On Thu, Jun 05, 2014 at 08:51:21AM -0400, Marc Dionne wrote: > On Wed, Jun 4, 2014 at 5:21 PM, J. Bruce Fields <bfields@xxxxxxxxxx> wrote: > > From: "J. Bruce Fields" <bfields@xxxxxxxxxx> > > > > Minor documentation updates: > > - refer to d_obtain_alias rather than d_alloc_anon > > - explain when to use d_splice_alias and when > > d_materialise_unique. > > - cut some details of d_splice_alias/d_materialise_unique > > implementation. > > > > Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx> > > --- > > Documentation/filesystems/nfs/Exporting | 38 +++++++++++++++++++------------ > > 1 file changed, 23 insertions(+), 15 deletions(-) > > > > diff --git a/Documentation/filesystems/nfs/Exporting b/Documentation/filesystems/nfs/Exporting > > index e543b1a..9b7de5b 100644 > > --- a/Documentation/filesystems/nfs/Exporting > > +++ b/Documentation/filesystems/nfs/Exporting > > @@ -66,23 +66,31 @@ b/ A per-superblock list "s_anon" of dentries which are the roots of > > > > c/ Helper routines to allocate anonymous dentries, and to help attach > > loose directory dentries at lookup time. They are: > > - d_alloc_anon(inode) will return a dentry for the given inode. > > + d_obtain_alias(inode) will return a dentry for the given inode. > > If the inode already has a dentry, one of those is returned. > > If it doesn't, a new anonymous (IS_ROOT and > > DCACHE_DISCONNECTED) dentry is allocated and attached. > > In the case of a directory, care is taken that only one dentry > > can ever be attached. > > - d_splice_alias(inode, dentry) will make sure that there is a > > - dentry with the same name and parent as the given dentry, and > > - which refers to the given inode. > > - If the inode is a directory and already has a dentry, then that > > - dentry is d_moved over the given dentry. > > - If the passed dentry gets attached, care is taken that this is > > - mutually exclusive to a d_alloc_anon operation. > > - If the passed dentry is used, NULL is returned, else the used > > - dentry is returned. This corresponds to the calling pattern of > > - ->lookup. > > - > > + d_splice_alias(inode, dentry) or d_materialise_unique(dentry, inode) > > + will introduce a new dentry into the tree; either the passed-in > > + dentry or a preexisting alias for the given inode (such as an > > + anonymous one created by d_obtain_alias), if appropriate. The two > > + functions differ in their handling of directories with preexisting > > + aliases: > > + d_splice_alias will use any existing IS_ROOT dentry, but it will > > + return -EIO rather than try to move a dentry with a different > > + parent. This is appropriate for local filesystems, which > > + should never see such an alias unless the filesystem is > > + corrupted somehow (for example, if two on-disk directory > > + entries refer to the same directory.) > > + d_obtain_alias will attempt to move any dentry. This is > > Should this be d_materialise_unique instead of d_obtain_alias ? Whoops, thanks for catching that. Fixed in the version at git://linux-nfs.org/~bfields/linux-topics.git for-viro --b. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
