[PATCH 3/3] btrfs: do not infinite loop in data reclaim if we aborted

[Josef Bacik <josef@toxicpanda.com>]

Error injection stressing uncovered a busy loop in our data reclaim
loop.  There are two cases here, one where we loop creating block groups
until space_info->full is set, or in the main loop we will skip erroring
out any tickets if space_info->full == 0.  Unfortunately if we aborted
the transaction then we will never allocate chunks or reclaim any space
and thus never get ->full, and you'll see stack traces like this

watchdog: BUG: soft lockup - CPU#0 stuck for 26s! [kworker/u4:4:139]
CPU: 0 PID: 139 Comm: kworker/u4:4 Tainted: G        W         5.13.0-rc1+ #328
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
Workqueue: events_unbound btrfs_async_reclaim_data_space
RIP: 0010:btrfs_join_transaction+0x12/0x20
RSP: 0018:ffffb2b780b77de0 EFLAGS: 00000246
RAX: ffffb2b781863d58 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000801 RSI: ffff987952b57400 RDI: ffff987940aa3000
RBP: ffff987954d55000 R08: 0000000000000001 R09: ffff98795539e8f0
R10: 000000000000000f R11: 000000000000000f R12: ffffffffffffffff
R13: ffff987952b574c8 R14: ffff987952b57400 R15: 0000000000000008
FS:  0000000000000000(0000) GS:ffff9879bbc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0703da4000 CR3: 0000000113398004 CR4: 0000000000370ef0
Call Trace:
 flush_space+0x4a8/0x660
 btrfs_async_reclaim_data_space+0x55/0x130
 process_one_work+0x1e9/0x380
 worker_thread+0x53/0x3e0
 ? process_one_work+0x380/0x380
 kthread+0x118/0x140
 ? __kthread_bind_mask+0x60/0x60
 ret_from_fork+0x1f/0x30

Fix this by checking to see if we have a btrfs fs error in either of the
reclaim loops, and if so fail the tickets and bail.  In addition to
this, fix maybe_fail_all_tickets() to not try to grant tickets if we've
aborted, simply fail everything.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
 fs/btrfs/space-info.c | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 42d0fa2092d4..077e54cdc29f 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -941,6 +941,7 @@ static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info,
 	struct reserve_ticket *ticket;
 	u64 tickets_id = space_info->tickets_id;
 	u64 first_ticket_bytes = 0;
+	const bool aborted = btrfs_has_fs_error(fs_info);
 
 	if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
 		btrfs_info(fs_info, "cannot satisfy tickets, dumping space info");
@@ -952,7 +953,7 @@ static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info,
 		ticket = list_first_entry(&space_info->tickets,
 					  struct reserve_ticket, list);
 
-		if (ticket->steal &&
+		if (!aborted && ticket->steal &&
 		    steal_from_global_rsv(fs_info, space_info, ticket))
 			return true;
 
@@ -968,15 +969,18 @@ static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info,
 		 */
 		if (first_ticket_bytes == 0)
 			first_ticket_bytes = ticket->bytes;
-		else if (first_ticket_bytes > ticket->bytes)
+		else if (!aborted && first_ticket_bytes > ticket->bytes)
 			return true;
 
-		if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
+		if (!aborted && btrfs_test_opt(fs_info, ENOSPC_DEBUG))
 			btrfs_info(fs_info, "failing ticket with %llu bytes",
 				   ticket->bytes);
 
 		remove_ticket(space_info, ticket);
-		ticket->error = -ENOSPC;
+		if (aborted)
+			ticket->error = -EIO;
+		else
+			ticket->error = -ENOSPC;
 		wake_up(&ticket->wait);
 
 		/*
@@ -985,7 +989,8 @@ static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info,
 		 * here to see if we can make progress with the next ticket in
 		 * the list.
 		 */
-		btrfs_try_granting_tickets(fs_info, space_info);
+		if (!aborted)
+			btrfs_try_granting_tickets(fs_info, space_info);
 	}
 	return (tickets_id != space_info->tickets_id);
 }
@@ -1253,6 +1258,10 @@ static void btrfs_async_reclaim_data_space(struct work_struct *work)
 			spin_unlock(&space_info->lock);
 			return;
 		}
+
+		/* Something happened, fail everything and bail. */
+		if (btrfs_has_fs_error(fs_info))
+			goto aborted_fs;
 		last_tickets_id = space_info->tickets_id;
 		spin_unlock(&space_info->lock);
 	}
@@ -1283,9 +1292,19 @@ static void btrfs_async_reclaim_data_space(struct work_struct *work)
 			} else {
 				flush_state = 0;
 			}
+
+			/* Something happened, fail everything and bail. */
+			if (btrfs_has_fs_error(fs_info))
+				goto aborted_fs;
+
 		}
 		spin_unlock(&space_info->lock);
 	}
+	return;
+aborted_fs:
+	maybe_fail_all_tickets(fs_info, space_info);
+	space_info->flush = 0;
+	spin_unlock(&space_info->lock);
 }
 
 void btrfs_init_async_reclaim_work(struct btrfs_fs_info *fs_info)
-- 
2.26.3