block: fix preallocate filter: don't do unaligned preallocate requests
There is a bug in handling BDRV_REQ_NO_WAIT flag: we still may wait in wait_serialising_requests() if request is unaligned. And this is possible for the only user of this flag (preallocate filter) if underlying file is unaligned to its request_alignment on start. So, we have to fix preallocate filter to do only aligned preallocate requests. Next, we should fix generic block/io.c somehow. Keeping in mind that preallocate is the only user of BDRV_REQ_NO_WAIT and that we have to fix its behavior now, it seems more safe to just assert that we never use BDRV_REQ_NO_WAIT with unaligned requests and add corresponding comment. Let's do so. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Denis V. Lunev <den@openvz.org> Message-Id: <20220215121609.38570-1-vsementsov@virtuozzo.com> [hreitz: Rebased on block GS/IO split] Signed-off-by: Hanna Reitz <hreitz@redhat.com>
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@ -2203,6 +2203,7 @@ static int coroutine_fn bdrv_co_do_zero_pwritev(BdrvChild *child,
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padding = bdrv_init_padding(bs, offset, bytes, &pad);
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if (padding) {
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assert(!(flags & BDRV_REQ_NO_WAIT));
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bdrv_make_request_serialising(req, align);
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bdrv_padding_rmw_read(child, req, &pad, true);
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@ -2339,6 +2340,7 @@ int coroutine_fn bdrv_co_pwritev_part(BdrvChild *child,
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* serialize the request to prevent interactions of the
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* widened region with other transactions.
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*/
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assert(!(flags & BDRV_REQ_NO_WAIT));
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bdrv_make_request_serialising(&req, align);
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bdrv_padding_rmw_read(child, &req, &pad, false);
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}
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@ -3387,6 +3389,8 @@ static int coroutine_fn bdrv_co_copy_range_internal(
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/* TODO We can support BDRV_REQ_NO_FALLBACK here */
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assert(!(read_flags & BDRV_REQ_NO_FALLBACK));
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assert(!(write_flags & BDRV_REQ_NO_FALLBACK));
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assert(!(read_flags & BDRV_REQ_NO_WAIT));
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assert(!(write_flags & BDRV_REQ_NO_WAIT));
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if (!dst || !dst->bs || !bdrv_is_inserted(dst->bs)) {
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return -ENOMEDIUM;
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@ -276,6 +276,10 @@ static bool coroutine_fn handle_write(BlockDriverState *bs, int64_t offset,
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int64_t end = offset + bytes;
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int64_t prealloc_start, prealloc_end;
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int ret;
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uint32_t file_align = bs->file->bs->bl.request_alignment;
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uint32_t prealloc_align = MAX(s->opts.prealloc_align, file_align);
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assert(QEMU_IS_ALIGNED(prealloc_align, file_align));
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if (!has_prealloc_perms(bs)) {
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/* We don't have state neither should try to recover it */
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@ -320,9 +324,14 @@ static bool coroutine_fn handle_write(BlockDriverState *bs, int64_t offset,
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/* Now we want new preallocation, as request writes beyond s->file_end. */
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prealloc_start = want_merge_zero ? MIN(offset, s->file_end) : s->file_end;
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prealloc_end = QEMU_ALIGN_UP(end + s->opts.prealloc_size,
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s->opts.prealloc_align);
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prealloc_start = QEMU_ALIGN_UP(
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want_merge_zero ? MIN(offset, s->file_end) : s->file_end,
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file_align);
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prealloc_end = QEMU_ALIGN_UP(
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MAX(prealloc_start, end) + s->opts.prealloc_size,
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prealloc_align);
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want_merge_zero = want_merge_zero && (prealloc_start <= offset);
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ret = bdrv_co_pwrite_zeroes(
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bs->file, prealloc_start, prealloc_end - prealloc_start,
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@ -112,7 +112,8 @@ typedef enum {
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/*
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* If we need to wait for other requests, just fail immediately. Used
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* only together with BDRV_REQ_SERIALISING.
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* only together with BDRV_REQ_SERIALISING. Used only with requests aligned
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* to request_alignment (corresponding assertions are in block/io.c).
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*/
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BDRV_REQ_NO_WAIT = 0x400,
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