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>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index a4157cf..77dd0a7 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -51,6 +51,7 @@
#include "compression.h"
#include "locking.h"
#include "free-space-cache.h"
+#include "inode-map.h"
struct btrfs_iget_args {
u64 ino;
@@ -3809,6 +3810,10 @@
BUG_ON(ret);
}
+ if (!(root == root->fs_info->tree_root ||
+ root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID))
+ btrfs_return_ino(root, inode->i_ino);
+
nr = trans->blocks_used;
btrfs_end_transaction(trans, root);
btrfs_btree_balance_dirty(root, nr);
@@ -4538,6 +4543,12 @@
return ERR_PTR(-ENOMEM);
}
+ /*
+ * we have to initialize this early, so we can reclaim the inode
+ * number if we fail afterwards in this function.
+ */
+ inode->i_ino = objectid;
+
if (dir) {
trace_btrfs_inode_request(dir);
@@ -4583,7 +4594,6 @@
goto fail;
inode_init_owner(inode, dir, mode);
- inode->i_ino = objectid;
inode_set_bytes(inode, 0);
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
@@ -4712,10 +4722,6 @@
if (!new_valid_dev(rdev))
return -EINVAL;
- err = btrfs_find_free_objectid(NULL, root, dir->i_ino, &objectid);
- if (err)
- return err;
-
/*
* 2 for inode item and ref
* 2 for dir items
@@ -4727,6 +4733,10 @@
btrfs_set_trans_block_group(trans, dir);
+ err = btrfs_find_free_ino(root, &objectid);
+ if (err)
+ goto out_unlock;
+
inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
dentry->d_name.len, dir->i_ino, objectid,
BTRFS_I(dir)->block_group, mode, &index);
@@ -4774,9 +4784,6 @@
u64 objectid;
u64 index = 0;
- err = btrfs_find_free_objectid(NULL, root, dir->i_ino, &objectid);
- if (err)
- return err;
/*
* 2 for inode item and ref
* 2 for dir items
@@ -4788,6 +4795,10 @@
btrfs_set_trans_block_group(trans, dir);
+ err = btrfs_find_free_ino(root, &objectid);
+ if (err)
+ goto out_unlock;
+
inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
dentry->d_name.len, dir->i_ino, objectid,
BTRFS_I(dir)->block_group, mode, &index);
@@ -4902,10 +4913,6 @@
u64 index = 0;
unsigned long nr = 1;
- err = btrfs_find_free_objectid(NULL, root, dir->i_ino, &objectid);
- if (err)
- return err;
-
/*
* 2 items for inode and ref
* 2 items for dir items
@@ -4916,6 +4923,10 @@
return PTR_ERR(trans);
btrfs_set_trans_block_group(trans, dir);
+ err = btrfs_find_free_ino(root, &objectid);
+ if (err)
+ goto out_fail;
+
inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
dentry->d_name.len, dir->i_ino, objectid,
BTRFS_I(dir)->block_group, S_IFDIR | mode,
@@ -7257,9 +7268,6 @@
if (name_len > BTRFS_MAX_INLINE_DATA_SIZE(root))
return -ENAMETOOLONG;
- err = btrfs_find_free_objectid(NULL, root, dir->i_ino, &objectid);
- if (err)
- return err;
/*
* 2 items for inode item and ref
* 2 items for dir items
@@ -7271,6 +7279,10 @@
btrfs_set_trans_block_group(trans, dir);
+ err = btrfs_find_free_ino(root, &objectid);
+ if (err)
+ goto out_unlock;
+
inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
dentry->d_name.len, dir->i_ino, objectid,
BTRFS_I(dir)->block_group, S_IFLNK|S_IRWXUGO,