[GFS2] Alter direct I/O path

As per comments received, alter the GFS2 direct I/O path so that
it uses the standard read functions "out of the box". Needs a
small change to one of the VFS functions. This reduces the size
of the code quite a lot and also removes the need for one new export.

Some more work remains to be done, but this is the bones of the
thing.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 16 insertions, 38 deletions

diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c
index 031270ad55e2..d33f6aa79731 100644
--- a/fs/gfs2/ops_address.c
+++ b/fs/gfs2/ops_address.c
@@ -589,8 +589,9 @@ static void gfs2_invalidatepage(struct page *page, unsigned long offset)
         return;
 }
 
-static ssize_t gfs2_direct_IO_write(struct kiocb *iocb, const struct iovec *iov,
-                                    loff_t offset, unsigned long nr_segs)
+static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
+                              const struct iovec *iov, loff_t offset,
+                              unsigned long nr_segs)
 {
         struct file *file = iocb->ki_filp;
         struct inode *inode = file->f_mapping->host;
@@ -598,8 +599,10 @@ static ssize_t gfs2_direct_IO_write(struct kiocb *iocb, const struct iovec *iov,
         struct gfs2_holder gh;
         int rv;
 
+        if (rw == READ)
+                mutex_lock(&inode->i_mutex);
         /*
-         * Shared lock, even though its write, since we do no allocation
+         * Shared lock, even if its a write, since we do no allocation
          * on this path. All we need change is atime.
          */
         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &gh);
@@ -607,6 +610,9 @@ static ssize_t gfs2_direct_IO_write(struct kiocb *iocb, const struct iovec *iov,
         if (rv)
                 goto out;
 
+        if (offset > i_size_read(inode))
+                goto out;
+
         /*
          * Should we return an error here? I can't see that O_DIRECT for
          * a journaled file makes any sense. For now we'll silently fall
@@ -619,48 +625,20 @@ static ssize_t gfs2_direct_IO_write(struct kiocb *iocb, const struct iovec *iov,
         if (gfs2_is_stuffed(ip))
                 goto out;
 
-        rv = __blockdev_direct_IO(WRITE, iocb, inode, inode->i_sb->s_bdev,
-                                  iov, offset, nr_segs, gfs2_get_block,
-                                  NULL, DIO_OWN_LOCKING);
+        rv = blockdev_direct_IO_own_locking(rw, iocb, inode,
+                                            inode->i_sb->s_bdev,
+                                            iov, offset, nr_segs,
+                                            gfs2_get_block, NULL);
 out:
         gfs2_glock_dq_m(1, &gh);
         gfs2_holder_uninit(&gh);
+        if (rw == READ)
+                mutex_unlock(&inode->i_mutex);
 
         return rv;
 }
 
 /**
- * gfs2_direct_IO
- *
- * This is called with a shared lock already held for the read path.
- * Currently, no locks are held when the write path is called.
- */
-static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
-                              const struct iovec *iov, loff_t offset,
-                              unsigned long nr_segs)
-{
-        struct file *file = iocb->ki_filp;
-        struct inode *inode = file->f_mapping->host;
-        struct gfs2_inode *ip = GFS2_I(inode);
-        struct gfs2_sbd *sdp = GFS2_SB(inode);
-        int ret;
-
-        if (rw == WRITE)
-                return gfs2_direct_IO_write(iocb, iov, offset, nr_segs);
-
-        if (gfs2_assert_warn(sdp, gfs2_glock_is_locked_by_me(ip->i_gl)) ||
-            gfs2_assert_warn(sdp, !gfs2_is_stuffed(ip)))
-                return -EINVAL;
-
-        mutex_lock(&inode->i_mutex);
-        ret = __blockdev_direct_IO(READ, iocb, inode, inode->i_sb->s_bdev, iov,
-                                   offset, nr_segs, gfs2_get_block, NULL,
-                                   DIO_OWN_LOCKING);
-        mutex_unlock(&inode->i_mutex);
-        return ret;
-}
-
-/**
  * stuck_releasepage - We're stuck in gfs2_releasepage().  Print stuff out.
  * @bh: the buffer we're stuck on
  *
@@ -765,7 +743,7 @@ int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
         }
         while (bh != head);
 
- out:
+out:
         return try_to_free_buffers(page);
 }