From 27a3507de91e3dd51a2cf8dca4b33623dd6eaa88 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Sun, 6 Jul 2014 20:09:59 +0100 Subject: [PATCH] Btrfs: reduce size of struct extent_state The tree field of struct extent_state was only used to figure out if an extent state was connected to an inode's io tree or not. For this we can just use the rb_node field itself. On a x86_64 system with this change the sizeof(struct extent_state) is reduced from 96 bytes down to 88 bytes, meaning that with a page size of 4096 bytes we can now store 46 extent states per page instead of 42. Signed-off-by: Filipe Manana Signed-off-by: Chris Mason --- fs/btrfs/extent_io.c | 37 ++++++++++++++++++++----------------- fs/btrfs/extent_io.h | 1 - 2 files changed, 20 insertions(+), 18 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 1009fa8a08ef..816e80e678bd 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -25,6 +25,11 @@ static struct kmem_cache *extent_state_cache; static struct kmem_cache *extent_buffer_cache; static struct bio_set *btrfs_bioset; +static inline bool extent_state_in_tree(const struct extent_state *state) +{ + return !RB_EMPTY_NODE(&state->rb_node); +} + #ifdef CONFIG_BTRFS_DEBUG static LIST_HEAD(buffers); static LIST_HEAD(states); @@ -59,9 +64,9 @@ void btrfs_leak_debug_check(void) while (!list_empty(&states)) { state = list_entry(states.next, struct extent_state, leak_list); - printk(KERN_ERR "BTRFS: state leak: start %llu end %llu " - "state %lu in tree %p refs %d\n", - state->start, state->end, state->state, state->tree, + pr_err("BTRFS: state leak: start %llu end %llu state %lu in tree %d refs %d\n", + state->start, state->end, state->state, + extent_state_in_tree(state), atomic_read(&state->refs)); list_del(&state->leak_list); kmem_cache_free(extent_state_cache, state); @@ -209,7 +214,7 @@ static struct extent_state *alloc_extent_state(gfp_t mask) return state; state->state = 0; state->private = 0; - state->tree = NULL; + RB_CLEAR_NODE(&state->rb_node); btrfs_leak_debug_add(&state->leak_list, &states); atomic_set(&state->refs, 1); init_waitqueue_head(&state->wq); @@ -222,7 +227,7 @@ void free_extent_state(struct extent_state *state) if (!state) return; if (atomic_dec_and_test(&state->refs)) { - WARN_ON(state->tree); + WARN_ON(extent_state_in_tree(state)); btrfs_leak_debug_del(&state->leak_list); trace_free_extent_state(state, _RET_IP_); kmem_cache_free(extent_state_cache, state); @@ -371,8 +376,8 @@ static void merge_state(struct extent_io_tree *tree, other->state == state->state) { merge_cb(tree, state, other); state->start = other->start; - other->tree = NULL; rb_erase(&other->rb_node, &tree->state); + RB_CLEAR_NODE(&other->rb_node); free_extent_state(other); } } @@ -383,8 +388,8 @@ static void merge_state(struct extent_io_tree *tree, other->state == state->state) { merge_cb(tree, state, other); state->end = other->end; - other->tree = NULL; rb_erase(&other->rb_node, &tree->state); + RB_CLEAR_NODE(&other->rb_node); free_extent_state(other); } } @@ -442,7 +447,6 @@ static int insert_state(struct extent_io_tree *tree, found->start, found->end, start, end); return -EEXIST; } - state->tree = tree; merge_state(tree, state); return 0; } @@ -486,7 +490,6 @@ static int split_state(struct extent_io_tree *tree, struct extent_state *orig, free_extent_state(prealloc); return -EEXIST; } - prealloc->tree = tree; return 0; } @@ -524,9 +527,9 @@ static struct extent_state *clear_state_bit(struct extent_io_tree *tree, wake_up(&state->wq); if (state->state == 0) { next = next_state(state); - if (state->tree) { + if (extent_state_in_tree(state)) { rb_erase(&state->rb_node, &tree->state); - state->tree = NULL; + RB_CLEAR_NODE(&state->rb_node); free_extent_state(state); } else { WARN_ON(1); @@ -606,8 +609,8 @@ again: cached_state = NULL; } - if (cached && cached->tree && cached->start <= start && - cached->end > start) { + if (cached && extent_state_in_tree(cached) && + cached->start <= start && cached->end > start) { if (clear) atomic_dec(&cached->refs); state = cached; @@ -843,7 +846,7 @@ again: if (cached_state && *cached_state) { state = *cached_state; if (state->start <= start && state->end > start && - state->tree) { + extent_state_in_tree(state)) { node = &state->rb_node; goto hit_next; } @@ -1069,7 +1072,7 @@ again: if (cached_state && *cached_state) { state = *cached_state; if (state->start <= start && state->end > start && - state->tree) { + extent_state_in_tree(state)) { node = &state->rb_node; goto hit_next; } @@ -1459,7 +1462,7 @@ int find_first_extent_bit(struct extent_io_tree *tree, u64 start, spin_lock(&tree->lock); if (cached_state && *cached_state) { state = *cached_state; - if (state->end == start - 1 && state->tree) { + if (state->end == start - 1 && extent_state_in_tree(state)) { n = rb_next(&state->rb_node); while (n) { state = rb_entry(n, struct extent_state, @@ -1905,7 +1908,7 @@ int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end, int bitset = 0; spin_lock(&tree->lock); - if (cached && cached->tree && cached->start <= start && + if (cached && extent_state_in_tree(cached) && cached->start <= start && cached->end > start) node = &cached->rb_node; else diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index ccc264e7bde1..1f608166fe67 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -108,7 +108,6 @@ struct extent_state { struct rb_node rb_node; /* ADD NEW ELEMENTS AFTER THIS */ - struct extent_io_tree *tree; wait_queue_head_t wq; atomic_t refs; unsigned long state; -- 2.30.2