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From 4ebabb66f4132186152edf8e1907fce436bf5c69 Mon Sep 17 00:00:00 2001
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Date: Mon, 27 Jan 2020 19:02:06 +0100
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Subject: [PATCH 095/116] virtiofsd: make lo_release() atomic
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Message-id: <20200127190227.40942-92-dgilbert@redhat.com>
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Patchwork-id: 93545
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O-Subject: [RHEL-AV-8.2 qemu-kvm PATCH 091/112] virtiofsd: make lo_release() atomic
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Bugzilla: 1694164
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RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Sergio Lopez Pascual <slp@redhat.com>
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From: Stefan Hajnoczi <stefanha@redhat.com>
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Hold the lock across both lo_map_get() and lo_map_remove() to prevent
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races between two FUSE_RELEASE requests. In this case I don't see a
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serious bug but it's safer to do things atomically.
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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(cherry picked from commit baed65c060c0e524530bc243eec427fb408bd477)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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tools/virtiofsd/passthrough_ll.c | 12 ++++++++----
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1 file changed, 8 insertions(+), 4 deletions(-)
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diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
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index 9414935..690edbc 100644
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--- a/tools/virtiofsd/passthrough_ll.c
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+++ b/tools/virtiofsd/passthrough_ll.c
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@@ -1772,14 +1772,18 @@ static void lo_release(fuse_req_t req, fuse_ino_t ino,
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struct fuse_file_info *fi)
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{
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struct lo_data *lo = lo_data(req);
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- int fd;
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+ struct lo_map_elem *elem;
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+ int fd = -1;
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(void)ino;
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- fd = lo_fi_fd(req, fi);
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-
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pthread_mutex_lock(&lo->mutex);
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- lo_map_remove(&lo->fd_map, fi->fh);
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+ elem = lo_map_get(&lo->fd_map, fi->fh);
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+ if (elem) {
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+ fd = elem->fd;
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+ elem = NULL;
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+ lo_map_remove(&lo->fd_map, fi->fh);
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+ }
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pthread_mutex_unlock(&lo->mutex);
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close(fd);
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--
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1.8.3.1
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