Merge tag 'exfat-for-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/linkinjeon/exfat

Pull exfat updates from Namjae Jeon:

 - Fix a remount failure caused by differing process masks by inheriting
   the original mount options during the remount process

 - Fix a potential divide-by-zero error and system crash in
   exfat_allocate_bitmap that occurred when the readahead count was zero

 - Add validation for directory cluster bitmap bits to prevent directory
   and root cluster from being incorrectly zeroed out on corrupted
   images

 - Clear the post-EOF page cache when extending a file to prevent stale
   mmap data from becoming visible, addressing an generic/363 failure

 - Fix a reference count leak in exfat_find by properly releasing the
   dentry set in specific error paths

* tag 'exfat-for-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/linkinjeon/exfat:
  exfat: fix remount failure in different process environments
  exfat: fix divide-by-zero in exfat_allocate_bitmap
  exfat: validate the cluster bitmap bits of directory
  exfat: zero out post-EOF page cache on file extension
  exfat: fix refcount leak in exfat_find

1 files changed, 25 insertions, 5 deletions

diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c
index 2d2d510f2372..5429041c7eaf 100644
--- a/fs/exfat/balloc.c
+++ b/fs/exfat/balloc.c
@@ -106,7 +106,7 @@ static int exfat_allocate_bitmap(struct super_block *sb,
 		(PAGE_SHIFT - sb->s_blocksize_bits);
 	for (i = 0; i < sbi->map_sectors; i++) {
 		/* Trigger the next readahead in advance. */
-		if (0 == (i % max_ra_count)) {
+		if (max_ra_count && 0 == (i % max_ra_count)) {
 			blk_start_plug(&plug);
 			for (j = i; j < min(max_ra_count, sbi->map_sectors - i) + i; j++)
 				sb_breadahead(sb, sector + j);
@@ -183,11 +183,10 @@ void exfat_free_bitmap(struct exfat_sb_info *sbi)
 	kvfree(sbi->vol_amap);
 }
 
-int exfat_set_bitmap(struct inode *inode, unsigned int clu, bool sync)
+int exfat_set_bitmap(struct super_block *sb, unsigned int clu, bool sync)
 {
 	int i, b;
 	unsigned int ent_idx;
-	struct super_block *sb = inode->i_sb;
 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
 
 	if (!is_valid_cluster(sbi, clu))
@@ -202,11 +201,10 @@ int exfat_set_bitmap(struct inode *inode, unsigned int clu, bool sync)
 	return 0;
 }
 
-int exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
+int exfat_clear_bitmap(struct super_block *sb, unsigned int clu, bool sync)
 {
 	int i, b;
 	unsigned int ent_idx;
-	struct super_block *sb = inode->i_sb;
 	struct exfat_sb_info *sbi = EXFAT_SB(sb);
 
 	if (!is_valid_cluster(sbi, clu))
@@ -226,6 +224,28 @@ int exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
 	return 0;
 }
 
+bool exfat_test_bitmap(struct super_block *sb, unsigned int clu)
+{
+	int i, b;
+	unsigned int ent_idx;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+
+	if (!sbi->vol_amap)
+		return true;
+
+	if (!is_valid_cluster(sbi, clu))
+		return false;
+
+	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
+	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
+	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
+
+	if (!test_bit_le(b, sbi->vol_amap[i]->b_data))
+		return false;
+
+	return true;
+}
+
 /*
  * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
  * the cluster heap.