MIRRORS/linux-yocto
1
0
Fork 0
mirror of git://git.yoctoproject.org/linux-yocto.git synced 2026-01-27 12:47:24 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

btrfs: make the rule checking more readable for should_cow_block()

Browse Source 
It's quite hard and unreadable the way the rule checks are organized in
should_cow_block(). We have a single if statement that returns 0 (false)
and it checks several conditions, with one them being a negated compound
condition which is particularly hard to reason immediately.

Improve on this by using multiple if statements, each checking a single
condition and returning immediately. Also change the return type from an
integer to a boolean, since all we need is to return true or false.

At least on x86_64 with Debian's gcc 14.2.0-19, this also reduces the
object code size by 64 bytes.

Before this change:

   $ size fs/btrfs/btrfs.ko
      text	   data	    bss	    dec	    hex	filename
   1913327	 161567	  15592	2090486	 1fe5f6	fs/btrfs/btrfs.ko

After this change:

   $ size fs/btrfs/btrfs.ko
      text	   data	    bss	    dec	    hex	filename
   1913263	 161567	  15592	2090422	 1fe5b6	fs/btrfs/btrfs.ko

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
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>
This commit is contained in:
Filipe Manana 2025-09-19 09:16:20 +01:00 committed by David Sterba
parent b7ff7b0d76
commit f07575bab6
1 changed files with 23 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
fs/btrfs/ctree.c
View File

@ -613,15 +613,12 @@ error_unlock_cow:
return ret;
}
static inline int should_cow_block(const struct btrfs_trans_handle *trans,
const struct btrfs_root *root,
const struct extent_buffer *buf)
static inline bool should_cow_block(const struct btrfs_trans_handle *trans,
const struct btrfs_root *root,
const struct extent_buffer *buf)
{
if (btrfs_is_testing(root->fs_info))
return 0;
/* Ensure we can see the FORCE_COW bit */
smp_mb__before_atomic();
return false;
/*
* We do not need to cow a block if
@ -634,13 +631,25 @@ static inline int should_cow_block(const struct btrfs_trans_handle *trans,
* after we've finished copying src root, we must COW the shared
* block to ensure the metadata consistency.
*/
if (btrfs_header_generation(buf) == trans->transid &&
!btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
!(btrfs_root_id(root) != BTRFS_TREE_RELOC_OBJECTID &&
btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
!test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
return 0;
return 1;
if (btrfs_header_generation(buf) != trans->transid)
return true;
if (btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN))
return true;
/* Ensure we can see the FORCE_COW bit. */
smp_mb__before_atomic();
if (test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
return true;
if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)
return false;
if (btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC))
return true;
return false;
}
/*