Commit d9891ae2 authored by Filipe Manana's avatar Filipe Manana Committed by David Sterba
Browse files

btrfs: unify index_cnt and csum_bytes from struct btrfs_inode 



The index_cnt field of struct btrfs_inode is used only for two purposes:

1) To store the index for the next entry added to a directory;

2) For the data relocation inode to track the logical start address of the
   block group currently being relocated.

For the relocation case we use index_cnt because it's not used for
anything else in the relocation use case - we could have used other fields
that are not used by relocation such as defrag_bytes, last_unlink_trans
or last_reflink_trans for example (among others).

Since the csum_bytes field is not used for directories, do the following
changes:

1) Put index_cnt and csum_bytes in a union, and index_cnt is only
   initialized when the inode is a directory. The csum_bytes is only
   accessed in IO paths for regular files, so we're fine here;

2) Use the defrag_bytes field for relocation, since the data relocation
   inode is never used for defrag purposes. And to make the naming better,
   alias it to reloc_block_group_start by using a union.

This reduces the size of struct btrfs_inode by 8 bytes in a release
kernel, from 1056 bytes down to 1048 bytes.

Reviewed-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent e2844cce

fs/btrfs/btrfs_inode.h

+29 −17
Original line number Diff line number Diff line
@@ -225,12 +225,21 @@ struct btrfs_inode { 
		u64 last_dir_index_offset;

	};



	union {

		/*

		 * Total number of bytes pending defrag, used by stat to check whether

		 * it needs COW. Protected by 'lock'.

		 * Used by inodes other than the data relocation inode.

		 */

		u64 defrag_bytes;



		/*

		 * Logical address of the block group being relocated.

		 * Used only by the data relocation inode.

		 */

		u64 reloc_block_group_start;

	};



	/*

	 * The size of the file stored in the metadata on disk.  data=ordered

	 * means the in-memory i_size might be larger than the size on disk
@@ -238,13 +247,22 @@ struct btrfs_inode { 
	 */

	u64 disk_i_size;



	union {

		/*

	 * If this is a directory then index_cnt is the counter for the index

	 * number for new files that are created. For an empty directory, this

	 * must be initialized to BTRFS_DIR_START_INDEX.

		 * If this is a directory then index_cnt is the counter for the

		 * index number for new files that are created. For an empty

		 * directory, this must be initialized to BTRFS_DIR_START_INDEX.

		 */

		u64 index_cnt;



		/*

		 * If this is not a directory, this is the number of bytes

		 * outstanding that are going to need csums. This is used in

		 * ENOSPC accounting. Protected by 'lock'.

		 */

		u64 csum_bytes;

	};



	/* Cache the directory index number to speed the dir/file remove */

	u64 dir_index;
@@ -266,12 +284,6 @@ struct btrfs_inode { 
	 */

	u64 last_reflink_trans;



	/*

	 * Number of bytes outstanding that are going to need csums.  This is

	 * used in ENOSPC accounting. Protected by 'lock'.

	 */

	u64 csum_bytes;



	/* Backwards incompatible flags, lower half of inode_item::flags  */

	u32 flags;

	/* Read-only compatibility flags, upper half of inode_item::flags */

fs/btrfs/delayed-inode.c

+2 −1
Original line number Diff line number Diff line
@@ -1914,6 +1914,7 @@ int btrfs_fill_inode(struct inode *inode, u32 *rdev) 
	BTRFS_I(inode)->i_otime_nsec = btrfs_stack_timespec_nsec(&inode_item->otime);



	inode->i_generation = BTRFS_I(inode)->generation;

	if (S_ISDIR(inode->i_mode))

		BTRFS_I(inode)->index_cnt = (u64)-1;



	mutex_unlock(&delayed_node->mutex);

fs/btrfs/inode.c

+15 −6
Original line number Diff line number Diff line
@@ -3856,7 +3856,9 @@ static int btrfs_read_locked_inode(struct inode *inode, 
	inode->i_rdev = 0;

	rdev = btrfs_inode_rdev(leaf, inode_item);



	if (S_ISDIR(inode->i_mode))

		BTRFS_I(inode)->index_cnt = (u64)-1;



	btrfs_inode_split_flags(btrfs_inode_flags(leaf, inode_item),

				&BTRFS_I(inode)->flags, &BTRFS_I(inode)->ro_flags);
@@ -6268,8 +6270,10 @@ int btrfs_create_new_inode(struct btrfs_trans_handle *trans, 
		if (ret)

			goto out;

	}

	/* index_cnt is ignored for everything but a dir. */



	if (S_ISDIR(inode->i_mode))

		BTRFS_I(inode)->index_cnt = BTRFS_DIR_START_INDEX;



	BTRFS_I(inode)->generation = trans->transid;

	inode->i_generation = BTRFS_I(inode)->generation;
@@ -8435,8 +8439,12 @@ struct inode *btrfs_alloc_inode(struct super_block *sb) 
	ei->disk_i_size = 0;

	ei->flags = 0;

	ei->ro_flags = 0;

	/*

	 * ->index_cnt will be properly initialized later when creating a new

	 * inode (btrfs_create_new_inode()) or when reading an existing inode

	 * from disk (btrfs_read_locked_inode()).

	 */

	ei->csum_bytes = 0;

	ei->index_cnt = (u64)-1;

	ei->dir_index = 0;

	ei->last_unlink_trans = 0;

	ei->last_reflink_trans = 0;
@@ -8511,8 +8519,9 @@ void btrfs_destroy_inode(struct inode *vfs_inode) 
	if (!S_ISDIR(vfs_inode->i_mode)) {

		WARN_ON(inode->delalloc_bytes);

		WARN_ON(inode->new_delalloc_bytes);

	}

		WARN_ON(inode->csum_bytes);

	}

	if (!root || !btrfs_is_data_reloc_root(root))

		WARN_ON(inode->defrag_bytes);



	/*

fs/btrfs/relocation.c

+6 −6
Original line number Diff line number Diff line
@@ -962,7 +962,7 @@ static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr, 
	if (!path)

		return -ENOMEM;



	bytenr -= BTRFS_I(reloc_inode)->index_cnt;

	bytenr -= BTRFS_I(reloc_inode)->reloc_block_group_start;

	ret = btrfs_lookup_file_extent(NULL, root, path,

			btrfs_ino(BTRFS_I(reloc_inode)), bytenr, 0);

	if (ret < 0)
@@ -2797,7 +2797,7 @@ static noinline_for_stack int prealloc_file_extent_cluster( 
	u64 alloc_hint = 0;

	u64 start;

	u64 end;

	u64 offset = inode->index_cnt;

	u64 offset = inode->reloc_block_group_start;

	u64 num_bytes;

	int nr;

	int ret = 0;
@@ -2951,7 +2951,7 @@ static int relocate_one_folio(struct inode *inode, struct file_ra_state *ra, 
			      int *cluster_nr, unsigned long index)

{

	struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);

	u64 offset = BTRFS_I(inode)->index_cnt;

	u64 offset = BTRFS_I(inode)->reloc_block_group_start;

	const unsigned long last_index = (cluster->end - offset) >> PAGE_SHIFT;

	gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);

	struct folio *folio;
@@ -3086,7 +3086,7 @@ static int relocate_one_folio(struct inode *inode, struct file_ra_state *ra, 
static int relocate_file_extent_cluster(struct inode *inode,

					const struct file_extent_cluster *cluster)

{

	u64 offset = BTRFS_I(inode)->index_cnt;

	u64 offset = BTRFS_I(inode)->reloc_block_group_start;

	unsigned long index;

	unsigned long last_index;

	struct file_ra_state *ra;
@@ -3915,7 +3915,7 @@ static noinline_for_stack struct inode *create_reloc_inode( 
		inode = NULL;

		goto out;

	}

	BTRFS_I(inode)->index_cnt = group->start;

	BTRFS_I(inode)->reloc_block_group_start = group->start;



	ret = btrfs_orphan_add(trans, BTRFS_I(inode));

out:
@@ -4395,7 +4395,7 @@ int btrfs_reloc_clone_csums(struct btrfs_ordered_extent *ordered) 
{

	struct btrfs_inode *inode = BTRFS_I(ordered->inode);

	struct btrfs_fs_info *fs_info = inode->root->fs_info;

	u64 disk_bytenr = ordered->file_offset + inode->index_cnt;

	u64 disk_bytenr = ordered->file_offset + inode->reloc_block_group_start;

	struct btrfs_root *csum_root = btrfs_csum_root(fs_info, disk_bytenr);

	LIST_HEAD(list);

	int ret;

fs/btrfs/tree-log.c

+2 −1
Original line number Diff line number Diff line
@@ -1644,6 +1644,7 @@ static noinline int fixup_inode_link_count(struct btrfs_trans_handle *trans, 
		if (ret)

			goto out;

	}

	if (S_ISDIR(inode->i_mode))

		BTRFS_I(inode)->index_cnt = (u64)-1;



	if (inode->i_nlink == 0) {