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, 0 insertions, 2 deletions

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index b2c5784092cf..f1ed3a1bf8aa 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -420,7 +420,6 @@ struct gfs2_tune {
         unsigned int gt_quota_scale_den; /* Denominator */
         unsigned int gt_quota_cache_secs;
         unsigned int gt_quota_quantum; /* Secs between syncs to quota file */
-        unsigned int gt_atime_quantum; /* Min secs between atime updates */
         unsigned int gt_new_files_jdata;
         unsigned int gt_max_readahead; /* Max bytes to read-ahead from disk */
         unsigned int gt_stall_secs; /* Detects trouble! */
@@ -433,7 +432,6 @@ enum {
         SDF_JOURNAL_CHECKED     = 0,
         SDF_JOURNAL_LIVE        = 1,
         SDF_SHUTDOWN            = 2,
-        SDF_NOATIME             = 3,
 };
 
 #define GFS2_FSNAME_LEN         256