On Tue, May 11, 2021 at 03:56:08PM +0100, Matthew Wilcox (Oracle) wrote:
> Some filesystems (eg AFS) need a valid file pointer for their ->readpage
> operation. Presumably none of them currently support deduplication,
> but it's just as easy to pass the struct file around as it is to pass
> the struct inode around, and it sets a good example for other users.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> ---
> fs/remap_range.c | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/fs/remap_range.c b/fs/remap_range.c
> index e4a5fdd7ad7b..982ba89aeeb6 100644
> --- a/fs/remap_range.c
> +++ b/fs/remap_range.c
> @@ -158,11 +158,11 @@ static int generic_remap_check_len(struct inode *inode_in,
> }
>
> /* Read a page's worth of file data into the page cache. */
> -static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
> +static struct page *vfs_dedupe_get_page(struct file *file, loff_t offset)
> {
> struct page *page;
>
> - page = read_mapping_page(inode->i_mapping, offset >> PAGE_SHIFT, NULL);
> + page = read_mapping_page(file->f_mapping, offset >> PAGE_SHIFT, file);
> if (IS_ERR(page))
> return page;
> if (!PageUptodate(page)) {
> @@ -199,8 +199,8 @@ static void vfs_unlock_two_pages(struct page *page1, struct page *page2)
> * Compare extents of two files to see if they are the same.
> * Caller must have locked both inodes to prevent write races.
> */
> -static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> - struct inode *dest, loff_t destoff,
> +static int vfs_dedupe_file_range_compare(struct file *src, loff_t srcoff,
> + struct file *dst, loff_t destoff,
I kinda wish you'd maintained the name pairing here. Why does destoff
go with dst instead of dst/dstoff or dest/destoff?
FWIW I try to vary the name lengths for similar variables these days,
because while my eyes are /fairly/ quick to distingiush 's' and 'd',
they're even faster if the width of the entire word is different.
(And yes, I had to break myself of the 'columns-must-line-up' habit.)
Using this method I've caught a few stupid variable name mixups in the
exchange-range code by doing a quick scan while ld takes an eternity to
link vmlinux together.
That aside, passing file pointers in seems like a good idea to me.
--D
> loff_t len, bool *is_same)
> {
> loff_t src_poff;
> @@ -229,7 +229,7 @@ static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> error = PTR_ERR(src_page);
> goto out_error;
> }
> - dest_page = vfs_dedupe_get_page(dest, destoff);
> + dest_page = vfs_dedupe_get_page(dst, destoff);
> if (IS_ERR(dest_page)) {
> error = PTR_ERR(dest_page);
> put_page(src_page);
> @@ -244,8 +244,8 @@ static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> * someone is invalidating pages on us and we lose.
> */
> if (!PageUptodate(src_page) || !PageUptodate(dest_page) ||
> - src_page->mapping != src->i_mapping ||
> - dest_page->mapping != dest->i_mapping) {
> + src_page->mapping != src->f_mapping ||
> + dest_page->mapping != dst->f_mapping) {
> same = false;
> goto unlock;
> }
> @@ -351,8 +351,8 @@ int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> if (remap_flags & REMAP_FILE_DEDUP) {
> bool is_same = false;
>
> - ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
> - inode_out, pos_out, *len, &is_same);
> + ret = vfs_dedupe_file_range_compare(file_in, pos_in,
> + file_out, pos_out, *len, &is_same);
> if (ret)
> return ret;
> if (!is_same)
> --
> 2.30.2
>
