iomap: move the direct IO code into a separate file (db074436) · Commits · e / devices / android_kernel_fairphone_FP5

fs/iomap.c

+0 −554

Original line number	Diff line number	Diff line
		@@ -90,12 +90,6 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
		return written ? written : ret;
		}

		static sector_t
		iomap_sector(struct iomap *iomap, loff_t pos)
		{
		return (iomap->addr + pos - iomap->offset) >> SECTOR_SHIFT;
		}

		static struct iomap_page *
		iomap_page_create(struct inode inode, struct page page)
		{
		@@ -1148,551 +1142,3 @@ vm_fault_t iomap_page_mkwrite(struct vm_fault vmf, const struct iomap_ops ops)
		return block_page_mkwrite_return(ret);
		}
		EXPORT_SYMBOL_GPL(iomap_page_mkwrite);

		/*
		* Private flags for iomap_dio, must not overlap with the public ones in
		* iomap.h:
		*/
		#define IOMAP_DIO_WRITE_FUA (1 << 28)
		#define IOMAP_DIO_NEED_SYNC (1 << 29)
		#define IOMAP_DIO_WRITE (1 << 30)
		#define IOMAP_DIO_DIRTY (1 << 31)

		struct iomap_dio {
		struct kiocb *iocb;
		iomap_dio_end_io_t *end_io;
		loff_t i_size;
		loff_t size;
		atomic_t ref;
		unsigned flags;
		int error;
		bool wait_for_completion;

		union {
		/* used during submission and for synchronous completion: */
		struct {
		struct iov_iter *iter;
		struct task_struct *waiter;
		struct request_queue *last_queue;
		blk_qc_t cookie;
		} submit;

		/* used for aio completion: */
		struct {
		struct work_struct work;
		} aio;
		};
		};

		int iomap_dio_iopoll(struct kiocb *kiocb, bool spin)
		{
		struct request_queue *q = READ_ONCE(kiocb->private);

		if (!q)
		return 0;
		return blk_poll(q, READ_ONCE(kiocb->ki_cookie), spin);
		}
		EXPORT_SYMBOL_GPL(iomap_dio_iopoll);

		static void iomap_dio_submit_bio(struct iomap_dio dio, struct iomap iomap,
		struct bio *bio)
		{
		atomic_inc(&dio->ref);

		if (dio->iocb->ki_flags & IOCB_HIPRI)
		bio_set_polled(bio, dio->iocb);

		dio->submit.last_queue = bdev_get_queue(iomap->bdev);
		dio->submit.cookie = submit_bio(bio);
		}

		static ssize_t iomap_dio_complete(struct iomap_dio *dio)
		{
		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,
		dio->error ? dio->error : dio->size,
		dio->flags);
		} else {
		ret = dio->error;
		}

		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;
		iocb->ki_pos += ret;
		}

		/*
		* 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 dio->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->flags & IOMAP_DIO_WRITE) && inode->i_mapping->nrpages) {
		int err;
		err = invalidate_inode_pages2_range(inode->i_mapping,
		offset >> PAGE_SHIFT,
		(offset + dio->size - 1) >> PAGE_SHIFT);
		if (err)
		dio_warn_stale_pagecache(iocb->ki_filp);
		}

		/*
		* If this is a DSYNC write, make sure we push it to stable storage now
		* that we've written data.
		*/
		if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC))
		ret = generic_write_sync(iocb, ret);

		inode_dio_end(file_inode(iocb->ki_filp));
		kfree(dio);

		return ret;
		}

		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), 0);
		}

		/*
		* 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);
		}

		static void iomap_dio_bio_end_io(struct bio *bio)
		{
		struct iomap_dio *dio = bio->bi_private;
		bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);

		if (bio->bi_status)
		iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status));

		if (atomic_dec_and_test(&dio->ref)) {
		if (dio->wait_for_completion) {
		struct task_struct *waiter = dio->submit.waiter;
		WRITE_ONCE(dio->submit.waiter, NULL);
		blk_wake_io_task(waiter);
		} else if (dio->flags & IOMAP_DIO_WRITE) {
		struct inode *inode = file_inode(dio->iocb->ki_filp);

		INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
		queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work);
		} else {
		iomap_dio_complete_work(&dio->aio.work);
		}
		}

		if (should_dirty) {
		bio_check_pages_dirty(bio);
		} else {
		bio_release_pages(bio, false);
		bio_put(bio);
		}
		}

		static void
		iomap_dio_zero(struct iomap_dio dio, struct iomap iomap, loff_t pos,
		unsigned len)
		{
		struct page *page = ZERO_PAGE(0);
		int flags = REQ_SYNC \| REQ_IDLE;
		struct bio *bio;

		bio = bio_alloc(GFP_KERNEL, 1);
		bio_set_dev(bio, iomap->bdev);
		bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
		bio->bi_private = dio;
		bio->bi_end_io = iomap_dio_bio_end_io;

		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);
		}

		static loff_t
		iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
		struct iomap_dio dio, struct iomap iomap)
		{
		unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev));
		unsigned int fs_block_size = i_blocksize(inode), pad;
		unsigned int align = iov_iter_alignment(dio->submit.iter);
		struct iov_iter iter;
		struct bio *bio;
		bool need_zeroout = false;
		bool use_fua = false;
		int nr_pages, ret = 0;
		size_t copied = 0;

		if ((pos \| length \| align) & ((1 << blkbits) - 1))
		return -EINVAL;

		if (iomap->type == IOMAP_UNWRITTEN) {
		dio->flags \|= IOMAP_DIO_UNWRITTEN;
		need_zeroout = true;
		}

		if (iomap->flags & IOMAP_F_SHARED)
		dio->flags \|= IOMAP_DIO_COW;

		if (iomap->flags & IOMAP_F_NEW) {
		need_zeroout = true;
		} else if (iomap->type == IOMAP_MAPPED) {
		/*
		* Use a FUA write if we need datasync semantics, this is a pure
		* data IO that doesn't require any metadata updates (including
		* after IO completion such as unwritten extent conversion) and
		* the underlying device supports FUA. This allows us to avoid
		* cache flushes on IO completion.
		*/
		if (!(iomap->flags & (IOMAP_F_SHARED\|IOMAP_F_DIRTY)) &&
		(dio->flags & IOMAP_DIO_WRITE_FUA) &&
		blk_queue_fua(bdev_get_queue(iomap->bdev)))
		use_fua = true;
		}

		/*
		* Operate on a partial iter trimmed to the extent we were called for.
		* We'll update the iter in the dio once we're done with this extent.
		*/
		iter = *dio->submit.iter;
		iov_iter_truncate(&iter, length);

		nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
		if (nr_pages <= 0)
		return nr_pages;

		if (need_zeroout) {
		/* zero out from the start of the block to the write offset */
		pad = pos & (fs_block_size - 1);
		if (pad)
		iomap_dio_zero(dio, iomap, pos - pad, pad);
		}

		do {
		size_t n;
		if (dio->error) {
		iov_iter_revert(dio->submit.iter, copied);
		return 0;
		}

		bio = bio_alloc(GFP_KERNEL, nr_pages);
		bio_set_dev(bio, iomap->bdev);
		bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
		bio->bi_write_hint = dio->iocb->ki_hint;
		bio->bi_ioprio = dio->iocb->ki_ioprio;
		bio->bi_private = dio;
		bio->bi_end_io = iomap_dio_bio_end_io;

		ret = bio_iov_iter_get_pages(bio, &iter);
		if (unlikely(ret)) {
		/*
		* 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.
		*/
		bio_put(bio);
		goto zero_tail;
		}

		n = bio->bi_iter.bi_size;
		if (dio->flags & IOMAP_DIO_WRITE) {
		bio->bi_opf = REQ_OP_WRITE \| REQ_SYNC \| REQ_IDLE;
		if (use_fua)
		bio->bi_opf \|= REQ_FUA;
		else
		dio->flags &= ~IOMAP_DIO_WRITE_FUA;
		task_io_account_write(n);
		} else {
		bio->bi_opf = REQ_OP_READ;
		if (dio->flags & IOMAP_DIO_DIRTY)
		bio_set_pages_dirty(bio);
		}

		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);
		} while (nr_pages);

		/*
		* 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.
		*/
		zero_tail:
		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)
		iomap_dio_zero(dio, iomap, pos, fs_block_size - pad);
		}
		return copied ? copied : ret;
		}

		static loff_t
		iomap_dio_hole_actor(loff_t length, struct iomap_dio *dio)
		{
		length = iov_iter_zero(length, dio->submit.iter);
		dio->size += length;
		return length;
		}

		static loff_t
		iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length,
		struct iomap_dio dio, struct iomap iomap)
		{
		struct iov_iter *iter = dio->submit.iter;
		size_t copied;

		BUG_ON(pos + length > PAGE_SIZE - offset_in_page(iomap->inline_data));

		if (dio->flags & IOMAP_DIO_WRITE) {
		loff_t size = inode->i_size;

		if (pos > size)
		memset(iomap->inline_data + size, 0, pos - size);
		copied = copy_from_iter(iomap->inline_data + pos, length, iter);
		if (copied) {
		if (pos + copied > size)
		i_size_write(inode, pos + copied);
		mark_inode_dirty(inode);
		}
		} else {
		copied = copy_to_iter(iomap->inline_data + pos, length, iter);
		}
		dio->size += copied;
		return copied;
		}

		static loff_t
		iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
		void data, struct iomap iomap)
		{
		struct iomap_dio *dio = data;

		switch (iomap->type) {
		case IOMAP_HOLE:
		if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE))
		return -EIO;
		return iomap_dio_hole_actor(length, dio);
		case IOMAP_UNWRITTEN:
		if (!(dio->flags & IOMAP_DIO_WRITE))
		return iomap_dio_hole_actor(length, dio);
		return iomap_dio_bio_actor(inode, pos, length, dio, iomap);
		case IOMAP_MAPPED:
		return iomap_dio_bio_actor(inode, pos, length, dio, iomap);
		case IOMAP_INLINE:
		return iomap_dio_inline_actor(inode, pos, length, dio, iomap);
		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.
		*/
		ssize_t
		iomap_dio_rw(struct kiocb iocb, struct iov_iter iter,
		const struct iomap_ops *ops, iomap_dio_end_io_t end_io)
		{
		struct address_space *mapping = iocb->ki_filp->f_mapping;
		struct inode *inode = file_inode(iocb->ki_filp);
		size_t count = iov_iter_count(iter);
		loff_t pos = iocb->ki_pos, start = pos;
		loff_t end = iocb->ki_pos + count - 1, ret = 0;
		unsigned int flags = IOMAP_DIRECT;
		bool wait_for_completion = is_sync_kiocb(iocb);
		struct blk_plug plug;
		struct iomap_dio *dio;

		lockdep_assert_held(&inode->i_rwsem);

		if (!count)
		return 0;

		dio = kmalloc(sizeof(*dio), GFP_KERNEL);
		if (!dio)
		return -ENOMEM;

		dio->iocb = iocb;
		atomic_set(&dio->ref, 1);
		dio->size = 0;
		dio->i_size = i_size_read(inode);
		dio->end_io = end_io;
		dio->error = 0;
		dio->flags = 0;

		dio->submit.iter = iter;
		dio->submit.waiter = current;
		dio->submit.cookie = BLK_QC_T_NONE;
		dio->submit.last_queue = NULL;

		if (iov_iter_rw(iter) == READ) {
		if (pos >= dio->i_size)
		goto out_free_dio;

		if (iter_is_iovec(iter) && iov_iter_rw(iter) == READ)
		dio->flags \|= IOMAP_DIO_DIRTY;
		} else {
		flags \|= IOMAP_WRITE;
		dio->flags \|= IOMAP_DIO_WRITE;

		/* for data sync or sync, we need sync completion processing */
		if (iocb->ki_flags & IOCB_DSYNC)
		dio->flags \|= IOMAP_DIO_NEED_SYNC;

		/*
		* For datasync only writes, we optimistically try using FUA for
		* this IO. 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_DSYNC \| IOCB_SYNC)) == IOCB_DSYNC)
		dio->flags \|= IOMAP_DIO_WRITE_FUA;
		}

		if (iocb->ki_flags & IOCB_NOWAIT) {
		if (filemap_range_has_page(mapping, start, end)) {
		ret = -EAGAIN;
		goto out_free_dio;
		}
		flags \|= IOMAP_NOWAIT;
		}

		ret = filemap_write_and_wait_range(mapping, start, end);
		if (ret)
		goto out_free_dio;

		/*
		* Try to invalidate cache pages for the range we're direct
		* writing. If this invalidation fails, tough, the write will
		* still work, but racing two incompatible write paths is a
		* pretty crazy thing to do, so we don't support it 100%.
		*/
		ret = invalidate_inode_pages2_range(mapping,
		start >> PAGE_SHIFT, end >> PAGE_SHIFT);
		if (ret)
		dio_warn_stale_pagecache(iocb->ki_filp);
		ret = 0;

		if (iov_iter_rw(iter) == WRITE && !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);
		do {
		ret = iomap_apply(inode, pos, count, flags, ops, dio,
		iomap_dio_actor);
		if (ret <= 0) {
		/* magic error code to fall back to buffered I/O */
		if (ret == -ENOTBLK) {
		wait_for_completion = true;
		ret = 0;
		}
		break;
		}
		pos += ret;

		if (iov_iter_rw(iter) == READ && pos >= dio->i_size)
		break;
		} while ((count = iov_iter_count(iter)) > 0);
		blk_finish_plug(&plug);

		if (ret < 0)
		iomap_dio_set_error(dio, ret);

		/*
		* If all the writes we issued were FUA, we don't need to flush the
		* cache on IO completion. Clear the sync flag for this case.
		*/
		if (dio->flags & IOMAP_DIO_WRITE_FUA)
		dio->flags &= ~IOMAP_DIO_NEED_SYNC;

		WRITE_ONCE(iocb->ki_cookie, dio->submit.cookie);
		WRITE_ONCE(iocb->private, dio->submit.last_queue);

		/*
		* We are about to drop our additional submission reference, which
		* might be the last reference to the dio. There are three 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)
		return -EIOCBQUEUED;

		for (;;) {
		set_current_state(TASK_UNINTERRUPTIBLE);
		if (!READ_ONCE(dio->submit.waiter))
		break;

		if (!(iocb->ki_flags & IOCB_HIPRI) \|\|
		!dio->submit.last_queue \|\|
		!blk_poll(dio->submit.last_queue,
		dio->submit.cookie, true))
		io_schedule();
		}
		__set_current_state(TASK_RUNNING);
		}

		return iomap_dio_complete(dio);

		out_free_dio:
		kfree(dio);
		return ret;
		}
		EXPORT_SYMBOL_GPL(iomap_dio_rw);

fs/iomap/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -6,6 +6,7 @@
		obj-$(CONFIG_FS_IOMAP) += iomap.o

		iomap-y += \
		direct-io.o \
		fiemap.o \
		seek.o

fs/iomap/direct-io.c

0 → 100644

+562 −0

File added.

Preview size limit exceeded, changes collapsed.

include/linux/iomap.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -7,6 +7,7 @@
		#include <linux/mm.h>
		#include <linux/types.h>
		#include <linux/mm_types.h>
		#include <linux/blkdev.h>

		struct address_space;
		struct fiemap_extent_info;
		@@ -69,6 +70,12 @@ struct iomap {
		const struct iomap_page_ops *page_ops;
		};

		static inline sector_t
		iomap_sector(struct iomap *iomap, loff_t pos)
		{
		return (iomap->addr + pos - iomap->offset) >> SECTOR_SHIFT;
		}

		/*
		* When a filesystem sets page_ops in an iomap mapping it returns, page_prepare
		* and page_done will be called for each page written to. This only applies to