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
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
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.
int (*releasepage) (struct page *, int);
void (*freepage)(struct page *);
ssize_t (*direct_IO)(struct kiocb *, struct iov_iter *iter);
+ /* isolate a page for migration */
+ bool (*isolate_page) (struct page *, isolate_mode_t);
/* migrate the contents of a page to the specified target */
int (*migratepage) (struct page *, struct page *);
+ /* put migration-failed page back to right list */
+ void (*putback_page) (struct page *);
int (*launder_page) (struct page *);
+
int (*is_partially_uptodate) (struct page *, unsigned long,
unsigned long);
void (*is_dirty_writeback) (struct page *, bool *, bool *);
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
and transfer data directly between the storage and the
application's address space.
+ isolate_page: Called by the VM when isolating a movable non-lru page.
+ If page is successfully isolated, VM marks the page as PG_isolated
+ via __SetPageIsolated.
+
migrate_page: This is used to compact the physical memory usage.
If the VM wants to relocate a page (maybe off a memory card
that is signalling imminent failure) it will pass a new page
transfer any private data across and update any references
that it has to the page.
+ putback_page: Called by the VM when isolated page's migration fails.
+
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.
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 *);
+ 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);
+ struct dentry *(*d_real)(struct dentry *, const struct inode *,
+ unsigned int);
};
d_revalidate: called when the VFS needs to revalidate a dentry. This
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
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
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
projects / cascardo / linux.git / blobdiff