[PATCH] kill ->put_inode

[linux-2.6-omap-h63xx.git] / Documentation / filesystems / vfs.txt

diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 9d019d35728f28bcb9ecfeaf5bd3a4227f026586..b7522c6cbae3758f77cb12e22b78825e43a3796d 100644 (file)
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -151,7 +151,7 @@ The get_sb() method has the following arguments:
   const char *dev_name: the device name we are mounting.
 
   void *data: arbitrary mount options, usually comes as an ASCII
-       string
+       string (see "Mount Options" section)
 
   struct vfsmount *mnt: a vfs-internal representation of a mount point
 
@@ -182,7 +182,7 @@ A fill_super() method implementation has the following arguments:
        must initialize this properly.
 
   void *data: arbitrary mount options, usually comes as an ASCII
-       string
+       string (see "Mount Options" section)
 
   int silent: whether or not to be silent on error
 
@@ -203,11 +203,8 @@ struct super_operations {
         struct inode *(*alloc_inode)(struct super_block *sb);
         void (*destroy_inode)(struct inode *);
 
-        void (*read_inode) (struct inode *);
-
         void (*dirty_inode) (struct inode *);
         int (*write_inode) (struct inode *, int);
-        void (*put_inode) (struct inode *);
         void (*drop_inode) (struct inode *);
         void (*delete_inode) (struct inode *);
         void (*put_super) (struct super_block *);
@@ -242,24 +239,12 @@ or bottom half).
        ->alloc_inode was defined and simply undoes anything done by
        ->alloc_inode.
 
-  read_inode: this method is called to read a specific inode from the
-        mounted filesystem.  The i_ino member in the struct inode is
-       initialized by the VFS to indicate which inode to read. Other
-       members are filled in by this method.
-
-       You can set this to NULL and use iget5_locked() instead of iget()
-       to read inodes.  This is necessary for filesystems for which the
-       inode number is not sufficient to identify an inode.
-
   dirty_inode: this method is called by the VFS to mark an inode dirty.
 
   write_inode: this method is called when the VFS needs to write an
        inode to disc.  The second parameter indicates whether the write
        should be synchronous or not, not all filesystems check this flag.
 
-  put_inode: called when the VFS inode is removed from the inode
-       cache.
-
   drop_inode: called when the last access to the inode is dropped,
        with the inode_lock spinlock held.
 
@@ -302,15 +287,16 @@ or bottom half).
 
   umount_begin: called when the VFS is unmounting a filesystem.
 
-  show_options: called by the VFS to show mount options for /proc/<pid>/mounts.
+  show_options: called by the VFS to show mount options for
+       /proc/<pid>/mounts.  (see "Mount Options" section)
 
   quota_read: called by the VFS to read from filesystem quota file.
 
   quota_write: called by the VFS to write to filesystem quota file.
 
-The read_inode() method is responsible for filling in the "i_op"
-field. This is a pointer to a "struct inode_operations" which
-describes the methods that can be performed on individual inodes.
+Whoever sets up the inode is responsible for filling in the "i_op" field. This
+is a pointer to a "struct inode_operations" which describes the methods that
+can be performed on individual inodes.
 
 
 The Inode Object
@@ -980,6 +966,49 @@ manipulate dentries:
 For further information on dentry locking, please refer to the document
 Documentation/filesystems/dentry-locking.txt.
 
+Mount Options
+=============
+
+Parsing options
+---------------
+
+On mount and remount the filesystem is passed a string containing a
+comma separated list of mount options.  The options can have either of
+these forms:
+
+  option
+  option=value
+
+The <linux/parser.h> header defines an API that helps parse these
+options.  There are plenty of examples on how to use it in existing
+filesystems.
+
+Showing options
+---------------
+
+If a filesystem accepts mount options, it must define show_options()
+to show all the currently active options.  The rules are:
+
+  - options MUST be shown which are not default or their values differ
+    from the default
+
+  - options MAY be shown which are enabled by default or have their
+    default value
+
+Options used only internally between a mount helper and the kernel
+(such as file descriptors), or which only have an effect during the
+mounting (such as ones controlling the creation of a journal) are exempt
+from the above rules.
+
+The underlying reason for the above rules is to make sure, that a
+mount can be accurately replicated (e.g. umounting and mounting again)
+based on the information found in /proc/mounts.
+
+A simple method of saving options at mount/remount time and showing
+them is provided with the save_mount_options() and
+generic_show_options() helper functions.  Please note, that using
+these may have drawbacks.  For more info see header comments for these
+functions in fs/namespace.c.
 
 Resources
 =========