linux/fs/btrfs/inode-map.h
Li Zefan 581bb05094 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>
2011-04-25 16:46:04 +08:00

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366 B
C

#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