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[PATCH v3 1/5] file-posix: split hdev_refresh_limits from raw_refresh_li
From: |
Maxim Levitsky |
Subject: |
[PATCH v3 1/5] file-posix: split hdev_refresh_limits from raw_refresh_limits |
Date: |
Thu, 17 Dec 2020 18:56:08 +0200 |
From: Tom Yan <tom.ty89@gmail.com>
We can and should get max transfer length and max segments for all host
devices / cdroms (on Linux).
Also use MIN_NON_ZERO instead when we clamp max transfer length against
max segments.
Signed-off-by: Tom Yan <tom.ty89@gmail.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
block/file-posix.c | 57 +++++++++++++++++++++++++++++++++-------------
1 file changed, 41 insertions(+), 16 deletions(-)
diff --git a/block/file-posix.c b/block/file-posix.c
index 9804681d5c..cbf1271773 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1166,6 +1166,10 @@ static int sg_get_max_transfer_length(int fd)
int max_bytes = 0;
if (ioctl(fd, BLKSECTGET, &max_bytes) == 0) {
+ /*
+ * BLKSECTGET for /dev/sg* character devices incorrectly returns
+ * the max transfer size in bytes (rather than in blocks).
+ */
return max_bytes;
} else {
return -errno;
@@ -1175,7 +1179,22 @@ static int sg_get_max_transfer_length(int fd)
#endif
}
-static int sg_get_max_segments(int fd)
+static int get_max_transfer_length(int fd)
+{
+#if defined(BLKSECTGET)
+ int sect = 0;
+
+ if (ioctl(fd, BLKSECTGET, §) == 0) {
+ return sect << 9;
+ } else {
+ return -errno;
+ }
+#else
+ return -ENOSYS;
+#endif
+}
+
+static int get_max_segments(int fd)
{
#ifdef CONFIG_LINUX
char buf[32];
@@ -1230,23 +1249,29 @@ static void raw_refresh_limits(BlockDriverState *bs,
Error **errp)
{
BDRVRawState *s = bs->opaque;
- if (bs->sg) {
- int ret = sg_get_max_transfer_length(s->fd);
+ raw_probe_alignment(bs, s->fd, errp);
+ bs->bl.min_mem_alignment = s->buf_align;
+ bs->bl.opt_mem_alignment = MAX(s->buf_align, qemu_real_host_page_size);
+}
+
+static void hdev_refresh_limits(BlockDriverState *bs, Error **errp)
+{
+ BDRVRawState *s = bs->opaque;
+
+ int ret = bs->sg ? sg_get_max_transfer_length(s->fd) :
+ get_max_transfer_length(s->fd);
- if (ret > 0 && ret <= BDRV_REQUEST_MAX_BYTES) {
- bs->bl.max_transfer = pow2floor(ret);
- }
+ if (ret > 0 && ret <= BDRV_REQUEST_MAX_BYTES) {
+ bs->bl.max_transfer = pow2floor(ret);
+ }
- ret = sg_get_max_segments(s->fd);
- if (ret > 0) {
- bs->bl.max_transfer = MIN(bs->bl.max_transfer,
- ret * qemu_real_host_page_size);
- }
+ ret = get_max_segments(s->fd);
+ if (ret > 0) {
+ bs->bl.max_transfer = MIN_NON_ZERO(bs->bl.max_transfer,
+ ret * qemu_real_host_page_size);
}
- raw_probe_alignment(bs, s->fd, errp);
- bs->bl.min_mem_alignment = s->buf_align;
- bs->bl.opt_mem_alignment = MAX(s->buf_align, qemu_real_host_page_size);
+ raw_refresh_limits(bs, errp);
}
static int check_for_dasd(int fd)
@@ -3600,7 +3625,7 @@ static BlockDriver bdrv_host_device = {
.bdrv_co_pdiscard = hdev_co_pdiscard,
.bdrv_co_copy_range_from = raw_co_copy_range_from,
.bdrv_co_copy_range_to = raw_co_copy_range_to,
- .bdrv_refresh_limits = raw_refresh_limits,
+ .bdrv_refresh_limits = hdev_refresh_limits,
.bdrv_io_plug = raw_aio_plug,
.bdrv_io_unplug = raw_aio_unplug,
.bdrv_attach_aio_context = raw_aio_attach_aio_context,
@@ -3724,7 +3749,7 @@ static BlockDriver bdrv_host_cdrom = {
.bdrv_co_preadv = raw_co_preadv,
.bdrv_co_pwritev = raw_co_pwritev,
.bdrv_co_flush_to_disk = raw_co_flush_to_disk,
- .bdrv_refresh_limits = raw_refresh_limits,
+ .bdrv_refresh_limits = hdev_refresh_limits,
.bdrv_io_plug = raw_aio_plug,
.bdrv_io_unplug = raw_aio_unplug,
.bdrv_attach_aio_context = raw_aio_attach_aio_context,
--
2.26.2