[PATCH 07/25] xfs: refactor non-power-of-two alignment checks

Darrick J. Wong
2023-12-31T20:26:04Z

Create a helper function that can compute if a 64-bit number is an
integer multiple of a 32-bit number, where the 32-bit number is not
required to be an even power of two. This is needed for some new code
for the realtime device, where we can set 37k allocation units and then
have to remap them.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
fs/xfs/xfs_file.c | 12 +++---------
fs/xfs/xfs_linux.h | 5 +++++
2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 8ac3bc98e4369..fdbeb6c3fbc44 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -47,15 +47,9 @@ xfs_is_falloc_aligned(
{
unsigned int alloc_unit = xfs_inode_alloc_unitsize(ip);

- if (!is_power_of_2(alloc_unit)) {
- u32 mod;
-
- div_u64_rem(pos, alloc_unit, &mod);
- if (mod)
- return false;
- div_u64_rem(len, alloc_unit, &mod);
- return mod == 0;
- }
+ if (!is_power_of_2(alloc_unit))
+ return isaligned_64(pos, alloc_unit) &&
+ isaligned_64(len, alloc_unit);

return !((pos | len) & (alloc_unit - 1));
}
diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h
index c24e0d52bc04e..13511ff810d18 100644
--- a/fs/xfs/xfs_linux.h
+++ b/fs/xfs/xfs_linux.h
@@ -200,6 +200,11 @@ static inline uint64_t howmany_64(uint64_t x, uint32_t y)
return x;
}

+static inline bool isaligned_64(uint64_t x, uint32_t y)
+{
+ return do_div(x, y) == 0;
+}
+
/* If @b is a power of 2, return log2(b). Else return -1. */
static inline int8_t log2_if_power2(unsigned long b)
{