selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 1085 insertions, 0 deletions

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
new file mode 100644
index 000000000..b3368d64e
--- /dev/null
+++ b/fs/iomap/direct-io.c
@@ -0,0 +1,1085 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2010 Red Hat, Inc.
+ * Copyright (c) 2016-2025 Christoph Hellwig.
+ */
+#include <linux/bio-integrity.h>
+#include <linux/blk-crypto.h>
+#include <linux/fscrypt.h>
+#include <linux/pagemap.h>
+#include <linux/iomap.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/fserror.h>
+#include <linux/init.h>
+#include "internal.h"
+#include "trace.h"
+
+#include "../internal.h"
+
+/*
+ * Private flags for iomap_dio, must not overlap with the public ones in
+ * iomap.h:
+ */
+#define IOMAP_DIO_NO_INVALIDATE	(1U << 26)
+#define IOMAP_DIO_COMP_WORK	(1U << 27)
+#define IOMAP_DIO_WRITE_THROUGH	(1U << 28)
+#define IOMAP_DIO_NEED_SYNC	(1U << 29)
+#define IOMAP_DIO_WRITE		(1U << 30)
+#define IOMAP_DIO_USER_BACKED	(1U << 31)
+
+struct iomap_dio {
+	struct kiocb		*iocb;
+	const struct iomap_dio_ops *dops;
+	loff_t			i_size;
+	loff_t			size;
+	atomic_t		ref;
+	unsigned		flags;
+	int			error;
+	size_t			done_before;
+	bool			wait_for_completion;
+
+	union {
+		/* used during submission and for synchronous completion: */
+		struct {
+			struct iov_iter		*iter;
+			struct task_struct	*waiter;
+		} submit;
+
+		/* used for aio completion: */
+		struct {
+			struct work_struct	work;
+		} aio;
+	};
+};
+
+static struct bio *iomap_dio_alloc_bio(const struct iomap_iter *iter,
+		struct iomap_dio *dio, unsigned short nr_vecs, blk_opf_t opf)
+{
+	if (dio->dops && dio->dops->bio_set)
+		return bio_alloc_bioset(iter->iomap.bdev, nr_vecs, opf,
+					GFP_KERNEL, dio->dops->bio_set);
+	return bio_alloc(iter->iomap.bdev, nr_vecs, opf, GFP_KERNEL);
+}
+
+static void iomap_dio_submit_bio(const struct iomap_iter *iter,
+		struct iomap_dio *dio, struct bio *bio, loff_t pos)
+{
+	struct kiocb *iocb = dio->iocb;
+
+	atomic_inc(&dio->ref);
+
+	/* Sync dio can't be polled reliably */
+	if ((iocb->ki_flags & IOCB_HIPRI) && !is_sync_kiocb(iocb)) {
+		bio->bi_opf |= REQ_POLLED;
+		WRITE_ONCE(iocb->private, bio);
+	}
+
+	if (dio->dops && dio->dops->submit_io) {
+		dio->dops->submit_io(iter, bio, pos);
+	} else {
+		WARN_ON_ONCE(iter->iomap.flags & IOMAP_F_ANON_WRITE);
+		blk_crypto_submit_bio(bio);
+	}
+}
+
+static inline enum fserror_type iomap_dio_err_type(const struct iomap_dio *dio)
+{
+	if (dio->flags & IOMAP_DIO_WRITE)
+		return FSERR_DIRECTIO_WRITE;
+	return FSERR_DIRECTIO_READ;
+}
+
+static inline bool should_report_dio_fserror(int error)
+{
+	switch (error) {
+	case 0:
+	case -EAGAIN:
+	case -ENOTBLK:
+		/* don't send fsnotify for success or magic retry codes */
+		return false;
+	default:
+		return true;
+	}
+}
+
+ssize_t iomap_dio_complete(struct iomap_dio *dio)
+{
+	const struct iomap_dio_ops *dops = dio->dops;
+	struct kiocb *iocb = dio->iocb;
+	loff_t offset = iocb->ki_pos;
+	ssize_t ret = dio->error;
+
+	if (dops && dops->end_io)
+		ret = dops->end_io(iocb, dio->size, ret, dio->flags);
+	if (should_report_dio_fserror(dio->error))
+		fserror_report_io(file_inode(iocb->ki_filp),
+				  iomap_dio_err_type(dio), offset, dio->size,
+				  dio->error, GFP_NOFS);
+
+	if (likely(!ret)) {
+		ret = dio->size;
+		/* check for short read */
+		if (offset + ret > dio->i_size &&
+		    !(dio->flags & IOMAP_DIO_WRITE))
+			ret = dio->i_size - offset;
+	}
+
+	/*
+	 * Try again to invalidate clean pages which might have been cached by
+	 * non-direct readahead, or faulted in by get_user_pages() if the source
+	 * of the write was an mmap'ed region of the file we're writing.  Either
+	 * 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 ->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 && dio->size && (dio->flags & IOMAP_DIO_WRITE) &&
+	    !(dio->flags & IOMAP_DIO_NO_INVALIDATE))
+		kiocb_invalidate_post_direct_write(iocb, dio->size);
+
+	inode_dio_end(file_inode(iocb->ki_filp));
+
+	if (ret > 0) {
+		iocb->ki_pos += ret;
+
+		/*
+		 * If this is a DSYNC write, make sure we push it to stable
+		 * storage now that we've written data.
+		 */
+		if (dio->flags & IOMAP_DIO_NEED_SYNC)
+			ret = generic_write_sync(iocb, ret);
+		if (ret > 0)
+			ret += dio->done_before;
+	}
+	trace_iomap_dio_complete(iocb, dio->error, ret);
+	kfree(dio);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iomap_dio_complete);
+
+static void iomap_dio_complete_work(struct work_struct *work)
+{
+	struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work);
+	struct kiocb *iocb = dio->iocb;
+
+	iocb->ki_complete(iocb, iomap_dio_complete(dio));
+}
+
+/*
+ * Set an error in the dio if none is set yet.  We have to use cmpxchg
+ * as the submission context and the completion context(s) can race to
+ * update the error.
+ */
+static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret)
+{
+	cmpxchg(&dio->error, 0, ret);
+}
+
+/*
+ * Called when dio->ref reaches zero from an I/O completion.
+ */
+static void iomap_dio_done(struct iomap_dio *dio)
+{
+	struct kiocb *iocb = dio->iocb;
+
+	if (dio->wait_for_completion) {
+		/*
+		 * Synchronous I/O, task itself will handle any completion work
+		 * that needs after IO. All we need to do is wake the task.
+		 */
+		struct task_struct *waiter = dio->submit.waiter;
+
+		WRITE_ONCE(dio->submit.waiter, NULL);
+		blk_wake_io_task(waiter);
+		return;
+	}
+
+	/*
+	 * Always run error completions in user context.  These are not
+	 * performance critical and some code relies on taking sleeping locks
+	 * for error handling.
+	 */
+	if (dio->error)
+		dio->flags |= IOMAP_DIO_COMP_WORK;
+
+	/*
+	 * Never invalidate pages from this context to avoid deadlocks with
+	 * buffered I/O completions when called from the ioend workqueue,
+	 * or avoid sleeping when called directly from ->bi_end_io.
+	 * Tough luck if you hit the tiny race with someone dirtying the range
+	 * right between this check and the actual completion.
+	 */
+	if ((dio->flags & IOMAP_DIO_WRITE) &&
+	    !(dio->flags & IOMAP_DIO_COMP_WORK)) {
+		if (dio->iocb->ki_filp->f_mapping->nrpages)
+			dio->flags |= IOMAP_DIO_COMP_WORK;
+		else
+			dio->flags |= IOMAP_DIO_NO_INVALIDATE;
+	}
+
+	if (dio->flags & IOMAP_DIO_COMP_WORK) {
+		struct inode *inode = file_inode(iocb->ki_filp);
+
+		/*
+		 * Async DIO completion that requires filesystem level
+		 * completion work gets punted to a work queue to complete as
+		 * the operation may require more IO to be issued to finalise
+		 * filesystem metadata changes or guarantee data integrity.
+		 */
+		INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
+		queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work);
+		return;
+	}
+
+	WRITE_ONCE(iocb->private, NULL);
+	iomap_dio_complete_work(&dio->aio.work);
+}
+
+static void __iomap_dio_bio_end_io(struct bio *bio, bool inline_completion)
+{
+	struct iomap_dio *dio = bio->bi_private;
+
+	if (bio_integrity(bio))
+		fs_bio_integrity_free(bio);
+
+	if (dio->flags & IOMAP_DIO_BOUNCE) {
+		bio_iov_iter_unbounce(bio, !!dio->error,
+				dio->flags & IOMAP_DIO_USER_BACKED);
+		bio_put(bio);
+	} else if (dio->flags & IOMAP_DIO_USER_BACKED) {
+		bio_check_pages_dirty(bio);
+	} else {
+		bio_release_pages(bio, false);
+		bio_put(bio);
+	}
+
+	/* Do not touch bio below, we just gave up our reference. */
+
+	if (atomic_dec_and_test(&dio->ref)) {
+		/*
+		 * Avoid another context switch for the completion when already
+		 * called from the ioend completion workqueue.
+		 */
+		if (inline_completion)
+			dio->flags &= ~IOMAP_DIO_COMP_WORK;
+		iomap_dio_done(dio);
+	}
+}
+
+void iomap_dio_bio_end_io(struct bio *bio)
+{
+	struct iomap_dio *dio = bio->bi_private;
+
+	if (bio->bi_status)
+		iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status));
+	__iomap_dio_bio_end_io(bio, false);
+}
+EXPORT_SYMBOL_GPL(iomap_dio_bio_end_io);
+
+u32 iomap_finish_ioend_direct(struct iomap_ioend *ioend)
+{
+	struct iomap_dio *dio = ioend->io_bio.bi_private;
+	u32 vec_count = ioend->io_bio.bi_vcnt;
+
+	if (ioend->io_error)
+		iomap_dio_set_error(dio, ioend->io_error);
+	__iomap_dio_bio_end_io(&ioend->io_bio, true);
+
+	/*
+	 * Return the number of bvecs completed as even direct I/O completions
+	 * do significant per-folio work and we'll still want to give up the
+	 * CPU after a lot of completions.
+	 */
+	return vec_count;
+}
+
+static int iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio,
+		loff_t pos, unsigned len)
+{
+	struct inode *inode = file_inode(dio->iocb->ki_filp);
+	struct bio *bio;
+	struct folio *zero_folio = largest_zero_folio();
+	int nr_vecs = max(1, i_blocksize(inode) / folio_size(zero_folio));
+
+	if (!len)
+		return 0;
+
+	/*
+	 * This limit shall never be reached as most filesystems have a
+	 * maximum blocksize of 64k.
+	 */
+	if (WARN_ON_ONCE(nr_vecs > BIO_MAX_VECS))
+		return -EINVAL;
+
+	bio = iomap_dio_alloc_bio(iter, dio, nr_vecs,
+				  REQ_OP_WRITE | REQ_SYNC | REQ_IDLE);
+	fscrypt_set_bio_crypt_ctx(bio, inode, pos, GFP_KERNEL);
+	bio->bi_iter.bi_sector = iomap_sector(&iter->iomap, pos);
+	bio->bi_private = dio;
+	bio->bi_end_io = iomap_dio_bio_end_io;
+
+	while (len > 0) {
+		unsigned int io_len = min(len, folio_size(zero_folio));
+
+		bio_add_folio_nofail(bio, zero_folio, io_len, 0);
+		len -= io_len;
+	}
+	iomap_dio_submit_bio(iter, dio, bio, pos);
+
+	return 0;
+}
+
+static ssize_t iomap_dio_bio_iter_one(struct iomap_iter *iter,
+		struct iomap_dio *dio, loff_t pos, unsigned int alignment,
+		blk_opf_t op)
+{
+	unsigned int nr_vecs;
+	struct bio *bio;
+	ssize_t ret;
+
+	if (dio->flags & IOMAP_DIO_BOUNCE)
+		nr_vecs = bio_iov_bounce_nr_vecs(dio->submit.iter, op);
+	else
+		nr_vecs = bio_iov_vecs_to_alloc(dio->submit.iter, BIO_MAX_VECS);
+
+	bio = iomap_dio_alloc_bio(iter, dio, nr_vecs, op);
+	fscrypt_set_bio_crypt_ctx(bio, iter->inode, pos, GFP_KERNEL);
+	bio->bi_iter.bi_sector = iomap_sector(&iter->iomap, pos);
+	bio->bi_write_hint = iter->inode->i_write_hint;
+	bio->bi_ioprio = dio->iocb->ki_ioprio;
+	bio->bi_private = dio;
+	bio->bi_end_io = iomap_dio_bio_end_io;
+
+
+	if (dio->flags & IOMAP_DIO_BOUNCE)
+		ret = bio_iov_iter_bounce(bio, dio->submit.iter,
+				iomap_max_bio_size(&iter->iomap), alignment);
+	else
+		ret = bio_iov_iter_get_pages(bio, dio->submit.iter,
+					     alignment - 1);
+	if (unlikely(ret))
+		goto out_put_bio;
+	ret = bio->bi_iter.bi_size;
+
+	/*
+	 * An atomic write bio must cover the complete length.  If it doesn't,
+	 * error out.
+	 */
+	if ((op & REQ_ATOMIC) && WARN_ON_ONCE(ret != iomap_length(iter))) {
+		ret = -EINVAL;
+		goto out_bio_release_pages;
+	}
+
+	if (iter->iomap.flags & IOMAP_F_INTEGRITY) {
+		if (dio->flags & IOMAP_DIO_WRITE)
+			fs_bio_integrity_generate(bio);
+		else
+			fs_bio_integrity_alloc(bio);
+	}
+
+	if (dio->flags & IOMAP_DIO_WRITE)
+		task_io_account_write(ret);
+	else if ((dio->flags & IOMAP_DIO_USER_BACKED) &&
+		 !(dio->flags & IOMAP_DIO_BOUNCE))
+		bio_set_pages_dirty(bio);
+
+	/*
+	 * We can only poll for single bio I/Os.
+	 */
+	if (iov_iter_count(dio->submit.iter))
+		dio->iocb->ki_flags &= ~IOCB_HIPRI;
+	iomap_dio_submit_bio(iter, dio, bio, pos);
+	return ret;
+
+out_bio_release_pages:
+	if (dio->flags & IOMAP_DIO_BOUNCE)
+		bio_iov_iter_unbounce(bio, true, false);
+	else
+		bio_release_pages(bio, false);
+out_put_bio:
+	bio_put(bio);
+	return ret;
+}
+
+static inline unsigned int iomap_dio_alignment(struct inode *inode,
+		struct block_device *bdev, unsigned int dio_flags)
+{
+	if (dio_flags & IOMAP_DIO_FSBLOCK_ALIGNED)
+		return i_blocksize(inode);
+	return bdev_logical_block_size(bdev);
+}
+
+static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
+{
+	const struct iomap *iomap = &iter->iomap;
+	struct inode *inode = iter->inode;
+	unsigned int fs_block_size = i_blocksize(inode), pad;
+	const loff_t length = iomap_length(iter);
+	loff_t pos = iter->pos;
+	blk_opf_t bio_opf = REQ_SYNC | REQ_IDLE;
+	bool need_zeroout = false;
+	u64 copied = 0;
+	size_t orig_count;
+	unsigned int alignment;
+	ssize_t ret = 0;
+
+	/*
+	 * File systems that write out of place and always allocate new blocks
+	 * need each bio to be block aligned as that's the unit of allocation.
+	 */
+	alignment = iomap_dio_alignment(inode, iomap->bdev, dio->flags);
+
+	if ((pos | length) & (alignment - 1))
+		return -EINVAL;
+
+	if (dio->flags & IOMAP_DIO_WRITE) {
+		bool need_completion_work = true;
+
+		switch (iomap->type) {
+		case IOMAP_MAPPED:
+			/*
+			 * Directly mapped I/O does not inherently need to do
+			 * work at I/O completion time.  But there are various
+			 * cases below where this will get set again.
+			 */
+			need_completion_work = false;
+			break;
+		case IOMAP_UNWRITTEN:
+			dio->flags |= IOMAP_DIO_UNWRITTEN;
+			need_zeroout = true;
+			break;
+		default:
+			break;
+		}
+
+		if (iomap->flags & IOMAP_F_ATOMIC_BIO) {
+			/*
+			 * Ensure that the mapping covers the full write
+			 * length, otherwise it won't be submitted as a single
+			 * bio, which is required to use hardware atomics.
+			 */
+			if (length != iter->len)
+				return -EINVAL;
+			bio_opf |= REQ_ATOMIC;
+		}
+
+		if (iomap->flags & IOMAP_F_SHARED) {
+			/*
+			 * Unsharing of needs to update metadata at I/O
+			 * completion time.
+			 */
+			need_completion_work = true;
+			dio->flags |= IOMAP_DIO_COW;
+		}
+
+		if (iomap->flags & IOMAP_F_NEW) {
+			/*
+			 * Newly allocated blocks might need recording in
+			 * metadata at I/O completion time.
+			 */
+			need_completion_work = true;
+			need_zeroout = true;
+		}
+
+		/*
+		 * Use a FUA write if we need datasync semantics and this is a
+		 * pure overwrite that doesn't require any metadata updates.
+		 *
+		 * This allows us to avoid cache flushes on I/O completion.
+		 */
+		if (dio->flags & IOMAP_DIO_WRITE_THROUGH) {
+			if (!need_completion_work &&
+			    !(iomap->flags & IOMAP_F_DIRTY) &&
+			    (!bdev_write_cache(iomap->bdev) ||
+			     bdev_fua(iomap->bdev)))
+				bio_opf |= REQ_FUA;
+			else
+				dio->flags &= ~IOMAP_DIO_WRITE_THROUGH;
+		}
+
+		/*
+		 * We can only do inline completion for pure overwrites that
+		 * don't require additional I/O at completion time.
+		 *
+		 * This rules out writes that need zeroing or metdata updates to
+		 * convert unwritten or shared extents.
+		 *
+		 * Writes that extend i_size are also not supported, but this is
+		 * handled in __iomap_dio_rw().
+		 */
+		if (need_completion_work)
+			dio->flags |= IOMAP_DIO_COMP_WORK;
+
+		bio_opf |= REQ_OP_WRITE;
+	} else {
+		bio_opf |= REQ_OP_READ;
+	}
+
+	/*
+	 * Save the original count and trim the iter to just the extent we
+	 * are operating on right now.  The iter will be re-expanded once
+	 * we are done.
+	 */
+	orig_count = iov_iter_count(dio->submit.iter);
+	iov_iter_truncate(dio->submit.iter, length);
+
+	if (!iov_iter_count(dio->submit.iter))
+		goto out;
+
+	/*
+	 * The rules for polled IO completions follow the guidelines as the
+	 * ones we set for inline and deferred completions. If none of those
+	 * are available for this IO, clear the polled flag.
+	 */
+	if (dio->flags & IOMAP_DIO_COMP_WORK)
+		dio->iocb->ki_flags &= ~IOCB_HIPRI;
+
+	if (need_zeroout) {
+		/* zero out from the start of the block to the write offset */
+		pad = pos & (fs_block_size - 1);
+
+		ret = iomap_dio_zero(iter, dio, pos - pad, pad);
+		if (ret)
+			goto out;
+	}
+
+	do {
+		/*
+		 * If completions already occurred and reported errors, give up now and
+		 * don't bother submitting more bios.
+		 */
+		if (unlikely(data_race(dio->error)))
+			goto out;
+
+		ret = iomap_dio_bio_iter_one(iter, dio, pos, alignment, bio_opf);
+		if (unlikely(ret < 0)) {
+			/*
+			 * We have to stop part way through an IO. We must fall
+			 * through to the sub-block tail zeroing here, otherwise
+			 * this short IO may expose stale data in the tail of
+			 * the block we haven't written data to.
+			 */
+			break;
+		}
+		dio->size += ret;
+		copied += ret;
+		pos += ret;
+		ret = 0;
+	} while (iov_iter_count(dio->submit.iter));
+
+	/*
+	 * We need to zeroout the tail of a sub-block write if the extent type
+	 * requires zeroing or the write extends beyond EOF. If we don't zero
+	 * the block tail in the latter case, we can expose stale data via mmap
+	 * reads of the EOF block.
+	 */
+	if (need_zeroout ||
+	    ((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode))) {
+		/* zero out from the end of the write to the end of the block */
+		pad = pos & (fs_block_size - 1);
+		if (pad)
+			ret = iomap_dio_zero(iter, dio, pos,
+					     fs_block_size - pad);
+	}
+out:
+	/* Undo iter limitation to current extent */
+	iov_iter_reexpand(dio->submit.iter, orig_count - copied);
+	if (copied)
+		return iomap_iter_advance(iter, copied);
+	return ret;
+}
+
+static int iomap_dio_hole_iter(struct iomap_iter *iter, struct iomap_dio *dio)
+{
+	loff_t length = iov_iter_zero(iomap_length(iter), dio->submit.iter);
+
+	dio->size += length;
+	if (!length)
+		return -EFAULT;
+	return iomap_iter_advance(iter, length);
+}
+
+static int iomap_dio_inline_iter(struct iomap_iter *iomi, struct iomap_dio *dio)
+{
+	const struct iomap *iomap = &iomi->iomap;
+	struct iov_iter *iter = dio->submit.iter;
+	void *inline_data = iomap_inline_data(iomap, iomi->pos);
+	loff_t length = iomap_length(iomi);
+	loff_t pos = iomi->pos;
+	u64 copied;
+
+	if (WARN_ON_ONCE(!inline_data))
+		return -EIO;
+
+	if (dio->flags & IOMAP_DIO_WRITE) {
+		loff_t size = iomi->inode->i_size;
+
+		if (pos > size)
+			memset(iomap_inline_data(iomap, size), 0, pos - size);
+		copied = copy_from_iter(inline_data, length, iter);
+		if (copied) {
+			if (pos + copied > size)
+				i_size_write(iomi->inode, pos + copied);
+			mark_inode_dirty(iomi->inode);
+		}
+	} else {
+		copied = copy_to_iter(inline_data, length, iter);
+	}
+	dio->size += copied;
+	if (!copied)
+		return -EFAULT;
+	return iomap_iter_advance(iomi, copied);
+}
+
+static int iomap_dio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
+{
+	switch (iter->iomap.type) {
+	case IOMAP_HOLE:
+		if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE))
+			return -EIO;
+		return iomap_dio_hole_iter(iter, dio);
+	case IOMAP_UNWRITTEN:
+		if (!(dio->flags & IOMAP_DIO_WRITE))
+			return iomap_dio_hole_iter(iter, dio);
+		return iomap_dio_bio_iter(iter, dio);
+	case IOMAP_MAPPED:
+		return iomap_dio_bio_iter(iter, dio);
+	case IOMAP_INLINE:
+		return iomap_dio_inline_iter(iter, dio);
+	case IOMAP_DELALLOC:
+		/*
+		 * DIO is not serialised against mmap() access at all, and so
+		 * if the page_mkwrite occurs between the writeback and the
+		 * iomap_iter() call in the DIO path, then it will see the
+		 * DELALLOC block that the page-mkwrite allocated.
+		 */
+		pr_warn_ratelimited("Direct I/O collision with buffered writes! File: %pD4 Comm: %.20s\n",
+				    dio->iocb->ki_filp, current->comm);
+		return -EIO;
+	default:
+		WARN_ON_ONCE(1);
+		return -EIO;
+	}
+}
+
+/*
+ * iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO
+ * is being issued as AIO or not.  This allows us to optimise pure data writes
+ * to use REQ_FUA rather than requiring generic_write_sync() to issue a
+ * REQ_FLUSH post write. This is slightly tricky because a single request here
+ * can be mapped into multiple disjoint IOs and only a subset of the IOs issued
+ * may be pure data writes. In that case, we still need to do a full data sync
+ * completion.
+ *
+ * When page faults are disabled and @dio_flags includes IOMAP_DIO_PARTIAL,
+ * __iomap_dio_rw can return a partial result if it encounters a non-resident
+ * page in @iter after preparing a transfer.  In that case, the non-resident
+ * pages can be faulted in and the request resumed with @done_before set to the
+ * number of bytes previously transferred.  The request will then complete with
+ * the correct total number of bytes transferred; this is essential for
+ * completing partial requests asynchronously.
+ *
+ * Returns -ENOTBLK In case of a page invalidation invalidation failure for
+ * writes.  The callers needs to fall back to buffered I/O in this case.
+ */
+struct iomap_dio *
+__iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
+		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
+		unsigned int dio_flags, void *private, size_t done_before)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	struct iomap_iter iomi = {
+		.inode		= inode,
+		.pos		= iocb->ki_pos,
+		.len		= iov_iter_count(iter),
+		.flags		= IOMAP_DIRECT,
+		.private	= private,
+	};
+	bool wait_for_completion =
+		is_sync_kiocb(iocb) || (dio_flags & IOMAP_DIO_FORCE_WAIT);
+	struct blk_plug plug;
+	struct iomap_dio *dio;
+	loff_t ret = 0;
+
+	trace_iomap_dio_rw_begin(iocb, iter, dio_flags, done_before);
+
+	if (!iomi.len)
+		return NULL;
+
+	dio = kmalloc_obj(*dio);
+	if (!dio)
+		return ERR_PTR(-ENOMEM);
+
+	dio->iocb = iocb;
+	atomic_set(&dio->ref, 1);
+	dio->size = 0;
+	dio->i_size = i_size_read(inode);
+	dio->dops = dops;
+	dio->error = 0;
+	dio->flags = dio_flags & (IOMAP_DIO_FSBLOCK_ALIGNED | IOMAP_DIO_BOUNCE);
+	dio->done_before = done_before;
+
+	dio->submit.iter = iter;
+	dio->submit.waiter = current;
+
+	if (iocb->ki_flags & IOCB_NOWAIT)
+		iomi.flags |= IOMAP_NOWAIT;
+
+	if (iov_iter_rw(iter) == READ) {
+		if (iomi.pos >= dio->i_size)
+			goto out_free_dio;
+
+		if (user_backed_iter(iter))
+			dio->flags |= IOMAP_DIO_USER_BACKED;
+
+		ret = kiocb_write_and_wait(iocb, iomi.len);
+		if (ret)
+			goto out_free_dio;
+	} else {
+		iomi.flags |= IOMAP_WRITE;
+		dio->flags |= IOMAP_DIO_WRITE;
+
+		if (dio_flags & IOMAP_DIO_OVERWRITE_ONLY) {
+			ret = -EAGAIN;
+			if (iomi.pos >= dio->i_size ||
+			    iomi.pos + iomi.len > dio->i_size)
+				goto out_free_dio;
+			iomi.flags |= IOMAP_OVERWRITE_ONLY;
+		}
+
+		if (iocb->ki_flags & IOCB_ATOMIC)
+			iomi.flags |= IOMAP_ATOMIC;
+
+		/* for data sync or sync, we need sync completion processing */
+		if (iocb_is_dsync(iocb)) {
+			dio->flags |= IOMAP_DIO_NEED_SYNC;
+
+		       /*
+			* For datasync only writes, we optimistically try using
+			* WRITE_THROUGH for this IO. This flag requires either
+			* FUA writes through the device's write cache, or a
+			* normal write to a device without a volatile write
+			* cache. For the former, Any non-FUA write that occurs
+			* will clear this flag, hence we know before completion
+			* whether a cache flush is necessary.
+			*/
+			if (!(iocb->ki_flags & IOCB_SYNC))
+				dio->flags |= IOMAP_DIO_WRITE_THROUGH;
+		}
+
+		/*
+		 * i_size updates must to happen from process context.
+		 */
+		if (iomi.pos + iomi.len > dio->i_size)
+			dio->flags |= IOMAP_DIO_COMP_WORK;
+
+		/*
+		 * Try to invalidate cache pages for the range we are writing.
+		 * If this invalidation fails, let the caller fall back to
+		 * buffered I/O.
+		 */
+		ret = kiocb_invalidate_pages(iocb, iomi.len);
+		if (ret) {
+			if (ret != -EAGAIN) {
+				trace_iomap_dio_invalidate_fail(inode, iomi.pos,
+								iomi.len);
+				if (iocb->ki_flags & IOCB_ATOMIC) {
+					/*
+					 * folio invalidation failed, maybe
+					 * this is transient, unlock and see if
+					 * the caller tries again.
+					 */
+					ret = -EAGAIN;
+				} else {
+					/* fall back to buffered write */
+					ret = -ENOTBLK;
+				}
+			}
+			goto out_free_dio;
+		}
+	}
+
+	if (!wait_for_completion && !inode->i_sb->s_dio_done_wq) {
+		ret = sb_init_dio_done_wq(inode->i_sb);
+		if (ret < 0)
+			goto out_free_dio;
+	}
+
+	inode_dio_begin(inode);
+
+	blk_start_plug(&plug);
+	while ((ret = iomap_iter(&iomi, ops)) > 0) {
+		iomi.status = iomap_dio_iter(&iomi, dio);
+
+		/*
+		 * We can only poll for single bio I/Os.
+		 */
+		iocb->ki_flags &= ~IOCB_HIPRI;
+	}
+
+	blk_finish_plug(&plug);
+
+	/*
+	 * We only report that we've read data up to i_size.
+	 * Revert iter to a state corresponding to that as some callers (such
+	 * as the splice code) rely on it.
+	 */
+	if (iov_iter_rw(iter) == READ && iomi.pos >= dio->i_size)
+		iov_iter_revert(iter, iomi.pos - dio->i_size);
+
+	if (ret == -EFAULT && dio->size && (dio_flags & IOMAP_DIO_PARTIAL)) {
+		if (!(iocb->ki_flags & IOCB_NOWAIT))
+			wait_for_completion = true;
+		ret = 0;
+	}
+
+	/* magic error code to fall back to buffered I/O */
+	if (ret == -ENOTBLK) {
+		wait_for_completion = true;
+		ret = 0;
+	}
+	if (ret < 0)
+		iomap_dio_set_error(dio, ret);
+
+	/*
+	 * If all the writes we issued were already written through to the
+	 * media, we don't need to flush the cache on IO completion. Clear the
+	 * sync flag for this case.
+	 *
+	 * Otherwise clear the inline completion flag if any sync work is
+	 * needed, as that needs to be performed from process context.
+	 */
+	if (dio->flags & IOMAP_DIO_WRITE_THROUGH)
+		dio->flags &= ~IOMAP_DIO_NEED_SYNC;
+	else if (dio->flags & IOMAP_DIO_NEED_SYNC)
+		dio->flags |= IOMAP_DIO_COMP_WORK;
+
+	/*
+	 * We are about to drop our additional submission reference, which
+	 * might be the last reference to the dio.  There are three different
+	 * ways we can progress here:
+	 *
+	 *  (a) If this is the last reference we will always complete and free
+	 *	the dio ourselves.
+	 *  (b) If this is not the last reference, and we serve an asynchronous
+	 *	iocb, we must never touch the dio after the decrement, the
+	 *	I/O completion handler will complete and free it.
+	 *  (c) If this is not the last reference, but we serve a synchronous
+	 *	iocb, the I/O completion handler will wake us up on the drop
+	 *	of the final reference, and we will complete and free it here
+	 *	after we got woken by the I/O completion handler.
+	 */
+	dio->wait_for_completion = wait_for_completion;
+	if (!atomic_dec_and_test(&dio->ref)) {
+		if (!wait_for_completion) {
+			trace_iomap_dio_rw_queued(inode, iomi.pos, iomi.len);
+			return ERR_PTR(-EIOCBQUEUED);
+		}
+
+		for (;;) {
+			set_current_state(TASK_UNINTERRUPTIBLE);
+			if (!READ_ONCE(dio->submit.waiter))
+				break;
+
+			blk_io_schedule();
+		}
+		__set_current_state(TASK_RUNNING);
+	}
+
+	return dio;
+
+out_free_dio:
+	kfree(dio);
+	if (ret)
+		return ERR_PTR(ret);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(__iomap_dio_rw);
+
+ssize_t
+iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
+		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
+		unsigned int dio_flags, void *private, size_t done_before)
+{
+	struct iomap_dio *dio;
+
+	dio = __iomap_dio_rw(iocb, iter, ops, dops, dio_flags, private,
+			     done_before);
+	if (IS_ERR_OR_NULL(dio))
+		return PTR_ERR_OR_ZERO(dio);
+	return iomap_dio_complete(dio);
+}
+EXPORT_SYMBOL_GPL(iomap_dio_rw);
+
+struct iomap_dio_simple {
+	struct kiocb		*iocb;
+	size_t			size;
+	unsigned int		dio_flags;
+	struct work_struct	work;
+	/*
+	 * Align @bio to a cacheline boundary so that, combined with the
+	 * front_pad passed to bioset_init(), the bio sits at the start of
+	 * a cacheline in memory returned by the (HWCACHE-aligned) bio
+	 * slab.  This keeps the hot fields block layer touches on submit
+	 * and completion (bi_iter, bi_status, ...) within a single line.
+	 */
+	struct bio		bio ____cacheline_aligned_in_smp;
+};
+
+static struct bio_set iomap_dio_simple_pool;
+
+static ssize_t iomap_dio_simple_complete(struct iomap_dio_simple *sr)
+{
+	struct bio *bio = &sr->bio;
+	struct kiocb *iocb = sr->iocb;
+	struct inode *inode = file_inode(iocb->ki_filp);
+	ssize_t ret;
+
+	if (unlikely(bio->bi_status)) {
+		ret = blk_status_to_errno(bio->bi_status);
+		if (should_report_dio_fserror(ret))
+			fserror_report_io(inode, FSERR_DIRECTIO_READ,
+					  iocb->ki_pos, sr->size, ret,
+					  GFP_NOFS);
+	} else {
+		ret = sr->size;
+		iocb->ki_pos += ret;
+	}
+
+	if (sr->dio_flags & IOMAP_DIO_USER_BACKED) {
+		bio_check_pages_dirty(bio);
+	} else {
+		bio_release_pages(bio, false);
+		bio_put(bio);
+	}
+	inode_dio_end(inode);
+	trace_iomap_dio_complete(iocb, ret < 0 ? ret : 0, ret);
+	return ret;
+}
+
+static void iomap_dio_simple_complete_work(struct work_struct *work)
+{
+	struct iomap_dio_simple *sr =
+		container_of(work, struct iomap_dio_simple, work);
+	struct kiocb *iocb = sr->iocb;
+
+	WRITE_ONCE(iocb->private, NULL);
+	iocb->ki_complete(iocb, iomap_dio_simple_complete(sr));
+}
+
+static void iomap_dio_simple_end_io(struct bio *bio)
+{
+	struct iomap_dio_simple *sr =
+		container_of(bio, struct iomap_dio_simple, bio);
+	struct kiocb *iocb = sr->iocb;
+
+	if (unlikely(sr->bio.bi_status)) {
+		struct inode *inode = file_inode(iocb->ki_filp);
+
+		INIT_WORK(&sr->work, iomap_dio_simple_complete_work);
+		queue_work(inode->i_sb->s_dio_done_wq, &sr->work);
+		return;
+	}
+
+	WRITE_ONCE(iocb->private, NULL);
+	iocb->ki_complete(iocb, iomap_dio_simple_complete(sr));
+}
+
+ssize_t __iomap_dio_read_simple(struct kiocb *iocb, struct iov_iter *iter,
+		struct iomap_iter *iomi)
+{
+	gfp_t gfp = (iomi->flags & IOMAP_NOWAIT) ? GFP_NOWAIT : GFP_KERNEL;
+	struct iomap_dio_simple *sr;
+	unsigned int alignment;
+	struct bio *bio;
+	ssize_t ret;
+
+	if (iomi->iomap.type != IOMAP_MAPPED ||
+	    iomi->iomap.offset + iomi->iomap.length < iomi->pos + iomi->len ||
+	    (iomi->iomap.flags & IOMAP_F_INTEGRITY)) {
+		ret = -ENOTBLK;
+		goto out_dio_end;
+	}
+
+	alignment = iomap_dio_alignment(iomi->inode, iomi->iomap.bdev, 0);
+	if ((iomi->pos | iomi->len) & (alignment - 1)) {
+		ret = -EINVAL;
+		goto out_dio_end;
+	}
+
+	if (unlikely(!iomi->inode->i_sb->s_dio_done_wq &&
+			!is_sync_kiocb(iocb))) {
+		ret = sb_init_dio_done_wq(iomi->inode->i_sb);
+		if (ret < 0)
+			goto out_dio_end;
+	}
+
+	trace_iomap_dio_rw_begin(iocb, iter, 0, 0);
+
+	bio = bio_alloc_bioset(iomi->iomap.bdev,
+			       bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS),
+			       REQ_OP_READ, gfp, &iomap_dio_simple_pool);
+	if (!bio) {
+		ret = -EAGAIN;
+		goto out_dio_end;
+	}
+	sr = container_of(bio, struct iomap_dio_simple, bio);
+	sr->iocb = iocb;
+	sr->dio_flags = 0;
+
+	bio->bi_iter.bi_sector = iomap_sector(&iomi->iomap, iomi->pos);
+	bio->bi_ioprio = iocb->ki_ioprio;
+
+	ret = bio_iov_iter_get_pages(bio, iter, alignment - 1);
+	if (unlikely(ret))
+		goto out_bio_put;
+
+	if (bio->bi_iter.bi_size != iomi->len) {
+		iov_iter_revert(iter, bio->bi_iter.bi_size);
+		ret = -ENOTBLK;
+		goto out_bio_release_pages;
+	}
+
+	sr->size = bio->bi_iter.bi_size;
+	if (user_backed_iter(iter)) {
+		bio_set_pages_dirty(bio);
+		sr->dio_flags |= IOMAP_DIO_USER_BACKED;
+	}
+
+	if (iocb->ki_flags & IOCB_NOWAIT)
+		bio->bi_opf |= REQ_NOWAIT;
+
+	if (is_sync_kiocb(iocb)) {
+		submit_bio_wait(bio);
+		return iomap_dio_simple_complete(sr);
+	}
+
+	if ((iocb->ki_flags & IOCB_HIPRI)) {
+		bio->bi_opf |= REQ_POLLED;
+		WRITE_ONCE(iocb->private, bio);
+	}
+	bio->bi_end_io = iomap_dio_simple_end_io;
+	submit_bio(bio);
+	trace_iomap_dio_rw_queued(iomi->inode, iocb->ki_pos, iomi->len);
+	return -EIOCBQUEUED;
+
+out_bio_release_pages:
+	bio_release_pages(bio, false);
+out_bio_put:
+	bio_put(bio);
+out_dio_end:
+	inode_dio_end(iomi->inode);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__iomap_dio_read_simple);
+
+static int __init iomap_dio_init(void)
+{
+	return bioset_init(&iomap_dio_simple_pool, 4,
+			   offsetof(struct iomap_dio_simple, bio),
+			   BIOSET_NEED_BVECS | BIOSET_PERCPU_CACHE);
+}
+fs_initcall(iomap_dio_init);