On Thu, Aug 16, 2012 at 08:47:03AM -0400, J. Bruce Fields wrote:
> On Thu, Aug 16, 2012 at 04:38:14PM +0400, Cyrill Gorcunov wrote:
> > On Thu, Aug 16, 2012 at 10:24:48AM +0400, Cyrill Gorcunov wrote:
> > > > > > On the other hand, if you want a real filehandle then wouldn't you want
> > > > > > to e.g. call the filesystem's ->encode_fh() if necessary, as
> > > > > > exportfs_encode_fh() does?
> > > > >
> > > > > Well, one of the problem I hit when I've been trying to use encode_fh
> > > > > is that every new implementation of encode_fh will require some size
> > > > > (even unknown) in buffer where encoded data pushed. Correct me please
> > > > > if I'm wrong. But with export_encode_inode_fh there is a small buffer
> > > > > with pretty known size needed on stack needed for printing data in
> > > > > fdinfo.
> > > >
> > > > You can just give encode_fh a too-small data and let it fail if it's not
> > > > big enough.
> > > >
> > > > (In practice I think everyone supports NFSv3 filehandles which have a
> > > > maximum size of 64 bytes.)
> > >
> > > I'll think about it, thanks!
> >
> > Hi Bruce, thinking a bit more I guess using general encode_fh is not that
> > convenient since it operates with dentries while our fdinfo output deals
> > with inodes. Thus I should either provide some new encode_fh variant
> > which would deal with inodes directly without "parents".
>
> I can't see why that wouldn't work.
Guys, would the patch below be more-less acceptible?
In inotify I think we could pass "parent" as NULL and use general
encode engine then (ie it will look like someone called for
name_to_handle_at on inotify target).
---
fs, exportfs: Add exportfs_encode_inode_fh helper
This helpers allows to use per-sb encode_fh
functionality where inodes come in as arguments
(say the caller has no dentries to provide).
Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
CC: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
CC: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
CC: "J. Bruce Fields" <bfields@xxxxxxxxxxxx>
CC: Alexey Dobriyan <adobriyan@xxxxxxxxx>
CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
CC: James Bottomley <jbottomley@xxxxxxxxxxxxx>
---
fs/exportfs/expfs.c | 19 ++++++++++++++-----
include/linux/exportfs.h | 2 ++
2 files changed, 16 insertions(+), 5 deletions(-)
Index: linux-2.6.git/fs/exportfs/expfs.c
===================================================================
--- linux-2.6.git.orig/fs/exportfs/expfs.c
+++ linux-2.6.git/fs/exportfs/expfs.c
@@ -341,10 +341,21 @@ static int export_encode_fh(struct inode
return type;
}
+int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
+ int *max_len, struct inode *parent)
+{
+ const struct export_operations *nop = inode->i_sb->s_export_op;
+
+ if (nop)
+ return nop->encode_fh(inode, fid->raw, max_len, parent);
+
+ return export_encode_fh(inode, fid, max_len, parent);
+}
+EXPORT_SYMBOL_GPL(exportfs_encode_inode_fh);
+
int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, int *max_len,
int connectable)
{
- const struct export_operations *nop = dentry->d_sb->s_export_op;
int error;
struct dentry *p = NULL;
struct inode *inode = dentry->d_inode, *parent = NULL;
@@ -357,10 +368,8 @@ int exportfs_encode_fh(struct dentry *de
*/
parent = p->d_inode;
}
- if (nop->encode_fh)
- error = nop->encode_fh(inode, fid->raw, max_len, parent);
- else
- error = export_encode_fh(inode, fid, max_len, parent);
+
+ error = exportfs_encode_inode_fh(inode, fid, max_len, parent);
dput(p);
return error;
Index: linux-2.6.git/include/linux/exportfs.h
===================================================================
--- linux-2.6.git.orig/include/linux/exportfs.h
+++ linux-2.6.git/include/linux/exportfs.h
@@ -177,6 +177,8 @@ struct export_operations {
int (*commit_metadata)(struct inode *inode);
};
+extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
+ int *max_len, struct inode *parent);
extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
int *max_len, int connectable);
extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
--
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