[RFC PATCH v4 4/8] fsdax: pass blocksize to dax_truncate_page()

[Zhang Yi]

From: Zhang Yi <yi.zhang@xxxxxxxxxx>

dax_truncate_page() always assumes the block size of the truncating
inode is i_blocksize(), this is not always true for some filesystems,
e.g. XFS does extent size alignment for realtime inodes. Drop this
assumption and pass the block size for zeroing into dax_truncate_page(),
allow filesystems to indicate the correct block size.

Suggested-by: Dave Chinner <david@xxxxxxxxxxxxx>
Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
---
 fs/dax.c            | 8 ++++----
 fs/ext2/inode.c     | 4 ++--
 fs/xfs/xfs_iomap.c  | 2 +-
 include/linux/dax.h | 4 ++--
 4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index becb4a6920c6..4cbd94fd96ed 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -25,6 +25,7 @@
 #include <linux/mmu_notifier.h>
 #include <linux/iomap.h>
 #include <linux/rmap.h>
+#include <linux/math64.h>
 #include <asm/pgalloc.h>
 
 #define CREATE_TRACE_POINTS
@@ -1403,11 +1404,10 @@ int dax_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
 }
 EXPORT_SYMBOL_GPL(dax_zero_range);
 
-int dax_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
-		const struct iomap_ops *ops)
+int dax_truncate_page(struct inode *inode, loff_t pos, unsigned int blocksize,
+		bool *did_zero, const struct iomap_ops *ops)
 {
-	unsigned int blocksize = i_blocksize(inode);
-	unsigned int off = pos & (blocksize - 1);
+	unsigned int off = rem_u64(pos, blocksize);
 
 	/* Block boundary? Nothing to do */
 	if (!off)
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 0caa1650cee8..337349c94adf 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1276,8 +1276,8 @@ static int ext2_setsize(struct inode *inode, loff_t newsize)
 	inode_dio_wait(inode);
 
 	if (IS_DAX(inode))
-		error = dax_truncate_page(inode, newsize, NULL,
-					  &ext2_iomap_ops);
+		error = dax_truncate_page(inode, newsize, i_blocksize(inode),
+					  NULL, &ext2_iomap_ops);
 	else
 		error = block_truncate_page(inode->i_mapping,
 				newsize, ext2_get_block);
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 32306804b01b..8cdfcbb5baa7 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -1474,7 +1474,7 @@ xfs_truncate_page(
 	unsigned int		blocksize = i_blocksize(inode);
 
 	if (IS_DAX(inode))
-		return dax_truncate_page(inode, pos, did_zero,
+		return dax_truncate_page(inode, pos, blocksize, did_zero,
 					&xfs_dax_write_iomap_ops);
 	return iomap_truncate_page(inode, pos, blocksize, did_zero,
 				   &xfs_buffered_write_iomap_ops);
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 9d3e3327af4c..4aa8ef7c8fd4 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -210,8 +210,8 @@ int dax_file_unshare(struct inode *inode, loff_t pos, loff_t len,
 		const struct iomap_ops *ops);
 int dax_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
 		const struct iomap_ops *ops);
-int dax_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
-		const struct iomap_ops *ops);
+int dax_truncate_page(struct inode *inode, loff_t pos, unsigned int blocksize,
+		bool *did_zero, const struct iomap_ops *ops);
 
 #if IS_ENABLED(CONFIG_DAX)
 int dax_read_lock(void);
-- 
2.39.2