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[PATCH] block/blkio: Tolerate device size changes
From: |
Alberto Faria |
Subject: |
[PATCH] block/blkio: Tolerate device size changes |
Date: |
Sat, 29 Oct 2022 13:20:31 +0100 |
Some libblkio drivers may be able to work with regular files (e.g.,
io_uring) or otherwise resizable devices. Conservatively set
BlockDriver::has_variable_length to true to ensure bdrv_nb_sectors()
always gives up-to-date results.
Also implement BlockDriver::bdrv_co_truncate for the case where no
preallocation is needed and the device already has a size compatible
with what was requested.
Signed-off-by: Alberto Faria <afaria@redhat.com>
---
This is based on Stefan's block tree:
https://gitlab.com/stefanha/qemu/-/commits/block
block/blkio.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/block/blkio.c b/block/blkio.c
index 82f26eedd2..190454cdbe 100644
--- a/block/blkio.c
+++ b/block/blkio.c
@@ -845,6 +845,31 @@ static int64_t blkio_getlength(BlockDriverState *bs)
return capacity;
}
+static int coroutine_fn blkio_truncate(BlockDriverState *bs, int64_t offset,
+ bool exact, PreallocMode prealloc,
+ BdrvRequestFlags flags, Error **errp)
+{
+ int64_t current_length;
+
+ if (prealloc != PREALLOC_MODE_OFF) {
+ error_setg(errp, "Unsupported preallocation mode '%s'",
+ PreallocMode_str(prealloc));
+ return -ENOTSUP;
+ }
+
+ current_length = blkio_getlength(bs);
+
+ if (offset > current_length) {
+ error_setg(errp, "Cannot grow device");
+ return -EINVAL;
+ } else if (exact && offset != current_length) {
+ error_setg(errp, "Cannot resize device");
+ return -ENOTSUP;
+ }
+
+ return 0;
+}
+
static int blkio_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
return 0;
@@ -960,10 +985,12 @@ static void blkio_refresh_limits(BlockDriverState *bs,
Error **errp)
{ \
.format_name = name, \
.protocol_name = name, \
+ .has_variable_length = true, \
.instance_size = sizeof(BDRVBlkioState), \
.bdrv_file_open = blkio_file_open, \
.bdrv_close = blkio_close, \
.bdrv_getlength = blkio_getlength, \
+ .bdrv_co_truncate = blkio_truncate, \
.bdrv_get_info = blkio_get_info, \
.bdrv_attach_aio_context = blkio_attach_aio_context, \
.bdrv_detach_aio_context = blkio_detach_aio_context, \
--
2.38.1
- [PATCH] block/blkio: Tolerate device size changes,
Alberto Faria <=