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btrfs: remove objectid from struct btrfs_inode on 64 bits platforms

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On 64 bits platforms we don't really need to have a dedicated member (the
objectid field) for the inode's number since we store in the VFS inode's
i_ino member, which is an unsigned long and this type is 64 bits wide on
64 bits platforms. We only need that field in case we are on a 32 bits
platform because the unsigned long type is 32 bits wide on such platforms
See commit 33345d0152 ("Btrfs: Always use 64bit inode number") regarding
this 64/32 bits detail.

The objectid field of struct btrfs_inode is also used to store the ID of
a root for directories that are stubs for unreferenced roots. In such
cases the inode is a directory and has the BTRFS_INODE_ROOT_STUB runtime
flag set.

So in order to reduce the size of btrfs_inode structure on 64 bits
platforms we can remove the objectid member and use the VFS inode's i_ino
member instead whenever we need to get the inode number. In case the inode
is a root stub (BTRFS_INODE_ROOT_STUB set) we can use the member
last_reflink_trans to store the ID of the unreferenced root, since such
inode is a directory and reflinks can't be done against directories.

So remove the objectid fields for 64 bits platforms and alias the
last_reflink_trans field with a name of ref_root_id in a union.
On a release kernel config, this reduces the size of struct btrfs_inode
from 1040 bytes down to 1032 bytes.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Filipe Manana 2024-05-05 13:47:02 +01:00 committed by David Sterba
parent 068fc8f914
commit 7a7bc21449
6 changed files with 45 additions and 34 deletions
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50
fs/btrfs/btrfs_inode.h
View File

@ -129,15 +129,14 @@ struct btrfs_inode {
/* which subvolume this inode belongs to */
struct btrfs_root *root;
#if BITS_PER_LONG == 32
/*
* This is either:
*
* 1) The objectid of the corresponding BTRFS_INODE_ITEM_KEY;
*
* 2) In case this a root stub inode (BTRFS_INODE_ROOT_STUB flag set),
* the ID of that root.
* The objectid of the corresponding BTRFS_INODE_ITEM_KEY.
* On 64 bits platforms we can get it from vfs_inode.i_ino, which is an
* unsigned long and therefore 64 bits on such platforms.
*/
u64 objectid;
#endif
/* Cached value of inode property 'compression'. */
u8 prop_compress;
@ -301,16 +300,25 @@ struct btrfs_inode {
*/
u64 last_unlink_trans;
/*
* The id/generation of the last transaction where this inode was
* either the source or the destination of a clone/dedupe operation.
* Used when logging an inode to know if there are shared extents that
* need special care when logging checksum items, to avoid duplicate
* checksum items in a log (which can lead to a corruption where we end
* up with missing checksum ranges after log replay).
* Protected by the vfs inode lock.
*/
u64 last_reflink_trans;
union {
/*
* The id/generation of the last transaction where this inode
* was either the source or the destination of a clone/dedupe
* operation. Used when logging an inode to know if there are
* shared extents that need special care when logging checksum
* items, to avoid duplicate checksum items in a log (which can
* lead to a corruption where we end up with missing checksum
* ranges after log replay). Protected by the VFS inode lock.
* Used for regular files only.
*/
u64 last_reflink_trans;
/*
* In case this a root stub inode (BTRFS_INODE_ROOT_STUB flag set),
* the ID of that root.
*/
u64 ref_root_id;
};
/* Backwards incompatible flags, lower half of inode_item::flags */
u32 flags;
@ -387,11 +395,19 @@ static inline u64 btrfs_ino(const struct btrfs_inode *inode)
static inline void btrfs_get_inode_key(const struct btrfs_inode *inode,
struct btrfs_key *key)
{
key->objectid = inode->objectid;
key->objectid = btrfs_ino(inode);
key->type = BTRFS_INODE_ITEM_KEY;
key->offset = 0;
}
static inline void btrfs_set_inode_number(struct btrfs_inode *inode, u64 ino)
{
#if BITS_PER_LONG == 32
inode->objectid = ino;
#endif
inode->vfs_inode.i_ino = ino;
}
static inline void btrfs_i_size_write(struct btrfs_inode *inode, u64 size)
{
i_size_write(&inode->vfs_inode, size);

3
fs/btrfs/disk-io.c
View File

@ -1928,7 +1928,7 @@ static int btrfs_init_btree_inode(struct super_block *sb)
if (!inode)
return -ENOMEM;
inode->i_ino = BTRFS_BTREE_INODE_OBJECTID;
btrfs_set_inode_number(BTRFS_I(inode), BTRFS_BTREE_INODE_OBJECTID);
set_nlink(inode, 1);
/*
* we set the i_size on the btree inode to the max possible int.
@ -1944,7 +1944,6 @@ static int btrfs_init_btree_inode(struct super_block *sb)
extent_map_tree_init(&BTRFS_I(inode)->extent_tree);
BTRFS_I(inode)->root = btrfs_grab_root(fs_info->tree_root);
BTRFS_I(inode)->objectid = BTRFS_BTREE_INODE_OBJECTID;
set_bit(BTRFS_INODE_DUMMY, &BTRFS_I(inode)->runtime_flags);
__insert_inode_hash(inode, hash);
fs_info->btree_inode = inode;

2
fs/btrfs/export.c
View File

@ -40,7 +40,7 @@ static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
if (parent) {
u64 parent_root_id;
fid->parent_objectid = BTRFS_I(parent)->objectid;
fid->parent_objectid = btrfs_ino(BTRFS_I(parent));
fid->parent_gen = parent->i_generation;
parent_root_id = btrfs_root_id(BTRFS_I(parent)->root);

17
fs/btrfs/inode.c
View File

@ -4340,7 +4340,7 @@ static int btrfs_unlink_subvol(struct btrfs_trans_handle *trans,
if (btrfs_ino(inode) == BTRFS_FIRST_FREE_OBJECTID) {
objectid = btrfs_root_id(inode->root);
} else if (btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID) {
objectid = inode->objectid;
objectid = inode->ref_root_id;
} else {
WARN_ON(1);
fscrypt_free_filename(&fname);
@ -5581,8 +5581,7 @@ static int btrfs_init_locked_inode(struct inode *inode, void *p)
{
struct btrfs_iget_args *args = p;
inode->i_ino = args->ino;
BTRFS_I(inode)->objectid = args->ino;
btrfs_set_inode_number(BTRFS_I(inode), args->ino);
BTRFS_I(inode)->root = btrfs_grab_root(args->root);
if (args->root && args->root == args->root->fs_info->tree_root &&
@ -5596,7 +5595,7 @@ static int btrfs_find_actor(struct inode *inode, void *opaque)
{
struct btrfs_iget_args *args = opaque;
return args->ino == BTRFS_I(inode)->objectid &&
return args->ino == btrfs_ino(BTRFS_I(inode)) &&
args->root == BTRFS_I(inode)->root;
}
@ -5673,11 +5672,11 @@ static struct inode *new_simple_dir(struct inode *dir,
return ERR_PTR(-ENOMEM);
BTRFS_I(inode)->root = btrfs_grab_root(root);
BTRFS_I(inode)->objectid = key->objectid;
BTRFS_I(inode)->ref_root_id = key->objectid;
set_bit(BTRFS_INODE_ROOT_STUB, &BTRFS_I(inode)->runtime_flags);
set_bit(BTRFS_INODE_DUMMY, &BTRFS_I(inode)->runtime_flags);
inode->i_ino = BTRFS_EMPTY_SUBVOL_DIR_OBJECTID;
btrfs_set_inode_number(BTRFS_I(inode), BTRFS_EMPTY_SUBVOL_DIR_OBJECTID);
/*
* We only need lookup, the rest is read-only and there's no inode
* associated with the dentry
@ -6150,7 +6149,7 @@ static int btrfs_insert_inode_locked(struct inode *inode)
{
struct btrfs_iget_args args;
args.ino = BTRFS_I(inode)->objectid;
args.ino = btrfs_ino(BTRFS_I(inode));
args.root = BTRFS_I(inode)->root;
return insert_inode_locked4(inode,
@ -6282,7 +6281,7 @@ int btrfs_create_new_inode(struct btrfs_trans_handle *trans,
ret = btrfs_get_free_objectid(root, &objectid);
if (ret)
goto out;
inode->i_ino = objectid;
btrfs_set_inode_number(BTRFS_I(inode), objectid);
ret = xa_reserve(&root->inodes, objectid, GFP_NOFS);
if (ret)
@ -6332,8 +6331,6 @@ int btrfs_create_new_inode(struct btrfs_trans_handle *trans,
BTRFS_INODE_NODATASUM;
}
BTRFS_I(inode)->objectid = objectid;
ret = btrfs_insert_inode_locked(inode);
if (ret < 0) {
if (!args->orphan)

4
fs/btrfs/ioctl.c
View File

@ -1918,7 +1918,7 @@ static int btrfs_search_path_in_tree_user(struct mnt_idmap *idmap,
{
struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
struct super_block *sb = inode->i_sb;
u64 upper_limit = BTRFS_I(inode)->objectid;
u64 upper_limit = btrfs_ino(BTRFS_I(inode));
u64 treeid = btrfs_root_id(BTRFS_I(inode)->root);
u64 dirid = args->dirid;
unsigned long item_off;
@ -2140,7 +2140,7 @@ static int btrfs_ioctl_ino_lookup_user(struct file *file, void __user *argp)
inode = file_inode(file);
if (args->dirid == BTRFS_FIRST_FREE_OBJECTID &&
BTRFS_I(inode)->objectid != BTRFS_FIRST_FREE_OBJECTID) {
btrfs_ino(BTRFS_I(inode)) != BTRFS_FIRST_FREE_OBJECTID) {
/*
* The subvolume does not exist under fd with which this is
* called

3
fs/btrfs/tests/btrfs-tests.c
View File

@ -61,8 +61,7 @@ struct inode *btrfs_new_test_inode(void)
return NULL;
inode->i_mode = S_IFREG;
inode->i_ino = BTRFS_FIRST_FREE_OBJECTID;
BTRFS_I(inode)->objectid = BTRFS_FIRST_FREE_OBJECTID;
btrfs_set_inode_number(BTRFS_I(inode), BTRFS_FIRST_FREE_OBJECTID);
inode_init_owner(&nop_mnt_idmap, inode, NULL, S_IFREG);
return inode;