Description: btrfs: do not ASSERT() if the newly created subvolume already got read
References:
 https://lore.kernel.org/lkml/CALGdzuo6awWdau3X=8XK547x2vX_-VoFmH1aPsqosRTQ5WzJVA%40mail.gmail.com/
 https://lore.kernel.org/all/6a80cb4b32af89787dadee728310e5e2ca85343f.1705741883.git.wqu%40suse.com/
Notes:
 carnil> Commit fixes 2dfb1e43f57d ("btrfs: preallocate anon block
 carnil> device at first phase of snapshot creation") in 5.9-rc1 (and
 carnil> backported to 5.8.3)
 bwh> Fixed as well in 6.6.18 and 6.7.6.
Bugs:
upstream: released (6.8-rc4) [e03ee2fe873eb68c1f9ba5112fee70303ebf9dfb]
6.1-upstream-stable: released (6.1.79) [66b317a2fc45b2ef66527ee3f8fa08fb5beab88d]
5.10-upstream-stable: released (5.10.210) [3f5d47eb163bceb1b9e613c9003bae5fefc0046f]
4.19-upstream-stable: N/A "Vulnerable code not present"
sid: released (6.7.7-1)
6.1-bookworm-security: released (6.1.82-1)
5.10-bullseye-security: needed
4.19-buster-security: N/A "Vulnerable code not present"