• David Howells's avatar
    afs: Build an abstraction around an "operation" concept · e49c7b2f
    David Howells authored
    Turn the afs_operation struct into the main way that most fileserver
    operations are managed.  Various things are added to the struct, including
    the following:
    
     (1) All the parameters and results of the relevant operations are moved
         into it, removing corresponding fields from the afs_call struct.
         afs_call gets a pointer to the op.
    
     (2) The target volume is made the main focus of the operation, rather than
         the target vnode(s), and a bunch of op->vnode->volume are made
         op->volume instead.
    
     (3) Two vnode records are defined (op->file[]) for the vnode(s) involved
         in most operations.  The vnode record (struct afs_vnode_param)
         contains:
    
    	- The vnode pointer.
    
    	- The fid of the vnode to be included in the parameters or that was
              returned in the reply (eg. FS.MakeDir).
    
    	- The status and callback information that may be returned in the
         	  reply about the vnode.
    
    	- Callback break and data version tracking for detecting
              simultaneous third-parth changes.
    
     (4) Pointers to dentries to be updated with new inodes.
    
     (5) An operations table pointer.  The table includes pointers to functions
         for issuing AFS and YFS-variant RPCs, handling the success and abort
         of an operation and handling post-I/O-lock local editing of a
         directory.
    
    To make this work, the following function restructuring is made:
    
     (A) The rotation loop that issues calls to fileservers that can be found
         in each function that wants to issue an RPC (such as afs_mkdir()) is
         extracted out into common code, in a new file called fs_operation.c.
    
     (B) The rotation loops, such as the one in afs_mkdir(), are replaced with
         a much smaller piece of code that allocates an operation, sets the
         parameters and then calls out to the common code to do the actual
         work.
    
     (C) The code for handling the success and failure of an operation are
         moved into operation functions (as (5) above) and these are called
         from the core code at appropriate times.
    
     (D) The pseudo inode getting stuff used by the dynamic root code is moved
         over into dynroot.c.
    
     (E) struct afs_iget_data is absorbed into the operation struct and
         afs_iget() expects to be given an op pointer and a vnode record.
    
     (F) Point (E) doesn't work for the root dir of a volume, but we know the
         FID in advance (it's always vnode 1, unique 1), so a separate inode
         getter, afs_root_iget(), is provided to special-case that.
    
     (G) The inode status init/update functions now also take an op and a vnode
         record.
    
     (H) The RPC marshalling functions now, for the most part, just take an
         afs_operation struct as their only argument.  All the data they need
         is held there.  The result delivery functions write their answers
         there as well.
    
     (I) The call is attached to the operation and then the operation core does
         the waiting.
    
    And then the new operation code is, for the moment, made to just initialise
    the operation, get the appropriate vnode I/O locks and do the same rotation
    loop as before.
    
    This lays the foundation for the following changes in the future:
    
     (*) Overhauling the rotation (again).
    
     (*) Support for asynchronous I/O, where the fileserver rotation must be
         done asynchronously also.
    Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
    e49c7b2f
write.c 21.3 KB