kernel.git/include/trace/events/btrfs.h, branch linux-6.8.y

btrfs: use the flags of an extent map to identify the compression type

2023-12-15T21:59:02Z

Currently, in struct extent_map, we use an unsigned int (32 bits) to identify the compression type of an extent and an unsigned long (64 bits on a 64 bits platform, 32 bits otherwise) for flags. We are only using 6 different flags, so an unsigned long is excessive and we can use flags to identify the compression type instead of using a dedicated 32 bits field. We can easily have tens or hundreds of thousands (or more) of extent maps on busy and large filesystems, specially with compression enabled or many or large files with tons of small extents. So it's convenient to have the extent_map structure as small as possible in order to use less memory. So remove the compression type field from struct extent_map, use flags to identify the compression type and shorten the flags field from an unsigned long to a u32. This saves 8 bytes (on 64 bits platforms) and reduces the size of the structure from 136 bytes down to 128 bytes, using now only two cache lines, and increases the number of extent maps we can have per 4K page from 30 to 32. By using a u32 for the flags instead of an unsigned long, we no longer use test_bit(), set_bit() and clear_bit(), but that level of atomicity is not needed as most flags are never cleared once set (before adding an extent map to the tree), and the ones that can be cleared or set after an extent map is added to the tree, are always performed while holding the write lock on the extent map tree, while the reader holds a lock on the tree or tests for a flag that never changes once the extent map is in the tree (such as compression flags). Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: remove no longer used EXTENT_MAP_DELALLOC block start value

2023-12-15T19:27:03Z

After commit ac3c0d36a2a2 ("btrfs: make fiemap more efficient and accurate reporting extent sharedness") we no longer need to create special extent maps during fiemap that have a block start with the EXTENT_MAP_DELALLOC value. So this block start value for extent maps is no longer used since then, therefore remove it. Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: always set extent_io_tree::inode and drop fs_info

2023-12-15T19:27:02Z

The extent_io_tree is embedded in several structures, notably in struct btrfs_inode. The fs_info is only used for reporting errors and for reference in trace points. We can get to the pointer through the inode, but not all io trees set it. However, we always know the owner and can recognize if inode is valid. For access helpers are provided, const variant for the trace points. This reduces size of extent_io_tree by 8 bytes and following structures in turn: - btrfs_inode 1104 -> 1088 - btrfs_device 520 -> 512 - btrfs_root 1360 -> 1344 - btrfs_transaction 456 -> 440 - btrfs_fs_info 3600 -> 3592 - reloc_control 1520 -> 1512 Reviewed-by: Josef Bacik Signed-off-by: David Sterba

btrfs: use a dedicated data structure for chunk maps

2023-12-15T19:27:02Z

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 Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: merge ordered work callbacks in btrfs_work into one

2023-10-12T14:44:10Z

There are two callbacks defined in btrfs_work but only two actually make use of them, otherwise there are NULLs. We can get rid of the freeing callback making it a special case of the normal work. This reduces the size of btrfs_work by 8 bytes, final layout: struct btrfs_work { btrfs_func_t func; /* 0 8 */ btrfs_ordered_func_t ordered_func; /* 8 8 */ struct work_struct normal_work; /* 16 32 */ struct list_head ordered_list; /* 48 16 */ /* --- cacheline 1 boundary (64 bytes) --- */ struct btrfs_workqueue * wq; /* 64 8 */ long unsigned int flags; /* 72 8 */ /* size: 80, cachelines: 2, members: 6 */ /* last cacheline: 16 bytes */ }; This in turn reduces size of other structures (on a release config): - async_chunk 160 -> 152 - async_submit_bio 152 -> 144 - btrfs_async_delayed_work 104 -> 96 - btrfs_caching_control 176 -> 168 - btrfs_delalloc_work 144 -> 136 - btrfs_fs_info 3608 -> 3600 - btrfs_ordered_extent 440 -> 424 - btrfs_writepage_fixup 104 -> 96 Signed-off-by: David Sterba

btrfs: tracepoints: add events for raid stripe tree

2023-10-12T14:44:10Z

Add trace events for raid-stripe-tree operations. Signed-off-by: Johannes Thumshirn Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: remove v0 extent handling

2023-08-21T12:54:48Z

The v0 extent item has been deprecated for a long time, and we don't have any report from the community either. So it's time to remove the v0 extent specific error handling, and just treat them as regular extent tree corruption. This patch would remove the btrfs_print_v0_err() helper, and enhance the involved error handling to treat them just as any extent tree corruption. No reports regarding v0 extents have been seen since the graceful handling was added in 2018. This involves: - btrfs_backref_add_tree_node() This change is a little tricky, the new code is changed to only handle BTRFS_TREE_BLOCK_REF_KEY and BTRFS_SHARED_BLOCK_REF_KEY. But this is safe, as we have rejected any unknown inline refs through btrfs_get_extent_inline_ref_type(). For keyed backrefs, we're safe to skip anything we don't know (that's if it can pass tree-checker in the first place). - btrfs_lookup_extent_info() - lookup_inline_extent_backref() - run_delayed_extent_op() - __btrfs_free_extent() - add_tree_block() Regular error handling of unexpected extent tree item, and abort transaction (if we have a trans handle). - remove_extent_data_ref() It's pretty much the same as the regular rejection of unknown backref key. But for this particular case, we can also remove a BUG_ON(). - extent_data_ref_count() We can remove the BTRFS_EXTENT_REF_V0_KEY BUG_ON(), as it would be rejected by the only caller. - btrfs_print_leaf() Remove the handling for BTRFS_EXTENT_REF_V0_KEY. Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: tracepoints: simplify raid56 events

2023-08-21T12:52:12Z

After commit 6bfd0133bee2 ("btrfs: raid56: switch scrub path to use a single function"), the raid56 implementation no longer uses different endio functions for RMW/recover/scrub. All read operations end in submit_read_wait_bio_list(), while all write operations end in submit_write_bios(). This means quite some trace events are out-of-date and no longer utilized. This patch would unify the trace events into just two: - trace_raid56_read() Replaces trace_raid56_read_partial(), trace_raid56_scrub_read() and trace_raid56_scrub_read_recover(). - trace_raid56_write() Replaces trace_raid56_write_stripe() and trace_raid56_scrub_write_stripe(). Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: tracepoints: also show actual number of the outstanding extents

2023-06-19T17:47:58Z

The btrfs_inode_mod_outstanding_extents trace event only shows the modified number to the number of outstanding extents. It would be helpful if we can see the resulting extent number as well. Signed-off-by: Naohiro Aota Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: add a btrfs_finish_ordered_extent helper

2023-06-19T11:59:37Z

Add a helper to complete an ordered_extent without first doing a lookup. The tracepoint cannot use the ordered_extent class as we also want to print the range. Reviewed-by: Johannes Thumshirn Reviewed-by: Josef Bacik Signed-off-by: Christoph Hellwig Reviewed-by: David Sterba Signed-off-by: David Sterba