GFS2: high time to take some time over atime

Until now, we've used the same scheme as GFS1 for atime. This has failed
since atime is a per vfsmnt flag, not a per fs flag and as such the
"noatime" flag was not getting passed down to the filesystems. This
patch removes all the "special casing" around atime updates and we
simply use the VFS's atime code.

The net result is that GFS2 will now support all the same atime related
mount options of any other filesystem on a per-vfsmnt basis. We do lose
the "lazy atime" updates, but we gain "relatime". We could add lazy
atime to the VFS at a later date, if there is a requirement for that
variant still - I suspect relatime will be enough.

Also we lose about 100 lines of code after this patch has been applied,
and I have a suspicion that it will speed things up a bit, even when
atime is "on". So it seems like a nice clean up as well.

From a user perspective, everything stays the same except the loss of
the per-fs atime quantum tweekable (ought to be per-vfsmnt at the very
least, and to be honest I don't think anybody ever used it) and that a
number of options which were ignored before now work correctly.

Please let me know if you've got any comments. I'm pushing this out
early so that you can all see what my plans are.

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

1 files changed, 8 insertions, 8 deletions

diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c
index ae7126aeb447..27563816e1c5 100644
--- a/fs/gfs2/ops_address.c
+++ b/fs/gfs2/ops_address.c
@@ -512,8 +512,8 @@ static int gfs2_readpage(struct file *file, struct page *page)
         int error;
 
         unlock_page(page);
-        gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &gh);
-        error = gfs2_glock_nq_atime(&gh);
+        gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
+        error = gfs2_glock_nq(&gh);
         if (unlikely(error))
                 goto out;
         error = AOP_TRUNCATED_PAGE;
@@ -594,8 +594,8 @@ static int gfs2_readpages(struct file *file, struct address_space *mapping,
         struct gfs2_holder gh;
         int ret;
 
-        gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &gh);
-        ret = gfs2_glock_nq_atime(&gh);
+        gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
+        ret = gfs2_glock_nq(&gh);
         if (unlikely(ret))
                 goto out_uninit;
         if (!gfs2_is_stuffed(ip))
@@ -636,8 +636,8 @@ static int gfs2_write_begin(struct file *file, struct address_space *mapping,
         unsigned to = from + len;
         struct page *page;
 
-        gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_ATIME, &ip->i_gh);
-        error = gfs2_glock_nq_atime(&ip->i_gh);
+        gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
+        error = gfs2_glock_nq(&ip->i_gh);
         if (unlikely(error))
                 goto out_uninit;
 
@@ -1000,8 +1000,8 @@ static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
          * unfortunately have the option of only flushing a range like
          * the VFS does.
          */
-        gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, GL_ATIME, &gh);
-        rv = gfs2_glock_nq_atime(&gh);
+        gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
+        rv = gfs2_glock_nq(&gh);
         if (rv)
                 return rv;
         rv = gfs2_ok_for_dio(ip, rw, offset);