From e5d9adbdab972a2172815c1174aed3fabcc448f1 Mon Sep 17 00:00:00 2001 From: Tomoki Sekiyama Date: Tue, 1 Oct 2013 17:09:53 -0400 Subject: [PATCH] qemu-ga: execute fsfreeze-freeze in reverse order of mounts Currently, fsfreeze-freeze may cause deadlock if a guest has loopback mounts of image files in its disk; e.g.: # mount | grep ^/ /dev/vda1 / type ext4 (rw,noatime,seclabel,data=ordered) /tmp/disk.img on /mnt type ext4 (rw,relatime,seclabel) To avoid the deadlock, this freezes filesystems in reverse order of mounts. Signed-off-by: Tomoki Sekiyama Reviewed-by: Eric Blake *fix up commit msg Signed-off-by: Michael Roth --- qga/commands-posix.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/qga/commands-posix.c b/qga/commands-posix.c index e199738c71..f453132b92 100644 --- a/qga/commands-posix.c +++ b/qga/commands-posix.c @@ -566,7 +566,7 @@ typedef struct FsMount { QTAILQ_ENTRY(FsMount) next; } FsMount; -typedef QTAILQ_HEAD(, FsMount) FsMountList; +typedef QTAILQ_HEAD(FsMountList, FsMount) FsMountList; static void free_fs_mount_list(FsMountList *mounts) { @@ -728,7 +728,7 @@ int64_t qmp_guest_fsfreeze_freeze(Error **err) /* cannot risk guest agent blocking itself on a write in this state */ ga_set_frozen(ga_state); - QTAILQ_FOREACH(mount, &mounts, next) { + QTAILQ_FOREACH_REVERSE(mount, &mounts, FsMountList, next) { fd = qemu_open(mount->dirname, O_RDONLY); if (fd == -1) { error_setg_errno(err, errno, "failed to open %s", mount->dirname); -- GitLab