On Fri, 2020-10-30 at 17:44 -0700, Eric Biggers wrote: > From: Eric Biggers <ebiggers@xxxxxxxxxx> > > Currently inode_init_always() doesn't initialize i_ino to 0. This is > unexpected because unlike the other inode fields that aren't initialized > by inode_init_always(), i_ino isn't guaranteed to end up back at its > initial value after the inode is freed. Only one filesystem (XFS) > actually sets set i_ino back to 0 when freeing its inodes. > > So, callers of new_inode() see some random previous i_ino. Normally > that's fine, since normally i_ino isn't accessed before being set. > There can be edge cases where that isn't necessarily true, though. > > The one I've run into is that on ext4, when creating an encrypted file, > the new file's encryption key has to be set up prior to the jbd2 > transaction, and thus prior to i_ino being set. If something goes > wrong, fs/crypto/ may log warning or error messages, which normally > include i_ino. So it needs to know whether it is valid to include i_ino > yet or not. Also, on some files i_ino needs to be hashed for use in the > crypto, so fs/crypto/ needs to know whether that can be done yet or not. > > There are ways this could be worked around, either in fs/crypto/ or in > fs/ext4/. But, it seems there's no reason not to just fix > inode_init_always() to do the expected thing and initialize i_ino to 0. > > So, do that, and also remove the initialization in jfs_fill_super() that > becomes redundant. > > Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> > --- > fs/inode.c | 1 + > fs/jfs/super.c | 1 - > 2 files changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/inode.c b/fs/inode.c > index 9d78c37b00b81..eb001129f157c 100644 > --- a/fs/inode.c > +++ b/fs/inode.c > @@ -142,6 +142,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode) > atomic_set(&inode->i_count, 1); > inode->i_op = &empty_iops; > inode->i_fop = &no_open_fops; > + inode->i_ino = 0; > inode->__i_nlink = 1; > inode->i_opflags = 0; > if (sb->s_xattr) > diff --git a/fs/jfs/super.c b/fs/jfs/super.c > index b2dc4d1f9dcc5..1f0ffabbde566 100644 > --- a/fs/jfs/super.c > +++ b/fs/jfs/super.c > @@ -551,7 +551,6 @@ static int jfs_fill_super(struct super_block *sb, void *data, int silent) > ret = -ENOMEM; > goto out_unload; > } > - inode->i_ino = 0; > inode->i_size = i_size_read(sb->s_bdev->bd_inode); > inode->i_mapping->a_ops = &jfs_metapage_aops; > inode_fake_hash(inode); > > base-commit: 5fc6b075e165f641fbc366b58b578055762d5f8c This seems like a reasonable thing to do. Acked-by: Jeff Layton <jlayton@xxxxxxxxxx>
