descriptors). The freshly allocated file structure is initialized with
a pointer to the dentry and a set of file operation member functions.
These are taken from the inode data. The open() file method is then
-called so the specific filesystem implementation can do it's work. You
+called so the specific filesystem implementation can do its work. You
can see that this is another switch performed by the VFS. The file
structure is placed into the file descriptor table for the process.
void (*put_super) (struct super_block *);
void (*write_super) (struct super_block *);
int (*sync_fs)(struct super_block *sb, int wait);
- void (*write_super_lockfs) (struct super_block *);
- void (*unlockfs) (struct super_block *);
+ int (*freeze_fs) (struct super_block *);
+ int (*unfreeze_fs) (struct super_block *);
int (*statfs) (struct dentry *, struct kstatfs *);
int (*remount_fs) (struct super_block *, int *, char *);
void (*clear_inode) (struct inode *);
a superblock. The second parameter indicates whether the method
should wait until the write out has been completed. Optional.
- write_super_lockfs: called when VFS is locking a filesystem and
+ freeze_fs: called when VFS is locking a filesystem and
forcing it into a consistent state. This method is currently
used by the Logical Volume Manager (LVM).
- unlockfs: called when VFS is unlocking a filesystem and making it writable
+ unfreeze_fs: called when VFS is unlocking a filesystem and making it writable
again.
- statfs: called when the VFS needs to get filesystem statistics. This
- is called with the kernel lock held
+ statfs: called when the VFS needs to get filesystem statistics.
remount_fs: called when the filesystem is remounted. This is called
with the kernel lock held
writing out the whole address_space.
The Writeback tag is used by filemap*wait* and sync_page* functions,
-via wait_on_page_writeback_range, to wait for all writeback to
+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.
address_space has finer control of write sizes.
The read process essentially only requires 'readpage'. The write
-process is more complicated and uses prepare_write/commit_write or
+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.
int (*set_page_dirty)(struct page *page);
int (*readpages)(struct file *filp, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages);
- int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
- int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
int (*write_begin)(struct file *, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata);
/* migrate the contents of a page to the specified target */
int (*migratepage) (struct page *, struct page *);
int (*launder_page) (struct page *);
+ int (*error_remove_page) (struct mapping *mapping, struct page *page);
};
writepage: called by the VM to write a dirty page to backing store.
readpages is only used for read-ahead, so read errors are
ignored. If anything goes wrong, feel free to give up.
- prepare_write: called by the generic write path in VM to set up a write
- request for a page. This indicates to the address space that
- the given range of bytes is about to be written. The
- address_space should check that the write will be able to
- complete, by allocating space if necessary and doing any other
- internal housekeeping. If the write will update parts of
- any basic-blocks on storage, then those blocks should be
- pre-read (if they haven't been read already) so that the
- updated blocks can be written out properly.
- The page will be locked.
-
- Note: the page _must not_ be marked uptodate in this function
- (or anywhere else) unless it actually is uptodate right now. As
- soon as a page is marked uptodate, it is possible for a concurrent
- read(2) to copy it to userspace.
-
- commit_write: If prepare_write succeeds, new data will be copied
- into the page and then commit_write will be called. It will
- typically update the size of the file (if appropriate) and
- mark the inode as dirty, and do any other related housekeeping
- operations. It should avoid returning an error if possible -
- errors should have been handled by prepare_write.
-
- write_begin: This is intended as a replacement for prepare_write. The
- key differences being that:
- - it returns a locked page (in *pagep) rather than being
- given a pre locked page;
- - it must be able to cope with short writes (where the
- length passed to write_begin is greater than the number
- of bytes copied into the page).
-
+ write_begin:
Called by the generic buffered write code to ask the filesystem to
prepare to write len bytes at the given offset in the file. The
address_space should check that the write will be able to complete,
The filesystem must return the locked pagecache page for the specified
offset, in *pagep, for the caller to write into.
+ It must be able to cope with short writes (where the length passed to
+ write_begin is greater than the number of bytes copied into the page).
+
flags is a field for AOP_FLAG_xxx flags, described in
include/linux/fs.h.
prevent redirtying the page, it is kept locked during the whole
operation.
+ error_remove_page: normally set to generic_error_remove_page if truncation
+ is ok for this address space. Used for memory failure handling.
+ Setting this implies you deal with pages going away under you,
+ unless you have them locked or reference counts increased.
+
+
The File Object
===============
int (*open) (struct inode *, struct file *);
int (*flush) (struct file *);
int (*release) (struct inode *, struct file *);
- int (*fsync) (struct file *, struct dentry *, int datasync);
+ int (*fsync) (struct file *, int datasync);
int (*aio_fsync) (struct kiocb *, int datasync);
int (*fasync) (int, struct file *, int);
int (*lock) (struct file *, int, struct file_lock *);
ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
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);
check_flags: called by the fcntl(2) system call for F_SETFL command
- dir_notify: called by the fcntl(2) system call for F_NOTIFY command
-
flock: called by the flock(2) system call
splice_write: called by the VFS to splice data from a pipe to a file. This
d_lookup: look up a dentry given its parent and path name component
It looks up the child of that given name from the dcache
hash table. If it is found, the reference count is incremented
- and the dentry is returned. The caller must use d_put()
+ and the dentry is returned. The caller must use dput()
to free the dentry when it finishes using it.
For further information on dentry locking, please refer to the document
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff