| Message ID | 20190901200836.14959-13-rgoldwyn@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Btrfs iomap | expand |
On Sun, Sep 01, 2019 at 03:08:33PM -0500, Goldwyn Rodrigues wrote: > From: Goldwyn Rodrigues <rgoldwyn@suse.com> > > This helps filesystems to perform tasks on the bio while > submitting for I/O. Since btrfs requires the position > we are working on, pass pos to iomap_dio_submit_bio() Please avoid passing function pointers in mutable data structures. I think the best idea here is to move the end_io handler into a structure that can be marked const, and to which we can add the submit handler later. Something like this: --- From d17419b6b4124e95088858d3dcea486db6be9ffa Mon Sep 17 00:00:00 2001 From: Christoph Hellwig <hch@lst.de> Date: Mon, 2 Sep 2019 18:39:34 +0200 Subject: iomap: move the direct I/O ->end_io callback into a structure Add a new iomap_dio_ops structure that for now just contains the end_io handler. This avoid storing the function pointer in a mutable structure, which is a possible exploit vector for kernel code execution, and prepares for adding a submit_io handler that btrfs needs. Signed-off-by: Christoph Hellwig <hch@lst.de> --- fs/iomap/direct-io.c | 17 +++++++++-------- fs/xfs/xfs_file.c | 6 +++++- include/linux/iomap.h | 9 ++++++--- 3 files changed, 20 insertions(+), 12 deletions(-) diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index 10517cea9682..cfe5f6a88945 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -24,7 +24,7 @@ struct iomap_dio { struct kiocb *iocb; - iomap_dio_end_io_t *end_io; + const struct iomap_dio_ops *dops; loff_t i_size; loff_t size; atomic_t ref; @@ -72,13 +72,14 @@ static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap, static ssize_t iomap_dio_complete(struct iomap_dio *dio) { + const struct iomap_dio_ops *dops = dio->dops; struct kiocb *iocb = dio->iocb; struct inode *inode = file_inode(iocb->ki_filp); loff_t offset = iocb->ki_pos; ssize_t ret; - if (dio->end_io) { - ret = dio->end_io(iocb, + if (dops && dops->end_io) { + ret = dops->end_io(iocb, dio->error ? dio->error : dio->size, dio->flags); } else { @@ -101,9 +102,9 @@ static ssize_t iomap_dio_complete(struct iomap_dio *dio) * one is a pretty crazy thing to do, so we don't support it 100%. If * this invalidation fails, tough, the write still worked... * - * And this page cache invalidation has to be after dio->end_io(), as - * some filesystems convert unwritten extents to real allocations in - * end_io() when necessary, otherwise a racing buffer read would cache + * And this page cache invalidation has to be after ->end_io(), as some + * filesystems convert unwritten extents to real allocations in + * ->end_io() when necessary, otherwise a racing buffer read would cache * zeros from unwritten extents. */ if (!dio->error && @@ -396,7 +397,7 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length, */ ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, - const struct iomap_ops *ops, iomap_dio_end_io_t end_io) + const struct iomap_ops *ops, const struct iomap_dio_ops *dops) { struct address_space *mapping = iocb->ki_filp->f_mapping; struct inode *inode = file_inode(iocb->ki_filp); @@ -421,7 +422,7 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, atomic_set(&dio->ref, 1); dio->size = 0; dio->i_size = i_size_read(inode); - dio->end_io = end_io; + dio->dops = dops; dio->error = 0; dio->flags = 0; diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 28101bbc0b78..0a2dc6b71c3c 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -440,6 +440,10 @@ xfs_dio_write_end_io( return error; } +static const struct iomap_dio_ops xfs_dio_write_ops = { + .end_io = xfs_dio_write_end_io, +}; + /* * xfs_file_dio_aio_write - handle direct IO writes * @@ -540,7 +544,7 @@ xfs_file_dio_aio_write( } trace_xfs_file_direct_write(ip, count, iocb->ki_pos); - ret = iomap_dio_rw(iocb, from, &xfs_iomap_ops, xfs_dio_write_end_io); + ret = iomap_dio_rw(iocb, from, &xfs_iomap_ops, &xfs_dio_write_ops); /* * If unaligned, this is the only IO in-flight. If it has not yet diff --git a/include/linux/iomap.h b/include/linux/iomap.h index bc499ceae392..d8c0769bb360 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -188,10 +188,13 @@ sector_t iomap_bmap(struct address_space *mapping, sector_t bno, */ #define IOMAP_DIO_UNWRITTEN (1 << 0) /* covers unwritten extent(s) */ #define IOMAP_DIO_COW (1 << 1) /* covers COW extent(s) */ -typedef int (iomap_dio_end_io_t)(struct kiocb *iocb, ssize_t ret, - unsigned flags); + +struct iomap_dio_ops { + int (*end_io)(struct kiocb *iocb, ssize_t ret, unsigned flags); +}; + ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, - const struct iomap_ops *ops, iomap_dio_end_io_t end_io); + const struct iomap_ops *ops, const struct iomap_dio_ops *dops); int iomap_dio_iopoll(struct kiocb *kiocb, bool spin); #ifdef CONFIG_SWAP
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index 5279029c7a3c..00b8af35cf97 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -59,7 +59,7 @@ int iomap_dio_iopoll(struct kiocb *kiocb, bool spin) EXPORT_SYMBOL_GPL(iomap_dio_iopoll); static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap, - struct bio *bio) + struct bio *bio, loff_t pos) { atomic_inc(&dio->ref); @@ -67,7 +67,13 @@ static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap, bio_set_polled(bio, dio->iocb); dio->submit.last_queue = bdev_get_queue(iomap->bdev); - dio->submit.cookie = submit_bio(bio); + if (iomap->submit_io) { + iomap->submit_io(bio, file_inode(dio->iocb->ki_filp), + pos); + dio->submit.cookie = BLK_QC_T_NONE; + } else { + dio->submit.cookie = submit_bio(bio); + } } static ssize_t iomap_dio_complete(struct iomap_dio *dio) @@ -195,7 +201,7 @@ iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos, get_page(page); __bio_add_page(bio, page, len, 0); bio_set_op_attrs(bio, REQ_OP_WRITE, flags); - iomap_dio_submit_bio(dio, iomap, bio); + iomap_dio_submit_bio(dio, iomap, bio, pos); } static loff_t @@ -301,11 +307,11 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, iov_iter_advance(dio->submit.iter, n); dio->size += n; - pos += n; copied += n; nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES); - iomap_dio_submit_bio(dio, iomap, bio); + iomap_dio_submit_bio(dio, iomap, bio, pos); + pos += n; } while (nr_pages); /* diff --git a/include/linux/iomap.h b/include/linux/iomap.h index 9c082d36286a..465d736d74ac 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -80,6 +80,7 @@ struct iomap { void *inline_data; void *private; /* filesystem private */ const struct iomap_page_ops *page_ops; + dio_submit_t *submit_io; }; static inline sector_t