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[Qemu-block] [PATCH 1/4] block: Add bdrv_get_request_alignment()
From: |
Eric Blake |
Subject: |
[Qemu-block] [PATCH 1/4] block: Add bdrv_get_request_alignment() |
Date: |
Thu, 2 Aug 2018 09:48:31 -0500 |
The next patch needs access to a device's minimum permitted
alignment, since NBD wants to advertise this to clients. Add
an accessor function, borrowing from blk_get_max_transfer()
for accessing a backend's block limits.
Signed-off-by: Eric Blake <address@hidden>
---
include/sysemu/block-backend.h | 1 +
block/block-backend.c | 7 +++++++
2 files changed, 8 insertions(+)
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index 830d873f24f..20f8bbbce37 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -176,6 +176,7 @@ bool blk_is_available(BlockBackend *blk);
void blk_lock_medium(BlockBackend *blk, bool locked);
void blk_eject(BlockBackend *blk, bool eject_flag);
int blk_get_flags(BlockBackend *blk);
+uint32_t blk_get_request_alignment(BlockBackend *blk);
uint32_t blk_get_max_transfer(BlockBackend *blk);
int blk_get_max_iov(BlockBackend *blk);
void blk_set_guest_block_size(BlockBackend *blk, int align);
diff --git a/block/block-backend.c b/block/block-backend.c
index f2f75a977d7..fb8c827d117 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -1798,6 +1798,13 @@ int blk_get_flags(BlockBackend *blk)
}
}
+/* Returns the minimum request alignment, in bytes; guaranteed nonzero */
+uint32_t blk_get_request_alignment(BlockBackend *blk)
+{
+ BlockDriverState *bs = blk_bs(blk);
+ return bs ? bs->bl.request_alignment : BDRV_SECTOR_SIZE;
+}
+
/* Returns the maximum transfer length, in bytes; guaranteed nonzero */
uint32_t blk_get_max_transfer(BlockBackend *blk)
{
--
2.14.4
[Qemu-block] [PATCH 3/4] iotests: Add 228 to test NBD on unaligned images, Eric Blake, 2018/08/02
[Qemu-block] [PATCH 4/4] nbd/client: Deal with unaligned size from server, Eric Blake, 2018/08/02