diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index d42f01e0fc1c..e59c08c0e529 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1593,12 +1593,24 @@ iomap_finish_ioends(struct iomap_ioend *ioend, int error)
 }
 EXPORT_SYMBOL_GPL(iomap_finish_ioends);
 
+/*
+ * Calculate the physical size of an ioend by rounding up to block granularity.
+ * io_size might be unaligned if the last block crossed an unaligned i_size
+ * boundary at creation time.
+ */
+static inline size_t iomap_ioend_size_aligned(struct iomap_ioend *ioend)
+{
+	return round_up(ioend->io_size, i_blocksize(ioend->io_inode));
+}
+
 /*
  * We can merge two adjacent ioends if they have the same set of work to do.
  */
 static bool
 iomap_ioend_can_merge(struct iomap_ioend *ioend, struct iomap_ioend *next)
 {
+	size_t size = iomap_ioend_size_aligned(ioend);
+
 	if (ioend->io_bio.bi_status != next->io_bio.bi_status)
 		return false;
 	if (next->io_flags & IOMAP_F_BOUNDARY)
@@ -1609,7 +1621,7 @@ iomap_ioend_can_merge(struct iomap_ioend *ioend, struct iomap_ioend *next)
 	if ((ioend->io_type == IOMAP_UNWRITTEN) ^
 	    (next->io_type == IOMAP_UNWRITTEN))
 		return false;
-	if (ioend->io_offset + ioend->io_size != next->io_offset)
+	if (ioend->io_offset + size != next->io_offset)
 		return false;
 	/*
 	 * Do not merge physically discontiguous ioends. The filesystem
@@ -1621,7 +1633,7 @@ iomap_ioend_can_merge(struct iomap_ioend *ioend, struct iomap_ioend *next)
 	 * submission so does not point to the start sector of the bio at
 	 * completion.
 	 */
-	if (ioend->io_sector + (ioend->io_size >> 9) != next->io_sector)
+	if (ioend->io_sector + (size >> 9) != next->io_sector)
 		return false;
 	return true;
 }
@@ -1638,7 +1650,8 @@ iomap_ioend_try_merge(struct iomap_ioend *ioend, struct list_head *more_ioends)
 		if (!iomap_ioend_can_merge(ioend, next))
 			break;
 		list_move_tail(&next->io_list, &ioend->io_list);
-		ioend->io_size += next->io_size;
+		ioend->io_size = iomap_ioend_size_aligned(ioend) +
+					next->io_size;
 	}
 }
 EXPORT_SYMBOL_GPL(iomap_ioend_try_merge);
@@ -1742,7 +1755,7 @@ static bool iomap_can_add_to_ioend(struct iomap_writepage_ctx *wpc, loff_t pos)
 		return false;
 	if (wpc->iomap.type != wpc->ioend->io_type)
 		return false;
-	if (pos != wpc->ioend->io_offset + wpc->ioend->io_size)
+	if (pos != wpc->ioend->io_offset + iomap_ioend_size_aligned(wpc->ioend))
 		return false;
 	if (iomap_sector(&wpc->iomap, pos) !=
 	    bio_end_sector(&wpc->ioend->io_bio))
@@ -1774,6 +1787,8 @@ static int iomap_add_to_ioend(struct iomap_writepage_ctx *wpc,
 {
 	struct iomap_folio_state *ifs = folio->private;
 	size_t poff = offset_in_folio(folio, pos);
+	loff_t isize = i_size_read(inode);
+	struct iomap_ioend *ioend;
 	int error;
 
 	if (!wpc->ioend || !iomap_can_add_to_ioend(wpc, pos)) {
@@ -1784,12 +1799,22 @@ static int iomap_add_to_ioend(struct iomap_writepage_ctx *wpc,
 		wpc->ioend = iomap_alloc_ioend(wpc, wbc, inode, pos);
 	}
 
-	if (!bio_add_folio(&wpc->ioend->io_bio, folio, len, poff))
+	ioend = wpc->ioend;
+	if (!bio_add_folio(&ioend->io_bio, folio, len, poff))
 		goto new_ioend;
 
 	if (ifs)
 		atomic_add(len, &ifs->write_bytes_pending);
-	wpc->ioend->io_size += len;
+
+	/*
+	 * If the ioend spans i_size, trim io_size to the former to provide
+	 * the fs with more accurate size information. This is useful for
+	 * completion time on-disk size updates.
+	 */
+	ioend->io_size = iomap_ioend_size_aligned(ioend) + len;
+	if (ioend->io_offset + ioend->io_size > isize)
+		ioend->io_size = isize - ioend->io_offset;
+
 	wbc_account_cgroup_owner(wbc, folio, len);
 	return 0;
 }
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 5675af6b740c..75bf54e76f3b 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -335,7 +335,7 @@ struct iomap_ioend {
 	u16			io_type;
 	u16			io_flags;	/* IOMAP_F_* */
 	struct inode		*io_inode;	/* file being written to */
-	size_t			io_size;	/* size of the extent */
+	size_t			io_size;	/* size of data within eof */
 	loff_t			io_offset;	/* offset in the file */
 	sector_t		io_sector;	/* start sector of ioend */
 	struct bio		io_bio;		/* MUST BE LAST! */
