On Thu, Jul 29, 2021 at 5:25 AM Matthew Wilcox (Oracle)
<willy@xxxxxxxxxxxxx> wrote:
> Remove the restriction that inline data must start on a page boundary
> in a file. This allows, for example, the first 2KiB to be stored out
> of line and the trailing 30 bytes to be stored inline.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> ---
> v2:
> - Rebase on top of iomap: Support file tail packing v9
>
> fs/iomap/buffered-io.c | 34 ++++++++++++++++------------------
> 1 file changed, 16 insertions(+), 18 deletions(-)
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 66b733537c46..50f18985ed13 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -209,28 +209,26 @@ static int iomap_read_inline_data(struct inode *inode, struct page *page,
> struct iomap *iomap)
> {
> size_t size = i_size_read(inode) - iomap->offset;
> + size_t poff = offset_in_page(iomap->offset);
> void *addr;
>
> if (PageUptodate(page))
> - return 0;
> + return PAGE_SIZE - poff;
>
> - /* inline data must start page aligned in the file */
> - if (WARN_ON_ONCE(offset_in_page(iomap->offset)))
> - return -EIO;
Maybe add a WARN_ON_ONCE(size > PAGE_SIZE - poff) here?
> if (WARN_ON_ONCE(size > PAGE_SIZE -
> offset_in_page(iomap->inline_data)))
> return -EIO;
> if (WARN_ON_ONCE(size > iomap->length))
> return -EIO;
> - if (WARN_ON_ONCE(page_has_private(page)))
> - return -EIO;
> + if (poff > 0)
> + iomap_page_create(inode, page);
>
> - addr = kmap_atomic(page);
> + addr = kmap_atomic(page) + poff;
Maybe kmap_local_page?
> memcpy(addr, iomap->inline_data, size);
> - memset(addr + size, 0, PAGE_SIZE - size);
> + memset(addr + size, 0, PAGE_SIZE - poff - size);
> kunmap_atomic(addr);
> - SetPageUptodate(page);
> - return 0;
> + iomap_set_range_uptodate(page, poff, PAGE_SIZE - poff);
> + return PAGE_SIZE - poff;
> }
>
> static inline bool iomap_block_needs_zeroing(struct inode *inode,
> @@ -252,13 +250,8 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> unsigned poff, plen;
> sector_t sector;
>
> - if (iomap->type == IOMAP_INLINE) {
> - int ret = iomap_read_inline_data(inode, page, iomap);
> -
> - if (ret)
> - return ret;
> - return PAGE_SIZE;
> - }
> + if (iomap->type == IOMAP_INLINE)
> + return iomap_read_inline_data(inode, page, iomap);
>
> /* zero post-eof blocks as the page may be mapped */
> iop = iomap_page_create(inode, page);
> @@ -593,10 +586,15 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
> static int iomap_write_begin_inline(struct inode *inode,
> struct page *page, struct iomap *srcmap)
> {
> + int ret;
> +
> /* needs more work for the tailpacking case, disable for now */
> if (WARN_ON_ONCE(srcmap->offset != 0))
> return -EIO;
> - return iomap_read_inline_data(inode, page, srcmap);
> + ret = iomap_read_inline_data(inode, page, srcmap);
> + if (ret < 0)
> + return ret;
> + return 0;
> }
>
> static int
> --
> 2.30.2
>
Thanks,
Andreas
