diff options
Diffstat (limited to 'Documentation/filesystems/vfs.txt')
| -rw-r--r-- | Documentation/filesystems/vfs.txt | 47 |
1 files changed, 14 insertions, 33 deletions
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index 829a7b7857a4..4b2084d0f1fb 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -386,7 +386,7 @@ struct inode_operations { ssize_t (*listxattr) (struct dentry *, char *, size_t); void (*update_time)(struct inode *, struct timespec *, int); int (*atomic_open)(struct inode *, struct dentry *, struct file *, - unsigned open_flag, umode_t create_mode, int *opened); + unsigned open_flag, umode_t create_mode); int (*tmpfile) (struct inode *, struct dentry *, umode_t); }; @@ -496,13 +496,15 @@ otherwise noted. atomic_open: called on the last component of an open. Using this optional method the filesystem can look up, possibly create and open the file in - one atomic operation. If it cannot perform this (e.g. the file type - turned out to be wrong) it may signal this by returning 1 instead of - usual 0 or -ve . This method is only called if the last component is - negative or needs lookup. Cached positive dentries are still handled by - f_op->open(). If the file was created, the FILE_CREATED flag should be - set in "opened". In case of O_EXCL the method must only succeed if the - file didn't exist and hence FILE_CREATED shall always be set on success. + one atomic operation. If it wants to leave actual opening to the + caller (e.g. if the file turned out to be a symlink, device, or just + something filesystem won't do atomic open for), it may signal this by + returning finish_no_open(file, dentry). This method is only called if + the last component is negative or needs lookup. Cached positive dentries + are still handled by f_op->open(). If the file was created, + FMODE_CREATED flag should be set in file->f_mode. In case of O_EXCL + the method must only succeed if the file didn't exist and hence FMODE_CREATED + shall always be set on success. tmpfile: called in the end of O_TMPFILE open(). Optional, equivalent to atomically creating, opening and unlinking a file in given directory. @@ -857,8 +859,6 @@ struct file_operations { ssize_t (*write_iter) (struct kiocb *, struct iov_iter *); int (*iterate) (struct file *, struct dir_context *); __poll_t (*poll) (struct file *, struct poll_table_struct *); - struct wait_queue_head * (*get_poll_head)(struct file *, __poll_t); - __poll_t (*poll_mask) (struct file *, __poll_t); long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); long (*compat_ioctl) (struct file *, unsigned int, unsigned long); int (*mmap) (struct file *, struct vm_area_struct *); @@ -903,17 +903,6 @@ otherwise noted. activity on this file and (optionally) go to sleep until there is activity. Called by the select(2) and poll(2) system calls - get_poll_head: Returns the struct wait_queue_head that callers can - wait on. Callers need to check the returned events using ->poll_mask - once woken. Can return NULL to indicate polling is not supported, - or any error code using the ERR_PTR convention to indicate that a - grave error occured and ->poll_mask shall not be called. - - poll_mask: return the mask of EPOLL* values describing the file descriptor - state. Called either before going to sleep on the waitqueue returned by - get_poll_head, or after it has been woken. If ->get_poll_head and - ->poll_mask are implemented ->poll does not need to be implement. - unlocked_ioctl: called by the ioctl(2) system call. compat_ioctl: called by the ioctl(2) system call when 32 bit system calls @@ -1000,8 +989,7 @@ struct dentry_operations { char *(*d_dname)(struct dentry *, char *, int); struct vfsmount *(*d_automount)(struct path *); int (*d_manage)(const struct path *, bool); - struct dentry *(*d_real)(struct dentry *, const struct inode *, - unsigned int, unsigned int); + struct dentry *(*d_real)(struct dentry *, const struct inode *); }; d_revalidate: called when the VFS needs to revalidate a dentry. This @@ -1135,22 +1123,15 @@ struct dentry_operations { dentry being transited from. 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 + the underlying dentries hidden by the overlay. It is used in two different modes: - 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. + non-NULL inode argument. - This method is never called with both non-NULL inode and non-zero flags. + With NULL inode the topmost real underlying dentry is returned. 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 |