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0431d926b3
The new checkpoint cache flush mechanism requires us to issue an unconditional cache flush before we start a new checkpoint. We don't want to block for this if we can help it, and we have a fair chunk of CPU work to do between starting the checkpoint and issuing the first journal IO. Hence it makes sense to amortise the latency cost of the cache flush by issuing it asynchronously and then waiting for it only when we need to issue the first IO in the transaction. To do this, we need async cache flush primitives to submit the cache flush bio and to wait on it. The block layer has no such primitives for filesystems, so roll our own for the moment. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Allison Henderson <allison.henderson@oracle.com> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
97 lines
2.2 KiB
C
97 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2019 Christoph Hellwig.
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*/
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#include "xfs.h"
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static inline unsigned int bio_max_vecs(unsigned int count)
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{
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return bio_max_segs(howmany(count, PAGE_SIZE));
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}
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static void
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xfs_flush_bdev_async_endio(
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struct bio *bio)
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{
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complete(bio->bi_private);
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}
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/*
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* Submit a request for an async cache flush to run. If the request queue does
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* not require flush operations, just skip it altogether. If the caller needs
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* to wait for the flush completion at a later point in time, they must supply a
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* valid completion. This will be signalled when the flush completes. The
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* caller never sees the bio that is issued here.
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*/
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void
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xfs_flush_bdev_async(
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struct bio *bio,
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struct block_device *bdev,
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struct completion *done)
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{
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struct request_queue *q = bdev->bd_disk->queue;
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if (!test_bit(QUEUE_FLAG_WC, &q->queue_flags)) {
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complete(done);
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return;
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}
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bio_init(bio, NULL, 0);
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bio_set_dev(bio, bdev);
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bio->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC;
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bio->bi_private = done;
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bio->bi_end_io = xfs_flush_bdev_async_endio;
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submit_bio(bio);
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}
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int
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xfs_rw_bdev(
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struct block_device *bdev,
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sector_t sector,
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unsigned int count,
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char *data,
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unsigned int op)
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{
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unsigned int is_vmalloc = is_vmalloc_addr(data);
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unsigned int left = count;
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int error;
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struct bio *bio;
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if (is_vmalloc && op == REQ_OP_WRITE)
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flush_kernel_vmap_range(data, count);
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bio = bio_alloc(GFP_KERNEL, bio_max_vecs(left));
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bio_set_dev(bio, bdev);
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bio->bi_iter.bi_sector = sector;
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bio->bi_opf = op | REQ_META | REQ_SYNC;
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do {
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struct page *page = kmem_to_page(data);
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unsigned int off = offset_in_page(data);
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unsigned int len = min_t(unsigned, left, PAGE_SIZE - off);
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while (bio_add_page(bio, page, len, off) != len) {
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struct bio *prev = bio;
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bio = bio_alloc(GFP_KERNEL, bio_max_vecs(left));
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bio_copy_dev(bio, prev);
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bio->bi_iter.bi_sector = bio_end_sector(prev);
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bio->bi_opf = prev->bi_opf;
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bio_chain(prev, bio);
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submit_bio(prev);
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}
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data += len;
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left -= len;
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} while (left > 0);
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error = submit_bio_wait(bio);
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bio_put(bio);
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if (is_vmalloc && op == REQ_OP_READ)
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invalidate_kernel_vmap_range(data, count);
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return error;
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}
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