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raw: Probe required direct I/O alignment

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Add a bs->request_alignment field that contains the required
offset/length alignment for I/O requests and fill it in the raw block
drivers. Use ioctls if possible, else see what alignment it takes for
O_DIRECT to succeed.

While at it, also expose the memory alignment requirements, which may be
(and in practice are) different from the disk alignment requirements.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Paolo Bonzini 2011-11-29 12:42:20 +01:00 • committed by Kevin Wolf
parent 1b7fd72955
commit c25f53b06e
4 changed files with 132 additions and 17 deletions
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41
block/raw-win32.c
View file

@ -202,6 +202,35 @@ static int set_sparse(int fd)
NULL, 0, NULL, 0, &returned, NULL);
}
static void raw_probe_alignment(BlockDriverState *bs)
{
BDRVRawState *s = bs->opaque;
DWORD sectorsPerCluster, freeClusters, totalClusters, count;
DISK_GEOMETRY_EX dg;
BOOL status;
if (s->type == FTYPE_CD) {
bs->request_alignment = 2048;
return;
}
if (s->type == FTYPE_HARDDISK) {
status = DeviceIoControl(s->hfile, IOCTL_DISK_GET_DRIVE_GEOMETRY_EX,
NULL, 0, &dg, sizeof(dg), &count, NULL);
if (status != 0) {
bs->request_alignment = dg.Geometry.BytesPerSector;
return;
}
/* try GetDiskFreeSpace too */
}
if (s->drive_path[0]) {
GetDiskFreeSpace(s->drive_path, &sectorsPerCluster,
&dg.Geometry.BytesPerSector,
&freeClusters, &totalClusters);
bs->request_alignment = dg.Geometry.BytesPerSector;
}
}
static void raw_parse_flags(int flags, int *access_flags, DWORD *overlapped)
{
assert(access_flags != NULL);
@ -269,6 +298,17 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
}
}
if (filename[0] && filename[1] == ':') {
snprintf(s->drive_path, sizeof(s->drive_path), "%c:\\", filename[0]);
} else if (filename[0] == '\\' && filename[1] == '\\') {
s->drive_path[0] = 0;
} else {
/* Relative path. */
char buf[MAX_PATH];
GetCurrentDirectory(MAX_PATH, buf);
snprintf(s->drive_path, sizeof(s->drive_path), "%c:\\", buf[0]);
}
s->hfile = CreateFile(filename, access_flags,
FILE_SHARE_READ, NULL,
OPEN_EXISTING, overlapped, NULL);
@ -293,6 +333,7 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
s->aio = aio;
}
raw_probe_alignment(bs);
ret = 0;
fail:
qemu_opts_del(opts);