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 ? Marc -- 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
