diff mbox series

[RFC,v3,01/16] vfs: export new_inode_pseudo

Message ID 20200914191707.380444-2-jlayton@kernel.org
State New
Headers show
Series ceph+fscrypt: context, filename and symlink support | expand

Commit Message

Jeff Layton Sept. 14, 2020, 7:16 p.m. UTC
Ceph needs to be able to allocate inodes ahead of a create that might
involve a fscrypt-encrypted inode. new_inode() almost fits the bill,
but it puts the inode on the sb->s_inodes list and when we go to hash
it, that might be done again.

We could work around that by setting I_CREATING on the new inode, but
that causes ilookup5 to return -ESTALE if something tries to find it
before I_NEW is cleared. To work around all of this, just use
new_inode_pseudo which doesn't add it to the list.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 fs/inode.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Eric Biggers Sept. 14, 2020, 11:33 p.m. UTC | #1
On Mon, Sep 14, 2020 at 03:16:52PM -0400, Jeff Layton wrote:
> Ceph needs to be able to allocate inodes ahead of a create that might
> involve a fscrypt-encrypted inode. new_inode() almost fits the bill,
> but it puts the inode on the sb->s_inodes list and when we go to hash
> it, that might be done again.
> 
> We could work around that by setting I_CREATING on the new inode, but
> that causes ilookup5 to return -ESTALE if something tries to find it
> before I_NEW is cleared. To work around all of this, just use
> new_inode_pseudo which doesn't add it to the list.
> 
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Signed-off-by: Jeff Layton <jlayton@kernel.org>

I'd still like to see an explanation for why ilookup5() shouldn't be fixed
instead.

- Eric
Al Viro Sept. 23, 2020, 3:41 a.m. UTC | #2
On Mon, Sep 14, 2020 at 03:16:52PM -0400, Jeff Layton wrote:
> Ceph needs to be able to allocate inodes ahead of a create that might
> involve a fscrypt-encrypted inode. new_inode() almost fits the bill,
> but it puts the inode on the sb->s_inodes list and when we go to hash
> it, that might be done again.
> 
> We could work around that by setting I_CREATING on the new inode, but
> that causes ilookup5 to return -ESTALE if something tries to find it
> before I_NEW is cleared. To work around all of this, just use
> new_inode_pseudo which doesn't add it to the list.

Er...  Why would you _not_ want -ESTALE in that situation?
Jeff Layton Sept. 23, 2020, 11:19 a.m. UTC | #3
On Wed, 2020-09-23 at 04:41 +0100, Al Viro wrote:
> On Mon, Sep 14, 2020 at 03:16:52PM -0400, Jeff Layton wrote:
> > Ceph needs to be able to allocate inodes ahead of a create that might
> > involve a fscrypt-encrypted inode. new_inode() almost fits the bill,
> > but it puts the inode on the sb->s_inodes list and when we go to hash
> > it, that might be done again.
> > 
> > We could work around that by setting I_CREATING on the new inode, but
> > that causes ilookup5 to return -ESTALE if something tries to find it
> > before I_NEW is cleared. To work around all of this, just use
> > new_inode_pseudo which doesn't add it to the list.
> 
> Er...  Why would you _not_ want -ESTALE in that situation?

I'm hashing the new inode just before sending the create request to the
MDS. When the reply comes in, the client then searches for that inode in
the hash. If I_NEW has been cleared in the meantime -- no problem. If
not, then we want the task handling the reply to wait until it is (and
not get back an -ESTALE).
diff mbox series

Patch

diff --git a/fs/inode.c b/fs/inode.c
index 72c4c347afb7..61554c2477ab 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -935,6 +935,7 @@  struct inode *new_inode_pseudo(struct super_block *sb)
 	}
 	return inode;
 }
+EXPORT_SYMBOL(new_inode_pseudo);
 
 /**
  *	new_inode 	- obtain an inode