Compression option in inode should not be changed after they have
been used, however, it may happen in below race case:
Thread A Thread B
- f2fs_ioc_set_compress_option
- check f2fs_is_mmap_file()
- check get_dirty_pages()
- check F2FS_HAS_BLOCKS()
- f2fs_file_mmap
- set_inode_flag(FI_MMAP_FILE)
- fault
- do_page_mkwrite
- f2fs_vm_page_mkwrite
- f2fs_get_block_locked
- fault_dirty_shared_page
- set_page_dirty
- update i_compress_algorithm
- update i_log_cluster_size
- update i_cluster_size
Avoid such race condition by covering f2fs_file_mmap() w/ inode lock.
Fixes: e1e8debec656 ("f2fs: add F2FS_IOC_SET_COMPRESS_OPTION ioctl")
Signed-off-by: Chao Yu <[email protected]>
---
fs/f2fs/file.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 7b097ab2f5e4..685ded62fc28 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -519,17 +519,25 @@ static loff_t f2fs_llseek(struct file *file, loff_t
offset, int whence)
static int f2fs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
struct inode *inode = file_inode(file);
+ int ret = 0;
if (unlikely(f2fs_cp_error(F2FS_I_SB(inode))))
return -EIO;
- if (!f2fs_is_compress_backend_ready(inode))
- return -EOPNOTSUPP;
+ inode_lock(inode);
+
+ if (!f2fs_is_compress_backend_ready(inode)) {
+ ret = -EOPNOTSUPP;
+ goto out_unlock;
+ }
file_accessed(file);
vma->vm_ops = &f2fs_file_vm_ops;
set_inode_flag(inode, FI_MMAP_FILE);
- return 0;
+
+out_unlock:
+ inode_unlock(inode);
+ return ret;
}
static int f2fs_file_open(struct inode *inode, struct file *filp)
--
2.40.1
_______________________________________________
Linux-f2fs-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
