linux/fs/btrfs/inode-map.h

#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
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> 2011-04-20 10:06:11 +08:00			`#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`