On 2024/5/18 1:29, Darrick J. Wong wrote:
> On Fri, May 17, 2024 at 07:13:53PM +0800, Zhang Yi wrote:
>> From: Zhang Yi <yi.zhang@xxxxxxxxxx>
>>
>> iomap_truncate_page() always assumes the block size of the truncating
>> inode is i_blocksize(), this is not always true for some filesystems,
>> e.g. XFS does extent size alignment for realtime inodes. Drop this
>> assumption and pass the block size for zeroing into
>> iomap_truncate_page(), allow filesystems to indicate the correct block
>> size.
>>
>> Suggested-by: Dave Chinner <david@xxxxxxxxxxxxx>
>> Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
>> ---
>> fs/iomap/buffered-io.c | 13 +++++++++----
>> fs/xfs/xfs_iomap.c | 3 ++-
>> include/linux/iomap.h | 4 ++--
>> 3 files changed, 13 insertions(+), 7 deletions(-)
>>
>> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
>> index 0926d216a5af..a0a0ac2c659c 100644
>> --- a/fs/iomap/buffered-io.c
>> +++ b/fs/iomap/buffered-io.c
>> @@ -17,6 +17,7 @@
>> #include <linux/bio.h>
>> #include <linux/sched/signal.h>
>> #include <linux/migrate.h>
>> +#include <linux/math64.h>
>> #include "trace.h"
>>
>> #include "../internal.h"
>> @@ -1445,11 +1446,15 @@ iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
>> EXPORT_SYMBOL_GPL(iomap_zero_range);
>>
>> int
>> -iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
>> - const struct iomap_ops *ops)
>> +iomap_truncate_page(struct inode *inode, loff_t pos, unsigned int blocksize,
>> + bool *did_zero, const struct iomap_ops *ops)
>> {
>> - unsigned int blocksize = i_blocksize(inode);
>> - unsigned int off = pos & (blocksize - 1);
>> + unsigned int off;
>> +
>> + if (is_power_of_2(blocksize))
>> + off = pos & (blocksize - 1);
>> + else
>> + div_u64_rem(pos, blocksize, &off);
>
> I wish this was a helper in math64.h somewhere.
>
> static inline u32 rem_u64(u64 dividend, u32 divisor)
> {
> if (likely(is_power_of_2(divisor)))
> return dividend & (divisor - 1);
>
> return dividend % divisor;
> }
>
> That way we skip the second division in div_u64_rem entirely, and the
> iomap/dax code becomes:
>
> unsigned int off = rem_u64(pos, blocksize); /* pos in block */
>
> Otherwise this looks like a straightforward mechanical change to me.
>
Yeah, we do need this helper.
Thanks,
Yi.
>
>>
>> /* Block boundary? Nothing to do */
>> if (!off)
>> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
>> index 2857ef1b0272..31ac07bb8425 100644
>> --- a/fs/xfs/xfs_iomap.c
>> +++ b/fs/xfs/xfs_iomap.c
>> @@ -1467,10 +1467,11 @@ xfs_truncate_page(
>> bool *did_zero)
>> {
>> struct inode *inode = VFS_I(ip);
>> + unsigned int blocksize = i_blocksize(inode);
>>
>> if (IS_DAX(inode))
>> return dax_truncate_page(inode, pos, did_zero,
>> &xfs_dax_write_iomap_ops);
>> - return iomap_truncate_page(inode, pos, did_zero,
>> + return iomap_truncate_page(inode, pos, blocksize, did_zero,
>> &xfs_buffered_write_iomap_ops);
>> }
>> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
>> index 6fc1c858013d..d67bf86ec582 100644
>> --- a/include/linux/iomap.h
>> +++ b/include/linux/iomap.h
>> @@ -273,8 +273,8 @@ int iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
>> const struct iomap_ops *ops);
>> int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len,
>> bool *did_zero, const struct iomap_ops *ops);
>> -int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
>> - const struct iomap_ops *ops);
>> +int iomap_truncate_page(struct inode *inode, loff_t pos, unsigned int blocksize,
>> + bool *did_zero, const struct iomap_ops *ops);
>> vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf,
>> const struct iomap_ops *ops);
>> int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
>> --
>> 2.39.2
>>
>>
