[PATCH v2 2/7] 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_prepare_valid_range() page by page, under the folio
lock and right after each folio is marked dirty; the same helper advances
zeroed_size and dirties the inode once the range is prepared.

Signed-off-by: Chi Zhiling <chizhiling@xxxxxxxxxx>
---
 fs/exfat/file.c | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index dc6df0b73373..6f7b50c7a075 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -724,6 +724,7 @@ static int exfat_prepare_valid_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;
@@ -744,12 +745,21 @@ static int exfat_prepare_valid_range(struct inode *inode, loff_t start,
 		folio_lock(folio);
 		if (folio->mapping == mapping) {
 			folio_mark_dirty(folio);
+			exfat_advance_valid_size(ei, next);
 			pos = next;
 		}
 		folio_unlock(folio);
 		folio_put(folio);
 	}
 
+	/*
+	 * Track zeroed_size by block, not page, because writeback stops
+	 * at i_size recording blocks wholly beyond it could skip a
+	 * later required zeroing.
+	 */
+	exfat_advance_zeroed_size(ei, round_up(next, i_blocksize(inode)));
+	mark_inode_dirty(inode);
+
 	return 0;
 }
 
@@ -794,11 +804,6 @@ static int exfat_extend_valid_size(struct inode *inode, loff_t new_valid_size)
 			filemap_invalidate_unlock(inode->i_mapping);
 			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);
 	}
 
 	return ret;
@@ -962,6 +967,7 @@ static vm_fault_t exfat_page_mkwrite(struct vm_fault *vmf)
 	struct exfat_inode_info *ei = EXFAT_I(inode);
 	vm_fault_t ret;
 	loff_t new_valid_size, mmap_valid_size, fault_page_start;
+	bool dirty = false;
 
 	if (!inode_trylock(inode))
 		return VM_FAULT_RETRY;
@@ -988,16 +994,7 @@ static vm_fault_t exfat_page_mkwrite(struct vm_fault *vmf)
 				return vmf_fs_error(err);
 			}
 		}
-
-		/*
-		 * Track zeroed_size by block, not page, because writeback stops
-		 * at i_size recording blocks wholly beyond it could skip a
-		 * later required zeroing.
-		 */
-		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);
+		dirty = true;
 	}
 
 	sb_start_pagefault(inode->i_sb);
@@ -1005,6 +1002,13 @@ 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 && dirty) {
+		exfat_advance_valid_size(ei, new_valid_size);
+		exfat_advance_zeroed_size(ei,
+				round_up(new_valid_size, i_blocksize(inode)));
+		mark_inode_dirty(inode);
+	}
+
 	filemap_invalidate_unlock_shared(inode->i_mapping);
 	sb_end_pagefault(inode->i_sb);
 	inode_unlock(inode);
-- 
2.53.0