IOCB_NOWAIT for async O_DIRECT IO (patch 6a43074e2f46) introduced two problems with BIO fragment handling for direct IOs: 1) The dio size processed is calculated by incrementing the ret variable by the size of the bio fragment issued for the dio. However, this size is obtained directly from bio->bi_iter.bi_size AFTER the bio submission which may result in referencing the bi_size value after the bio completed, resulting in an incorrect value use. 2) The ret variable is not incremented by the size of the last bio fragment issued for the bio, leading to an invalid IO size being returned to the user. Fix both problem by using dio->size (which is incremented before the bio submission) to update the value of ret after bio submissions, including for the last bio fragment issued. Fixes: 6a43074e2f46 ("block: properly handle IOCB_NOWAIT for async O_DIRECT IO") Reported-by: Masato Suzuki <masato.suzuki@wdc.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/block_dev.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 22591bad9353..a6f7c892cb4a 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -439,6 +439,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
ret = -EAGAIN;
goto error;
}
+ ret = dio->size;
if (polled)
WRITE_ONCE(iocb->ki_cookie, qc);
@@ -465,7 +466,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
ret = -EAGAIN;
goto error;
}
- ret += bio->bi_iter.bi_size;
+ ret = dio->size;
bio = bio_alloc(gfp, nr_pages);
if (!bio) {