| Message ID | 20201031004420.87678-1-ebiggers@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | fs/inode.c: make inode_init_always() initialize i_ino to 0 | expand |
On Fri, Oct 30, 2020 at 05:44:20PM -0700, Eric Biggers wrote: > From: Eric Biggers <ebiggers@google.com> > > 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@google.com> > --- > 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? - Eric
On Fri, 2020-10-30 at 17:44 -0700, Eric Biggers wrote: > From: Eric Biggers <ebiggers@google.com> > > 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@google.com> > --- > 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@kernel.org>
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@google.com> > > > > 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@google.com> > > --- > > 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?
On Fri, Nov 20, 2020 at 10:50:30AM -0800, Eric Biggers wrote: > 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@google.com> > > > > > > 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@google.com> > > > --- > > > 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.
On Wed, Dec 02, 2020 at 01:19:15PM -0800, Eric Biggers wrote: > On Fri, Nov 20, 2020 at 10:50:30AM -0800, Eric Biggers wrote: > > 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@google.com> > > > > > > > > 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@google.com> > > > > --- > > > > 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. Ping.
On Mon, Jan 04, 2021 at 10:54:02AM -0800, Eric Biggers wrote: > On Wed, Dec 02, 2020 at 01:19:15PM -0800, Eric Biggers wrote: > > On Fri, Nov 20, 2020 at 10:50:30AM -0800, Eric Biggers wrote: > > > 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@google.com> > > > > > > > > > > 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@google.com> > > > > > --- > > > > > 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. > > Ping. Applied.
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);