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: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 1ee3f45d50a0957f9d8a78cc5dea1bcbdeade242..a1c2e922a5dd6a68dcf2ff89deb1877c4ef07f79 100644 (file)
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -225,11 +225,20 @@ struct btrfs_inode {
                u64 last_dir_index_offset;
        };
 
-       /*
-        * Total number of bytes pending defrag, used by stat to check whether
-        * it needs COW. Protected by 'lock'.
-        */
-       u64 defrag_bytes;
+       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
@@ -238,12 +247,21 @@ struct btrfs_inode {
         */
        u64 disk_i_size;
 
-       /*
-        * 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;
+       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.
+                */
+               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 */

diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index 40e617c7e8a1333828aa2b4d1f27a3c8a09c6945..483c141dc488f9f9ae8b87989ab8cc7328f72408 100644 (file)
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -1914,7 +1914,8 @@ 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;
-       BTRFS_I(inode)->index_cnt = (u64)-1;
+       if (S_ISDIR(inode->i_mode))
+               BTRFS_I(inode)->index_cnt = (u64)-1;
 
        mutex_unlock(&delayed_node->mutex);
        btrfs_release_delayed_node(delayed_node);

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 2a8bc014579ef2af86026bec9444924ea1856b6b..94dd338837bf8f564436781de5cdada19d6acdc3 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3856,7 +3856,9 @@ static int btrfs_read_locked_inode(struct inode *inode,
        inode->i_rdev = 0;
        rdev = btrfs_inode_rdev(leaf, inode_item);
 
-       BTRFS_I(inode)->index_cnt = (u64)-1;
+       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. */
-       BTRFS_I(inode)->index_cnt = BTRFS_DIR_START_INDEX;
+
+       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;
@@ -8511,9 +8519,10 @@ 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);
        }
-       WARN_ON(inode->csum_bytes);
-       WARN_ON(inode->defrag_bytes);
+       if (!root || !btrfs_is_data_reloc_root(root))
+               WARN_ON(inode->defrag_bytes);
 
        /*
         * This can happen where we create an inode, but somebody else also

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 8b24bb5a0aa189fe23d44a6fa54ba4df5151efac..9f35524b6664e45435808a61b1bb44bf9f647117 100644 (file)
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -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 @@ release_folio:
 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;

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 0bce1d45e25267e6f7e82681de48b50e0d00b1d3..e6294d2bb78b8a1b71d08da39e45f82ae98187ac 100644 (file)
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -1644,7 +1644,8 @@ static noinline int fixup_inode_link_count(struct btrfs_trans_handle *trans,
                if (ret)
                        goto out;
        }
-       BTRFS_I(inode)->index_cnt = (u64)-1;
+       if (S_ISDIR(inode->i_mode))
+               BTRFS_I(inode)->index_cnt = (u64)-1;
 
        if (inode->i_nlink == 0) {
                if (S_ISDIR(inode->i_mode)) {