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linux-next/fs/btrfs/space-info.h
Josef Bacik 7f9fe61440 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>
2020-05-25 11:25:22 +02:00

154 lines
4.9 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef BTRFS_SPACE_INFO_H
#define BTRFS_SPACE_INFO_H
struct btrfs_space_info {
spinlock_t lock;
u64 total_bytes; /* total bytes in the space,
this doesn't take mirrors into account */
u64 bytes_used; /* total bytes used,
this doesn't take mirrors into account */
u64 bytes_pinned; /* total bytes pinned, will be freed when the
transaction finishes */
u64 bytes_reserved; /* total bytes the allocator has reserved for
current allocations */
u64 bytes_may_use; /* number of bytes that may be used for
delalloc/allocations */
u64 bytes_readonly; /* total bytes that are read only */
u64 max_extent_size; /* This will hold the maximum extent size of
the space info if we had an ENOSPC in the
allocator. */
unsigned int full:1; /* indicates that we cannot allocate any more
chunks for this space */
unsigned int chunk_alloc:1; /* set if we are allocating a chunk */
unsigned int flush:1; /* set if we are trying to make space */
unsigned int force_alloc; /* set if we need to force a chunk
alloc for this space */
u64 disk_used; /* total bytes used on disk */
u64 disk_total; /* total bytes on disk, takes mirrors into
account */
u64 flags;
/*
* bytes_pinned is kept in line with what is actually pinned, as in
* we've called update_block_group and dropped the bytes_used counter
* and increased the bytes_pinned counter. However this means that
* bytes_pinned does not reflect the bytes that will be pinned once the
* delayed refs are flushed, so this counter is inc'ed every time we
* call btrfs_free_extent so it is a realtime count of what will be
* freed once the transaction is committed. It will be zeroed every
* time the transaction commits.
*/
struct percpu_counter total_bytes_pinned;
struct list_head list;
/* Protected by the spinlock 'lock'. */
struct list_head ro_bgs;
struct list_head priority_tickets;
struct list_head tickets;
/*
* Size of space that needs to be reclaimed in order to satisfy pending
* tickets
*/
u64 reclaim_size;
/*
* tickets_id just indicates the next ticket will be handled, so note
* it's not stored per ticket.
*/
u64 tickets_id;
struct rw_semaphore groups_sem;
/* for block groups in our same type */
struct list_head block_groups[BTRFS_NR_RAID_TYPES];
struct kobject kobj;
struct kobject *block_group_kobjs[BTRFS_NR_RAID_TYPES];
};
struct reserve_ticket {
u64 bytes;
int error;
bool steal;
struct list_head list;
wait_queue_head_t wait;
};
static inline bool btrfs_mixed_space_info(struct btrfs_space_info *space_info)
{
return ((space_info->flags & BTRFS_BLOCK_GROUP_METADATA) &&
(space_info->flags & BTRFS_BLOCK_GROUP_DATA));
}
/*
*
* Declare a helper function to detect underflow of various space info members
*/
#define DECLARE_SPACE_INFO_UPDATE(name, trace_name) \
static inline void \
btrfs_space_info_update_##name(struct btrfs_fs_info *fs_info, \
struct btrfs_space_info *sinfo, \
s64 bytes) \
{ \
const u64 abs_bytes = (bytes < 0) ? -bytes : bytes; \
lockdep_assert_held(&sinfo->lock); \
trace_update_##name(fs_info, sinfo, sinfo->name, bytes); \
trace_btrfs_space_reservation(fs_info, trace_name, \
sinfo->flags, abs_bytes, \
bytes > 0); \
if (bytes < 0 && sinfo->name < -bytes) { \
WARN_ON(1); \
sinfo->name = 0; \
return; \
} \
sinfo->name += bytes; \
}
DECLARE_SPACE_INFO_UPDATE(bytes_may_use, "space_info");
DECLARE_SPACE_INFO_UPDATE(bytes_pinned, "pinned");
int btrfs_init_space_info(struct btrfs_fs_info *fs_info);
void btrfs_update_space_info(struct btrfs_fs_info *info, u64 flags,
u64 total_bytes, u64 bytes_used,
u64 bytes_readonly,
struct btrfs_space_info **space_info);
struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info,
u64 flags);
u64 __pure btrfs_space_info_used(struct btrfs_space_info *s_info,
bool may_use_included);
void btrfs_clear_space_info_full(struct btrfs_fs_info *info);
void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *info, u64 bytes,
int dump_block_groups);
int btrfs_reserve_metadata_bytes(struct btrfs_root *root,
struct btrfs_block_rsv *block_rsv,
u64 orig_bytes,
enum btrfs_reserve_flush_enum flush);
void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info);
int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info, u64 bytes,
enum btrfs_reserve_flush_enum flush);
static inline void btrfs_space_info_free_bytes_may_use(
struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info,
u64 num_bytes)
{
spin_lock(&space_info->lock);
btrfs_space_info_update_bytes_may_use(fs_info, space_info, -num_bytes);
btrfs_try_granting_tickets(fs_info, space_info);
spin_unlock(&space_info->lock);
}
#endif /* BTRFS_SPACE_INFO_H */