On Fri, Nov 06, 2020 at 09:52:05AM -0800, Eric Biggers wrote: > On Fri, Oct 30, 2020 at 05:44:20PM -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); > > > > Al, any thoughts on this? > Ping?
