[PATCH v2 2/4] exfat: hold the invalidate lock while truncating

[Chi Zhiling <chizhiling@163.com>]

From: Chi Zhiling <chizhiling@kylinos.cn>

truncate_setsize() ends in truncate_inode_pages(), which is documented
as being "Called under (and serialised by) inode->i_rwsem and
mapping->invalidate_lock".

Hold invalidate_lock while executing truncate_setsize() to ensure that
truncate and mmap writes are mutually exclusive. This can simplify the
handling in exfat_page_mkwrite().

Signed-off-by: Chi Zhiling <chizhiling@kylinos.cn>
---
 fs/exfat/file.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index b30aec858da6..81eeb76ef94b 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -413,6 +413,7 @@ int exfat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		 * about to be freed.
 		 */
 		inode_dio_wait(inode);
+		filemap_invalidate_lock(inode->i_mapping);
 		truncate_setsize(inode, attr->ia_size);
 
 		/*
@@ -420,6 +421,7 @@ int exfat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		 * is already written by it, so mark_inode_dirty() is unneeded.
 		 */
 		exfat_truncate(inode);
+		filemap_invalidate_unlock(inode->i_mapping);
 	} else
 		mark_inode_dirty(inode);
 
@@ -784,8 +786,10 @@ static int exfat_extend_valid_size(struct inode *inode, loff_t new_valid_size)
 		ret = exfat_zero_new_range(inode, gap_start, new_valid_size);
 		filemap_invalidate_unlock(inode->i_mapping);
 		if (ret) {
+			filemap_invalidate_lock(inode->i_mapping);
 			truncate_setsize(inode, old_valid_size);
 			exfat_truncate(inode);
+			filemap_invalidate_unlock(inode->i_mapping);
 			return ret;
 		}
 
-- 
2.53.0