[PATCH v2 6/7] exfat: advance valid_size while zeroing new ranges

[Chi Zhiling]

From: Chi Zhiling <chizhiling@xxxxxxxxxx>

valid_size is currently updated only after the range has been zeroed, so
it lags the folios that were just marked uptodate and dirty.

Advance it from exfat_zero_new_range() page by page, under the folio
lock and right after the folio is marked dirty.  exfat_extend_valid_size()
then only advances zeroed_size, and exfat_page_mkwrite() advances
valid_size once iomap_page_mkwrite() has returned the locked folio.

Signed-off-by: Chi Zhiling <chizhiling@xxxxxxxxxx>
---
 fs/exfat/file.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index 6bd2b6d28a82..d92997dc8eec 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -666,6 +666,7 @@ int exfat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 static int exfat_zero_new_range(struct inode *inode, loff_t start, loff_t end)
 {
 	struct address_space *mapping = inode->i_mapping;
+	struct exfat_inode_info *ei = EXFAT_I(inode);
 	loff_t next, pos = start;
 	struct folio *folio;
 	pgoff_t index;
@@ -683,6 +684,7 @@ static int exfat_zero_new_range(struct inode *inode, loff_t start, loff_t end)
 		folio_lock(folio);
 		if (folio->mapping == mapping) {
 			folio_mark_dirty(folio);
+			exfat_advance_valid_size(ei, next);
 			pos = next;
 		}
 		folio_unlock(folio);
@@ -732,7 +734,6 @@ static int exfat_extend_valid_size(struct inode *inode, loff_t new_valid_size)
 			return ret;
 		}
 
-		exfat_set_valid_size(ei, new_valid_size);
 		exfat_advance_zeroed_size(ei,
 				round_up(new_valid_size, i_blocksize(inode)));
 		mark_inode_dirty(inode);
@@ -925,7 +926,6 @@ static vm_fault_t exfat_page_mkwrite(struct vm_fault *vmf)
 		 */
 		exfat_advance_zeroed_size(ei,
 				round_up(new_valid_size, i_blocksize(inode)));
-		exfat_set_valid_size(ei, new_valid_size);
 		mark_inode_dirty(inode);
 	}
 
@@ -934,6 +934,9 @@ static vm_fault_t exfat_page_mkwrite(struct vm_fault *vmf)
 
 	filemap_invalidate_lock_shared(inode->i_mapping);
 	ret = iomap_page_mkwrite(vmf, &exfat_iomap_ops, NULL);
+	if (ret == VM_FAULT_LOCKED)
+		exfat_advance_valid_size(ei, new_valid_size);
+
 	filemap_invalidate_unlock_shared(inode->i_mapping);
 	sb_end_pagefault(inode->i_sb);
 	inode_unlock(inode);
-- 
2.53.0