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Commit b73e5282 authored by Chao Yu's avatar Chao Yu Committed by Jaegeuk Kim
Browse files

f2fs: reposition unlock_new_inode to prevent accessing invalid inode 



As the race condition on the inode cache, following scenario can appear:
[Thread a]				[Thread b]
					->f2fs_mkdir
					  ->f2fs_add_link
					    ->__f2fs_add_link
					      ->init_inode_metadata failed here
->gc_thread_func
  ->f2fs_gc
    ->do_garbage_collect
      ->gc_data_segment
        ->f2fs_iget
          ->iget_locked
            ->wait_on_inode
					  ->unlock_new_inode
        ->move_data_page
					  ->make_bad_inode
					  ->iput

When we fail in create/symlink/mkdir/mknod/tmpfile, the new allocated inode
should be set as bad to avoid being accessed by other thread. But in above
scenario, it allows f2fs to access the invalid inode before this inode was set
as bad.
This patch fix the potential problem, and this issue was found by code review.

change log from v1:
 o Add condition judgment in gc_data_segment() suggested by Changman Lee.
 o use iget_failed to simplify code.

Signed-off-by: default avatarChao Yu <chao2.yu@samsung.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 3304b564

fs/f2fs/gc.c

+1 −1
Original line number Diff line number Diff line
@@ -593,7 +593,7 @@ next_step: 


		if (phase == 2) {

			inode = f2fs_iget(sb, dni.ino);

			if (IS_ERR(inode))

			if (IS_ERR(inode) || is_bad_inode(inode))

				continue;



			start_bidx = start_bidx_of_node(nofs, F2FS_I(inode));

fs/f2fs/namei.c

+5 −15
Original line number Diff line number Diff line
@@ -134,9 +134,7 @@ static int f2fs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 
	return 0;

out:

	clear_nlink(inode);

	unlock_new_inode(inode);

	make_bad_inode(inode);

	iput(inode);

	iget_failed(inode);

	alloc_nid_failed(sbi, ino);

	return err;

}
@@ -267,9 +265,7 @@ static int f2fs_symlink(struct inode *dir, struct dentry *dentry, 
	return err;

out:

	clear_nlink(inode);

	unlock_new_inode(inode);

	make_bad_inode(inode);

	iput(inode);

	iget_failed(inode);

	alloc_nid_failed(sbi, inode->i_ino);

	return err;

}
@@ -308,9 +304,7 @@ static int f2fs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 
out_fail:

	clear_inode_flag(F2FS_I(inode), FI_INC_LINK);

	clear_nlink(inode);

	unlock_new_inode(inode);

	make_bad_inode(inode);

	iput(inode);

	iget_failed(inode);

	alloc_nid_failed(sbi, inode->i_ino);

	return err;

}
@@ -354,9 +348,7 @@ static int f2fs_mknod(struct inode *dir, struct dentry *dentry, 
	return 0;

out:

	clear_nlink(inode);

	unlock_new_inode(inode);

	make_bad_inode(inode);

	iput(inode);

	iget_failed(inode);

	alloc_nid_failed(sbi, inode->i_ino);

	return err;

}
@@ -688,9 +680,7 @@ release_out: 
out:

	f2fs_unlock_op(sbi);

	clear_nlink(inode);

	unlock_new_inode(inode);

	make_bad_inode(inode);

	iput(inode);

	iget_failed(inode);

	alloc_nid_failed(sbi, inode->i_ino);

	return err;

}