diff options
Diffstat (limited to 'Documentation/filesystems/vfs.txt')
| -rw-r--r-- | Documentation/filesystems/vfs.txt | 51 |
1 files changed, 29 insertions, 22 deletions
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index a47cc819f37b..045f3e055a28 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -3,7 +3,7 @@ Original author: Richard Gooch <rgooch@atnf.csiro.au> - Last updated on October 28, 2005 + Last updated on June 24, 2007. Copyright (C) 1999 Richard Gooch Copyright (C) 2005 Pekka Enberg @@ -107,7 +107,7 @@ file /proc/filesystems. struct file_system_type ----------------------- -This describes the filesystem. As of kernel 2.6.13, the following +This describes the filesystem. As of kernel 2.6.22, the following members are defined: struct file_system_type { @@ -119,6 +119,8 @@ struct file_system_type { struct module *owner; struct file_system_type * next; struct list_head fs_supers; + struct lock_class_key s_lock_key; + struct lock_class_key s_umount_key; }; name: the name of the filesystem type, such as "ext2", "iso9660", @@ -137,11 +139,12 @@ struct file_system_type { next: for internal VFS use: you should initialize this to NULL + s_lock_key, s_umount_key: lockdep-specific + The get_sb() method has the following arguments: - struct super_block *sb: the superblock structure. This is partially - initialized by the VFS and the rest must be initialized by the - get_sb() method + struct file_system_type *fs_type: decribes the filesystem, partly initialized + by the specific filesystem code int flags: mount flags @@ -150,12 +153,13 @@ The get_sb() method has the following arguments: void *data: arbitrary mount options, usually comes as an ASCII string - int silent: whether or not to be silent on error + struct vfsmount *mnt: a vfs-internal representation of a mount point The get_sb() method must determine if the block device specified -in the superblock contains a filesystem of the type the method -supports. On success the method returns the superblock pointer, on -failure it returns NULL. +in the dev_name and fs_type contains a filesystem of the type the method +supports. If it succeeds in opening the named block device, it initializes a +struct super_block descriptor for the filesystem contained by the block device. +On failure it returns an error. The most interesting member of the superblock structure that the get_sb() method fills in is the "s_op" field. This is a pointer to @@ -193,7 +197,7 @@ struct super_operations ----------------------- This describes how the VFS can manipulate the superblock of your -filesystem. As of kernel 2.6.13, the following members are defined: +filesystem. As of kernel 2.6.22, the following members are defined: struct super_operations { struct inode *(*alloc_inode)(struct super_block *sb); @@ -216,8 +220,6 @@ struct super_operations { void (*clear_inode) (struct inode *); void (*umount_begin) (struct super_block *); - void (*sync_inodes) (struct super_block *sb, - struct writeback_control *wbc); int (*show_options)(struct seq_file *, struct vfsmount *); ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t); @@ -300,9 +302,6 @@ or bottom half). umount_begin: called when the VFS is unmounting a filesystem. - sync_inodes: called when the VFS is writing out dirty data associated with - a superblock. - show_options: called by the VFS to show mount options for /proc/<pid>/mounts. quota_read: called by the VFS to read from filesystem quota file. @@ -324,7 +323,7 @@ struct inode_operations ----------------------- This describes how the VFS can manipulate an inode in your -filesystem. As of kernel 2.6.13, the following members are defined: +filesystem. As of kernel 2.6.22, the following members are defined: struct inode_operations { int (*create) (struct inode *,struct dentry *,int, struct nameidata *); @@ -348,6 +347,7 @@ struct inode_operations { ssize_t (*getxattr) (struct dentry *, const char *, void *, size_t); ssize_t (*listxattr) (struct dentry *, char *, size_t); int (*removexattr) (struct dentry *, const char *); + void (*truncate_range)(struct inode *, loff_t, loff_t); }; Again, all methods are called without any locks being held, unless @@ -444,6 +444,9 @@ otherwise noted. removexattr: called by the VFS to remove an extended attribute from a file. This method is called by removexattr(2) system call. + truncate_range: a method provided by the underlying filesystem to truncate a + range of blocks , i.e. punch a hole somewhere in a file. + The Address Space Object ======================== @@ -522,7 +525,7 @@ struct address_space_operations ------------------------------- This describes how the VFS can manipulate mapping of a file to page cache in -your filesystem. As of kernel 2.6.16, the following members are defined: +your filesystem. As of kernel 2.6.22, the following members are defined: struct address_space_operations { int (*writepage)(struct page *page, struct writeback_control *wbc); @@ -543,6 +546,7 @@ struct address_space_operations { int); /* migrate the contents of a page to the specified target */ int (*migratepage) (struct page *, struct page *); + int (*launder_page) (struct page *); }; writepage: called by the VM to write a dirty page to backing store. @@ -689,6 +693,10 @@ struct address_space_operations { transfer any private data across and update any references that it has to the page. + launder_page: Called before freeing a page - it writes back the dirty page. To + prevent redirtying the page, it is kept locked during the whole + operation. + The File Object =============== @@ -699,9 +707,10 @@ struct file_operations ---------------------- This describes how the VFS can manipulate an open file. As of kernel -2.6.17, the following members are defined: +2.6.22, the following members are defined: struct file_operations { + struct module *owner; loff_t (*llseek) (struct file *, loff_t, int); ssize_t (*read) (struct file *, char __user *, size_t, loff_t *); ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *); @@ -728,10 +737,8 @@ struct file_operations { int (*check_flags)(int); int (*dir_notify)(struct file *filp, unsigned long arg); int (*flock) (struct file *, int, struct file_lock *); - ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, size_t, unsigned -int); - ssize_t (*splice_read)(struct file *, struct pipe_inode_info *, size_t, unsigned -int); + ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, size_t, unsigned int); + ssize_t (*splice_read)(struct file *, struct pipe_inode_info *, size_t, unsigned int); }; Again, all methods are called without any locks being held, unless |