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From bcbf10c15f43cfc079622c25ef282688965a7128 Mon Sep 17 00:00:00 2001
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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Tue, 13 Nov 2012 10:34:17 +0100
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Subject: [PATCH] nbd: fixes to read-only handling
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We do not need BLKROSET if the kernel supports setting flags.
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Also, always do BLKROSET even for a read-write export, otherwise
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the read-only state remains "sticky" after the invocation of
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"qemu-nbd -r".
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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(cherry picked from commit c8969eded252058e90e91f12f75f32aceae46ec9)
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Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
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---
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nbd.c | 25 ++++++++++++-------------
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1 file changed, 12 insertions(+), 13 deletions(-)
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diff --git a/nbd.c b/nbd.c
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index 206f75c..19f6cd8 100644
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--- a/nbd.c
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+++ b/nbd.c
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@@ -399,24 +399,23 @@ int nbd_init(int fd, int csock, uint32_t flags, off_t size, size_t blocksize)
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return -serrno;
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}
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- if (flags & NBD_FLAG_READ_ONLY) {
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- int read_only = 1;
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- TRACE("Setting readonly attribute");
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-
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- if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) {
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+ if (ioctl(fd, NBD_SET_FLAGS, flags) < 0) {
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+ if (errno == ENOTTY) {
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+ int read_only = (flags & NBD_FLAG_READ_ONLY) != 0;
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+ TRACE("Setting readonly attribute");
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+
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+ if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) {
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+ int serrno = errno;
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+ LOG("Failed setting read-only attribute");
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+ return -serrno;
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+ }
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+ } else {
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int serrno = errno;
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- LOG("Failed setting read-only attribute");
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+ LOG("Failed setting flags");
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return -serrno;
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}
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}
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- if (ioctl(fd, NBD_SET_FLAGS, flags) < 0
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- && errno != ENOTTY) {
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- int serrno = errno;
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- LOG("Failed setting flags");
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- return -serrno;
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- }
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-
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TRACE("Negotiation ended");
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return 0;
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