On Wed, Sep 19, 2018 at 7:03 PM, Nikolaus Rath <Nikolaus@xxxxxxxx> wrote: > Hi, > > Are there any conditions under which a write to the fuse file descriptor > may block? > > It seems to me that this should never be the case - except possibly when > sending a FUSE_NOTIFY_INVAL_ENTRY or FUSE_NOTIFY_DELETE request that is > related for to an ongoing file system operation. Here would would much > appreciate if someone could clarify what operations exactly would cause > the write to block. NOTIFY_INVAL_ENTRY and NOTIFY_DELETE lock the parent directory i_mutex. Operations which run under i_mutex of parent are: lookup, symlink, mknod, mkdir, unlink, rmdir, rename, link, create, rename2. Operations which run under i_mutex of object: setattr, unlink, rmdir, rename, setxattr, removexattr, readdir, readdirplus, rename2. > Is it possible that the write blocks indefinitely > because new related operations keep coming? Or will the kernel suspend > sending any new related requests and just wait for the existing ones to > terminate? Shouldn't block indefinitely (lock does not allow starving), unless there's a deadlock caused by calling the invalidate from an op that is itself already holding i_mutex on the parent. Thanks, Miklos
