From 963030817060e4f109be1993b9ae8f81dbf5e11a Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Mon, 13 Jul 2009 21:29:25 -0400 Subject: Btrfs: use hybrid extents+bitmap rb tree for free space Currently btrfs has a problem where it can use a ridiculous amount of RAM simply tracking free space. As free space gets fragmented, we end up with thousands of entries on an rb-tree per block group, which usually spans 1 gig of area. Since we currently don't ever flush free space cache back to disk this gets to be a bit unweildly on large fs's with lots of fragmentation. This patch solves this problem by using PAGE_SIZE bitmaps for parts of the free space cache. Initially we calculate a threshold of extent entries we can handle, which is however many extent entries we can cram into 16k of ram. The maximum amount of RAM that should ever be used to track 1 gigabyte of diskspace will be 32k of RAM, which scales much better than we did before. Once we pass the extent threshold, we start adding bitmaps and using those instead for tracking the free space. This patch also makes it so that any free space thats less than 4 * sectorsize we go ahead and put into a bitmap. This is nice since we try and allocate out of the front of a block group, so if the front of a block group is heavily fragmented and then has a huge chunk of free space at the end, we go ahead and add the fragmented areas to bitmaps and use a normal extent entry to track the big chunk at the back of the block group. I've also taken the opportunity to revamp how we search for free space. Previously we indexed free space via an offset indexed rb tree and a bytes indexed rb tree. I've dropped the bytes indexed rb tree and use only the offset indexed rb tree. This cuts the number of tree operations we were doing previously down by half, and gives us a little bit of a better allocation pattern since we will always start from a specific offset and search forward from there, instead of searching for the size we need and try and get it as close as possible to the offset we want. I've given this a healthy amount of testing pre-new format stuff, as well as post-new format stuff. I've booted up my fedora box which is installed on btrfs with this patch and ran with it for a few days without issues. I've not seen any performance regressions in any of my tests. Since the last patch Yan Zheng fixed a problem where we could have overlapping entries, so updating their offset inline would cause problems. Thanks, Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/free-space-cache.c | 1001 ++++++++++++++++++++++++++++++++++--------- 1 file changed, 787 insertions(+), 214 deletions(-) (limited to 'fs/btrfs/free-space-cache.c') diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index 4538e48581a..ab8cad8b46c 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -16,45 +16,46 @@ * Boston, MA 021110-1307, USA. */ +#include #include +#include #include "ctree.h" #include "free-space-cache.h" #include "transaction.h" -struct btrfs_free_space { - struct rb_node bytes_index; - struct rb_node offset_index; - u64 offset; - u64 bytes; -}; +#define BITS_PER_BITMAP (PAGE_CACHE_SIZE * 8) +#define MAX_CACHE_BYTES_PER_GIG (32 * 1024) -static int tree_insert_offset(struct rb_root *root, u64 offset, - struct rb_node *node) +static inline unsigned long offset_to_bit(u64 bitmap_start, u64 sectorsize, + u64 offset) { - struct rb_node **p = &root->rb_node; - struct rb_node *parent = NULL; - struct btrfs_free_space *info; + BUG_ON(offset < bitmap_start); + offset -= bitmap_start; + return (unsigned long)(div64_u64(offset, sectorsize)); +} - while (*p) { - parent = *p; - info = rb_entry(parent, struct btrfs_free_space, offset_index); +static inline unsigned long bytes_to_bits(u64 bytes, u64 sectorsize) +{ + return (unsigned long)(div64_u64(bytes, sectorsize)); +} - if (offset < info->offset) - p = &(*p)->rb_left; - else if (offset > info->offset) - p = &(*p)->rb_right; - else - return -EEXIST; - } +static inline u64 offset_to_bitmap(struct btrfs_block_group_cache *block_group, + u64 offset) +{ + u64 bitmap_start; + u64 bytes_per_bitmap; - rb_link_node(node, parent, p); - rb_insert_color(node, root); + bytes_per_bitmap = BITS_PER_BITMAP * block_group->sectorsize; + bitmap_start = offset - block_group->key.objectid; + bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap); + bitmap_start *= bytes_per_bitmap; + bitmap_start += block_group->key.objectid; - return 0; + return bitmap_start; } -static int tree_insert_bytes(struct rb_root *root, u64 bytes, - struct rb_node *node) +static int tree_insert_offset(struct rb_root *root, u64 offset, + struct rb_node *node, int bitmap) { struct rb_node **p = &root->rb_node; struct rb_node *parent = NULL; @@ -62,12 +63,34 @@ static int tree_insert_bytes(struct rb_root *root, u64 bytes, while (*p) { parent = *p; - info = rb_entry(parent, struct btrfs_free_space, bytes_index); + info = rb_entry(parent, struct btrfs_free_space, offset_index); - if (bytes < info->bytes) + if (offset < info->offset) { p = &(*p)->rb_left; - else + } else if (offset > info->offset) { p = &(*p)->rb_right; + } else { + /* + * we could have a bitmap entry and an extent entry + * share the same offset. If this is the case, we want + * the extent entry to always be found first if we do a + * linear search through the tree, since we want to have + * the quickest allocation time, and allocating from an + * extent is faster than allocating from a bitmap. So + * if we're inserting a bitmap and we find an entry at + * this offset, we want to go right, or after this entry + * logically. If we are inserting an extent and we've + * found a bitmap, we want to go left, or before + * logically. + */ + if (bitmap) { + WARN_ON(info->bitmap); + p = &(*p)->rb_right; + } else { + WARN_ON(!info->bitmap); + p = &(*p)->rb_left; + } + } } rb_link_node(node, parent, p); @@ -79,110 +102,142 @@ static int tree_insert_bytes(struct rb_root *root, u64 bytes, /* * searches the tree for the given offset. * - * fuzzy == 1: this is used for allocations where we are given a hint of where - * to look for free space. Because the hint may not be completely on an offset - * mark, or the hint may no longer point to free space we need to fudge our - * results a bit. So we look for free space starting at or after offset with at - * least bytes size. We prefer to find as close to the given offset as we can. - * Also if the offset is within a free space range, then we will return the free - * space that contains the given offset, which means we can return a free space - * chunk with an offset before the provided offset. - * - * fuzzy == 0: this is just a normal tree search. Give us the free space that - * starts at the given offset which is at least bytes size, and if its not there - * return NULL. + * fuzzy - If this is set, then we are trying to make an allocation, and we just + * want a section that has at least bytes size and comes at or after the given + * offset. */ -static struct btrfs_free_space *tree_search_offset(struct rb_root *root, - u64 offset, u64 bytes, - int fuzzy) +static struct btrfs_free_space * +tree_search_offset(struct btrfs_block_group_cache *block_group, + u64 offset, int bitmap_only, int fuzzy) { - struct rb_node *n = root->rb_node; - struct btrfs_free_space *entry, *ret = NULL; + struct rb_node *n = block_group->free_space_offset.rb_node; + struct btrfs_free_space *entry, *prev = NULL; + + /* find entry that is closest to the 'offset' */ + while (1) { + if (!n) { + entry = NULL; + break; + } - while (n) { entry = rb_entry(n, struct btrfs_free_space, offset_index); + prev = entry; - if (offset < entry->offset) { - if (fuzzy && - (!ret || entry->offset < ret->offset) && - (bytes <= entry->bytes)) - ret = entry; + if (offset < entry->offset) n = n->rb_left; - } else if (offset > entry->offset) { - if (fuzzy && - (entry->offset + entry->bytes - 1) >= offset && - bytes <= entry->bytes) { - ret = entry; - break; - } + else if (offset > entry->offset) n = n->rb_right; - } else { - if (bytes > entry->bytes) { - n = n->rb_right; - continue; - } - ret = entry; + else break; - } } - return ret; -} - -/* - * return a chunk at least bytes size, as close to offset that we can get. - */ -static struct btrfs_free_space *tree_search_bytes(struct rb_root *root, - u64 offset, u64 bytes) -{ - struct rb_node *n = root->rb_node; - struct btrfs_free_space *entry, *ret = NULL; + if (bitmap_only) { + if (!entry) + return NULL; + if (entry->bitmap) + return entry; - while (n) { - entry = rb_entry(n, struct btrfs_free_space, bytes_index); + /* + * bitmap entry and extent entry may share same offset, + * in that case, bitmap entry comes after extent entry. + */ + n = rb_next(n); + if (!n) + return NULL; + entry = rb_entry(n, struct btrfs_free_space, offset_index); + if (entry->offset != offset) + return NULL; - if (bytes < entry->bytes) { + WARN_ON(!entry->bitmap); + return entry; + } else if (entry) { + if (entry->bitmap) { /* - * We prefer to get a hole size as close to the size we - * are asking for so we don't take small slivers out of - * huge holes, but we also want to get as close to the - * offset as possible so we don't have a whole lot of - * fragmentation. + * if previous extent entry covers the offset, + * we should return it instead of the bitmap entry */ - if (offset <= entry->offset) { - if (!ret) - ret = entry; - else if (entry->bytes < ret->bytes) - ret = entry; - else if (entry->offset < ret->offset) - ret = entry; + n = &entry->offset_index; + while (1) { + n = rb_prev(n); + if (!n) + break; + prev = rb_entry(n, struct btrfs_free_space, + offset_index); + if (!prev->bitmap) { + if (prev->offset + prev->bytes > offset) + entry = prev; + break; + } } - n = n->rb_left; - } else if (bytes > entry->bytes) { - n = n->rb_right; + } + return entry; + } + + if (!prev) + return NULL; + + /* find last entry before the 'offset' */ + entry = prev; + if (entry->offset > offset) { + n = rb_prev(&entry->offset_index); + if (n) { + entry = rb_entry(n, struct btrfs_free_space, + offset_index); + BUG_ON(entry->offset > offset); } else { - /* - * Ok we may have multiple chunks of the wanted size, - * so we don't want to take the first one we find, we - * want to take the one closest to our given offset, so - * keep searching just in case theres a better match. - */ - n = n->rb_right; - if (offset > entry->offset) - continue; - else if (!ret || entry->offset < ret->offset) - ret = entry; + if (fuzzy) + return entry; + else + return NULL; } } - return ret; + if (entry->bitmap) { + n = &entry->offset_index; + while (1) { + n = rb_prev(n); + if (!n) + break; + prev = rb_entry(n, struct btrfs_free_space, + offset_index); + if (!prev->bitmap) { + if (prev->offset + prev->bytes > offset) + return prev; + break; + } + } + if (entry->offset + BITS_PER_BITMAP * + block_group->sectorsize > offset) + return entry; + } else if (entry->offset + entry->bytes > offset) + return entry; + + if (!fuzzy) + return NULL; + + while (1) { + if (entry->bitmap) { + if (entry->offset + BITS_PER_BITMAP * + block_group->sectorsize > offset) + break; + } else { + if (entry->offset + entry->bytes > offset) + break; + } + + n = rb_next(&entry->offset_index); + if (!n) + return NULL; + entry = rb_entry(n, struct btrfs_free_space, offset_index); + } + return entry; } static void unlink_free_space(struct btrfs_block_group_cache *block_group, struct btrfs_free_space *info) { rb_erase(&info->offset_index, &block_group->free_space_offset); - rb_erase(&info->bytes_index, &block_group->free_space_bytes); + block_group->free_extents--; } static int link_free_space(struct btrfs_block_group_cache *block_group, @@ -190,17 +245,311 @@ static int link_free_space(struct btrfs_block_group_cache *block_group, { int ret = 0; - - BUG_ON(!info->bytes); + BUG_ON(!info->bitmap && !info->bytes); ret = tree_insert_offset(&block_group->free_space_offset, info->offset, - &info->offset_index); + &info->offset_index, (info->bitmap != NULL)); if (ret) return ret; - ret = tree_insert_bytes(&block_group->free_space_bytes, info->bytes, - &info->bytes_index); - if (ret) - return ret; + block_group->free_extents++; + return ret; +} + +static void recalculate_thresholds(struct btrfs_block_group_cache *block_group) +{ + u64 max_bytes, possible_bytes; + + /* + * The goal is to keep the total amount of memory used per 1gb of space + * at or below 32k, so we need to adjust how much memory we allow to be + * used by extent based free space tracking + */ + max_bytes = MAX_CACHE_BYTES_PER_GIG * + (div64_u64(block_group->key.offset, 1024 * 1024 * 1024)); + + possible_bytes = (block_group->total_bitmaps * PAGE_CACHE_SIZE) + + (sizeof(struct btrfs_free_space) * + block_group->extents_thresh); + + if (possible_bytes > max_bytes) { + int extent_bytes = max_bytes - + (block_group->total_bitmaps * PAGE_CACHE_SIZE); + + if (extent_bytes <= 0) { + block_group->extents_thresh = 0; + return; + } + + block_group->extents_thresh = extent_bytes / + (sizeof(struct btrfs_free_space)); + } +} + +static void bitmap_clear_bits(struct btrfs_free_space *info, u64 offset, u64 bytes, + u64 sectorsize) +{ + unsigned long start, end; + unsigned long i; + + start = offset_to_bit(info->offset, sectorsize, offset); + end = start + bytes_to_bits(bytes, sectorsize); + BUG_ON(end > BITS_PER_BITMAP); + + for (i = start; i < end; i++) + clear_bit(i, info->bitmap); + + info->bytes -= bytes; +} + +static void bitmap_set_bits(struct btrfs_free_space *info, u64 offset, u64 bytes, + u64 sectorsize) +{ + unsigned long start, end; + unsigned long i; + + start = offset_to_bit(info->offset, sectorsize, offset); + end = start + bytes_to_bits(bytes, sectorsize); + BUG_ON(end > BITS_PER_BITMAP); + + for (i = start; i < end; i++) + set_bit(i, info->bitmap); + + info->bytes += bytes; +} + +static int search_bitmap(struct btrfs_block_group_cache *block_group, + struct btrfs_free_space *bitmap_info, u64 *offset, + u64 *bytes) +{ + unsigned long found_bits = 0; + unsigned long bits, i; + unsigned long next_zero; + + i = offset_to_bit(bitmap_info->offset, block_group->sectorsize, + max_t(u64, *offset, bitmap_info->offset)); + bits = bytes_to_bits(*bytes, block_group->sectorsize); + + for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i); + i < BITS_PER_BITMAP; + i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i + 1)) { + next_zero = find_next_zero_bit(bitmap_info->bitmap, + BITS_PER_BITMAP, i); + if ((next_zero - i) >= bits) { + found_bits = next_zero - i; + break; + } + i = next_zero; + } + + if (found_bits) { + *offset = (u64)(i * block_group->sectorsize) + + bitmap_info->offset; + *bytes = (u64)(found_bits) * block_group->sectorsize; + return 0; + } + + return -1; +} + +static struct btrfs_free_space *find_free_space(struct btrfs_block_group_cache + *block_group, u64 *offset, + u64 *bytes, int debug) +{ + struct btrfs_free_space *entry; + struct rb_node *node; + int ret; + + if (!block_group->free_space_offset.rb_node) + return NULL; + + entry = tree_search_offset(block_group, + offset_to_bitmap(block_group, *offset), + 0, 1); + if (!entry) + return NULL; + + for (node = &entry->offset_index; node; node = rb_next(node)) { + entry = rb_entry(node, struct btrfs_free_space, offset_index); + if (entry->bytes < *bytes) + continue; + + if (entry->bitmap) { + ret = search_bitmap(block_group, entry, offset, bytes); + if (!ret) + return entry; + continue; + } + + *offset = entry->offset; + *bytes = entry->bytes; + return entry; + } + + return NULL; +} + +static void add_new_bitmap(struct btrfs_block_group_cache *block_group, + struct btrfs_free_space *info, u64 offset) +{ + u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize; + int max_bitmaps = (int)div64_u64(block_group->key.offset + + bytes_per_bg - 1, bytes_per_bg); + BUG_ON(block_group->total_bitmaps >= max_bitmaps); + + info->offset = offset_to_bitmap(block_group, offset); + link_free_space(block_group, info); + block_group->total_bitmaps++; + + recalculate_thresholds(block_group); +} + +static noinline int remove_from_bitmap(struct btrfs_block_group_cache *block_group, + struct btrfs_free_space *bitmap_info, + u64 *offset, u64 *bytes) +{ + u64 end; + +again: + end = bitmap_info->offset + + (u64)(BITS_PER_BITMAP * block_group->sectorsize) - 1; + + if (*offset > bitmap_info->offset && *offset + *bytes > end) { + bitmap_clear_bits(bitmap_info, *offset, + end - *offset + 1, block_group->sectorsize); + *bytes -= end - *offset + 1; + *offset = end + 1; + } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) { + bitmap_clear_bits(bitmap_info, *offset, + *bytes, block_group->sectorsize); + *bytes = 0; + } + + if (*bytes) { + if (!bitmap_info->bytes) { + unlink_free_space(block_group, bitmap_info); + kfree(bitmap_info->bitmap); + kfree(bitmap_info); + block_group->total_bitmaps--; + recalculate_thresholds(block_group); + } + + bitmap_info = tree_search_offset(block_group, + offset_to_bitmap(block_group, + *offset), + 1, 0); + if (!bitmap_info) + return -EINVAL; + + if (!bitmap_info->bitmap) + return -EAGAIN; + + goto again; + } else if (!bitmap_info->bytes) { + unlink_free_space(block_group, bitmap_info); + kfree(bitmap_info->bitmap); + kfree(bitmap_info); + block_group->total_bitmaps--; + recalculate_thresholds(block_group); + } + + return 0; +} + +static int insert_into_bitmap(struct btrfs_block_group_cache *block_group, + struct btrfs_free_space *info) +{ + struct btrfs_free_space *bitmap_info; + int added = 0; + u64 bytes, offset, end; + int ret; + + /* + * If we are below the extents threshold then we can add this as an + * extent, and don't have to deal with the bitmap + */ + if (block_group->free_extents < block_group->extents_thresh && + info->bytes > block_group->sectorsize * 4) + return 0; + + /* + * some block groups are so tiny they can't be enveloped by a bitmap, so + * don't even bother to create a bitmap for this + */ + if (BITS_PER_BITMAP * block_group->sectorsize > + block_group->key.offset) + return 0; + + bytes = info->bytes; + offset = info->offset; + +again: + bitmap_info = tree_search_offset(block_group, + offset_to_bitmap(block_group, offset), + 1, 0); + if (!bitmap_info) { + BUG_ON(added); + goto new_bitmap; + } + + end = bitmap_info->offset + + (u64)(BITS_PER_BITMAP * block_group->sectorsize); + + if (offset >= bitmap_info->offset && offset + bytes > end) { + bitmap_set_bits(bitmap_info, offset, end - offset, + block_group->sectorsize); + bytes -= end - offset; + offset = end; + added = 0; + } else if (offset >= bitmap_info->offset && offset + bytes <= end) { + bitmap_set_bits(bitmap_info, offset, bytes, + block_group->sectorsize); + bytes = 0; + } else { + BUG(); + } + + if (!bytes) { + ret = 1; + goto out; + } else + goto again; + +new_bitmap: + if (info && info->bitmap) { + add_new_bitmap(block_group, info, offset); + added = 1; + info = NULL; + goto again; + } else { + spin_unlock(&block_group->tree_lock); + + /* no pre-allocated info, allocate a new one */ + if (!info) { + info = kzalloc(sizeof(struct btrfs_free_space), + GFP_NOFS); + if (!info) { + spin_lock(&block_group->tree_lock); + ret = -ENOMEM; + goto out; + } + } + + /* allocate the bitmap */ + info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS); + spin_lock(&block_group->tree_lock); + if (!info->bitmap) { + ret = -ENOMEM; + goto out; + } + goto again; + } + +out: + if (info) { + if (info->bitmap) + kfree(info->bitmap); + kfree(info); + } return ret; } @@ -208,8 +557,8 @@ static int link_free_space(struct btrfs_block_group_cache *block_group, int btrfs_add_free_space(struct btrfs_block_group_cache *block_group, u64 offset, u64 bytes) { - struct btrfs_free_space *right_info; - struct btrfs_free_space *left_info; + struct btrfs_free_space *right_info = NULL; + struct btrfs_free_space *left_info = NULL; struct btrfs_free_space *info = NULL; int ret = 0; @@ -227,18 +576,38 @@ int btrfs_add_free_space(struct btrfs_block_group_cache *block_group, * are adding, if there is remove that struct and add a new one to * cover the entire range */ - right_info = tree_search_offset(&block_group->free_space_offset, - offset+bytes, 0, 0); - left_info = tree_search_offset(&block_group->free_space_offset, - offset-1, 0, 1); + right_info = tree_search_offset(block_group, offset + bytes, 0, 0); + if (right_info && rb_prev(&right_info->offset_index)) + left_info = rb_entry(rb_prev(&right_info->offset_index), + struct btrfs_free_space, offset_index); + else + left_info = tree_search_offset(block_group, offset - 1, 0, 0); - if (right_info) { + /* + * If there was no extent directly to the left or right of this new + * extent then we know we're going to have to allocate a new extent, so + * before we do that see if we need to drop this into a bitmap + */ + if ((!left_info || left_info->bitmap) && + (!right_info || right_info->bitmap)) { + ret = insert_into_bitmap(block_group, info); + + if (ret < 0) { + goto out; + } else if (ret) { + ret = 0; + goto out; + } + } + + if (right_info && !right_info->bitmap) { unlink_free_space(block_group, right_info); info->bytes += right_info->bytes; kfree(right_info); } - if (left_info && left_info->offset + left_info->bytes == offset) { + if (left_info && !left_info->bitmap && + left_info->offset + left_info->bytes == offset) { unlink_free_space(block_group, left_info); info->offset = left_info->offset; info->bytes += left_info->bytes; @@ -248,11 +617,11 @@ int btrfs_add_free_space(struct btrfs_block_group_cache *block_group, ret = link_free_space(block_group, info); if (ret) kfree(info); - +out: spin_unlock(&block_group->tree_lock); if (ret) { - printk(KERN_ERR "btrfs: unable to add free space :%d\n", ret); + printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret); BUG_ON(ret == -EEXIST); } @@ -263,40 +632,65 @@ int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group, u64 offset, u64 bytes) { struct btrfs_free_space *info; + struct btrfs_free_space *next_info = NULL; int ret = 0; spin_lock(&block_group->tree_lock); - info = tree_search_offset(&block_group->free_space_offset, offset, 0, - 1); - if (info && info->offset == offset) { - if (info->bytes < bytes) { - printk(KERN_ERR "Found free space at %llu, size %llu," - "trying to use %llu\n", - (unsigned long long)info->offset, - (unsigned long long)info->bytes, - (unsigned long long)bytes); +again: + info = tree_search_offset(block_group, offset, 0, 0); + if (!info) { + WARN_ON(1); + goto out_lock; + } + + if (info->bytes < bytes && rb_next(&info->offset_index)) { + u64 end; + next_info = rb_entry(rb_next(&info->offset_index), + struct btrfs_free_space, + offset_index); + + if (next_info->bitmap) + end = next_info->offset + BITS_PER_BITMAP * + block_group->sectorsize - 1; + else + end = next_info->offset + next_info->bytes; + + if (next_info->bytes < bytes || + next_info->offset > offset || offset > end) { + printk(KERN_CRIT "Found free space at %llu, size %llu," + " trying to use %llu\n", + (unsigned long long)info->offset, + (unsigned long long)info->bytes, + (unsigned long long)bytes); WARN_ON(1); ret = -EINVAL; - spin_unlock(&block_group->tree_lock); - goto out; + goto out_lock; } - unlink_free_space(block_group, info); - if (info->bytes == bytes) { - kfree(info); - spin_unlock(&block_group->tree_lock); - goto out; + info = next_info; + } + + if (info->bytes == bytes) { + unlink_free_space(block_group, info); + if (info->bitmap) { + kfree(info->bitmap); + block_group->total_bitmaps--; } + kfree(info); + goto out_lock; + } + if (!info->bitmap && info->offset == offset) { + unlink_free_space(block_group, info); info->offset += bytes; info->bytes -= bytes; + link_free_space(block_group, info); + goto out_lock; + } - ret = link_free_space(block_group, info); - spin_unlock(&block_group->tree_lock); - BUG_ON(ret); - } else if (info && info->offset < offset && - info->offset + info->bytes >= offset + bytes) { + if (!info->bitmap && info->offset <= offset && + info->offset + info->bytes >= offset + bytes) { u64 old_start = info->offset; /* * we're freeing space in the middle of the info, @@ -312,7 +706,9 @@ int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group, info->offset = offset + bytes; info->bytes = old_end - info->offset; ret = link_free_space(block_group, info); - BUG_ON(ret); + WARN_ON(ret); + if (ret) + goto out_lock; } else { /* the hole we're creating ends at the end * of the info struct, just free the info @@ -320,32 +716,22 @@ int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group, kfree(info); } spin_unlock(&block_group->tree_lock); - /* step two, insert a new info struct to cover anything - * before the hole + + /* step two, insert a new info struct to cover + * anything before the hole */ ret = btrfs_add_free_space(block_group, old_start, offset - old_start); - BUG_ON(ret); - } else { - spin_unlock(&block_group->tree_lock); - if (!info) { - printk(KERN_ERR "couldn't find space %llu to free\n", - (unsigned long long)offset); - printk(KERN_ERR "cached is %d, offset %llu bytes %llu\n", - block_group->cached, - (unsigned long long)block_group->key.objectid, - (unsigned long long)block_group->key.offset); - btrfs_dump_free_space(block_group, bytes); - } else if (info) { - printk(KERN_ERR "hmm, found offset=%llu bytes=%llu, " - "but wanted offset=%llu bytes=%llu\n", - (unsigned long long)info->offset, - (unsigned long long)info->bytes, - (unsigned long long)offset, - (unsigned long long)bytes); - } - WARN_ON(1); + WARN_ON(ret); + goto out; } + + ret = remove_from_bitmap(block_group, info, &offset, &bytes); + if (ret == -EAGAIN) + goto again; + BUG_ON(ret); +out_lock: + spin_unlock(&block_group->tree_lock); out: return ret; } @@ -361,10 +747,13 @@ void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group, info = rb_entry(n, struct btrfs_free_space, offset_index); if (info->bytes >= bytes) count++; - printk(KERN_ERR "entry offset %llu, bytes %llu\n", + printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n", (unsigned long long)info->offset, - (unsigned long long)info->bytes); + (unsigned long long)info->bytes, + (info->bitmap) ? "yes" : "no"); } + printk(KERN_INFO "block group has cluster?: %s\n", + list_empty(&block_group->cluster_list) ? "no" : "yes"); printk(KERN_INFO "%d blocks of free space at or bigger than bytes is" "\n", count); } @@ -397,26 +786,35 @@ __btrfs_return_cluster_to_free_space( { struct btrfs_free_space *entry; struct rb_node *node; + bool bitmap; spin_lock(&cluster->lock); if (cluster->block_group != block_group) goto out; + bitmap = cluster->points_to_bitmap; + cluster->block_group = NULL; cluster->window_start = 0; + list_del_init(&cluster->block_group_list); + cluster->points_to_bitmap = false; + + if (bitmap) + goto out; + node = rb_first(&cluster->root); - while(node) { + while (node) { entry = rb_entry(node, struct btrfs_free_space, offset_index); node = rb_next(&entry->offset_index); rb_erase(&entry->offset_index, &cluster->root); - link_free_space(block_group, entry); + BUG_ON(entry->bitmap); + tree_insert_offset(&block_group->free_space_offset, + entry->offset, &entry->offset_index, 0); } - list_del_init(&cluster->block_group_list); - - btrfs_put_block_group(cluster->block_group); - cluster->block_group = NULL; cluster->root.rb_node = NULL; + out: spin_unlock(&cluster->lock); + btrfs_put_block_group(block_group); return 0; } @@ -425,20 +823,28 @@ void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group) struct btrfs_free_space *info; struct rb_node *node; struct btrfs_free_cluster *cluster; - struct btrfs_free_cluster *safe; + struct list_head *head; spin_lock(&block_group->tree_lock); - - list_for_each_entry_safe(cluster, safe, &block_group->cluster_list, - block_group_list) { + while ((head = block_group->cluster_list.next) != + &block_group->cluster_list) { + cluster = list_entry(head, struct btrfs_free_cluster, + block_group_list); WARN_ON(cluster->block_group != block_group); __btrfs_return_cluster_to_free_space(block_group, cluster); + if (need_resched()) { + spin_unlock(&block_group->tree_lock); + cond_resched(); + spin_lock(&block_group->tree_lock); + } } - while ((node = rb_last(&block_group->free_space_bytes)) != NULL) { - info = rb_entry(node, struct btrfs_free_space, bytes_index); + while ((node = rb_last(&block_group->free_space_offset)) != NULL) { + info = rb_entry(node, struct btrfs_free_space, offset_index); unlink_free_space(block_group, info); + if (info->bitmap) + kfree(info->bitmap); kfree(info); if (need_resched()) { spin_unlock(&block_group->tree_lock); @@ -446,6 +852,7 @@ void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group) spin_lock(&block_group->tree_lock); } } + spin_unlock(&block_group->tree_lock); } @@ -453,27 +860,37 @@ u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group, u64 offset, u64 bytes, u64 empty_size) { struct btrfs_free_space *entry = NULL; + u64 bytes_search = bytes + empty_size; u64 ret = 0; spin_lock(&block_group->tree_lock); - entry = tree_search_offset(&block_group->free_space_offset, offset, - bytes + empty_size, 1); + entry = find_free_space(block_group, &offset, &bytes_search, 0); if (!entry) - entry = tree_search_bytes(&block_group->free_space_bytes, - offset, bytes + empty_size); - if (entry) { + goto out; + + ret = offset; + if (entry->bitmap) { + bitmap_clear_bits(entry, offset, bytes, + block_group->sectorsize); + if (!entry->bytes) { + unlink_free_space(block_group, entry); + kfree(entry->bitmap); + kfree(entry); + block_group->total_bitmaps--; + recalculate_thresholds(block_group); + } + } else { unlink_free_space(block_group, entry); - ret = entry->offset; entry->offset += bytes; entry->bytes -= bytes; - if (!entry->bytes) kfree(entry); else link_free_space(block_group, entry); } - spin_unlock(&block_group->tree_lock); +out: + spin_unlock(&block_group->tree_lock); return ret; } @@ -517,6 +934,47 @@ int btrfs_return_cluster_to_free_space( return ret; } +static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group, + struct btrfs_free_cluster *cluster, + u64 bytes, u64 min_start) +{ + struct btrfs_free_space *entry; + int err; + u64 search_start = cluster->window_start; + u64 search_bytes = bytes; + u64 ret = 0; + + spin_lock(&block_group->tree_lock); + spin_lock(&cluster->lock); + + if (!cluster->points_to_bitmap) + goto out; + + if (cluster->block_group != block_group) + goto out; + + entry = tree_search_offset(block_group, search_start, 0, 0); + + if (!entry || !entry->bitmap) + goto out; + + search_start = min_start; + search_bytes = bytes; + + err = search_bitmap(block_group, entry, &search_start, + &search_bytes); + if (err) + goto out; + + ret = search_start; + bitmap_clear_bits(entry, ret, bytes, block_group->sectorsize); +out: + spin_unlock(&cluster->lock); + spin_unlock(&block_group->tree_lock); + + return ret; +} + /* * given a cluster, try to allocate 'bytes' from it, returns 0 * if it couldn't find anything suitably large, or a logical disk offset @@ -530,6 +988,10 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group, struct rb_node *node; u64 ret = 0; + if (cluster->points_to_bitmap) + return btrfs_alloc_from_bitmap(block_group, cluster, bytes, + min_start); + spin_lock(&cluster->lock); if (bytes > cluster->max_size) goto out; @@ -567,9 +1029,73 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group, } out: spin_unlock(&cluster->lock); + return ret; } +static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group, + struct btrfs_free_space *entry, + struct btrfs_free_cluster *cluster, + u64 offset, u64 bytes, u64 min_bytes) +{ + unsigned long next_zero; + unsigned long i; + unsigned long search_bits; + unsigned long total_bits; + unsigned long found_bits; + unsigned long start = 0; + unsigned long total_found = 0; + bool found = false; + + i = offset_to_bit(entry->offset, block_group->sectorsize, + max_t(u64, offset, entry->offset)); + search_bits = bytes_to_bits(min_bytes, block_group->sectorsize); + total_bits = bytes_to_bits(bytes, block_group->sectorsize); + +again: + found_bits = 0; + for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i); + i < BITS_PER_BITMAP; + i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) { + next_zero = find_next_zero_bit(entry->bitmap, + BITS_PER_BITMAP, i); + if (next_zero - i >= search_bits) { + found_bits = next_zero - i; + break; + } + i = next_zero; + } + + if (!found_bits) + return -1; + + if (!found) { + start = i; + found = true; + } + + total_found += found_bits; + + if (cluster->max_size < found_bits * block_group->sectorsize) + cluster->max_size = found_bits * block_group->sectorsize; + + if (total_found < total_bits) { + i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, next_zero); + if (i - start > total_bits * 2) { + total_found = 0; + cluster->max_size = 0; + found = false; + } + goto again; + } + + cluster->window_start = start * block_group->sectorsize + + entry->offset; + cluster->points_to_bitmap = true; + + return 0; +} + /* * here we try to find a cluster of blocks in a block group. The goal * is to find at least bytes free and up to empty_size + bytes free. @@ -587,12 +1113,12 @@ int btrfs_find_space_cluster(struct btrfs_trans_handle *trans, struct btrfs_free_space *entry = NULL; struct rb_node *node; struct btrfs_free_space *next; - struct btrfs_free_space *last; + struct btrfs_free_space *last = NULL; u64 min_bytes; u64 window_start; u64 window_free; u64 max_extent = 0; - int total_retries = 0; + bool found_bitmap = false; int ret; /* for metadata, allow allocates with more holes */ @@ -620,30 +1146,79 @@ int btrfs_find_space_cluster(struct btrfs_trans_handle *trans, goto out; } again: - min_bytes = min(min_bytes, bytes + empty_size); - entry = tree_search_bytes(&block_group->free_space_bytes, - offset, min_bytes); + entry = tree_search_offset(block_group, offset, found_bitmap, 1); if (!entry) { ret = -ENOSPC; goto out; } + + /* + * If found_bitmap is true, we exhausted our search for extent entries, + * and we just want to search all of the bitmaps that we can find, and + * ignore any extent entries we find. + */ + while (entry->bitmap || found_bitmap || + (!entry->bitmap && entry->bytes < min_bytes)) { + struct rb_node *node = rb_next(&entry->offset_index); + + if (entry->bitmap && entry->bytes > bytes + empty_size) { + ret = btrfs_bitmap_cluster(block_group, entry, cluster, + offset, bytes + empty_size, + min_bytes); + if (!ret) + goto got_it; + } + + if (!node) { + ret = -ENOSPC; + goto out; + } + entry = rb_entry(node, struct btrfs_free_space, offset_index); + } + + /* + * We already searched all the extent entries from the passed in offset + * to the end and didn't find enough space for the cluster, and we also + * didn't find any bitmaps that met our criteria, just go ahead and exit + */ + if (found_bitmap) { + ret = -ENOSPC; + goto out; + } + + cluster->points_to_bitmap = false; window_start = entry->offset; window_free = entry->bytes; last = entry; max_extent = entry->bytes; - while(1) { + while (1) { /* out window is just right, lets fill it */ if (window_free >= bytes + empty_size) break; node = rb_next(&last->offset_index); if (!node) { + if (found_bitmap) + goto again; ret = -ENOSPC; goto out; } next = rb_entry(node, struct btrfs_free_space, offset_index); + /* + * we found a bitmap, so if this search doesn't result in a + * cluster, we know to go and search again for the bitmaps and + * start looking for space there + */ + if (next->bitmap) { + if (!found_bitmap) + offset = next->offset; + found_bitmap = true; + last = next; + continue; + } + /* * we haven't filled the empty size and the window is * very large. reset and try again @@ -655,19 +1230,6 @@ again: window_free = entry->bytes; last = entry; max_extent = 0; - total_retries++; - if (total_retries % 64 == 0) { - if (min_bytes >= (bytes + empty_size)) { - ret = -ENOSPC; - goto out; - } - /* - * grow our allocation a bit, we're not having - * much luck - */ - min_bytes *= 2; - goto again; - } } else { last = next; window_free += next->bytes; @@ -685,11 +1247,19 @@ again: * The cluster includes an rbtree, but only uses the offset index * of each free space cache entry. */ - while(1) { + while (1) { node = rb_next(&entry->offset_index); - unlink_free_space(block_group, entry); + if (entry->bitmap && node) { + entry = rb_entry(node, struct btrfs_free_space, + offset_index); + continue; + } else if (entry->bitmap && !node) { + break; + } + + rb_erase(&entry->offset_index, &block_group->free_space_offset); ret = tree_insert_offset(&cluster->root, entry->offset, - &entry->offset_index); + &entry->offset_index, 0); BUG_ON(ret); if (!node || entry == last) @@ -697,8 +1267,10 @@ again: entry = rb_entry(node, struct btrfs_free_space, offset_index); } - ret = 0; + cluster->max_size = max_extent; +got_it: + ret = 0; atomic_inc(&block_group->count); list_add_tail(&cluster->block_group_list, &block_group->cluster_list); cluster->block_group = block_group; @@ -718,6 +1290,7 @@ void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster) spin_lock_init(&cluster->refill_lock); cluster->root.rb_node = NULL; cluster->max_size = 0; + cluster->points_to_bitmap = false; INIT_LIST_HEAD(&cluster->block_group_list); cluster->block_group = NULL; } -- cgit v1.2.3 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/free-space-cache.c | 42 +++++++++++++++++++++++------------------- 1 file changed, 23 insertions(+), 19 deletions(-) (limited to 'fs/btrfs/free-space-cache.c') diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index ab8cad8b46c..af99b78b288 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -238,6 +238,7 @@ static void unlink_free_space(struct btrfs_block_group_cache *block_group, { rb_erase(&info->offset_index, &block_group->free_space_offset); block_group->free_extents--; + block_group->free_space -= info->bytes; } static int link_free_space(struct btrfs_block_group_cache *block_group, @@ -251,6 +252,7 @@ static int link_free_space(struct btrfs_block_group_cache *block_group, if (ret) return ret; + block_group->free_space += info->bytes; block_group->free_extents++; return ret; } @@ -285,36 +287,40 @@ static void recalculate_thresholds(struct btrfs_block_group_cache *block_group) } } -static void bitmap_clear_bits(struct btrfs_free_space *info, u64 offset, u64 bytes, - u64 sectorsize) +static void bitmap_clear_bits(struct btrfs_block_group_cache *block_group, + struct btrfs_free_space *info, u64 offset, + u64 bytes) { unsigned long start, end; unsigned long i; - start = offset_to_bit(info->offset, sectorsize, offset); - end = start + bytes_to_bits(bytes, sectorsize); + start = offset_to_bit(info->offset, block_group->sectorsize, offset); + end = start + bytes_to_bits(bytes, block_group->sectorsize); BUG_ON(end > BITS_PER_BITMAP); for (i = start; i < end; i++) clear_bit(i, info->bitmap); info->bytes -= bytes; + block_group->free_space -= bytes; } -static void bitmap_set_bits(struct btrfs_free_space *info, u64 offset, u64 bytes, - u64 sectorsize) +static void bitmap_set_bits(struct btrfs_block_group_cache *block_group, + struct btrfs_free_space *info, u64 offset, + u64 bytes) { unsigned long start, end; unsigned long i; - start = offset_to_bit(info->offset, sectorsize, offset); - end = start + bytes_to_bits(bytes, sectorsize); + start = offset_to_bit(info->offset, block_group->sectorsize, offset); + end = start + bytes_to_bits(bytes, block_group->sectorsize); BUG_ON(end > BITS_PER_BITMAP); for (i = start; i < end; i++) set_bit(i, info->bitmap); info->bytes += bytes; + block_group->free_space += bytes; } static int search_bitmap(struct btrfs_block_group_cache *block_group, @@ -414,13 +420,12 @@ again: (u64)(BITS_PER_BITMAP * block_group->sectorsize) - 1; if (*offset > bitmap_info->offset && *offset + *bytes > end) { - bitmap_clear_bits(bitmap_info, *offset, - end - *offset + 1, block_group->sectorsize); + bitmap_clear_bits(block_group, bitmap_info, *offset, + end - *offset + 1); *bytes -= end - *offset + 1; *offset = end + 1; } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) { - bitmap_clear_bits(bitmap_info, *offset, - *bytes, block_group->sectorsize); + bitmap_clear_bits(block_group, bitmap_info, *offset, *bytes); *bytes = 0; } @@ -495,14 +500,13 @@ again: (u64)(BITS_PER_BITMAP * block_group->sectorsize); if (offset >= bitmap_info->offset && offset + bytes > end) { - bitmap_set_bits(bitmap_info, offset, end - offset, - block_group->sectorsize); + bitmap_set_bits(block_group, bitmap_info, offset, + end - offset); bytes -= end - offset; offset = end; added = 0; } else if (offset >= bitmap_info->offset && offset + bytes <= end) { - bitmap_set_bits(bitmap_info, offset, bytes, - block_group->sectorsize); + bitmap_set_bits(block_group, bitmap_info, offset, bytes); bytes = 0; } else { BUG(); @@ -870,8 +874,7 @@ u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group, ret = offset; if (entry->bitmap) { - bitmap_clear_bits(entry, offset, bytes, - block_group->sectorsize); + bitmap_clear_bits(block_group, entry, offset, bytes); if (!entry->bytes) { unlink_free_space(block_group, entry); kfree(entry->bitmap); @@ -891,6 +894,7 @@ u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group, out: spin_unlock(&block_group->tree_lock); + return ret; } @@ -967,7 +971,7 @@ static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group, goto out; ret = search_start; - bitmap_clear_bits(entry, ret, bytes, block_group->sectorsize); + bitmap_clear_bits(block_group, entry, ret, bytes); out: spin_unlock(&cluster->lock); spin_unlock(&block_group->tree_lock); -- cgit v1.2.3 From 6606bb97e146a387932efee263745b7240a11193 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 31 Jul 2009 11:03:58 -0400 Subject: Btrfs: fix btrfs_remove_from_free_space corner case Yan Zheng hit a problem where we tried to remove some free space but failed because we couldn't find the free space entry. This is because the free space was held within a bitmap that had a starting offset well before the actual offset of the free space, and there were free space extents that were in the same range as that offset, so tree_search_offset returned with NULL because we couldn't find a free space extent that had that offset. This is fixed by making sure that if we fail to find the entry, we re-search again with bitmap_only set to 1 and do an offset_to_bitmap so we can get the appropriate bitmap. A similar problem happens in btrfs_alloc_from_bitmap for the clustering code, but that is not as bad since we will just go and redo our cluster allocation. Also this adds some debugging checks to make sure that the free space we are trying to remove from the bitmap is in fact there. This can probably go away after a while, but since this code is only used by the tree-logging stuff it would be nice to run with it for a while to make sure there are no problems. Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/free-space-cache.c | 73 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 64 insertions(+), 9 deletions(-) (limited to 'fs/btrfs/free-space-cache.c') diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index af99b78b288..5edcee3a617 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -414,11 +414,29 @@ static noinline int remove_from_bitmap(struct btrfs_block_group_cache *block_gro u64 *offset, u64 *bytes) { u64 end; + u64 search_start, search_bytes; + int ret; again: end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * block_group->sectorsize) - 1; + /* + * XXX - this can go away after a few releases. + * + * since the only user of btrfs_remove_free_space is the tree logging + * stuff, and the only way to test that is under crash conditions, we + * want to have this debug stuff here just in case somethings not + * working. Search the bitmap for the space we are trying to use to + * make sure its actually there. If its not there then we need to stop + * because something has gone wrong. + */ + search_start = *offset; + search_bytes = *bytes; + ret = search_bitmap(block_group, bitmap_info, &search_start, + &search_bytes); + BUG_ON(ret < 0 || search_start != *offset); + if (*offset > bitmap_info->offset && *offset + *bytes > end) { bitmap_clear_bits(block_group, bitmap_info, *offset, end - *offset + 1); @@ -430,6 +448,7 @@ again: } if (*bytes) { + struct rb_node *next = rb_next(&bitmap_info->offset_index); if (!bitmap_info->bytes) { unlink_free_space(block_group, bitmap_info); kfree(bitmap_info->bitmap); @@ -438,16 +457,36 @@ again: recalculate_thresholds(block_group); } - bitmap_info = tree_search_offset(block_group, - offset_to_bitmap(block_group, - *offset), - 1, 0); - if (!bitmap_info) + /* + * no entry after this bitmap, but we still have bytes to + * remove, so something has gone wrong. + */ + if (!next) return -EINVAL; + bitmap_info = rb_entry(next, struct btrfs_free_space, + offset_index); + + /* + * if the next entry isn't a bitmap we need to return to let the + * extent stuff do its work. + */ if (!bitmap_info->bitmap) return -EAGAIN; + /* + * Ok the next item is a bitmap, but it may not actually hold + * the information for the rest of this free space stuff, so + * look for it, and if we don't find it return so we can try + * everything over again. + */ + search_start = *offset; + search_bytes = *bytes; + ret = search_bitmap(block_group, bitmap_info, &search_start, + &search_bytes); + if (ret < 0 || search_start != *offset) + return -EAGAIN; + goto again; } else if (!bitmap_info->bytes) { unlink_free_space(block_group, bitmap_info); @@ -644,8 +683,17 @@ int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group, again: info = tree_search_offset(block_group, offset, 0, 0); if (!info) { - WARN_ON(1); - goto out_lock; + /* + * oops didn't find an extent that matched the space we wanted + * to remove, look for a bitmap instead + */ + info = tree_search_offset(block_group, + offset_to_bitmap(block_group, offset), + 1, 0); + if (!info) { + WARN_ON(1); + goto out_lock; + } } if (info->bytes < bytes && rb_next(&info->offset_index)) { @@ -957,8 +1005,15 @@ static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group, if (cluster->block_group != block_group) goto out; - entry = tree_search_offset(block_group, search_start, 0, 0); - + /* + * search_start is the beginning of the bitmap, but at some point it may + * be a good idea to point to the actual start of the free area in the + * bitmap, so do the offset_to_bitmap trick anyway, and set bitmap_only + * to 1 to make sure we get the bitmap entry + */ + entry = tree_search_offset(block_group, + offset_to_bitmap(block_group, search_start), + 1, 0); if (!entry || !entry->bitmap) goto out; -- cgit v1.2.3