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[Qemu-devel] [PULL 16/41] block: Fix target variable of BLKSECTGET ioctl
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PULL 16/41] block: Fix target variable of BLKSECTGET ioctl |
Date: |
Fri, 27 Jan 2017 14:45:24 +0100 |
From: Eric Farman <address@hidden>
Commit 6f6071745bd0 ("raw-posix: Fetch max sectors for host block device")
introduced a routine to call the kernel BLKSECTGET ioctl, which stores the
result back to user space. However, the size of the data returned depends
on the routine handling the ioctl. The (compat_)blkdev_ioctl returns a
short, while sg_ioctl returns an int. Thus, on big-endian systems, we can
find ourselves accidentally shifting the result to a much larger value.
(On s390x, a short is 16 bits while an int is 32 bits.)
Also, the two ioctl handlers return values in different scales (block
returns sectors, while sg returns bytes), so some tweaking of the outputs
is required such that hdev_get_max_transfer_length returns a value in a
consistent set of units.
Signed-off-by: Eric Farman <address@hidden>
Message-Id: <address@hidden>
Reviewed-by: Fam Zheng <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
block/file-posix.c | 17 ++++++++++-------
include/block/block.h | 1 +
2 files changed, 11 insertions(+), 7 deletions(-)
diff --git a/block/file-posix.c b/block/file-posix.c
index 28b47d9..9f83725 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -651,12 +651,15 @@ static void raw_reopen_abort(BDRVReopenState *state)
state->opaque = NULL;
}
-static int hdev_get_max_transfer_length(int fd)
+static int hdev_get_max_transfer_length(BlockDriverState *bs, int fd)
{
#ifdef BLKSECTGET
- int max_sectors = 0;
- if (ioctl(fd, BLKSECTGET, &max_sectors) == 0) {
- return max_sectors;
+ int max_bytes = 0;
+ short max_sectors = 0;
+ if (bs->sg && ioctl(fd, BLKSECTGET, &max_bytes) == 0) {
+ return max_bytes;
+ } else if (!bs->sg && ioctl(fd, BLKSECTGET, &max_sectors) == 0) {
+ return max_sectors << BDRV_SECTOR_BITS;
} else {
return -errno;
}
@@ -672,9 +675,9 @@ static void raw_refresh_limits(BlockDriverState *bs, Error
**errp)
if (!fstat(s->fd, &st)) {
if (S_ISBLK(st.st_mode)) {
- int ret = hdev_get_max_transfer_length(s->fd);
- if (ret > 0 && ret <= BDRV_REQUEST_MAX_SECTORS) {
- bs->bl.max_transfer = pow2floor(ret << BDRV_SECTOR_BITS);
+ int ret = hdev_get_max_transfer_length(bs, s->fd);
+ if (ret > 0 && ret <= BDRV_REQUEST_MAX_BYTES) {
+ bs->bl.max_transfer = pow2floor(ret);
}
}
}
diff --git a/include/block/block.h b/include/block/block.h
index 8b0dcda..4e81f20 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -116,6 +116,7 @@ typedef struct HDGeometry {
#define BDRV_REQUEST_MAX_SECTORS MIN(SIZE_MAX >> BDRV_SECTOR_BITS, \
INT_MAX >> BDRV_SECTOR_BITS)
+#define BDRV_REQUEST_MAX_BYTES (BDRV_REQUEST_MAX_SECTORS << BDRV_SECTOR_BITS)
/*
* Allocation status flags
--
1.8.3.1
- [Qemu-devel] [PULL 08/41] memory: tune mtree_print_mr() to dump mr type, (continued)
- [Qemu-devel] [PULL 08/41] memory: tune mtree_print_mr() to dump mr type, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 12/41] hw/isa/lpc_ich9: negotiate SMI broadcast on pc-q35-2.9+ machine types, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 11/41] hw/isa/lpc_ich9: add broadcast SMI feature, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 13/41] block/iscsi: avoid data corruption with cache=writeback, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 09/41] memory: hmp: add "-f" for "info mtree", Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 10/41] hw/isa/lpc_ich9: add SMI feature negotiation via fw_cfg, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 14/41] Introduce DEVICE_CATEGORY_CPU for CPU devices, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 15/41] hw/scsi: Fix debug message of cdb structure in scsi-generic, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 17/41] block: get max_transfer limit for char (scsi-generic) devices, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 18/41] x86-KVM: Supply TSC and APIC clock rates to guest like VMWare, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 16/41] block: Fix target variable of BLKSECTGET ioctl,
Paolo Bonzini <=
- [Qemu-devel] [PULL 19/41] pc: Enable vmware-cpuid-freq CPU option for 2.9+ machine types, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 23/41] char: add qemu_chr_fe_add_watch() Returns description, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 20/41] block/iscsi: statically link qemu_iscsi_opts, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 24/41] doc: fix spelling, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 21/41] tests: fix linking test-char on win32, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 26/41] char: use a static array for backends, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 25/41] char: use a const CharDriver, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 22/41] qemu-options: stdio is available on win32, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 28/41] char: fold single-user functions in caller, Paolo Bonzini, 2017/01/27
- [Qemu-devel] [PULL 30/41] char: use a feature bit for replay, Paolo Bonzini, 2017/01/27