kernel/linux.git/fs/btrfs/delayed-ref.h, branch linux-7.1.y

btrfs: move ref-verify under CONFIG_BTRFS_DEBUG

2025-09-22T08:54:32+00:00

Remove CONFIG_BTRFS_FS_REF_VERIFY Kconfig and add it as part of CONFIG_BTRFS_DEBUG. This should not be impactful to the performance of debug. The struct btrfs_ref takes an additional u64, btrfs_fs_info takes an additional spinlock_t and rb_root. All of the ref_verify logic is still protected by a mount option. Signed-off-by: Leo Martins Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: constify more pointer parameters

2025-07-21T21:53:26+00:00

Another batch of pointer parameter constifications. This is for clarity and minor addition to type safety. There are no observable effects in the assembly code and .ko measured on release config. Signed-off-by: David Sterba

btrfs: remove BTRFS_REF_LAST from enum btrfs_ref_type

2025-05-15T12:30:47+00:00

Commit b28b1f0ce44c ("btrfs: delayed-ref: Introduce better documented delayed ref structures") introduced BTRFS_REF_LAST, which can be used for sanity checking, e.g. in switch/case or for loops. In btrfs_ref_type() there is an assertion ASSERT(ref->type == BTRFS_REF_DATA || ref->type == BTRFS_REF_METADATA); to validate the values so we don't need the ending enum. Signed-off-by: Yangtao Li Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: update include and forward declarations in headers

2025-03-18T19:35:43+00:00

Pass over all header files and add missing forward declarations, includes or fix include types. Signed-off-by: David Sterba

btrfs: move select_delayed_ref() and export it

2025-01-13T13:53:13+00:00

This helper is how we select the delayed ref to run once we've selected the delayed ref head. I need this exported to add a unit test for delayed refs, and it's more natural home is in delayed-ref.c. Rename it to btrfs_select_delayed_ref and move it into delayed-ref.c. Reviewed-by: Boris Burkov Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: update stale comment for struct btrfs_delayed_ref_node::add_list

2024-11-11T13:34:22+00:00

The comment refers to a list in the respective delayed ref head that no longer exists (ref_list), it was replaced with a rbtree (ref_tree) in commit 0e0adbcfdc90 ("btrfs: track refs in a rb_tree instead of a list"). So update the stale comment to refer to the rbtree instead of the old list. Reviewed-by: Johannes Thumshirn Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: track delayed ref heads in an xarray

2024-11-11T13:34:21+00:00

Currently we use a red black tree (rb-tree) to track the delayed ref heads (in struct btrfs_delayed_ref_root::href_root). This however is not very efficient when the number of delayed ref heads is large (and it's very common to be at least in the order of thousands) since rb-trees are binary trees. For example for 10K delayed ref heads, the tree has a depth of 13. Besides that, inserting into the tree requires navigating through it and pulling useless cache lines in the process since the red black tree nodes are embedded within the delayed ref head structure - on the other hand, by being embedded, it requires no extra memory allocations. We can improve this by using an xarray instead which has a much higher branching factor than a red black tree (binary balanced tree) and is more cache friendly and behaves like a resizable array, with a much better search and insertion complexity than a red black tree. This only has one small disadvantage which is that insertion will sometimes require allocating memory for the xarray - which may fail (not that often since it uses a kmem_cache) - but on the other hand we can reduce the delayed ref head structure size by 24 bytes (from 152 down to 128 bytes) after removing the embedded red black tree node, meaning than we can now fit 32 delayed ref heads per 4K page instead of 26, and that gain compensates for the occasional memory allocations needed for the xarray nodes. We also end up using only 2 cache lines instead of 3 per delayed ref head. Running the following fs_mark test showed some improvements: $ cat test.sh #!/bin/bash DEV=/dev/nullb0 MNT=/mnt/nullb0 MOUNT_OPTIONS="-o ssd" FILES=100000 THREADS=$(nproc --all) echo "performance" | \ tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor mkfs.btrfs -f $DEV mount $MOUNT_OPTIONS $DEV $MNT OPTS="-S 0 -L 5 -n $FILES -s 0 -t $THREADS -k" for ((i = 1; i <= $THREADS; i++)); do OPTS="$OPTS -d $MNT/d$i" done fs_mark $OPTS umount $MNT Before this patch: FSUse% Count Size Files/sec App Overhead 10 1200000 0 171845.7 12253839 16 2400000 0 230898.7 12308254 23 3600000 0 212292.9 12467768 30 4800000 0 195737.8 12627554 46 6000000 0 171055.2 12783329 After this patch: FSUse% Count Size Files/sec App Overhead 10 1200000 0 173835.0 12246131 16 2400000 0 233537.8 12271746 23 3600000 0 220398.7 12307737 30 4800000 0 204483.6 12392318 40 6000000 0 182923.3 12771843 Reviewed-by: Boris Burkov Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: add comments regarding locking to struct btrfs_delayed_ref_root

2024-11-11T13:34:21+00:00

Add some comments to struct btrfs_delayed_ref_root's fields to mention what its spinlock protects. Reviewed-by: Boris Burkov Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: pass fs_info to btrfs_delete_ref_head()

2024-11-11T13:34:20+00:00

One of the following patches in the series will need to access fs_info at btrfs_delete_ref_head(), so pass a fs_info argument to it. Reviewed-by: Boris Burkov Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: pass fs_info to functions that search for delayed ref heads

2024-11-11T13:34:20+00:00

One of the following patches in the series will need to access fs_info in the function find_ref_head(), so pass a fs_info argument to it as well as to the functions btrfs_select_ref_head() and btrfs_find_delayed_ref_head() which call find_ref_head(). Reviewed-by: Boris Burkov Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba