get rid of 'parent' argument of ->d_compare()

[cascardo/linux.git] / Documentation / filesystems / vfs.txt

diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 900360c..9ace359 100644 (file)
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -364,7 +364,6 @@ struct inode_operations {
        int (*atomic_open)(struct inode *, struct dentry *, struct file *,
                        unsigned open_flag, umode_t create_mode, int *opened);
        int (*tmpfile) (struct inode *, struct dentry *, umode_t);
        int (*atomic_open)(struct inode *, struct dentry *, struct file *,
                        unsigned open_flag, umode_t create_mode, int *opened);
        int (*tmpfile) (struct inode *, struct dentry *, umode_t);

-       int (*dentry_open)(struct dentry *, struct file *, const struct cred *);

 };
 
 Again, all methods are called without any locks being held, unless
 };
 
 Again, all methods are called without any locks being held, unless


@@ -534,9 +533,7 @@ __sync_single_inode) to check if ->writepages has been successful in
 writing out the whole address_space.
 
 The Writeback tag is used by filemap*wait* and sync_page* functions,
 writing out the whole address_space.
 
 The Writeback tag is used by filemap*wait* and sync_page* functions,

-via filemap_fdatawait_range, to wait for all writeback to
-complete.  While waiting ->sync_page (if defined) will be called on
-each page that is found to require writeback.
+via filemap_fdatawait_range, to wait for all writeback to complete.

 
 An address_space handler may attach extra information to a page,
 typically using the 'private' field in the 'struct page'.  If such
 
 An address_space handler may attach extra information to a page,
 typically using the 'private' field in the 'struct page'.  If such


@@ -554,8 +551,8 @@ address_space has finer control of write sizes.
 
 The read process essentially only requires 'readpage'.  The write
 process is more complicated and uses write_begin/write_end or
 
 The read process essentially only requires 'readpage'.  The write
 process is more complicated and uses write_begin/write_end or

-set_page_dirty to write data into the address_space, and writepage,
-sync_page, and writepages to writeback data to storage.
+set_page_dirty to write data into the address_space, and writepage
+and writepages to writeback data to storage.

 
 Adding and removing pages to/from an address_space is protected by the
 inode's i_mutex.
 
 Adding and removing pages to/from an address_space is protected by the
 inode's i_mutex.


@@ -701,13 +698,6 @@ struct address_space_operations {
        but instead uses bmap to find out where the blocks in the file
        are and uses those addresses directly.
 
        but instead uses bmap to find out where the blocks in the file
        are and uses those addresses directly.
 

-  dentry_open: *WARNING: probably going away soon, do not use!* This is an
-       alternative to f_op->open(), the difference is that this method may open
-       a file not necessarily originating from the same filesystem as the one
-       i_op->open() was called on.  It may be useful for stacking filesystems
-       which want to allow native I/O directly on underlying files.
-
-

   invalidatepage: If a page has PagePrivate set, then invalidatepage
         will be called when part or all of the page is to be removed
        from the address space.  This generally corresponds to either a
   invalidatepage: If a page has PagePrivate set, then invalidatepage
         will be called when part or all of the page is to be removed
        from the address space.  This generally corresponds to either a


@@ -941,14 +931,17 @@ struct dentry_operations {
        int (*d_revalidate)(struct dentry *, unsigned int);
        int (*d_weak_revalidate)(struct dentry *, unsigned int);
        int (*d_hash)(const struct dentry *, struct qstr *);
        int (*d_revalidate)(struct dentry *, unsigned int);
        int (*d_weak_revalidate)(struct dentry *, unsigned int);
        int (*d_hash)(const struct dentry *, struct qstr *);

-       int (*d_compare)(const struct dentry *, const struct dentry *,
+       int (*d_compare)(const struct dentry *,

                        unsigned int, const char *, const struct qstr *);
        int (*d_delete)(const struct dentry *);
                        unsigned int, const char *, const struct qstr *);
        int (*d_delete)(const struct dentry *);

+       int (*d_init)(struct dentry *);

        void (*d_release)(struct dentry *);
        void (*d_iput)(struct dentry *, struct inode *);
        char *(*d_dname)(struct dentry *, char *, int);
        struct vfsmount *(*d_automount)(struct path *);
        int (*d_manage)(struct dentry *, bool);
        void (*d_release)(struct dentry *);
        void (*d_iput)(struct dentry *, struct inode *);
        char *(*d_dname)(struct dentry *, char *, int);
        struct vfsmount *(*d_automount)(struct path *);
        int (*d_manage)(struct dentry *, bool);

+       struct dentry *(*d_real)(struct dentry *, const struct inode *,
+                                unsigned int);

 };
 
   d_revalidate: called when the VFS needs to revalidate a dentry. This
 };
 
   d_revalidate: called when the VFS needs to revalidate a dentry. This


@@ -1014,6 +1007,8 @@ struct dentry_operations {
        always cache a reachable dentry. d_delete must be constant and
        idempotent.
 
        always cache a reachable dentry. d_delete must be constant and
        idempotent.
 

+  d_init: called when a dentry is allocated
+

   d_release: called when a dentry is really deallocated
 
   d_iput: called when a dentry loses its inode (just prior to its
   d_release: called when a dentry is really deallocated
 
   d_iput: called when a dentry loses its inode (just prior to its


@@ -1033,6 +1028,14 @@ struct dentry_operations {
        at the end of the buffer, and returns a pointer to the first char.
        dynamic_dname() helper function is provided to take care of this.
 
        at the end of the buffer, and returns a pointer to the first char.
        dynamic_dname() helper function is provided to take care of this.
 

+       Example :
+
+       static char *pipefs_dname(struct dentry *dent, char *buffer, int buflen)
+       {
+               return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]",
+                               dentry->d_inode->i_ino);
+       }
+

   d_automount: called when an automount dentry is to be traversed (optional).
        This should create a new VFS mount record and return the record to the
        caller.  The caller is supplied with a path parameter giving the
   d_automount: called when an automount dentry is to be traversed (optional).
        This should create a new VFS mount record and return the record to the
        caller.  The caller is supplied with a path parameter giving the


@@ -1071,13 +1074,23 @@ struct dentry_operations {
        This function is only used if DCACHE_MANAGE_TRANSIT is set on the
        dentry being transited from.
 
        This function is only used if DCACHE_MANAGE_TRANSIT is set on the
        dentry being transited from.
 

-Example :
+  d_real: overlay/union type filesystems implement this method to return one of
+       the underlying dentries hidden by the overlay.  It is used in three
+       different modes:

 
 

-static char *pipefs_dname(struct dentry *dent, char *buffer, int buflen)
-{
-       return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]",
-                               dentry->d_inode->i_ino);
-}
+       Called from open it may need to copy-up the file depending on the
+       supplied open flags.  This mode is selected with a non-zero flags
+       argument.  In this mode the d_real method can return an error.
+
+       Called from file_dentry() it returns the real dentry matching the inode
+       argument.  The real dentry may be from a lower layer already copied up,
+       but still referenced from the file.  This mode is selected with a
+       non-NULL inode argument.  This will always succeed.
+
+       With NULL inode and zero flags the topmost real underlying dentry is
+       returned.  This will always succeed.
+
+       This method is never called with both non-NULL inode and non-zero flags.

 
 Each dentry has a pointer to its parent dentry, as well as a hash list
 of child dentries. Child dentries are basically like files in a
 
 Each dentry has a pointer to its parent dentry, as well as a hash list
 of child dentries. Child dentries are basically like files in a