From 581bb050941b4f220f84d3e5ed6dace3d42dd382 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Wed, 20 Apr 2011 10:06:11 +0800 Subject: 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 --- fs/btrfs/inode-map.h | 11 +++++++++++ 1 file changed, 11 insertions(+) create mode 100644 fs/btrfs/inode-map.h (limited to 'fs/btrfs/inode-map.h') diff --git a/fs/btrfs/inode-map.h b/fs/btrfs/inode-map.h new file mode 100644 index 000000000000..eb918451b492 --- /dev/null +++ b/fs/btrfs/inode-map.h @@ -0,0 +1,11 @@ +#ifndef __BTRFS_INODE_MAP +#define __BTRFS_INODE_MAP + +void btrfs_init_free_ino_ctl(struct btrfs_root *root); +void btrfs_unpin_free_ino(struct btrfs_root *root); +void btrfs_return_ino(struct btrfs_root *root, u64 objectid); +int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid); + +int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid); + +#endif -- cgit v1.2.2 From 82d5902d9c681be37ffa9d70482907f9f0b7ec1f Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Wed, 20 Apr 2011 10:33:24 +0800 Subject: Btrfs: Support reading/writing on disk free ino cache This is similar to block group caching. We dedicate a special inode in fs tree to save free ino cache. At the very first time we create/delete a file after mount, the free ino cache will be loaded from disk into memory. When the fs tree is commited, the cache will be written back to disk. To keep compatibility, we check the root generation against the generation of the special inode when loading the cache, so the loading will fail if the btrfs filesystem was mounted in an older kernel before. Signed-off-by: Li Zefan --- fs/btrfs/inode-map.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/btrfs/inode-map.h') diff --git a/fs/btrfs/inode-map.h b/fs/btrfs/inode-map.h index eb918451b492..ddb347bfee23 100644 --- a/fs/btrfs/inode-map.h +++ b/fs/btrfs/inode-map.h @@ -5,6 +5,8 @@ void btrfs_init_free_ino_ctl(struct btrfs_root *root); void btrfs_unpin_free_ino(struct btrfs_root *root); void btrfs_return_ino(struct btrfs_root *root, u64 objectid); int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid); +int btrfs_save_ino_cache(struct btrfs_root *root, + struct btrfs_trans_handle *trans); int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid); -- cgit v1.2.2