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authorJosef Bacik <josef@toxicpanda.com>2020-03-13 22:58:05 +0300
committerDavid Sterba <dsterba@suse.com>2020-05-25 12:25:22 +0300
commit7f9fe614407692f670601a634621138233ac00d7 (patch)
tree966a2257879bdbe6a6ab50d91d89265abea406db /fs/btrfs/space-info.h
parent876de781b0da240fcf8d29514c34607e147e5a94 (diff)
downloadlinux-7f9fe614407692f670601a634621138233ac00d7.tar.xz
btrfs: improve global reserve stealing logic
For unlink transactions and block group removal btrfs_start_transaction_fallback_global_rsv will first try to start an ordinary transaction and if it fails it will fall back to reserving the required amount by stealing from the global reserve. This is problematic because of all the same reasons we had with previous iterations of the ENOSPC handling, thundering herd. We get a bunch of failures all at once, everybody tries to allocate from the global reserve, some win and some lose, we get an ENSOPC. Fix this behavior by introducing BTRFS_RESERVE_FLUSH_ALL_STEAL. It's used to mark unlink reservation. To fix this we need to integrate this logic into the normal ENOSPC infrastructure. We still go through all of the normal flushing work, and at the moment we begin to fail all the tickets we try to satisfy any tickets that are allowed to steal by stealing from the global reserve. If this works we start the flushing system over again just like we would with a normal ticket satisfaction. This serializes our global reserve stealing, so we don't have the thundering herd problem. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Tested-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/space-info.h')
-rw-r--r--fs/btrfs/space-info.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/btrfs/space-info.h b/fs/btrfs/space-info.h
index 0a5001ef1481..c3c64019950a 100644
--- a/fs/btrfs/space-info.h
+++ b/fs/btrfs/space-info.h
@@ -78,6 +78,7 @@ struct btrfs_space_info {
struct reserve_ticket {
u64 bytes;
int error;
+ bool steal;
struct list_head list;
wait_queue_head_t wait;
};