• C
    add a vfs_fsync helper · 4c728ef5
    Christoph Hellwig 提交于
    Fsync currently has a fdatawrite/fdatawait pair around the method call,
    and a mutex_lock/unlock of the inode mutex.  All callers of fsync have
    to duplicate this, but we have a few and most of them don't quite get
    it right.  This patch adds a new vfs_fsync that takes care of this.
    It's a little more complicated as usual as ->fsync might get a NULL file
    pointer and just a dentry from nfsd, but otherwise gets afile and we
    want to take the mapping and file operations from it when it is there.
    
    Notes on the fsync callers:
    
     - ecryptfs wasn't calling filemap_fdatawrite / filemap_fdatawait on the
       	lower file
     - coda wasn't calling filemap_fdatawrite / filemap_fdatawait on the host
    	file, and returning 0 when ->fsync was missing
     - shm wasn't calling either filemap_fdatawrite / filemap_fdatawait nor
       taking i_mutex.  Now given that shared memory doesn't have disk
       backing not doing anything in fsync seems fine and I left it out of
       the vfs_fsync conversion for now, but in that case we might just
       not pass it through to the lower file at all but just call the no-op
       simple_sync_file directly.
    
    [and now actually export vfs_fsync]
    Signed-off-by: NChristoph Hellwig <hch@lst.de>
    Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
    4c728ef5
vfs.c 50.7 KB