[PATCH 6/7] xfs: refactor non-power-of-two alignment checks

Darrick J. Wong
2024-03-27T01:52:34Z

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>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
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 64278f8acaeee..d1d4158441bd9 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 8f07c9f6157fb..ac355328121ac 100644
--- a/fs/xfs/xfs_linux.h
+++ b/fs/xfs/xfs_linux.h
@@ -198,6 +198,11 @@ 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)
{