ocfs2: revert iput deferring code in ocfs2_drop_dentry_lock

The following patches are reverted in this patch because these patches
caused performance regression in the remote unlink() calls.

  ea455f8ab683 - ocfs2: Push out dropping of dentry lock to ocfs2_wq
  f7b1aa69be13 - ocfs2: Fix deadlock on umount
  5fd131893793 - ocfs2: Don't oops in ocfs2_kill_sb on a failed mount

Previous patches in this series removed the possible deadlocks from
downconvert thread so the above patches shouldn't be needed anymore.

The regression is caused because these patches delay the iput() in case
of dentry unlocks.  This also delays the unlocking of the open lockres.
The open lockresource is required to test if the inode can be wiped from
disk or not.  When the deleting node does not get the open lock, it
marks it as orphan (even though it is not in use by another
node/process) and causes a journal checkpoint.  This delays operations
following the inode eviction.  This also moves the inode to the orphaned
inode which further causes more I/O and a lot of unneccessary orphans.

The following script can be used to generate the load causing issues:

  declare -a create
  declare -a remove
  declare -a iterations=(1 2 4 8 16 32 64 128 256 512 1024 2048 4096 8192 16384)
  unique="`mktemp -u XXXXX`"
  script="/tmp/idontknow-${unique}.sh"
  cat <<EOF > "${script}"
  for n in {1..8}; do mkdir -p test/dir\${n}
    eval touch test/dir\${n}/foo{1.."\$1"}
  done
  EOF
  chmod 700 "${script}"

  function fcreate ()
  {
    exec 2>&1 /usr/bin/time --format=%E "${script}" "$1"
  }

  function fremove ()
  {
    exec 2>&1 /usr/bin/time --format=%E ssh node2 "cd `pwd`; rm -Rf test*"
  }

  function fcp ()
  {
    exec 2>&1 /usr/bin/time --format=%E ssh node3 "cd `pwd`; cp -R test test.new"
  }

  echo -------------------------------------------------
  echo "| # files | create #s | copy #s | remove #s |"
  echo -------------------------------------------------
  for ((x=0; x < ${#iterations[*]} ; x++)) do
    create[$x]="`fcreate ${iterations[$x]}`"
    copy[$x]="`fcp ${iterations[$x]}`"
    remove[$x]="`fremove`"
    printf "| %8d | %9s | %9s | %9s |\n" ${iterations[$x]} ${create[$x]} ${copy[$x]} ${remove[$x]}
  done
  rm "${script}"
  echo "------------------------"

Signed-off-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 58 deletions

diff --git a/fs/ocfs2/dcache.c b/fs/ocfs2/dcache.c
index 0d3a97d2d5f6..e2e05a106beb 100644
--- a/fs/ocfs2/dcache.c
+++ b/fs/ocfs2/dcache.c
@@ -37,7 +37,6 @@
 #include "dlmglue.h"
 #include "file.h"
 #include "inode.h"
-#include "super.h"
 #include "ocfs2_trace.h"
 
 void ocfs2_dentry_attach_gen(struct dentry *dentry)
@@ -346,52 +345,6 @@ out_attach:
         return ret;
 }
 
-DEFINE_SPINLOCK(dentry_list_lock);
-
-/* We limit the number of dentry locks to drop in one go. We have
- * this limit so that we don't starve other users of ocfs2_wq. */
-#define DL_INODE_DROP_COUNT 64
-
-/* Drop inode references from dentry locks */
-static void __ocfs2_drop_dl_inodes(struct ocfs2_super *osb, int drop_count)
-{
-        struct ocfs2_dentry_lock *dl;
-
-        spin_lock(&dentry_list_lock);
-        while (osb->dentry_lock_list && (drop_count < 0 || drop_count--)) {
-                dl = osb->dentry_lock_list;
-                osb->dentry_lock_list = dl->dl_next;
-                spin_unlock(&dentry_list_lock);
-                iput(dl->dl_inode);
-                kfree(dl);
-                spin_lock(&dentry_list_lock);
-        }
-        spin_unlock(&dentry_list_lock);
-}
-
-void ocfs2_drop_dl_inodes(struct work_struct *work)
-{
-        struct ocfs2_super *osb = container_of(work, struct ocfs2_super,
-                                               dentry_lock_work);
-
-        __ocfs2_drop_dl_inodes(osb, DL_INODE_DROP_COUNT);
-        /*
-         * Don't queue dropping if umount is in progress. We flush the
-         * list in ocfs2_dismount_volume
-         */
-        spin_lock(&dentry_list_lock);
-        if (osb->dentry_lock_list &&
-            !ocfs2_test_osb_flag(osb, OCFS2_OSB_DROP_DENTRY_LOCK_IMMED))
-                queue_work(ocfs2_wq, &osb->dentry_lock_work);
-        spin_unlock(&dentry_list_lock);
-}
-
-/* Flush the whole work queue */
-void ocfs2_drop_all_dl_inodes(struct ocfs2_super *osb)
-{
-        __ocfs2_drop_dl_inodes(osb, -1);
-}
-
 /*
  * ocfs2_dentry_iput() and friends.
  *
@@ -416,24 +369,16 @@ void ocfs2_drop_all_dl_inodes(struct ocfs2_super *osb)
 static void ocfs2_drop_dentry_lock(struct ocfs2_super *osb,
                                    struct ocfs2_dentry_lock *dl)
 {
+        iput(dl->dl_inode);
         ocfs2_simple_drop_lockres(osb, &dl->dl_lockres);
         ocfs2_lock_res_free(&dl->dl_lockres);
-
-        /* We leave dropping of inode reference to ocfs2_wq as that can
-         * possibly lead to inode deletion which gets tricky */
-        spin_lock(&dentry_list_lock);
-        if (!osb->dentry_lock_list &&
-            !ocfs2_test_osb_flag(osb, OCFS2_OSB_DROP_DENTRY_LOCK_IMMED))
-                queue_work(ocfs2_wq, &osb->dentry_lock_work);
-        dl->dl_next = osb->dentry_lock_list;
-        osb->dentry_lock_list = dl;
-        spin_unlock(&dentry_list_lock);
+        kfree(dl);
 }
 
 void ocfs2_dentry_lock_put(struct ocfs2_super *osb,
                            struct ocfs2_dentry_lock *dl)
 {
-        int unlock;
+        int unlock = 0;
 
         BUG_ON(dl->dl_count == 0);