From 817d52f8dba26d0295c26035531c30ce5f1e3c3e Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Mon, 13 Jul 2009 21:29:25 -0400 Subject: Btrfs: async block group caching This patch moves the caching of the block group off to a kthread in order to allow people to allocate sooner. Instead of blocking up behind the caching mutex, we instead kick of the caching kthread, and then attempt to make an allocation. If we cannot, we wait on the block groups caching waitqueue, which the caching kthread will wake the waiting threads up everytime it finds 2 meg worth of space, and then again when its finished caching. This is how I tested the speedup from this mkfs the disk mount the disk fill the disk up with fs_mark unmount the disk mount the disk time touch /mnt/foo Without my changes this took 11 seconds on my box, with these changes it now takes 1 second. Another change thats been put in place is we lock the super mirror's in the pinned extent map in order to keep us from adding that stuff as free space when caching the block group. This doesn't really change anything else as far as the pinned extent map is concerned, since for actual pinned extents we use EXTENT_DIRTY, but it does mean that when we unmount we have to go in and unlock those extents to keep from leaking memory. I've also added a check where when we are reading block groups from disk, if the amount of space used == the size of the block group, we go ahead and mark the block group as cached. This drastically reduces the amount of time it takes to cache the block groups. Using the same test as above, except doing a dd to a file and then unmounting, it used to take 33 seconds to umount, now it takes 3 seconds. This version uses the commit_root in the caching kthread, and then keeps track of how many async caching threads are running at any given time so if one of the async threads is still running as we cross transactions we can wait until its finished before handling the pinned extents. Thank you, Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/tree-log.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/btrfs/tree-log.c') diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index c13922206d1b..195606862618 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -264,7 +264,7 @@ static int process_one_buffer(struct btrfs_root *log, { if (wc->pin) btrfs_update_pinned_extents(log->fs_info->extent_root, - eb->start, eb->len, 1); + eb->start, eb->len, 1, 0); if (btrfs_buffer_uptodate(eb, gen)) { if (wc->write) -- cgit v1.2.3 From 631c07c8d12bcc6ce4a0fbfbd64ea843d78e2b10 Mon Sep 17 00:00:00 2001 From: Julia Lawall Date: Mon, 27 Jul 2009 13:57:00 -0400 Subject: Btrfs: Correct redundant test in add_inode_ref dir has already been tested. It seems that this test should be on the recently returned value inode. A simplified version of the semantic match that finds this problem is as follows: (http://www.emn.fr/x-info/coccinelle/) Signed-off-by: Julia Lawall Signed-off-by: Chris Mason --- fs/btrfs/tree-log.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/btrfs/tree-log.c') diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 195606862618..11d0787c6188 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -797,7 +797,7 @@ static noinline int add_inode_ref(struct btrfs_trans_handle *trans, return -ENOENT; inode = read_one_inode(root, key->objectid); - BUG_ON(!dir); + BUG_ON(!inode); ref_ptr = btrfs_item_ptr_offset(eb, slot); ref_end = ref_ptr + btrfs_item_size_nr(eb, slot); -- cgit v1.2.3 From 68b38550ddbea13d296184bf69edff387618b1d3 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Mon, 27 Jul 2009 13:57:01 -0400 Subject: Btrfs: change how we unpin extents We are racy with async block caching and unpinning extents. This patch makes things much less complicated by only unpinning the extent if the block group is cached. We check the block_group->cached var under the block_group->lock spin lock. If it is set to BTRFS_CACHE_FINISHED then we update the pinned counters, and unpin the extent and add the free space back. If it is not set to this, we start the caching of the block group so the next time we unpin extents we can unpin the extent. This keeps us from racing with the async caching threads, lets us kill the fs wide async thread counter, and keeps us from having to set DELALLOC bits for every extent we hit if there are caching kthreads going. One thing that needed to be changed was btrfs_free_super_mirror_extents. Now instead of just looking for LOCKED extents, we also look for DIRTY extents, since we could have left some extents pinned in the previous transaction that will never get freed now that we are unmounting, which would cause us to leak memory. So btrfs_free_super_mirror_extents has been changed to btrfs_free_pinned_extents, and it will clear the extents locked for the super mirror, and any remaining pinned extents that may be present. Thank you, Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/ctree.h | 5 +- fs/btrfs/disk-io.c | 3 +- fs/btrfs/extent-tree.c | 149 ++++++++++++++----------------------------------- fs/btrfs/tree-log.c | 2 +- 4 files changed, 46 insertions(+), 113 deletions(-) (limited to 'fs/btrfs/tree-log.c') diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 42b03c4ee494..17ad92c29cfd 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -845,7 +845,6 @@ struct btrfs_fs_info { atomic_t async_submit_draining; atomic_t nr_async_bios; atomic_t async_delalloc_pages; - atomic_t async_caching_threads; /* * this is used by the balancing code to wait for all the pending @@ -1926,7 +1925,7 @@ int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, struct btrfs_root *root, unsigned long count); int btrfs_lookup_extent(struct btrfs_root *root, u64 start, u64 len); int btrfs_update_pinned_extents(struct btrfs_root *root, - u64 bytenr, u64 num, int pin, int mark_free); + u64 bytenr, u64 num, int pin); int btrfs_drop_leaf_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *leaf); int btrfs_cross_ref_exist(struct btrfs_trans_handle *trans, @@ -2011,7 +2010,7 @@ void btrfs_delalloc_reserve_space(struct btrfs_root *root, struct inode *inode, u64 bytes); void btrfs_delalloc_free_space(struct btrfs_root *root, struct inode *inode, u64 bytes); -void btrfs_free_super_mirror_extents(struct btrfs_fs_info *info); +void btrfs_free_pinned_extents(struct btrfs_fs_info *info); /* ctree.c */ int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key, int level, int *slot); diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index ec2c915f7f4a..c658397c7473 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1567,7 +1567,6 @@ struct btrfs_root *open_ctree(struct super_block *sb, atomic_set(&fs_info->async_delalloc_pages, 0); atomic_set(&fs_info->async_submit_draining, 0); atomic_set(&fs_info->nr_async_bios, 0); - atomic_set(&fs_info->async_caching_threads, 0); fs_info->sb = sb; fs_info->max_extent = (u64)-1; fs_info->max_inline = 8192 * 1024; @@ -2339,7 +2338,7 @@ int close_ctree(struct btrfs_root *root) free_extent_buffer(root->fs_info->csum_root->commit_root); btrfs_free_block_groups(root->fs_info); - btrfs_free_super_mirror_extents(root->fs_info); + btrfs_free_pinned_extents(root->fs_info); del_fs_roots(fs_info); diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 508df5f7d2ea..08188f1615d9 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -153,18 +153,26 @@ block_group_cache_tree_search(struct btrfs_fs_info *info, u64 bytenr, return ret; } -void btrfs_free_super_mirror_extents(struct btrfs_fs_info *info) +/* + * We always set EXTENT_LOCKED for the super mirror extents so we don't + * overwrite them, so those bits need to be unset. Also, if we are unmounting + * with pinned extents still sitting there because we had a block group caching, + * we need to clear those now, since we are done. + */ +void btrfs_free_pinned_extents(struct btrfs_fs_info *info) { u64 start, end, last = 0; int ret; while (1) { ret = find_first_extent_bit(&info->pinned_extents, last, - &start, &end, EXTENT_LOCKED); + &start, &end, + EXTENT_LOCKED|EXTENT_DIRTY); if (ret) break; - unlock_extent(&info->pinned_extents, start, end, GFP_NOFS); + clear_extent_bits(&info->pinned_extents, start, end, + EXTENT_LOCKED|EXTENT_DIRTY, GFP_NOFS); last = end+1; } } @@ -209,8 +217,7 @@ static u64 add_new_free_space(struct btrfs_block_group_cache *block_group, while (start < end) { ret = find_first_extent_bit(&info->pinned_extents, start, &extent_start, &extent_end, - EXTENT_DIRTY|EXTENT_LOCKED| - EXTENT_DELALLOC); + EXTENT_DIRTY|EXTENT_LOCKED); if (ret) break; @@ -238,67 +245,6 @@ static u64 add_new_free_space(struct btrfs_block_group_cache *block_group, return total_added; } -DEFINE_MUTEX(discard_mutex); - -/* - * if async kthreads are running when we cross transactions, we mark any pinned - * extents with EXTENT_DELALLOC and then let the caching kthreads clean up those - * extents when they are done. Also we run this from btrfs_finish_extent_commit - * in case there were some pinned extents that were missed because we had - * already cached that block group. - */ -static void btrfs_discard_pinned_extents(struct btrfs_fs_info *fs_info, - struct btrfs_block_group_cache *cache) -{ - u64 start, end, last; - int ret; - - if (!cache) - last = 0; - else - last = cache->key.objectid; - - mutex_lock(&discard_mutex); - while (1) { - ret = find_first_extent_bit(&fs_info->pinned_extents, last, - &start, &end, EXTENT_DELALLOC); - if (ret) - break; - - if (cache && start >= cache->key.objectid + cache->key.offset) - break; - - - if (!cache) { - cache = btrfs_lookup_block_group(fs_info, start); - BUG_ON(!cache); - - start = max(start, cache->key.objectid); - end = min(end, cache->key.objectid + cache->key.offset - 1); - - if (block_group_cache_done(cache)) - btrfs_add_free_space(cache, start, - end - start + 1); - cache = NULL; - } else { - start = max(start, cache->key.objectid); - end = min(end, cache->key.objectid + cache->key.offset - 1); - btrfs_add_free_space(cache, start, end - start + 1); - } - - clear_extent_bits(&fs_info->pinned_extents, start, end, - EXTENT_DELALLOC, GFP_NOFS); - last = end + 1; - - if (need_resched()) { - mutex_unlock(&discard_mutex); - cond_resched(); - mutex_lock(&discard_mutex); - } - } - mutex_unlock(&discard_mutex); -} - static int caching_kthread(void *data) { struct btrfs_block_group_cache *block_group = data; @@ -317,7 +263,6 @@ static int caching_kthread(void *data) if (!path) return -ENOMEM; - atomic_inc(&fs_info->async_caching_threads); atomic_inc(&block_group->space_info->caching_threads); last = max_t(u64, block_group->key.objectid, BTRFS_SUPER_INFO_OFFSET); again: @@ -399,13 +344,9 @@ next: err: btrfs_free_path(path); up_read(&fs_info->extent_root->commit_root_sem); - atomic_dec(&fs_info->async_caching_threads); atomic_dec(&block_group->space_info->caching_threads); wake_up(&block_group->caching_q); - if (!ret) - btrfs_discard_pinned_extents(fs_info, block_group); - return 0; } @@ -1867,7 +1808,7 @@ static int run_one_delayed_ref(struct btrfs_trans_handle *trans, BUG_ON(ret); } btrfs_update_pinned_extents(root, node->bytenr, - node->num_bytes, 1, 0); + node->num_bytes, 1); update_reserved_extents(root, node->bytenr, node->num_bytes, 0); } @@ -3100,19 +3041,15 @@ static u64 first_logical_byte(struct btrfs_root *root, u64 search_start) } int btrfs_update_pinned_extents(struct btrfs_root *root, - u64 bytenr, u64 num, int pin, int mark_free) + u64 bytenr, u64 num, int pin) { u64 len; struct btrfs_block_group_cache *cache; struct btrfs_fs_info *fs_info = root->fs_info; - if (pin) { + if (pin) set_extent_dirty(&fs_info->pinned_extents, bytenr, bytenr + num - 1, GFP_NOFS); - } else { - clear_extent_dirty(&fs_info->pinned_extents, - bytenr, bytenr + num - 1, GFP_NOFS); - } while (num > 0) { cache = btrfs_lookup_block_group(fs_info, bytenr); @@ -3128,14 +3065,34 @@ int btrfs_update_pinned_extents(struct btrfs_root *root, spin_unlock(&cache->space_info->lock); fs_info->total_pinned += len; } else { + int unpin = 0; + + /* + * in order to not race with the block group caching, we + * only want to unpin the extent if we are cached. If + * we aren't cached, we want to start async caching this + * block group so we can free the extent the next time + * around. + */ spin_lock(&cache->space_info->lock); spin_lock(&cache->lock); - cache->pinned -= len; - cache->space_info->bytes_pinned -= len; + unpin = (cache->cached == BTRFS_CACHE_FINISHED); + if (likely(unpin)) { + cache->pinned -= len; + cache->space_info->bytes_pinned -= len; + fs_info->total_pinned -= len; + } spin_unlock(&cache->lock); spin_unlock(&cache->space_info->lock); - fs_info->total_pinned -= len; - if (block_group_cache_done(cache) && mark_free) + + if (likely(unpin)) + clear_extent_dirty(&fs_info->pinned_extents, + bytenr, bytenr + len -1, + GFP_NOFS); + else + cache_block_group(cache); + + if (unpin) btrfs_add_free_space(cache, bytenr, len); } btrfs_put_block_group(cache); @@ -3181,27 +3138,15 @@ int btrfs_copy_pinned(struct btrfs_root *root, struct extent_io_tree *copy) u64 last = 0; u64 start; u64 end; - bool caching_kthreads = false; struct extent_io_tree *pinned_extents = &root->fs_info->pinned_extents; int ret; - if (atomic_read(&root->fs_info->async_caching_threads)) - caching_kthreads = true; - while (1) { ret = find_first_extent_bit(pinned_extents, last, &start, &end, EXTENT_DIRTY); if (ret) break; - /* - * we need to make sure that the pinned extents don't go away - * while we are caching block groups - */ - if (unlikely(caching_kthreads)) - set_extent_delalloc(pinned_extents, start, end, - GFP_NOFS); - set_extent_dirty(copy, start, end, GFP_NOFS); last = end + 1; } @@ -3215,12 +3160,6 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans, u64 start; u64 end; int ret; - int mark_free = 1; - - ret = find_first_extent_bit(&root->fs_info->pinned_extents, 0, - &start, &end, EXTENT_DELALLOC); - if (!ret) - mark_free = 0; while (1) { ret = find_first_extent_bit(unpin, 0, &start, &end, @@ -3231,16 +3170,12 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans, ret = btrfs_discard_extent(root, start, end + 1 - start); /* unlocks the pinned mutex */ - btrfs_update_pinned_extents(root, start, end + 1 - start, 0, - mark_free); + btrfs_update_pinned_extents(root, start, end + 1 - start, 0); clear_extent_dirty(unpin, start, end, GFP_NOFS); cond_resched(); } - if (unlikely(!mark_free)) - btrfs_discard_pinned_extents(root->fs_info, NULL); - return ret; } @@ -3281,7 +3216,7 @@ static int pin_down_bytes(struct btrfs_trans_handle *trans, pinit: btrfs_set_path_blocking(path); /* unlocks the pinned mutex */ - btrfs_update_pinned_extents(root, bytenr, num_bytes, 1, 0); + btrfs_update_pinned_extents(root, bytenr, num_bytes, 1); BUG_ON(err < 0); return 0; @@ -3592,7 +3527,7 @@ int btrfs_free_extent(struct btrfs_trans_handle *trans, if (root_objectid == BTRFS_TREE_LOG_OBJECTID) { WARN_ON(owner >= BTRFS_FIRST_FREE_OBJECTID); /* unlocks the pinned mutex */ - btrfs_update_pinned_extents(root, bytenr, num_bytes, 1, 0); + btrfs_update_pinned_extents(root, bytenr, num_bytes, 1); update_reserved_extents(root, bytenr, num_bytes, 0); ret = 0; } else if (owner < BTRFS_FIRST_FREE_OBJECTID) { diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 11d0787c6188..d91b0de7c502 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -264,7 +264,7 @@ static int process_one_buffer(struct btrfs_root *log, { if (wc->pin) btrfs_update_pinned_extents(log->fs_info->extent_root, - eb->start, eb->len, 1, 0); + eb->start, eb->len, 1); if (btrfs_buffer_uptodate(eb, gen)) { if (wc->write) -- cgit v1.2.3