exfat: fix i_blocks for files truncated over 4 GiB

[ Upstream commit 92fba08 ]

In exfat_truncate(), the computation of inode->i_blocks is wrong if
the file is larger than 4 GiB because a 32-bit variable is used as a
mask. This is fixed and simplified by using round_up().

Also fix the same buggy computation in exfat_read_root() and another
(correct) one in exfat_fill_inode(). The latter was fixed another way
last month but can be simplified by using round_up() as well. See:

  commit 0c336d6 ("exfat: fix incorrect loading of i_blocks for
                        large files")

Fixes: 98d9170 ("exfat: add file operations")
Cc: stable@vger.kernel.org # v5.7+
Suggested-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Christophe Vu-Brugier <christophe.vu-brugier@seagate.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

fs/exfat/file.c

@@ -251,8 +251,8 @@ void exfat_truncate(struct inode *inode, loff_t size)
 	else
 		mark_inode_dirty(inode);
 
-	inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1)) &
-			~(sbi->cluster_size - 1)) >> inode->i_blkbits;
+	inode->i_blocks = round_up(i_size_read(inode), sbi->cluster_size) >>
+				inode->i_blkbits;
 write_size:
 	aligned_size = i_size_read(inode);
 	if (aligned_size & (blocksize - 1)) {

fs/exfat/inode.c

@@ -602,8 +602,8 @@ static int exfat_fill_inode(struct inode *inode, struct exfat_dir_entry *info)
 
 	exfat_save_attr(inode, info->attr);
 
-	inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1)) &
-		~((loff_t)sbi->cluster_size - 1)) >> inode->i_blkbits;
+	inode->i_blocks = round_up(i_size_read(inode), sbi->cluster_size) >>
+				inode->i_blkbits;
 	inode->i_mtime = info->mtime;
 	inode->i_ctime = info->mtime;
 	ei->i_crtime = info->crtime;

fs/exfat/super.c

@@ -364,8 +364,8 @@ static int exfat_read_root(struct inode *inode)
 	inode->i_op = &exfat_dir_inode_operations;
 	inode->i_fop = &exfat_dir_operations;
 
-	inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1))
-			& ~(sbi->cluster_size - 1)) >> inode->i_blkbits;
+	inode->i_blocks = round_up(i_size_read(inode), sbi->cluster_size) >>
+				inode->i_blkbits;
 	ei->i_pos = ((loff_t)sbi->root_dir << 32) | 0xffffffff;
 	ei->i_size_aligned = i_size_read(inode);
 	ei->i_size_ondisk = i_size_read(inode);