diff options
Diffstat (limited to 'Documentation/filesystems/nfs/Exporting')
| -rw-r--r-- | Documentation/filesystems/nfs/Exporting | 27 |
1 files changed, 19 insertions, 8 deletions
diff --git a/Documentation/filesystems/nfs/Exporting b/Documentation/filesystems/nfs/Exporting index 520a4becb75c..63889149f532 100644 --- a/Documentation/filesystems/nfs/Exporting +++ b/Documentation/filesystems/nfs/Exporting @@ -56,13 +56,25 @@ a/ A dentry flag DCACHE_DISCONNECTED which is set on any dentry that might not be part of the proper prefix. This is set when anonymous dentries are created, and cleared when a dentry is noticed to be a child of a dentry which is in the proper - prefix. - -b/ A per-superblock list "s_anon" of dentries which are the roots of - subtrees that are not in the proper prefix. These dentries, as - well as the proper prefix, need to be released at unmount time. As - these dentries will not be hashed, they are linked together on the - d_hash list_head. + prefix. If the refcount on a dentry with this flag set + becomes zero, the dentry is immediately discarded, rather than being + kept in the dcache. If a dentry that is not already in the dcache + is repeatedly accessed by filehandle (as NFSD might do), an new dentry + will be a allocated for each access, and discarded at the end of + the access. + + Note that such a dentry can acquire children, name, ancestors, etc. + without losing DCACHE_DISCONNECTED - that flag is only cleared when + subtree is successfully reconnected to root. Until then dentries + in such subtree are retained only as long as there are references; + refcount reaching zero means immediate eviction, same as for unhashed + dentries. That guarantees that we won't need to hunt them down upon + umount. + +b/ A primitive for creation of secondary roots - d_obtain_root(inode). + Those do _not_ bear DCACHE_DISCONNECTED. They are placed on the + per-superblock list (->s_roots), so they can be located at umount + time for eviction purposes. c/ Helper routines to allocate anonymous dentries, and to help attach loose directory dentries at lookup time. They are: @@ -77,7 +89,6 @@ c/ Helper routines to allocate anonymous dentries, and to help attach (such as an anonymous one created by d_obtain_alias), if appropriate. It returns NULL when the passed-in dentry is used, following the calling convention of ->lookup. - Filesystem Issues ----------------- |