[PATCH v5 1/6] ilog2: add max_pow_of_two_factor()
From: John Garry <john.g.garry@oracle.com>
Date: 2025-07-09 10:03:16
Also in:
dm-devel, linux-block, linux-xfs, lkml
Subsystem:
filesystems (vfs and infrastructure), the rest, xfs filesystem · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds, Carlos Maiolino
Relocate the function max_pow_of_two_factor() to common ilog2.h from the xfs code, as it will be used elsewhere. Also simplify the function, as advised by Mikulas Patocka. Signed-off-by: John Garry <john.g.garry@oracle.com> --- fs/xfs/xfs_mount.c | 5 ----- include/linux/log2.h | 14 ++++++++++++++ 2 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 29276fe60df9..6c669ae082d4 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c@@ -672,11 +672,6 @@ static inline xfs_extlen_t xfs_calc_atomic_write_max(struct xfs_mount *mp) return rounddown_pow_of_two(XFS_B_TO_FSB(mp, MAX_RW_COUNT)); } -static inline unsigned int max_pow_of_two_factor(const unsigned int nr) -{ - return 1 << (ffs(nr) - 1); -} - /* * If the data device advertises atomic write support, limit the size of data * device atomic writes to the greatest power-of-two factor of the AG size so
diff --git a/include/linux/log2.h b/include/linux/log2.h
index 1366cb688a6d..2eac3fc9303d 100644
--- a/include/linux/log2.h
+++ b/include/linux/log2.h@@ -255,4 +255,18 @@ int __bits_per(unsigned long n) ) : \ __bits_per(n) \ ) + +/** + * max_pow_of_two_factor - return highest power-of-2 factor + * @n: parameter + * + * find highest power-of-2 which is evenly divisible into n. + * 0 is returned for n == 0 or 1. + */ +static inline __attribute__((const)) +unsigned int max_pow_of_two_factor(unsigned int n) +{ + return n & -n; +} + #endif /* _LINUX_LOG2_H */
--
2.43.5