Re: [PATCHv7 3/6] iomap: Refactor some iop related accessor functions

Andreas Gruenbacher
2023-06-05T14:17:08Z

On Mon, Jun 5, 2023 at 12:55 PM Ritesh Harjani (IBM)
<ritesh.list@gmail.com> wrote:
> We would eventually use iomap_iop_** function naming by the rest of the
> buffered-io iomap code. This patch update function arguments and naming
> from iomap_set_range_uptodate() -> iomap_iop_set_range_uptodate().
> iop_set_range_uptodate() then becomes an accessor function used by
> iomap_iop_** functions.
>
> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
> ---
> fs/iomap/buffered-io.c | 111 +++++++++++++++++++++++------------------
> 1 file changed, 63 insertions(+), 48 deletions(-)
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 6fffda355c45..136f57ccd0be 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -24,14 +24,14 @@
> #define IOEND_BATCH_SIZE 4096
>
> /*
> - * Structure allocated for each folio when block size < folio size
> - * to track sub-folio uptodate status and I/O completions.
> + * Structure allocated for each folio to track per-block uptodate state
> + * and I/O completions.
> */
> struct iomap_page {
> atomic_t read_bytes_pending;
> atomic_t write_bytes_pending;
> - spinlock_t uptodate_lock;
> - unsigned long uptodate[];
> + spinlock_t state_lock;
> + unsigned long state[];
> };
>
> static inline struct iomap_page *to_iomap_page(struct folio *folio)
> @@ -43,6 +43,48 @@ static inline struct iomap_page *to_iomap_page(struct folio *folio)
>
> static struct bio_set iomap_ioend_bioset;
>
> +static bool iop_test_full_uptodate(struct folio *folio)
> +{
> + struct iomap_page *iop = to_iomap_page(folio);
> + struct inode *inode = folio->mapping->host;
> +
> + return bitmap_full(iop->state, i_blocks_per_folio(inode, folio));
> +}

Can this be called iop_test_fully_uptodate(), please?

> +
> +static bool iop_test_block_uptodate(struct folio *folio, unsigned int block)
> +{
> + struct iomap_page *iop = to_iomap_page(folio);
> +
> + return test_bit(block, iop->state);
> +}
> +
> +static void iop_set_range_uptodate(struct inode *inode, struct folio *folio,
> + size_t off, size_t len)
> +{
> + struct iomap_page *iop = to_iomap_page(folio);

Note that to_iomap_page() does folio_test_private() followed by
folio_get_private(), which doesn't really make sense in places where
we know that iop is defined. Maybe we want to split that up.

> + unsigned int first_blk = off >> inode->i_blkbits;
> + unsigned int last_blk = (off + len - 1) >> inode->i_blkbits;
> + unsigned int nr_blks = last_blk - first_blk + 1;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&iop->state_lock, flags);
> + bitmap_set(iop->state, first_blk, nr_blks);
> + if (iop_test_full_uptodate(folio))
> + folio_mark_uptodate(folio);
> + spin_unlock_irqrestore(&iop->state_lock, flags);
> +}
> +
> +static void iomap_iop_set_range_uptodate(struct inode *inode,
> + struct folio *folio, size_t off, size_t len)
> +{
> + struct iomap_page *iop = to_iomap_page(folio);
> +
> + if (iop)
> + iop_set_range_uptodate(inode, folio, off, len);
> + else
> + folio_mark_uptodate(folio);
> +}

This patch passes the inode into iomap_iop_set_range_uptodate() and
removes the iop argument. Can this be done in a separate patch,
please?

We have a few places like the above, where we look up the iop without
using it. Would a function like folio_has_iop() make more sense?

> +
> static struct iomap_page *iomap_iop_alloc(struct inode *inode,
> struct folio *folio, unsigned int flags)
> {
> @@ -58,12 +100,12 @@ static struct iomap_page *iomap_iop_alloc(struct inode *inode,
> else
> gfp = GFP_NOFS | __GFP_NOFAIL;
>
> - iop = kzalloc(struct_size(iop, uptodate, BITS_TO_LONGS(nr_blocks)),
> + iop = kzalloc(struct_size(iop, state, BITS_TO_LONGS(nr_blocks)),
> gfp);
> if (iop) {
> - spin_lock_init(&iop->uptodate_lock);
> + spin_lock_init(&iop->state_lock);
> if (folio_test_uptodate(folio))
> - bitmap_fill(iop->uptodate, nr_blocks);
> + bitmap_fill(iop->state, nr_blocks);
> folio_attach_private(folio, iop);
> }
> return iop;
> @@ -72,14 +114,12 @@ static struct iomap_page *iomap_iop_alloc(struct inode *inode,
> static void iomap_iop_free(struct folio *folio)
> {
> struct iomap_page *iop = to_iomap_page(folio);
> - struct inode *inode = folio->mapping->host;
> - unsigned int nr_blocks = i_blocks_per_folio(inode, folio);
>
> if (!iop)
> return;
> WARN_ON_ONCE(atomic_read(&iop->read_bytes_pending));
> WARN_ON_ONCE(atomic_read(&iop->write_bytes_pending));
> - WARN_ON_ONCE(bitmap_full(iop->uptodate, nr_blocks) !=
> + WARN_ON_ONCE(iop_test_full_uptodate(folio) !=
> folio_test_uptodate(folio));
> folio_detach_private(folio);
> kfree(iop);
> @@ -111,7 +151,7 @@ static void iomap_adjust_read_range(struct inode *inode, struct folio *folio,
>
> /* move forward for each leading block marked uptodate */
> for (i = first; i <= last; i++) {
> - if (!test_bit(i, iop->uptodate))
> + if (!iop_test_block_uptodate(folio, i))
> break;
> *pos += block_size;
> poff += block_size;
> @@ -121,7 +161,7 @@ static void iomap_adjust_read_range(struct inode *inode, struct folio *folio,
>
> /* truncate len if we find any trailing uptodate block(s) */
> for ( ; i <= last; i++) {
> - if (test_bit(i, iop->uptodate)) {
> + if (iop_test_block_uptodate(folio, i)) {
> plen -= (last - i + 1) * block_size;
> last = i - 1;
> break;
> @@ -145,30 +185,6 @@ static void iomap_adjust_read_range(struct inode *inode, struct folio *folio,
> *lenp = plen;
> }
>
> -static void iomap_iop_set_range_uptodate(struct folio *folio,
> - struct iomap_page *iop, size_t off, size_t len)
> -{
> - struct inode *inode = folio->mapping->host;
> - unsigned first = off >> inode->i_blkbits;
> - unsigned last = (off + len - 1) >> inode->i_blkbits;
> - unsigned long flags;
> -
> - spin_lock_irqsave(&iop->uptodate_lock, flags);
> - bitmap_set(iop->uptodate, first, last - first + 1);
> - if (bitmap_full(iop->uptodate, i_blocks_per_folio(inode, folio)))
> - folio_mark_uptodate(folio);
> - spin_unlock_irqrestore(&iop->uptodate_lock, flags);
> -}
> -
> -static void iomap_set_range_uptodate(struct folio *folio,
> - struct iomap_page *iop, size_t off, size_t len)
> -{
> - if (iop)
> - iomap_iop_set_range_uptodate(folio, iop, off, len);
> - else
> - folio_mark_uptodate(folio);
> -}
> -
> static void iomap_finish_folio_read(struct folio *folio, size_t offset,
> size_t len, int error)
> {
> @@ -178,7 +194,8 @@ static void iomap_finish_folio_read(struct folio *folio, size_t offset,
> folio_clear_uptodate(folio);
> folio_set_error(folio);
> } else {
> - iomap_set_range_uptodate(folio, iop, offset, len);
> + iomap_iop_set_range_uptodate(folio->mapping->host, folio,
> + offset, len);
> }
>
> if (!iop || atomic_sub_and_test(len, &iop->read_bytes_pending))
> @@ -214,7 +231,6 @@ struct iomap_readpage_ctx {
> static int iomap_read_inline_data(const struct iomap_iter *iter,
> struct folio *folio)
> {
> - struct iomap_page *iop;
> const struct iomap *iomap = iomap_iter_srcmap(iter);
> size_t size = i_size_read(iter->inode) - iomap->offset;
> size_t poff = offset_in_page(iomap->offset);
> @@ -232,15 +248,14 @@ static int iomap_read_inline_data(const struct iomap_iter *iter,
> if (WARN_ON_ONCE(size > iomap->length))
> return -EIO;
> if (offset > 0)
> - iop = iomap_iop_alloc(iter->inode, folio, iter->flags);
> - else
> - iop = to_iomap_page(folio);
> + iomap_iop_alloc(iter->inode, folio, iter->flags);
>
> addr = kmap_local_folio(folio, offset);
> memcpy(addr, iomap->inline_data, size);
> memset(addr + size, 0, PAGE_SIZE - poff - size);
> kunmap_local(addr);
> - iomap_set_range_uptodate(folio, iop, offset, PAGE_SIZE - poff);
> + iomap_iop_set_range_uptodate(iter->inode, folio, offset,
> + PAGE_SIZE - poff);
> return 0;
> }
>
> @@ -277,7 +292,7 @@ static loff_t iomap_readpage_iter(const struct iomap_iter *iter,
>
> if (iomap_block_needs_zeroing(iter, pos)) {
> folio_zero_range(folio, poff, plen);
> - iomap_set_range_uptodate(folio, iop, poff, plen);
> + iomap_iop_set_range_uptodate(iter->inode, folio, poff, plen);
> goto done;
> }
>
> @@ -452,7 +467,7 @@ bool iomap_is_partially_uptodate(struct folio *folio, size_t from, size_t count)
> last = (from + count - 1) >> inode->i_blkbits;
>
> for (i = first; i <= last; i++)
> - if (!test_bit(i, iop->uptodate))
> + if (!iop_test_block_uptodate(folio, i))
> return false;
> return true;
> }
> @@ -591,7 +606,7 @@ static int __iomap_write_begin(const struct iomap_iter *iter, loff_t pos,
> if (status)
> return status;
> }
> - iomap_set_range_uptodate(folio, iop, poff, plen);
> + iomap_iop_set_range_uptodate(iter->inode, folio, poff, plen);
> } while ((block_start += plen) < block_end);
>
> return 0;
> @@ -698,7 +713,6 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
> static size_t __iomap_write_end(struct inode *inode, loff_t pos, size_t len,
> size_t copied, struct folio *folio)
> {
> - struct iomap_page *iop = to_iomap_page(folio);
> flush_dcache_folio(folio);
>
> /*
> @@ -714,7 +728,8 @@ static size_t __iomap_write_end(struct inode *inode, loff_t pos, size_t len,
> */
> if (unlikely(copied < len && !folio_test_uptodate(folio)))
> return 0;
> - iomap_set_range_uptodate(folio, iop, offset_in_folio(folio, pos), len);
> + iomap_iop_set_range_uptodate(inode, folio, offset_in_folio(folio, pos),
> + len);
> filemap_dirty_folio(inode->i_mapping, folio);
> return copied;
> }
> @@ -1630,7 +1645,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
> * invalid, grab a new one.
> */
> for (i = 0; i < nblocks && pos < end_pos; i++, pos += len) {
> - if (iop && !test_bit(i, iop->uptodate))
> + if (iop && !iop_test_block_uptodate(folio, i))
> continue;
>
> error = wpc->ops->map_blocks(wpc, inode, pos);
> --
> 2.40.1
>

Thanks,
Andreas