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authorLukas Czerner <lczerner@redhat.com>2019-05-10 21:45:33 -0400
committerTheodore Ts'o <tytso@mit.edu>2019-05-10 21:45:33 -0400
commit57a0da28ced8707cb9f79f071a016b9d005caf5a (patch)
treeae7aa73980716ce76c8d30ff37211a6e457a629e
parent0d52154bb0a700abb459a2cbce0a30fc2549b67e (diff)
downloadlinux-57a0da28ced8707cb9f79f071a016b9d005caf5a.tar.bz2
ext4: fix data corruption caused by overlapping unaligned and aligned IO
Unaligned AIO must be serialized because the zeroing of partial blocks of unaligned AIO can result in data corruption in case it's overlapping another in flight IO. Currently we wait for all unwritten extents before we submit unaligned AIO which protects data in case of unaligned AIO is following overlapping IO. However if a unaligned AIO is followed by overlapping aligned AIO we can still end up corrupting data. To fix this, we must make sure that the unaligned AIO is the only IO in flight by waiting for unwritten extents conversion not just before the IO submission, but right after it as well. This problem can be reproduced by xfstest generic/538 Signed-off-by: Lukas Czerner <lczerner@redhat.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org
-rw-r--r--fs/ext4/file.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 98ec11f69cd4..2c5baa5e8291 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -264,6 +264,13 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
}
ret = __generic_file_write_iter(iocb, from);
+ /*
+ * Unaligned direct AIO must be the only IO in flight. Otherwise
+ * overlapping aligned IO after unaligned might result in data
+ * corruption.
+ */
+ if (ret == -EIOCBQUEUED && unaligned_aio)
+ ext4_unwritten_wait(inode);
inode_unlock(inode);
if (ret > 0)