Re: [PATCH] iomap: Switch to offset_in_page for clarity

From: Darrick J. Wong
Date: Fri Aug 10 2018 - 14:45:44 EST


[add linux-xfs to cc]

On Fri, Aug 10, 2018 at 04:56:27PM +0200, Andreas Gruenbacher wrote:
> Instead of open-coding pos & (PAGE_SIZE - 1) and pos & ~PAGE_MASK, use
> the offset_in_page macro.
>
> Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>

Looks ok, will test...
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>

--D

> ---
> fs/iomap.c | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/fs/iomap.c b/fs/iomap.c
> index 13cdcf33e6c0..ae317ac7e925 100644
> --- a/fs/iomap.c
> +++ b/fs/iomap.c
> @@ -150,7 +150,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> {
> struct iomap_readpage_ctx *ctx = data;
> struct page *page = ctx->cur_page;
> - unsigned poff = pos & (PAGE_SIZE - 1);
> + unsigned poff = offset_in_page(pos);
> unsigned plen = min_t(loff_t, PAGE_SIZE - poff, length);
> bool is_contig = false;
> sector_t sector;
> @@ -280,7 +280,7 @@ iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length,
> loff_t done, ret;
>
> for (done = 0; done < length; done += ret) {
> - if (ctx->cur_page && ((pos + done) & (PAGE_SIZE - 1)) == 0) {
> + if (ctx->cur_page && offset_in_page(pos + done) == 0) {
> if (!ctx->cur_page_in_bio)
> unlock_page(ctx->cur_page);
> put_page(ctx->cur_page);
> @@ -382,9 +382,9 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len,
> loff_t block_size = i_blocksize(inode);
> loff_t block_start = pos & ~(block_size - 1);
> loff_t block_end = (pos + len + block_size - 1) & ~(block_size - 1);
> - unsigned poff = block_start & (PAGE_SIZE - 1);
> + unsigned poff = offset_in_page(block_start);
> unsigned plen = min_t(loff_t, PAGE_SIZE - poff, block_end - block_start);
> - unsigned from = pos & (PAGE_SIZE - 1), to = from + len;
> + unsigned from = offset_in_page(pos), to = from + len;
>
> WARN_ON_ONCE(i_blocksize(inode) < PAGE_SIZE);
>
> @@ -538,7 +538,7 @@ iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> unsigned long bytes; /* Bytes to write to page */
> size_t copied; /* Bytes copied from user */
>
> - offset = (pos & (PAGE_SIZE - 1));
> + offset = offset_in_page(pos);
> bytes = min_t(unsigned long, PAGE_SIZE - offset,
> iov_iter_count(i));
> again:
> @@ -652,7 +652,7 @@ iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> unsigned long offset; /* Offset into pagecache page */
> unsigned long bytes; /* Bytes to write to page */
>
> - offset = (pos & (PAGE_SIZE - 1));
> + offset = offset_in_page(pos);
> bytes = min_t(loff_t, PAGE_SIZE - offset, length);
>
> rpage = __iomap_read_page(inode, pos);
> @@ -744,7 +744,7 @@ iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
> do {
> unsigned offset, bytes;
>
> - offset = pos & (PAGE_SIZE - 1); /* Within page */
> + offset = offset_in_page(pos);
> bytes = min_t(loff_t, PAGE_SIZE - offset, count);
>
> if (IS_DAX(inode))
> @@ -837,7 +837,7 @@ int iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
>
> /* page is wholly or partially inside EOF */
> if (((page->index + 1) << PAGE_SHIFT) > size)
> - length = size & ~PAGE_MASK;
> + length = offset_in_page(size);
> else
> length = PAGE_SIZE;
>
> @@ -1000,7 +1000,7 @@ page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff,
> goto out_unlock_not_found;
>
> for (off = 0; off < PAGE_SIZE; off += bsize) {
> - if ((*lastoff & ~PAGE_MASK) >= off + bsize)
> + if (offset_in_page(*lastoff) >= off + bsize)
> continue;
> if (ops->is_partially_uptodate(page, off, bsize) == seek_data) {
> unlock_page(page);
> --
> 2.17.1
>