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[PATCH 01/11] file-posix: fix max_iov for /dev/sg devices
From: |
Paolo Bonzini |
Subject: |
[PATCH 01/11] file-posix: fix max_iov for /dev/sg devices |
Date: |
Thu, 24 Jun 2021 20:04:13 +0200 |
Even though it was only called for devices that have bs->sg set (which
must be character devices), sg_get_max_segments looked at /sys/dev/block
which only works for block devices.
On Linux the sg driver has its own way to provide the maximum number of
iovecs in a scatter/gather list, so add support for it. The block device
path is kept because it will be reinstated in the next patches.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
---
block/file-posix.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/block/file-posix.c b/block/file-posix.c
index b3fbb9bd63..b8dc19ce1a 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1178,6 +1178,17 @@ static int sg_get_max_segments(int fd)
goto out;
}
+ if (S_ISCHR(st.st_mode)) {
+ if (ioctl(fd, SG_GET_SG_TABLESIZE, &ret) == 0) {
+ return ret;
+ }
+ return -ENOTSUP;
+ }
+
+ if (!S_ISBLK(st.st_mode)) {
+ return -ENOTSUP;
+ }
+
sysfspath = g_strdup_printf("/sys/dev/block/%u:%u/queue/max_segments",
major(st.st_rdev), minor(st.st_rdev));
sysfd = open(sysfspath, O_RDONLY);
--
2.31.1
- [PATCH v5 00/11] block: file-posix queue, Paolo Bonzini, 2021/06/24
- [PATCH 01/11] file-posix: fix max_iov for /dev/sg devices,
Paolo Bonzini <=
- [PATCH 02/11] scsi-generic: pass max_segments via max_iov field in BlockLimits, Paolo Bonzini, 2021/06/24
- [PATCH 03/11] osdep: provide ROUND_DOWN macro, Paolo Bonzini, 2021/06/24
- [PATCH 04/11] block-backend: align max_transfer to request alignment, Paolo Bonzini, 2021/06/24
- [PATCH 07/11] block: feature detection for host block support, Paolo Bonzini, 2021/06/24
- [PATCH 10/11] block: detect DKIOCGETBLOCKCOUNT/SIZE before use, Paolo Bonzini, 2021/06/24