[PATCH AUTOSEL 5.1 028/141] f2fs: Fix accounting for unusable blocks

Sasha Levin
2019-07-19T04:03:55Z

From: Daniel Rosenberg <drosen@google.com>

[ Upstream commit a4c3ecaaadac5693f555cfef1c9eecf4c39df818 ]

Fixes possible underflows when dealing with unusable blocks.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/f2fs/f2fs.h | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 2ba2478d0663..f1157d5c62bb 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1761,8 +1761,12 @@ static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,

if (!__allow_reserved_blocks(sbi, inode, true))
avail_user_block_count -= F2FS_OPTION(sbi).root_reserved_blocks;
- if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
- avail_user_block_count -= sbi->unusable_block_count;
+ if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
+ if (avail_user_block_count > sbi->unusable_block_count)
+ avail_user_block_count -= sbi->unusable_block_count;
+ else
+ avail_user_block_count = 0;
+ }
if (unlikely(sbi->total_valid_block_count > avail_user_block_count)) {
diff = sbi->total_valid_block_count - avail_user_block_count;
if (diff > *count)
@@ -1958,7 +1962,7 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi,
struct inode *inode, bool is_inode)
{
block_t valid_block_count;
- unsigned int valid_node_count;
+ unsigned int valid_node_count, user_block_count;
int err;

if (is_inode) {
@@ -1985,10 +1989,11 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi,

if (!__allow_reserved_blocks(sbi, inode, false))
valid_block_count += F2FS_OPTION(sbi).root_reserved_blocks;
+ user_block_count = sbi->user_block_count;
if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
- valid_block_count += sbi->unusable_block_count;
+ user_block_count -= sbi->unusable_block_count;

- if (unlikely(valid_block_count > sbi->user_block_count)) {
+ if (unlikely(valid_block_count > user_block_count)) {
spin_unlock(&sbi->stat_lock);
goto enospc;
}
--
2.20.1