Blame SOURCES/kvm-virtiofsd-Fix-breakage-due-to-fuse_init_in-size-chan.patch

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From 1da951c4c3b4e403a6c1668a54e6264381c0003d Mon Sep 17 00:00:00 2001
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From: Vivek Goyal <vgoyal@redhat.com>
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Date: Tue, 8 Feb 2022 15:48:04 -0500
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Subject: [PATCH 1/3] virtiofsd: Fix breakage due to fuse_init_in size change
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RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
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RH-MergeRequest: 193: virtiofsd: Fix breakage due to fuse_init_in size change
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RH-Commit: [1/1] 5809db034f9361fb462181d71e7cdde1324f8e54
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RH-Bugzilla: 2097209
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RH-Acked-by: German Maglione <None>
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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RH-Acked-by: Vivek Goyal <None>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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Kernel version 5.17 has increased the size of "struct fuse_init_in" struct.
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Previously this struct was 16 bytes and now it has been extended to
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64 bytes in size.
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Once qemu headers are updated to latest, it will expect to receive 64 byte
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size struct (for protocol version major 7 and minor > 6). But if guest is
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booting older kernel (older than 5.17), then it still sends older
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fuse_init_in of size 16 bytes. And do_init() fails. It is expecting
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64 byte struct. And this results in mount of virtiofs failing.
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Fix this by parsing 16 bytes only for now. Separate patches will be
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posted which will parse rest of the bytes and enable new functionality.
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Right now we don't support any of the new functionality, so we don't
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lose anything by not parsing bytes beyond 16.
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Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
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Message-Id: <20220208204813.682906-2-vgoyal@redhat.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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(cherry picked from commit a086d54c6ffa38f7e71f182b63a25315304a3392)
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---
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 tools/virtiofsd/fuse_lowlevel.c | 4 +++-
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 1 file changed, 3 insertions(+), 1 deletion(-)
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diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c
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index e4679c73ab..5d431a7038 100644
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--- a/tools/virtiofsd/fuse_lowlevel.c
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+++ b/tools/virtiofsd/fuse_lowlevel.c
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@@ -1880,6 +1880,8 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid,
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                     struct fuse_mbuf_iter *iter)
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 {
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     size_t compat_size = offsetof(struct fuse_init_in, max_readahead);
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+    size_t compat2_size = offsetof(struct fuse_init_in, flags) +
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+                              sizeof(uint32_t);
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     struct fuse_init_in *arg;
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     struct fuse_init_out outarg;
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     struct fuse_session *se = req->se;
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@@ -1897,7 +1899,7 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid,
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     /* ...and now consume the new fields. */
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     if (arg->major == 7 && arg->minor >= 6) {
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-        if (!fuse_mbuf_iter_advance(iter, sizeof(*arg) - compat_size)) {
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+        if (!fuse_mbuf_iter_advance(iter, compat2_size - compat_size)) {
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             fuse_reply_err(req, EINVAL);
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             return;
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         }
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-- 
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2.35.3
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