diff options
author | Filipe Manana <fdmanana@suse.com> | 2023-11-21 14:38:38 +0100 |
---|---|---|
committer | David Sterba <dsterba@suse.com> | 2023-12-15 20:27:02 +0100 |
commit | 7dc66abb5a47778d7db327783a0ba172b8cff0b5 (patch) | |
tree | 66fef581a2f31904aae1c15f9fdbbc7aec798132 /include/trace/events | |
parent | btrfs: use btrfs_next_item() at scrub.c:find_first_extent_item() (diff) | |
download | linux-7dc66abb5a47778d7db327783a0ba172b8cff0b5.tar.xz linux-7dc66abb5a47778d7db327783a0ba172b8cff0b5.zip |
btrfs: use a dedicated data structure for chunk maps
Currently we abuse the extent_map structure for two purposes:
1) To actually represent extents for inodes;
2) To represent chunk mappings.
This is odd and has several disadvantages:
1) To create a chunk map, we need to do two memory allocations: one for
an extent_map structure and another one for a map_lookup structure, so
more potential for an allocation failure and more complicated code to
manage and link two structures;
2) For a chunk map we actually only use 3 fields (24 bytes) of the
respective extent map structure: the 'start' field to have the logical
start address of the chunk, the 'len' field to have the chunk's size,
and the 'orig_block_len' field to contain the chunk's stripe size.
Besides wasting a memory, it's also odd and not intuitive at all to
have the stripe size in a field named 'orig_block_len'.
We are also using 'block_len' of the extent_map structure to contain
the chunk size, so we have 2 fields for the same value, 'len' and
'block_len', which is pointless;
3) When an extent map is associated to a chunk mapping, we set the bit
EXTENT_FLAG_FS_MAPPING on its flags and then make its member named
'map_lookup' point to the associated map_lookup structure. This means
that for an extent map associated to an inode extent, we are not using
this 'map_lookup' pointer, so wasting 8 bytes (on a 64 bits platform);
4) Extent maps associated to a chunk mapping are never merged or split so
it's pointless to use the existing extent map infrastructure.
So add a dedicated data structure named 'btrfs_chunk_map' to represent
chunk mappings, this is basically the existing map_lookup structure with
some extra fields:
1) 'start' to contain the chunk logical address;
2) 'chunk_len' to contain the chunk's length;
3) 'stripe_size' for the stripe size;
4) 'rb_node' for insertion into a rb tree;
5) 'refs' for reference counting.
This way we do a single memory allocation for chunk mappings and we don't
waste memory for them with unused/unnecessary fields from an extent_map.
We also save 8 bytes from the extent_map structure by removing the
'map_lookup' pointer, so the size of struct extent_map is reduced from
144 bytes down to 136 bytes, and we can now have 30 extents map per 4K
page instead of 28.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'include/trace/events')
-rw-r--r-- | include/trace/events/btrfs.h | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h index 279a7a0c90c0..4a95097ab590 100644 --- a/include/trace/events/btrfs.h +++ b/include/trace/events/btrfs.h @@ -21,7 +21,7 @@ struct btrfs_delayed_data_ref; struct btrfs_delayed_ref_head; struct btrfs_block_group; struct btrfs_free_cluster; -struct map_lookup; +struct btrfs_chunk_map; struct extent_buffer; struct btrfs_work; struct btrfs_workqueue; @@ -277,8 +277,7 @@ DEFINE_EVENT(btrfs__inode, btrfs_inode_evict, { (1 << EXTENT_FLAG_COMPRESSED), "COMPRESSED" },\ { (1 << EXTENT_FLAG_PREALLOC), "PREALLOC" },\ { (1 << EXTENT_FLAG_LOGGING), "LOGGING" },\ - { (1 << EXTENT_FLAG_FILLING), "FILLING" },\ - { (1 << EXTENT_FLAG_FS_MAPPING), "FS_MAPPING" }) + { (1 << EXTENT_FLAG_FILLING), "FILLING" }) TRACE_EVENT_CONDITION(btrfs_get_extent, @@ -1061,7 +1060,7 @@ DEFINE_EVENT(btrfs_delayed_ref_head, run_delayed_ref_head, DECLARE_EVENT_CLASS(btrfs__chunk, TP_PROTO(const struct btrfs_fs_info *fs_info, - const struct map_lookup *map, u64 offset, u64 size), + const struct btrfs_chunk_map *map, u64 offset, u64 size), TP_ARGS(fs_info, map, offset, size), @@ -1095,7 +1094,7 @@ DECLARE_EVENT_CLASS(btrfs__chunk, DEFINE_EVENT(btrfs__chunk, btrfs_chunk_alloc, TP_PROTO(const struct btrfs_fs_info *fs_info, - const struct map_lookup *map, u64 offset, u64 size), + const struct btrfs_chunk_map *map, u64 offset, u64 size), TP_ARGS(fs_info, map, offset, size) ); @@ -1103,7 +1102,7 @@ DEFINE_EVENT(btrfs__chunk, btrfs_chunk_alloc, DEFINE_EVENT(btrfs__chunk, btrfs_chunk_free, TP_PROTO(const struct btrfs_fs_info *fs_info, - const struct map_lookup *map, u64 offset, u64 size), + const struct btrfs_chunk_map *map, u64 offset, u64 size), TP_ARGS(fs_info, map, offset, size) ); |