f2fs: fix to truncate preallocated blocks in f2fs_file_open()

chenyuwen reports a f2fs bug as below:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000011
 fscrypt_set_bio_crypt_ctx+0x78/0x1e8
 f2fs_grab_read_bio+0x78/0x208
 f2fs_submit_page_read+0x44/0x154
 f2fs_get_read_data_page+0x288/0x5f4
 f2fs_get_lock_data_page+0x60/0x190
 truncate_partial_data_page+0x108/0x4fc
 f2fs_do_truncate_blocks+0x344/0x5f0
 f2fs_truncate_blocks+0x6c/0x134
 f2fs_truncate+0xd8/0x200
 f2fs_iget+0x20c/0x5ac
 do_garbage_collect+0x5d0/0xf6c
 f2fs_gc+0x22c/0x6a4
 f2fs_disable_checkpoint+0xc8/0x310
 f2fs_fill_super+0x14bc/0x1764
 mount_bdev+0x1b4/0x21c
 f2fs_mount+0x20/0x30
 legacy_get_tree+0x50/0xbc
 vfs_get_tree+0x5c/0x1b0
 do_new_mount+0x298/0x4cc
 path_mount+0x33c/0x5fc
 __arm64_sys_mount+0xcc/0x15c
 invoke_syscall+0x60/0x150
 el0_svc_common+0xb8/0xf8
 do_el0_svc+0x28/0xa0
 el0_svc+0x24/0x84
 el0t_64_sync_handler+0x88/0xec

It is because inode.i_crypt_info is not initialized during below path:
- mount
 - f2fs_fill_super
  - f2fs_disable_checkpoint
   - f2fs_gc
    - f2fs_iget
     - f2fs_truncate

So, let's relocate truncation of preallocated blocks to f2fs_file_open(),
after fscrypt_file_open().

Fixes: d4dd19ec1ea0 ("f2fs: do not expose unwritten blocks to user by DIO")
Reported-by: chenyuwen <yuwen.chen@xjmz.com>
Closes: https://lore.kernel.org/linux-kernel/20240517085327.1188515-1-yuwen.chen@xjmz.com
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 86d4f7b1988130cf05685ba30c3f34f2fb88a30f..9688df332147e521954769765b03f206d9ca0045 100644 (file)
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -803,6 +803,7 @@ enum {
        FI_COW_FILE,            /* indicate COW file */
        FI_ATOMIC_COMMITTED,    /* indicate atomic commit completed except disk sync */
        FI_ATOMIC_REPLACE,      /* indicate atomic replace */
+       FI_OPENED_FILE,         /* indicate file has been opened */
        FI_MAX,                 /* max flag, never be used */
 };
 

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 0cbaeb97c7f526efadc21d58877a9adbd404935d..c50213da474d74f163fe2e9a48d420c3ebaeaf56 100644 (file)
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -554,6 +554,42 @@ static int f2fs_file_mmap(struct file *file, struct vm_area_struct *vma)
        return 0;
 }
 
+static int finish_preallocate_blocks(struct inode *inode)
+{
+       int ret;
+
+       inode_lock(inode);
+       if (is_inode_flag_set(inode, FI_OPENED_FILE)) {
+               inode_unlock(inode);
+               return 0;
+       }
+
+       if (!file_should_truncate(inode)) {
+               set_inode_flag(inode, FI_OPENED_FILE);
+               inode_unlock(inode);
+               return 0;
+       }
+
+       f2fs_down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
+       filemap_invalidate_lock(inode->i_mapping);
+
+       truncate_setsize(inode, i_size_read(inode));
+       ret = f2fs_truncate(inode);
+
+       filemap_invalidate_unlock(inode->i_mapping);
+       f2fs_up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
+
+       if (!ret)
+               set_inode_flag(inode, FI_OPENED_FILE);
+
+       inode_unlock(inode);
+       if (ret)
+               return ret;
+
+       file_dont_truncate(inode);
+       return 0;
+}
+
 static int f2fs_file_open(struct inode *inode, struct file *filp)
 {
        int err = fscrypt_file_open(inode, filp);
@@ -571,7 +607,11 @@ static int f2fs_file_open(struct inode *inode, struct file *filp)
        filp->f_mode |= FMODE_NOWAIT;
        filp->f_mode |= FMODE_CAN_ODIRECT;
 
-       return dquot_file_open(inode, filp);
+       err = dquot_file_open(inode, filp);
+       if (err)
+               return err;
+
+       return finish_preallocate_blocks(inode);
 }
 
 void f2fs_truncate_data_blocks_range(struct dnode_of_data *dn, int count)

diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index 9290b396e11ce37b905bc10deff911d889c8ef8f..dbfebbddf6754104eec0243c574c6426fc5fe7e9 100644 (file)
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -613,14 +613,6 @@ make_now:
        }
        f2fs_set_inode_flags(inode);
 
-       if (file_should_truncate(inode) &&
-                       !is_sbi_flag_set(sbi, SBI_POR_DOING)) {
-               ret = f2fs_truncate(inode);
-               if (ret)
-                       goto bad_inode;
-               file_dont_truncate(inode);
-       }
-
        unlock_new_inode(inode);
        trace_f2fs_iget(inode);
        return inode;