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author | Li Zefan <lizf@cn.fujitsu.com> | 2011-04-20 02:06:11 (GMT) |
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committer | Li Zefan <lizf@cn.fujitsu.com> | 2011-04-25 08:46:04 (GMT) |
commit | 581bb050941b4f220f84d3e5ed6dace3d42dd382 (patch) | |
tree | 5ebd56af5eb3612f508419b188dfc18e959e7c94 /fs/btrfs/free-space-cache.c | |
parent | 34d52cb6c50b5a43901709998f59fb1c5a43dc4a (diff) | |
download | linux-fsl-qoriq-581bb050941b4f220f84d3e5ed6dace3d42dd382.tar.xz |
Btrfs: Cache free inode numbers in memory
Currently btrfs stores the highest objectid of the fs tree, and it always
returns (highest+1) inode number when we create a file, so inode numbers
won't be reclaimed when we delete files, so we'll run out of inode numbers
as we keep create/delete files in 32bits machines.
This fixes it, and it works similarly to how we cache free space in block
cgroups.
We start a kernel thread to read the file tree. By scanning inode items,
we know which chunks of inode numbers are free, and we cache them in
an rb-tree.
Because we are searching the commit root, we have to carefully handle the
cross-transaction case.
The rb-tree is a hybrid extent+bitmap tree, so if we have too many small
chunks of inode numbers, we'll use bitmaps. Initially we allow 16K ram
of extents, and a bitmap will be used if we exceed this threshold. The
extents threshold is adjusted in runtime.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Diffstat (limited to 'fs/btrfs/free-space-cache.c')
-rw-r--r-- | fs/btrfs/free-space-cache.c | 96 |
1 files changed, 76 insertions, 20 deletions
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index d4fb4f0..2ce89bf 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -25,6 +25,7 @@ #include "transaction.h" #include "disk-io.h" #include "extent_io.h" +#include "inode-map.h" #define BITS_PER_BITMAP (PAGE_CACHE_SIZE * 8) #define MAX_CACHE_BYTES_PER_GIG (32 * 1024) @@ -105,7 +106,7 @@ int create_free_space_inode(struct btrfs_root *root, u64 objectid; int ret; - ret = btrfs_find_free_objectid(trans, root, 0, &objectid); + ret = btrfs_find_free_objectid(root, &objectid); if (ret < 0) return ret; @@ -1496,10 +1497,9 @@ bool try_merge_free_space(struct btrfs_free_space_ctl *ctl, return merged; } -int btrfs_add_free_space(struct btrfs_block_group_cache *block_group, - u64 offset, u64 bytes) +int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl, + u64 offset, u64 bytes) { - struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl; struct btrfs_free_space *info; int ret = 0; @@ -1751,11 +1751,29 @@ out: return 0; } -void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group) +void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl) { - struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl; struct btrfs_free_space *info; struct rb_node *node; + + spin_lock(&ctl->tree_lock); + while ((node = rb_last(&ctl->free_space_offset)) != NULL) { + info = rb_entry(node, struct btrfs_free_space, offset_index); + unlink_free_space(ctl, info); + kfree(info->bitmap); + kmem_cache_free(btrfs_free_space_cachep, info); + if (need_resched()) { + spin_unlock(&ctl->tree_lock); + cond_resched(); + spin_lock(&ctl->tree_lock); + } + } + spin_unlock(&ctl->tree_lock); +} + +void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group) +{ + struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl; struct btrfs_free_cluster *cluster; struct list_head *head; @@ -1773,21 +1791,9 @@ void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group) spin_lock(&ctl->tree_lock); } } - - while ((node = rb_last(&ctl->free_space_offset)) != NULL) { - info = rb_entry(node, struct btrfs_free_space, offset_index); - unlink_free_space(ctl, info); - if (info->bitmap) - kfree(info->bitmap); - kmem_cache_free(btrfs_free_space_cachep, info); - if (need_resched()) { - spin_unlock(&ctl->tree_lock); - cond_resched(); - spin_lock(&ctl->tree_lock); - } - } - spin_unlock(&ctl->tree_lock); + + __btrfs_remove_free_space_cache(ctl); } u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group, @@ -2352,3 +2358,53 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group, return ret; } + +/* + * Find the left-most item in the cache tree, and then return the + * smallest inode number in the item. + * + * Note: the returned inode number may not be the smallest one in + * the tree, if the left-most item is a bitmap. + */ +u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root) +{ + struct btrfs_free_space_ctl *ctl = fs_root->free_ino_ctl; + struct btrfs_free_space *entry = NULL; + u64 ino = 0; + + spin_lock(&ctl->tree_lock); + + if (RB_EMPTY_ROOT(&ctl->free_space_offset)) + goto out; + + entry = rb_entry(rb_first(&ctl->free_space_offset), + struct btrfs_free_space, offset_index); + + if (!entry->bitmap) { + ino = entry->offset; + + unlink_free_space(ctl, entry); + entry->offset++; + entry->bytes--; + if (!entry->bytes) + kmem_cache_free(btrfs_free_space_cachep, entry); + else + link_free_space(ctl, entry); + } else { + u64 offset = 0; + u64 count = 1; + int ret; + + ret = search_bitmap(ctl, entry, &offset, &count); + BUG_ON(ret); + + ino = offset; + bitmap_clear_bits(ctl, entry, offset, 1); + if (entry->bytes == 0) + free_bitmap(ctl, entry); + } +out: + spin_unlock(&ctl->tree_lock); + + return ino; +} |