[RFCv5 3/5] iomap: Add iop's uptodate state handling functions

["Ritesh Harjani (IBM)" <ritesh.list@gmail.com>]

Firstly this patch renames iop->uptodate to iop->state bitmap.
This is because we will add dirty state to iop->state bitmap in later
patches. So it makes sense to rename the iop->uptodate bitmap to
iop->state.

Secondly this patch also adds other helpers for uptodate state bitmap
handling of iop->state.

No functionality change in this patch.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
 fs/iomap/buffered-io.c | 78 +++++++++++++++++++++++++++++++-----------
 1 file changed, 58 insertions(+), 20 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index e732581dc2d4..5103b644e115 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 +43,47 @@ static inline struct iomap_page *to_iomap_page(struct folio *folio)
 
 static struct bio_set iomap_ioend_bioset;
 
+/*
+ * inline helpers for bitmap operations on iop->state
+ */
+static inline void iop_set_range(struct iomap_page *iop, unsigned int start_blk,
+				 unsigned int nr_blks)
+{
+	bitmap_set(iop->state, start_blk, nr_blks);
+}
+
+static inline bool iop_test_block(struct iomap_page *iop, unsigned int block)
+{
+	return test_bit(block, iop->state);
+}
+
+static inline bool iop_bitmap_full(struct iomap_page *iop,
+				   unsigned int blks_per_folio)
+{
+	return bitmap_full(iop->state, blks_per_folio);
+}
+
+/*
+ * iop related helpers for checking uptodate/dirty state of per-block
+ * or range of blocks within a folio
+ */
+static bool iop_test_full_uptodate(struct folio *folio)
+{
+	struct iomap_page *iop = to_iomap_page(folio);
+	struct inode *inode = folio->mapping->host;
+
+	WARN_ON(!iop);
+	return iop_bitmap_full(iop, i_blocks_per_folio(inode, folio));
+}
+
+static bool iop_test_block_uptodate(struct folio *folio, unsigned int block)
+{
+	struct iomap_page *iop = to_iomap_page(folio);
+
+	WARN_ON(!iop);
+	return iop_test_block(iop, block);
+}
+
 static void iop_set_range_uptodate(struct inode *inode, struct folio *folio,
 				   size_t off, size_t len)
 {
@@ -53,12 +94,11 @@ static void iop_set_range_uptodate(struct inode *inode, struct folio *folio,
 	unsigned long flags;
 
 	if (iop) {
-		spin_lock_irqsave(&iop->uptodate_lock, flags);
-		bitmap_set(iop->uptodate, first_blk, nr_blks);
-		if (bitmap_full(iop->uptodate,
-				i_blocks_per_folio(inode, folio)))
+		spin_lock_irqsave(&iop->state_lock, flags);
+		iop_set_range(iop, first_blk, nr_blks);
+		if (iop_test_full_uptodate(folio))
 			folio_mark_uptodate(folio);
-		spin_unlock_irqrestore(&iop->uptodate_lock, flags);
+		spin_unlock_irqrestore(&iop->state_lock, flags);
 	} else {
 		folio_mark_uptodate(folio);
 	}
@@ -79,12 +119,12 @@ static struct iomap_page *iop_alloc(struct inode *inode, struct folio *folio,
 	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);
+			iop_set_range(iop, 0, nr_blocks);
 		folio_attach_private(folio, iop);
 	}
 	return iop;
@@ -93,15 +133,13 @@ static struct iomap_page *iop_alloc(struct inode *inode, struct folio *folio,
 static void 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) !=
-			folio_test_uptodate(folio));
+	WARN_ON_ONCE(iop_test_full_uptodate(folio) !=
+		     folio_test_uptodate(folio));
 	folio_detach_private(folio);
 	kfree(iop);
 }
@@ -132,7 +170,7 @@ 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;
@@ -142,7 +180,7 @@ 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;
@@ -450,7 +488,7 @@ 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;
 }
@@ -1634,7 +1672,7 @@ 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);
-- 
2.39.2