ext4: use swap macro in mext_page_double_lock
PATCH 1/1 ext4: use swap macro in mext_page_double_lock
Make use of the swap macro and remove unnecessary variable *tmp*. This makes the code easier to read and maintain. Also, reduces the stack usage.
This code was detected with the help of Coccinelle.
--- fs/ext4/move_extent.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
fs/ext4/move_extent.c +1 -3
@@ -134,9 +134,7 @@ mext_page_double_lock(struct inode *inode1, struct inode *inode2, mapping[0 ] = inode1->i_mapping; mapping[1 ] = inode2->i_mapping; }else { -pgoff_t tmp = index1; - index1 = index2; - index2 = tmp; +swap (index1, index2); mapping[0 ] = inode2->i_mapping; mapping[1 ] = inode1->i_mapping; }
Signature · 1 line
2.7.4
Theodore Y. Ts'o
maintainerQuoted 7 lines · Gustavo A. R. Silva
Make use of the swap macro and remove unnecessary variable *tmp*. This makes the code easier to read and maintain. Also, reduces the stack usage.
This code was detected with the help of Coccinelle.
Signed-off-by Gustavo A. R. Silva <[email protected]>
It doesn't actually reduce stack usage. Look at the definition of swap() in include/linux/kernel.h:
#define swap(a, b) \
do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)It removes the variable "tmp", and replace it with "__tmp".
It slightly reduces the number of lines of code, so it slightly makes the code easier to maintainer. But I think you are really over-promising how much this commit helps.
Regards,
- Ted
Hi Theodore,
Quoted 12 lines · Theodore Y. Ts'o
Quoted 7 lines · Gustavo A. R. Silva
Make use of the swap macro and remove unnecessary variable *tmp*. This makes the code easier to read and maintain. Also, reduces the stack usage.
This code was detected with the help of Coccinelle.
Signed-off-by Gustavo A. R. Silva <[email protected]>It doesn't actually reduce stack usage. Look at the definition of
swap()ininclude/linux/kernel.h:
Quoted 9 lines
#define swap(a, b) \ do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)It removes the variable "tmp", and replace it with "
__tmp".It slightly reduces the number of lines of code, so it slightly makes the code easier to maintainer. But I think you are really over-promising how much this commit helps.
I'll remove that part from the changelog and send it again.
Thanks
--
Gustavo