From 57fd5a5ff8b48b99e90b22fc143082aba755c6c0 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Fri, 7 Aug 2009 09:59:15 -0400 Subject: Btrfs: tweak congestion backoff The btrfs io submission thread tries to back off congested devices in favor of rotating off to another disk. But, it tries to make sure it submits at least some IO before rotating on (the others may be congested too), and so it has a magic number of requests it tries to write before it hops. This makes the magic number smaller. Testing shows that we're spending too much time on congested devices and leaving the other devices idle. Signed-off-by: Chris Mason --- fs/btrfs/volumes.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/btrfs/volumes.c') diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 5dbefd11b4af..a7e53773e743 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -276,7 +276,7 @@ loop_lock: * is now congested. Back off and let other work structs * run instead */ - if (pending && bdi_write_congested(bdi) && batch_run > 32 && + if (pending && bdi_write_congested(bdi) && batch_run > 8 && fs_info->fs_devices->open_devices > 1) { struct io_context *ioc; -- cgit v1.2.1 From 890871be854b5f5e43e7ba2475f706209906cc24 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 2 Sep 2009 16:24:52 -0400 Subject: Btrfs: switch extent_map to a rw lock There are two main users of the extent_map tree. The first is regular file inodes, where it is evenly spread between readers and writers. The second is the chunk allocation tree, which maps blocks from logical addresses to phyiscal ones, and it is 99.99% reads. The mapping tree is a point of lock contention during heavy IO workloads, so this commit switches things to a rw lock. Signed-off-by: Chris Mason --- fs/btrfs/volumes.c | 40 ++++++++++++++++++++-------------------- 1 file changed, 20 insertions(+), 20 deletions(-) (limited to 'fs/btrfs/volumes.c') diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index a7e53773e743..d2358c06bbd9 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1749,9 +1749,9 @@ static int btrfs_relocate_chunk(struct btrfs_root *root, * step two, delete the device extents and the * chunk tree entries */ - spin_lock(&em_tree->lock); + read_lock(&em_tree->lock); em = lookup_extent_mapping(em_tree, chunk_offset, 1); - spin_unlock(&em_tree->lock); + read_unlock(&em_tree->lock); BUG_ON(em->start > chunk_offset || em->start + em->len < chunk_offset); @@ -1780,9 +1780,9 @@ static int btrfs_relocate_chunk(struct btrfs_root *root, ret = btrfs_remove_block_group(trans, extent_root, chunk_offset); BUG_ON(ret); - spin_lock(&em_tree->lock); + write_lock(&em_tree->lock); remove_extent_mapping(em_tree, em); - spin_unlock(&em_tree->lock); + write_unlock(&em_tree->lock); kfree(map); em->bdev = NULL; @@ -2294,9 +2294,9 @@ again: em->block_len = em->len; em_tree = &extent_root->fs_info->mapping_tree.map_tree; - spin_lock(&em_tree->lock); + write_lock(&em_tree->lock); ret = add_extent_mapping(em_tree, em); - spin_unlock(&em_tree->lock); + write_unlock(&em_tree->lock); BUG_ON(ret); free_extent_map(em); @@ -2491,9 +2491,9 @@ int btrfs_chunk_readonly(struct btrfs_root *root, u64 chunk_offset) int readonly = 0; int i; - spin_lock(&map_tree->map_tree.lock); + read_lock(&map_tree->map_tree.lock); em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1); - spin_unlock(&map_tree->map_tree.lock); + read_unlock(&map_tree->map_tree.lock); if (!em) return 1; @@ -2518,11 +2518,11 @@ void btrfs_mapping_tree_free(struct btrfs_mapping_tree *tree) struct extent_map *em; while (1) { - spin_lock(&tree->map_tree.lock); + write_lock(&tree->map_tree.lock); em = lookup_extent_mapping(&tree->map_tree, 0, (u64)-1); if (em) remove_extent_mapping(&tree->map_tree, em); - spin_unlock(&tree->map_tree.lock); + write_unlock(&tree->map_tree.lock); if (!em) break; kfree(em->bdev); @@ -2540,9 +2540,9 @@ int btrfs_num_copies(struct btrfs_mapping_tree *map_tree, u64 logical, u64 len) struct extent_map_tree *em_tree = &map_tree->map_tree; int ret; - spin_lock(&em_tree->lock); + read_lock(&em_tree->lock); em = lookup_extent_mapping(em_tree, logical, len); - spin_unlock(&em_tree->lock); + read_unlock(&em_tree->lock); BUG_ON(!em); BUG_ON(em->start > logical || em->start + em->len < logical); @@ -2604,9 +2604,9 @@ again: atomic_set(&multi->error, 0); } - spin_lock(&em_tree->lock); + read_lock(&em_tree->lock); em = lookup_extent_mapping(em_tree, logical, *length); - spin_unlock(&em_tree->lock); + read_unlock(&em_tree->lock); if (!em && unplug_page) return 0; @@ -2763,9 +2763,9 @@ int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree, u64 stripe_nr; int i, j, nr = 0; - spin_lock(&em_tree->lock); + read_lock(&em_tree->lock); em = lookup_extent_mapping(em_tree, chunk_start, 1); - spin_unlock(&em_tree->lock); + read_unlock(&em_tree->lock); BUG_ON(!em || em->start != chunk_start); map = (struct map_lookup *)em->bdev; @@ -3053,9 +3053,9 @@ static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key, logical = key->offset; length = btrfs_chunk_length(leaf, chunk); - spin_lock(&map_tree->map_tree.lock); + read_lock(&map_tree->map_tree.lock); em = lookup_extent_mapping(&map_tree->map_tree, logical, 1); - spin_unlock(&map_tree->map_tree.lock); + read_unlock(&map_tree->map_tree.lock); /* already mapped? */ if (em && em->start <= logical && em->start + em->len > logical) { @@ -3114,9 +3114,9 @@ static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key, map->stripes[i].dev->in_fs_metadata = 1; } - spin_lock(&map_tree->map_tree.lock); + write_lock(&map_tree->map_tree.lock); ret = add_extent_mapping(&map_tree->map_tree, em); - spin_unlock(&map_tree->map_tree.lock); + write_unlock(&map_tree->map_tree.lock); BUG_ON(ret); free_extent_map(em); -- cgit v1.2.1 From ba1bf4818baf68d914ef9e3b06fbea6acb674fe4 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 11 Sep 2009 16:11:19 -0400 Subject: Btrfs: make balance code choose more wisely when relocating Currently, we can panic the box if the first block group we go to move is of a type where there is no space left to move those extents. For example, if we fill the disk up with data, and then we try to balance and we have no room to move the data nor room to allocate new chunks, we will panic. Change this by checking to see if we have room to move this chunk around, and if not, return -ENOSPC and move on to the next chunk. This will make sure we remove block groups that are moveable, like if we have alot of empty metadata block groups, and then that way we make room to be able to balance our data chunks as well. Tested this with an fs that would panic on btrfs-vol -b normally, but no longer panics with this patch. V1->V2: -actually search for a free extent on the device to make sure we can allocate a chunk if need be. -fix btrfs_shrink_device to make sure we actually try to relocate all the chunks, and then if we can't return -ENOSPC so if we are doing a btrfs-vol -r we don't remove the device with data still on it. -check to make sure the block group we are going to relocate isn't the last one in that particular space -fix a bug in btrfs_shrink_device where we would change the device's size and not fix it if we fail to do our relocate Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/volumes.c | 75 +++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 57 insertions(+), 18 deletions(-) (limited to 'fs/btrfs/volumes.c') diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index d2358c06bbd9..be953afe804c 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -719,10 +719,9 @@ error: * called very infrequently and that a given device has a small number * of extents */ -static noinline int find_free_dev_extent(struct btrfs_trans_handle *trans, - struct btrfs_device *device, - u64 num_bytes, u64 *start, - u64 *max_avail) +int find_free_dev_extent(struct btrfs_trans_handle *trans, + struct btrfs_device *device, u64 num_bytes, + u64 *start, u64 *max_avail) { struct btrfs_key key; struct btrfs_root *root = device->dev_root; @@ -1736,6 +1735,10 @@ static int btrfs_relocate_chunk(struct btrfs_root *root, extent_root = root->fs_info->extent_root; em_tree = &root->fs_info->mapping_tree.map_tree; + ret = btrfs_can_relocate(extent_root, chunk_offset); + if (ret) + return -ENOSPC; + /* step one, relocate all the extents inside this chunk */ ret = btrfs_relocate_block_group(extent_root, chunk_offset); BUG_ON(ret); @@ -1807,12 +1810,15 @@ static int btrfs_relocate_sys_chunks(struct btrfs_root *root) struct btrfs_key found_key; u64 chunk_tree = chunk_root->root_key.objectid; u64 chunk_type; + bool retried = false; + int failed = 0; int ret; path = btrfs_alloc_path(); if (!path) return -ENOMEM; +again: key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID; key.offset = (u64)-1; key.type = BTRFS_CHUNK_ITEM_KEY; @@ -1842,7 +1848,10 @@ static int btrfs_relocate_sys_chunks(struct btrfs_root *root) ret = btrfs_relocate_chunk(chunk_root, chunk_tree, found_key.objectid, found_key.offset); - BUG_ON(ret); + if (ret == -ENOSPC) + failed++; + else if (ret) + BUG(); } if (found_key.offset == 0) @@ -1850,6 +1859,14 @@ static int btrfs_relocate_sys_chunks(struct btrfs_root *root) key.offset = found_key.offset - 1; } ret = 0; + if (failed && !retried) { + failed = 0; + retried = true; + goto again; + } else if (failed && retried) { + WARN_ON(1); + ret = -ENOSPC; + } error: btrfs_free_path(path); return ret; @@ -1894,6 +1911,8 @@ int btrfs_balance(struct btrfs_root *dev_root) continue; ret = btrfs_shrink_device(device, old_size - size_to_free); + if (ret == -ENOSPC) + break; BUG_ON(ret); trans = btrfs_start_transaction(dev_root, 1); @@ -1938,9 +1957,8 @@ int btrfs_balance(struct btrfs_root *dev_root) chunk = btrfs_item_ptr(path->nodes[0], path->slots[0], struct btrfs_chunk); - key.offset = found_key.offset; /* chunk zero is special */ - if (key.offset == 0) + if (found_key.offset == 0) break; btrfs_release_path(chunk_root, path); @@ -1948,7 +1966,8 @@ int btrfs_balance(struct btrfs_root *dev_root) chunk_root->root_key.objectid, found_key.objectid, found_key.offset); - BUG_ON(ret); + BUG_ON(ret && ret != -ENOSPC); + key.offset = found_key.offset - 1; } ret = 0; error: @@ -1974,10 +1993,13 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size) u64 chunk_offset; int ret; int slot; + int failed = 0; + bool retried = false; struct extent_buffer *l; struct btrfs_key key; struct btrfs_super_block *super_copy = &root->fs_info->super_copy; u64 old_total = btrfs_super_total_bytes(super_copy); + u64 old_size = device->total_bytes; u64 diff = device->total_bytes - new_size; if (new_size >= device->total_bytes) @@ -1987,12 +2009,6 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size) if (!path) return -ENOMEM; - trans = btrfs_start_transaction(root, 1); - if (!trans) { - ret = -ENOMEM; - goto done; - } - path->reada = 2; lock_chunks(root); @@ -2001,8 +2017,8 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size) if (device->writeable) device->fs_devices->total_rw_bytes -= diff; unlock_chunks(root); - btrfs_end_transaction(trans, root); +again: key.objectid = device->devid; key.offset = (u64)-1; key.type = BTRFS_DEV_EXTENT_KEY; @@ -2017,6 +2033,7 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size) goto done; if (ret) { ret = 0; + btrfs_release_path(root, path); break; } @@ -2024,14 +2041,18 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size) slot = path->slots[0]; btrfs_item_key_to_cpu(l, &key, path->slots[0]); - if (key.objectid != device->devid) + if (key.objectid != device->devid) { + btrfs_release_path(root, path); break; + } dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent); length = btrfs_dev_extent_length(l, dev_extent); - if (key.offset + length <= new_size) + if (key.offset + length <= new_size) { + btrfs_release_path(root, path); break; + } chunk_tree = btrfs_dev_extent_chunk_tree(l, dev_extent); chunk_objectid = btrfs_dev_extent_chunk_objectid(l, dev_extent); @@ -2040,8 +2061,26 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size) ret = btrfs_relocate_chunk(root, chunk_tree, chunk_objectid, chunk_offset); - if (ret) + if (ret && ret != -ENOSPC) goto done; + if (ret == -ENOSPC) + failed++; + key.offset -= 1; + } + + if (failed && !retried) { + failed = 0; + retried = true; + goto again; + } else if (failed && retried) { + ret = -ENOSPC; + lock_chunks(root); + + device->total_bytes = old_size; + if (device->writeable) + device->fs_devices->total_rw_bytes += diff; + unlock_chunks(root); + goto done; } /* Shrinking succeeded, else we would be at "done". */ -- cgit v1.2.1