btrfs: fix qgroup reserve leaks in cow_file_range

In the Linux kernel, the following vulnerability has been resolved:

btrfs: fix qgroup reserve leaks in cow_file_range

In the buffered write path, the dirty page owns the qgroup reserve until

it creates an ordered_extent.

Therefore, any errors that occur before the ordered_extent is created

must free that reservation, or else the space is leaked. The fstest

generic/475 exercises various IO error paths, and is able to trigger

errors in cow_file_range where we fail to get to allocating the ordered

extent. Note that because we *do* clear delalloc, we are likely to

remove the inode from the delalloc list, so the inodes/pages to not have

invalidate/launder called on them in the commit abort path.

This results in failures at the unmount stage of the test that look like:

BTRFS: error (device dm-8 state EA) in cleanup_transaction:2018: errno=-5 IO failure

BTRFS: error (device dm-8 state EA) in btrfs_replace_file_extents:2416: errno=-5 IO failure

BTRFS warning (device dm-8 state EA): qgroup 0/5 has unreleased space, type 0 rsv 28672

------------[ cut here ]------------

WARNING: CPU: 3 PID: 22588 at fs/btrfs/disk-io.c:4333 close_ctree+0x222/0x4d0 [btrfs]

Modules linked in: btrfs blake2b_generic libcrc32c xor zstd_compress raid6_pq

CPU: 3 PID: 22588 Comm: umount Kdump: loaded Tainted: G W 6.10.0-rc7-gab56fde445b8 #21

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014

RIP: 0010:close_ctree+0x222/0x4d0 [btrfs]

RSP: 0018:ffffb4465283be00 EFLAGS: 00010202

RAX: 0000000000000001 RBX: ffffa1a1818e1000 RCX: 0000000000000001

RDX: 0000000000000000 RSI: ffffb4465283bbe0 RDI: ffffa1a19374fcb8

RBP: ffffa1a1818e13c0 R08: 0000000100028b16 R09: 0000000000000000

R10: 0000000000000003 R11: 0000000000000003 R12: ffffa1a18ad7972c

R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

FS: 00007f9168312b80(0000) GS:ffffa1a4afcc0000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f91683c9140 CR3: 000000010acaa000 CR4: 00000000000006f0

Call Trace:

<TASK>

? close_ctree+0x222/0x4d0 [btrfs]

? __warn.cold+0x8e/0xea

? close_ctree+0x222/0x4d0 [btrfs]

? report_bug+0xff/0x140

? handle_bug+0x3b/0x70

? exc_invalid_op+0x17/0x70

? asm_exc_invalid_op+0x1a/0x20

? close_ctree+0x222/0x4d0 [btrfs]

generic_shutdown_super+0x70/0x160

kill_anon_super+0x11/0x40

btrfs_kill_super+0x11/0x20 [btrfs]

deactivate_locked_super+0x2e/0xa0

cleanup_mnt+0xb5/0x150

task_work_run+0x57/0x80

syscall_exit_to_user_mode+0x121/0x130

do_syscall_64+0xab/0x1a0

entry_SYSCALL_64_after_hwframe+0x77/0x7f

RIP: 0033:0x7f916847a887

---[ end trace 0000000000000000 ]---

BTRFS error (device dm-8 state EA): qgroup reserved space leaked

Cases 2 and 3 in the out_reserve path both pertain to this type of leak

and must free the reserved qgroup data. Because it is already an error

path, I opted not to handle the possible errors in

btrfs_free_qgroup_data.