1 files changed, 679 insertions, 0 deletions

diff --git a/fs/bcachefs/fs-io-direct.c b/fs/bcachefs/fs-io-direct.c
new file mode 100644
index 000000000000..6a9557e7ecab
--- /dev/null
+++ b/fs/bcachefs/fs-io-direct.c
@@ -0,0 +1,679 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef NO_BCACHEFS_FS
+
+#include "bcachefs.h"
+#include "alloc_foreground.h"
+#include "fs.h"
+#include "fs-io.h"
+#include "fs-io-direct.h"
+#include "fs-io-pagecache.h"
+#include "io_read.h"
+#include "io_write.h"
+
+#include <linux/kthread.h>
+#include <linux/pagemap.h>
+#include <linux/prefetch.h>
+#include <linux/task_io_accounting_ops.h>
+
+/* O_DIRECT reads */
+
+struct dio_read {
+	struct closure			cl;
+	struct kiocb			*req;
+	long				ret;
+	bool				should_dirty;
+	struct bch_read_bio		rbio;
+};
+
+static void bio_check_or_release(struct bio *bio, bool check_dirty)
+{
+	if (check_dirty) {
+		bio_check_pages_dirty(bio);
+	} else {
+		bio_release_pages(bio, false);
+		bio_put(bio);
+	}
+}
+
+static void bch2_dio_read_complete(struct closure *cl)
+{
+	struct dio_read *dio = container_of(cl, struct dio_read, cl);
+
+	dio->req->ki_complete(dio->req, dio->ret);
+	bio_check_or_release(&dio->rbio.bio, dio->should_dirty);
+}
+
+static void bch2_direct_IO_read_endio(struct bio *bio)
+{
+	struct dio_read *dio = bio->bi_private;
+
+	if (bio->bi_status)
+		dio->ret = blk_status_to_errno(bio->bi_status);
+
+	closure_put(&dio->cl);
+}
+
+static void bch2_direct_IO_read_split_endio(struct bio *bio)
+{
+	struct dio_read *dio = bio->bi_private;
+	bool should_dirty = dio->should_dirty;
+
+	bch2_direct_IO_read_endio(bio);
+	bio_check_or_release(bio, should_dirty);
+}
+
+static int bch2_direct_IO_read(struct kiocb *req, struct iov_iter *iter)
+{
+	struct file *file = req->ki_filp;
+	struct bch_inode_info *inode = file_bch_inode(file);
+	struct bch_fs *c = inode->v.i_sb->s_fs_info;
+	struct bch_io_opts opts;
+	struct dio_read *dio;
+	struct bio *bio;
+	loff_t offset = req->ki_pos;
+	bool sync = is_sync_kiocb(req);
+	size_t shorten;
+	ssize_t ret;
+
+	bch2_inode_opts_get(&opts, c, &inode->ei_inode);
+
+	if ((offset|iter->count) & (block_bytes(c) - 1))
+		return -EINVAL;
+
+	ret = min_t(loff_t, iter->count,
+		    max_t(loff_t, 0, i_size_read(&inode->v) - offset));
+
+	if (!ret)
+		return ret;
+
+	shorten = iov_iter_count(iter) - round_up(ret, block_bytes(c));
+	iter->count -= shorten;
+
+	bio = bio_alloc_bioset(NULL,
+			       bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS),
+			       REQ_OP_READ,
+			       GFP_KERNEL,
+			       &c->dio_read_bioset);
+
+	bio->bi_end_io = bch2_direct_IO_read_endio;
+
+	dio = container_of(bio, struct dio_read, rbio.bio);
+	closure_init(&dio->cl, NULL);
+
+	/*
+	 * this is a _really_ horrible hack just to avoid an atomic sub at the
+	 * end:
+	 */
+	if (!sync) {
+		set_closure_fn(&dio->cl, bch2_dio_read_complete, NULL);
+		atomic_set(&dio->cl.remaining,
+			   CLOSURE_REMAINING_INITIALIZER -
+			   CLOSURE_RUNNING +
+			   CLOSURE_DESTRUCTOR);
+	} else {
+		atomic_set(&dio->cl.remaining,
+			   CLOSURE_REMAINING_INITIALIZER + 1);
+	}
+
+	dio->req	= req;
+	dio->ret	= ret;
+	/*
+	 * This is one of the sketchier things I've encountered: we have to skip
+	 * the dirtying of requests that are internal from the kernel (i.e. from
+	 * loopback), because we'll deadlock on page_lock.
+	 */
+	dio->should_dirty = iter_is_iovec(iter);
+
+	goto start;
+	while (iter->count) {
+		bio = bio_alloc_bioset(NULL,
+				       bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS),
+				       REQ_OP_READ,
+				       GFP_KERNEL,
+				       &c->bio_read);
+		bio->bi_end_io		= bch2_direct_IO_read_split_endio;
+start:
+		bio->bi_opf		= REQ_OP_READ|REQ_SYNC;
+		bio->bi_iter.bi_sector	= offset >> 9;
+		bio->bi_private		= dio;
+
+		ret = bio_iov_iter_get_pages(bio, iter);
+		if (ret < 0) {
+			/* XXX: fault inject this path */
+			bio->bi_status = BLK_STS_RESOURCE;
+			bio_endio(bio);
+			break;
+		}
+
+		offset += bio->bi_iter.bi_size;
+
+		if (dio->should_dirty)
+			bio_set_pages_dirty(bio);
+
+		if (iter->count)
+			closure_get(&dio->cl);
+
+		bch2_read(c, rbio_init(bio, opts), inode_inum(inode));
+	}
+
+	iter->count += shorten;
+
+	if (sync) {
+		closure_sync(&dio->cl);
+		closure_debug_destroy(&dio->cl);
+		ret = dio->ret;
+		bio_check_or_release(&dio->rbio.bio, dio->should_dirty);
+		return ret;
+	} else {
+		return -EIOCBQUEUED;
+	}
+}
+
+ssize_t bch2_read_iter(struct kiocb *iocb, struct iov_iter *iter)
+{
+	struct file *file = iocb->ki_filp;
+	struct bch_inode_info *inode = file_bch_inode(file);
+	struct address_space *mapping = file->f_mapping;
+	size_t count = iov_iter_count(iter);
+	ssize_t ret;
+
+	if (!count)
+		return 0; /* skip atime */
+
+	if (iocb->ki_flags & IOCB_DIRECT) {
+		struct blk_plug plug;
+
+		if (unlikely(mapping->nrpages)) {
+			ret = filemap_write_and_wait_range(mapping,
+						iocb->ki_pos,
+						iocb->ki_pos + count - 1);
+			if (ret < 0)
+				goto out;
+		}
+
+		file_accessed(file);
+
+		blk_start_plug(&plug);
+		ret = bch2_direct_IO_read(iocb, iter);
+		blk_finish_plug(&plug);
+
+		if (ret >= 0)
+			iocb->ki_pos += ret;
+	} else {
+		bch2_pagecache_add_get(inode);
+		ret = generic_file_read_iter(iocb, iter);
+		bch2_pagecache_add_put(inode);
+	}
+out:
+	return bch2_err_class(ret);
+}
+
+/* O_DIRECT writes */
+
+struct dio_write {
+	struct kiocb			*req;
+	struct address_space		*mapping;
+	struct bch_inode_info		*inode;
+	struct mm_struct		*mm;
+	unsigned			loop:1,
+					extending:1,
+					sync:1,
+					flush:1,
+					free_iov:1;
+	struct quota_res		quota_res;
+	u64				written;
+
+	struct iov_iter			iter;
+	struct iovec			inline_vecs[2];
+
+	/* must be last: */
+	struct bch_write_op		op;
+};
+
+static bool bch2_check_range_allocated(struct bch_fs *c, subvol_inum inum,
+				       u64 offset, u64 size,
+				       unsigned nr_replicas, bool compressed)
+{
+	struct btree_trans *trans = bch2_trans_get(c);
+	struct btree_iter iter;
+	struct bkey_s_c k;
+	u64 end = offset + size;
+	u32 snapshot;
+	bool ret = true;
+	int err;
+retry:
+	bch2_trans_begin(trans);
+
+	err = bch2_subvolume_get_snapshot(trans, inum.subvol, &snapshot);
+	if (err)
+		goto err;
+
+	for_each_btree_key_norestart(trans, iter, BTREE_ID_extents,
+			   SPOS(inum.inum, offset, snapshot),
+			   BTREE_ITER_SLOTS, k, err) {
+		if (bkey_ge(bkey_start_pos(k.k), POS(inum.inum, end)))
+			break;
+
+		if (k.k->p.snapshot != snapshot ||
+		    nr_replicas > bch2_bkey_replicas(c, k) ||
+		    (!compressed && bch2_bkey_sectors_compressed(k))) {
+			ret = false;
+			break;
+		}
+	}
+
+	offset = iter.pos.offset;
+	bch2_trans_iter_exit(trans, &iter);
+err:
+	if (bch2_err_matches(err, BCH_ERR_transaction_restart))
+		goto retry;
+	bch2_trans_put(trans);
+
+	return err ? false : ret;
+}
+
+static noinline bool bch2_dio_write_check_allocated(struct dio_write *dio)
+{
+	struct bch_fs *c = dio->op.c;
+	struct bch_inode_info *inode = dio->inode;
+	struct bio *bio = &dio->op.wbio.bio;
+
+	return bch2_check_range_allocated(c, inode_inum(inode),
+				dio->op.pos.offset, bio_sectors(bio),
+				dio->op.opts.data_replicas,
+				dio->op.opts.compression != 0);
+}
+
+static void bch2_dio_write_loop_async(struct bch_write_op *);
+static __always_inline long bch2_dio_write_done(struct dio_write *dio);
+
+/*
+ * We're going to return -EIOCBQUEUED, but we haven't finished consuming the
+ * iov_iter yet, so we need to stash a copy of the iovec: it might be on the
+ * caller's stack, we're not guaranteed that it will live for the duration of
+ * the IO:
+ */
+static noinline int bch2_dio_write_copy_iov(struct dio_write *dio)
+{
+	struct iovec *iov = dio->inline_vecs;
+
+	/*
+	 * iov_iter has a single embedded iovec - nothing to do:
+	 */
+	if (iter_is_ubuf(&dio->iter))
+		return 0;
+
+	/*
+	 * We don't currently handle non-iovec iov_iters here - return an error,
+	 * and we'll fall back to doing the IO synchronously:
+	 */
+	if (!iter_is_iovec(&dio->iter))
+		return -1;
+
+	if (dio->iter.nr_segs > ARRAY_SIZE(dio->inline_vecs)) {
+		iov = kmalloc_array(dio->iter.nr_segs, sizeof(*iov),
+				    GFP_KERNEL);
+		if (unlikely(!iov))
+			return -ENOMEM;
+
+		dio->free_iov = true;
+	}
+
+	memcpy(iov, dio->iter.__iov, dio->iter.nr_segs * sizeof(*iov));
+	dio->iter.__iov = iov;
+	return 0;
+}
+
+static void bch2_dio_write_flush_done(struct closure *cl)
+{
+	struct dio_write *dio = container_of(cl, struct dio_write, op.cl);
+	struct bch_fs *c = dio->op.c;
+
+	closure_debug_destroy(cl);
+
+	dio->op.error = bch2_journal_error(&c->journal);
+
+	bch2_dio_write_done(dio);
+}
+
+static noinline void bch2_dio_write_flush(struct dio_write *dio)
+{
+	struct bch_fs *c = dio->op.c;
+	struct bch_inode_unpacked inode;
+	int ret;
+
+	dio->flush = 0;
+
+	closure_init(&dio->op.cl, NULL);
+
+	if (!dio->op.error) {
+		ret = bch2_inode_find_by_inum(c, inode_inum(dio->inode), &inode);
+		if (ret) {
+			dio->op.error = ret;
+		} else {
+			bch2_journal_flush_seq_async(&c->journal, inode.bi_journal_seq,
+						     &dio->op.cl);
+			bch2_inode_flush_nocow_writes_async(c, dio->inode, &dio->op.cl);
+		}
+	}
+
+	if (dio->sync) {
+		closure_sync(&dio->op.cl);
+		closure_debug_destroy(&dio->op.cl);
+	} else {
+		continue_at(&dio->op.cl, bch2_dio_write_flush_done, NULL);
+	}
+}
+
+static __always_inline long bch2_dio_write_done(struct dio_write *dio)
+{
+	struct kiocb *req = dio->req;
+	struct bch_inode_info *inode = dio->inode;
+	bool sync = dio->sync;
+	long ret;
+
+	if (unlikely(dio->flush)) {
+		bch2_dio_write_flush(dio);
+		if (!sync)
+			return -EIOCBQUEUED;
+	}
+
+	bch2_pagecache_block_put(inode);
+
+	if (dio->free_iov)
+		kfree(dio->iter.__iov);
+
+	ret = dio->op.error ?: ((long) dio->written << 9);
+	bio_put(&dio->op.wbio.bio);
+
+	/* inode->i_dio_count is our ref on inode and thus bch_fs */
+	inode_dio_end(&inode->v);
+
+	if (ret < 0)
+		ret = bch2_err_class(ret);
+
+	if (!sync) {
+		req->ki_complete(req, ret);
+		ret = -EIOCBQUEUED;
+	}
+	return ret;
+}
+
+static __always_inline void bch2_dio_write_end(struct dio_write *dio)
+{
+	struct bch_fs *c = dio->op.c;
+	struct kiocb *req = dio->req;
+	struct bch_inode_info *inode = dio->inode;
+	struct bio *bio = &dio->op.wbio.bio;
+
+	req->ki_pos	+= (u64) dio->op.written << 9;
+	dio->written	+= dio->op.written;
+
+	if (dio->extending) {
+		spin_lock(&inode->v.i_lock);
+		if (req->ki_pos > inode->v.i_size)
+			i_size_write(&inode->v, req->ki_pos);
+		spin_unlock(&inode->v.i_lock);
+	}
+
+	if (dio->op.i_sectors_delta || dio->quota_res.sectors) {
+		mutex_lock(&inode->ei_quota_lock);
+		__bch2_i_sectors_acct(c, inode, &dio->quota_res, dio->op.i_sectors_delta);
+		__bch2_quota_reservation_put(c, inode, &dio->quota_res);
+		mutex_unlock(&inode->ei_quota_lock);
+	}
+
+	bio_release_pages(bio, false);
+
+	if (unlikely(dio->op.error))
+		set_bit(EI_INODE_ERROR, &inode->ei_flags);
+}
+
+static __always_inline long bch2_dio_write_loop(struct dio_write *dio)
+{
+	struct bch_fs *c = dio->op.c;
+	struct kiocb *req = dio->req;
+	struct address_space *mapping = dio->mapping;
+	struct bch_inode_info *inode = dio->inode;
+	struct bch_io_opts opts;
+	struct bio *bio = &dio->op.wbio.bio;
+	unsigned unaligned, iter_count;
+	bool sync = dio->sync, dropped_locks;
+	long ret;
+
+	bch2_inode_opts_get(&opts, c, &inode->ei_inode);
+
+	while (1) {
+		iter_count = dio->iter.count;
+
+		EBUG_ON(current->faults_disabled_mapping);
+		current->faults_disabled_mapping = mapping;
+
+		ret = bio_iov_iter_get_pages(bio, &dio->iter);
+
+		dropped_locks = fdm_dropped_locks();
+
+		current->faults_disabled_mapping = NULL;
+
+		/*
+		 * If the fault handler returned an error but also signalled
+		 * that it dropped & retook ei_pagecache_lock, we just need to
+		 * re-shoot down the page cache and retry:
+		 */
+		if (dropped_locks && ret)
+			ret = 0;
+
+		if (unlikely(ret < 0))
+			goto err;
+
+		if (unlikely(dropped_locks)) {
+			ret = bch2_write_invalidate_inode_pages_range(mapping,
+					req->ki_pos,
+					req->ki_pos + iter_count - 1);
+			if (unlikely(ret))
+				goto err;
+
+			if (!bio->bi_iter.bi_size)
+				continue;
+		}
+
+		unaligned = bio->bi_iter.bi_size & (block_bytes(c) - 1);
+		bio->bi_iter.bi_size -= unaligned;
+		iov_iter_revert(&dio->iter, unaligned);
+
+		if (!bio->bi_iter.bi_size) {
+			/*
+			 * bio_iov_iter_get_pages was only able to get <
+			 * blocksize worth of pages:
+			 */
+			ret = -EFAULT;
+			goto err;
+		}
+
+		bch2_write_op_init(&dio->op, c, opts);
+		dio->op.end_io		= sync
+			? NULL
+			: bch2_dio_write_loop_async;
+		dio->op.target		= dio->op.opts.foreground_target;
+		dio->op.write_point	= writepoint_hashed((unsigned long) current);
+		dio->op.nr_replicas	= dio->op.opts.data_replicas;
+		dio->op.subvol		= inode->ei_subvol;
+		dio->op.pos		= POS(inode->v.i_ino, (u64) req->ki_pos >> 9);
+		dio->op.devs_need_flush	= &inode->ei_devs_need_flush;
+
+		if (sync)
+			dio->op.flags |= BCH_WRITE_SYNC;
+		dio->op.flags |= BCH_WRITE_CHECK_ENOSPC;
+
+		ret = bch2_quota_reservation_add(c, inode, &dio->quota_res,
+						 bio_sectors(bio), true);
+		if (unlikely(ret))
+			goto err;
+
+		ret = bch2_disk_reservation_get(c, &dio->op.res, bio_sectors(bio),
+						dio->op.opts.data_replicas, 0);
+		if (unlikely(ret) &&
+		    !bch2_dio_write_check_allocated(dio))
+			goto err;
+
+		task_io_account_write(bio->bi_iter.bi_size);
+
+		if (unlikely(dio->iter.count) &&
+		    !dio->sync &&
+		    !dio->loop &&
+		    bch2_dio_write_copy_iov(dio))
+			dio->sync = sync = true;
+
+		dio->loop = true;
+		closure_call(&dio->op.cl, bch2_write, NULL, NULL);
+
+		if (!sync)
+			return -EIOCBQUEUED;
+
+		bch2_dio_write_end(dio);
+
+		if (likely(!dio->iter.count) || dio->op.error)
+			break;
+
+		bio_reset(bio, NULL, REQ_OP_WRITE);
+	}
+out:
+	return bch2_dio_write_done(dio);
+err:
+	dio->op.error = ret;
+
+	bio_release_pages(bio, false);
+
+	bch2_quota_reservation_put(c, inode, &dio->quota_res);
+	goto out;
+}
+
+static noinline __cold void bch2_dio_write_continue(struct dio_write *dio)
+{
+	struct mm_struct *mm = dio->mm;
+
+	bio_reset(&dio->op.wbio.bio, NULL, REQ_OP_WRITE);
+
+	if (mm)
+		kthread_use_mm(mm);
+	bch2_dio_write_loop(dio);
+	if (mm)
+		kthread_unuse_mm(mm);
+}
+
+static void bch2_dio_write_loop_async(struct bch_write_op *op)
+{
+	struct dio_write *dio = container_of(op, struct dio_write, op);
+
+	bch2_dio_write_end(dio);
+
+	if (likely(!dio->iter.count) || dio->op.error)
+		bch2_dio_write_done(dio);
+	else
+		bch2_dio_write_continue(dio);
+}
+
+ssize_t bch2_direct_write(struct kiocb *req, struct iov_iter *iter)
+{
+	struct file *file = req->ki_filp;
+	struct address_space *mapping = file->f_mapping;
+	struct bch_inode_info *inode = file_bch_inode(file);
+	struct bch_fs *c = inode->v.i_sb->s_fs_info;
+	struct dio_write *dio;
+	struct bio *bio;
+	bool locked = true, extending;
+	ssize_t ret;
+
+	prefetch(&c->opts);
+	prefetch((void *) &c->opts + 64);
+	prefetch(&inode->ei_inode);
+	prefetch((void *) &inode->ei_inode + 64);
+
+	inode_lock(&inode->v);
+
+	ret = generic_write_checks(req, iter);
+	if (unlikely(ret <= 0))
+		goto err;
+
+	ret = file_remove_privs(file);
+	if (unlikely(ret))
+		goto err;
+
+	ret = file_update_time(file);
+	if (unlikely(ret))
+		goto err;
+
+	if (unlikely((req->ki_pos|iter->count) & (block_bytes(c) - 1)))
+		goto err;
+
+	inode_dio_begin(&inode->v);
+	bch2_pagecache_block_get(inode);
+
+	extending = req->ki_pos + iter->count > inode->v.i_size;
+	if (!extending) {
+		inode_unlock(&inode->v);
+		locked = false;
+	}
+
+	bio = bio_alloc_bioset(NULL,
+			       bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS),
+			       REQ_OP_WRITE,
+			       GFP_KERNEL,
+			       &c->dio_write_bioset);
+	dio = container_of(bio, struct dio_write, op.wbio.bio);
+	dio->req		= req;
+	dio->mapping		= mapping;
+	dio->inode		= inode;
+	dio->mm			= current->mm;
+	dio->loop		= false;
+	dio->extending		= extending;
+	dio->sync		= is_sync_kiocb(req) || extending;
+	dio->flush		= iocb_is_dsync(req) && !c->opts.journal_flush_disabled;
+	dio->free_iov		= false;
+	dio->quota_res.sectors	= 0;
+	dio->written		= 0;
+	dio->iter		= *iter;
+	dio->op.c		= c;
+
+	if (unlikely(mapping->nrpages)) {
+		ret = bch2_write_invalidate_inode_pages_range(mapping,
+						req->ki_pos,
+						req->ki_pos + iter->count - 1);
+		if (unlikely(ret))
+			goto err_put_bio;
+	}
+
+	ret = bch2_dio_write_loop(dio);
+err:
+	if (locked)
+		inode_unlock(&inode->v);
+	return ret;
+err_put_bio:
+	bch2_pagecache_block_put(inode);
+	bio_put(bio);
+	inode_dio_end(&inode->v);
+	goto err;
+}
+
+void bch2_fs_fs_io_direct_exit(struct bch_fs *c)
+{
+	bioset_exit(&c->dio_write_bioset);
+	bioset_exit(&c->dio_read_bioset);
+}
+
+int bch2_fs_fs_io_direct_init(struct bch_fs *c)
+{
+	if (bioset_init(&c->dio_read_bioset,
+			4, offsetof(struct dio_read, rbio.bio),
+			BIOSET_NEED_BVECS))
+		return -BCH_ERR_ENOMEM_dio_read_bioset_init;
+
+	if (bioset_init(&c->dio_write_bioset,
+			4, offsetof(struct dio_write, op.wbio.bio),
+			BIOSET_NEED_BVECS))
+		return -BCH_ERR_ENOMEM_dio_write_bioset_init;
+
+	return 0;
+}
+
+#endif /* NO_BCACHEFS_FS */