Hello Jens, Ming, Jan, and all others, the following patches have been verified by a customer to fix a silent data corruption which he has been seeing since "72ecad2 block: support a full bio worth of IO for simplified bdev direct-io". The patches are based on our observation that the corruption is only observed if the __blkdev_direct_IO_simple() code path is executed, and if that happens, "short writes" are observed in this code path, which causes a fallback to buffered IO, while the application continues submitting direct IO requests. In v4, I've separated out the "get as many pages as the bio can hold" functionality into a new helper. This way other callers can migrate to the new helper if deemed appropriate. Changing the semantics of bio_iov_iter_get_pages() for all callers, as Ming originally suggested, seems too intrusive to me at this time. Regards, Martin Changes wrt v1: - 1/3: minor formatting change (Christoph) - 2/3: split off the leak fix (Ming) - 3/3: give up if bio_iov_iter_get_pages() returns an error (Jan) - 3/3: warn if space in bio exhausted (Jan) - 3/3: add comments Changes wrt v3: - split previous 3/3 into two patches (3/4, 4/4). - 3/4: add a new helper to retrieve as many pages as possible (Ming) - 3/4: put pages in case of error (Ming) Martin Wilck (4): block: bio_iov_iter_get_pages: fix size of last iovec blkdev: __blkdev_direct_IO_simple: fix leak in error case block: add bio_iov_iter_get_all_pages() helper blkdev: __blkdev_direct_IO_simple: make sure to fill up the bio block/bio.c | 61 +++++++++++++++++++++++++++++++++++++-------- fs/block_dev.c | 18 +++++++++---- include/linux/bio.h | 1 + 3 files changed, 64 insertions(+), 16 deletions(-) -- 2.17.1
