On Wed, 28 Nov 2012 18:23:44 +0400 Pavel Shilovsky <[email protected]> wrote:
> We don't need to permit a write to the area locked with a read lock > by any process including the process that issues the write. > > Signed-off-by: Pavel Shilovsky <[email protected]> > --- > fs/cifs/cifsproto.h | 2 +- > fs/cifs/file.c | 27 ++++++++++++++++++--------- > 2 files changed, 19 insertions(+), 10 deletions(-) > > diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h > index 7e1562d..4883f95 100644 > --- a/fs/cifs/cifsproto.h > +++ b/fs/cifs/cifsproto.h > @@ -187,7 +187,7 @@ extern void cifs_mark_open_files_invalid(struct cifs_tcon > *tcon); > extern bool cifs_find_lock_conflict(struct cifsFileInfo *cfile, __u64 offset, > __u64 length, __u8 type, > struct cifsLockInfo **conf_lock, > - bool rw_check); > + int rw_check); > extern void cifs_add_pending_open(struct cifs_fid *fid, > struct tcon_link *tlink, > struct cifs_pending_open *open); > diff --git a/fs/cifs/file.c b/fs/cifs/file.c > index f8fe1bd..e7fc39c 100644 > --- a/fs/cifs/file.c > +++ b/fs/cifs/file.c > @@ -765,10 +765,15 @@ cifs_del_lock_waiters(struct cifsLockInfo *lock) > } > } > > +#define CIFS_LOCK_OP 0 > +#define CIFS_READ_OP 1 > +#define CIFS_WRITE_OP 2 > + > +/* @rw_check : 0 - no op, 1 - read, 2 - write */ > static bool > cifs_find_fid_lock_conflict(struct cifs_fid_locks *fdlocks, __u64 offset, > __u64 length, __u8 type, struct cifsFileInfo *cfile, > - struct cifsLockInfo **conf_lock, bool rw_check) > + struct cifsLockInfo **conf_lock, int rw_check) > { > struct cifsLockInfo *li; > struct cifsFileInfo *cur_cfile = fdlocks->cfile; > @@ -778,9 +783,13 @@ cifs_find_fid_lock_conflict(struct cifs_fid_locks > *fdlocks, __u64 offset, > if (offset + length <= li->offset || > offset >= li->offset + li->length) > continue; > - if (rw_check && server->ops->compare_fids(cfile, cur_cfile) && > - current->tgid == li->pid) > - continue; > + if (rw_check != CIFS_LOCK_OP && current->tgid == li->pid && > + server->ops->compare_fids(cfile, cur_cfile)) { > + /* shared lock prevents write op through the same fid */ > + if (!(li->type & server->vals->shared_lock_type) || > + rw_check != CIFS_WRITE_OP) > + continue; > + } > if ((type & server->vals->shared_lock_type) && > ((server->ops->compare_fids(cfile, cur_cfile) && > current->tgid == li->pid) || type == li->type)) > @@ -795,7 +804,7 @@ cifs_find_fid_lock_conflict(struct cifs_fid_locks > *fdlocks, __u64 offset, > bool > cifs_find_lock_conflict(struct cifsFileInfo *cfile, __u64 offset, __u64 > length, > __u8 type, struct cifsLockInfo **conf_lock, > - bool rw_check) > + int rw_check) > { > bool rc = false; > struct cifs_fid_locks *cur; > @@ -831,7 +840,7 @@ cifs_lock_test(struct cifsFileInfo *cfile, __u64 offset, > __u64 length, > down_read(&cinode->lock_sem); > > exist = cifs_find_lock_conflict(cfile, offset, length, type, > - &conf_lock, false); > + &conf_lock, CIFS_LOCK_OP); > if (exist) { > flock->fl_start = conf_lock->offset; > flock->fl_end = conf_lock->offset + conf_lock->length - 1; > @@ -878,7 +887,7 @@ try_again: > down_write(&cinode->lock_sem); > > exist = cifs_find_lock_conflict(cfile, lock->offset, lock->length, > - lock->type, &conf_lock, false); > + lock->type, &conf_lock, CIFS_LOCK_OP); > if (!exist && cinode->can_cache_brlcks) { > list_add_tail(&lock->llist, &cfile->llist->locks); > up_write(&cinode->lock_sem); > @@ -2472,7 +2481,7 @@ cifs_writev(struct kiocb *iocb, const struct iovec *iov, > down_read(&cinode->lock_sem); > if (!cifs_find_lock_conflict(cfile, pos, iov_length(iov, nr_segs), > server->vals->exclusive_lock_type, NULL, > - true)) { > + CIFS_WRITE_OP)) { > mutex_lock(&inode->i_mutex); > rc = __generic_file_aio_write(iocb, iov, nr_segs, > &iocb->ki_pos); > @@ -2907,7 +2916,7 @@ cifs_strict_readv(struct kiocb *iocb, const struct > iovec *iov, > down_read(&cinode->lock_sem); > if (!cifs_find_lock_conflict(cfile, pos, iov_length(iov, nr_segs), > tcon->ses->server->vals->shared_lock_type, > - NULL, true)) > + NULL, CIFS_READ_OP)) > rc = generic_file_aio_read(iocb, iov, nr_segs, pos); > up_read(&cinode->lock_sem); > return rc; Code looks ok I guess. I'll have to take your word for it that the windows locking semantics here are correct though... Reviewed-by: Jeff Layton <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
