• David Howells's avatar
    afs: Fix application of status and callback to be under same lock · a58823ac
    David Howells authored
    When applying the status and callback in the response of an operation,
    apply them in the same critical section so that there's no race between
    checking the callback state and checking status-dependent state (such as
    the data version).
    
    Fix this by:
    
     (1) Allocating a joint {status,callback} record (afs_status_cb) before
         calling the RPC function for each vnode for which the RPC reply
         contains a status or a status plus a callback.  A flag is set in the
         record to indicate if a callback was actually received.
    
     (2) These records are passed into the RPC functions to be filled in.  The
         afs_decode_status() and yfs_decode_status() functions are removed and
         the cb_lock is no longer taken.
    
     (3) xdr_decode_AFSFetchStatus() and xdr_decode_YFSFetchStatus() no longer
         update the vnode.
    
     (4) xdr_decode_AFSCallBack() and xdr_decode_YFSCallBack() no longer update
         the vnode.
    
     (5) vnodes, expected data-version numbers and callback break counters
         (cb_break) no longer need to be passed to the reply delivery
         functions.
    
         Note that, for the moment, the file locking functions still need
         access to both the call and the vnode at the same time.
    
     (6) afs_vnode_commit_status() is now given the cb_break value and the
         expected data_version and the task of applying the status and the
         callback to the vnode are now done here.
    
         This is done under a single taking of vnode->cb_lock.
    
     (7) afs_pages_written_back() is now called by afs_store_data() rather than
         by the reply delivery function.
    
         afs_pages_written_back() has been moved to before the call point and
         is now given the first and last page numbers rather than a pointer to
         the call.
    
     (8) The indicator from YFS.RemoveFile2 as to whether the target file
         actually got removed (status.abort_code == VNOVNODE) rather than
         merely dropping a link is now checked in afs_unlink rather than in
         xdr_decode_YFSFetchStatus().
    
    Supplementary fixes:
    
     (*) afs_cache_permit() now gets the caller_access mask from the
         afs_status_cb object rather than picking it out of the vnode's status
         record.  afs_fetch_status() returns caller_access through its argument
         list for this purpose also.
    
     (*) afs_inode_init_from_status() now uses a write lock on cb_lock rather
         than a read lock and now sets the callback inside the same critical
         section.
    
    Fixes: c435ee34 ("afs: Overhaul the callback handling")
    Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
    a58823ac
security.c 10.2 KB