[XFS] shrink mrlock_t

The writer field is not needed for non_DEBU builds so remove it. While
we're at i also clean up the interface for is locked asserts to go through
and xfs_iget.c helper with an interface like the xfs_ilock routines to
isolated the XFS codebase from mrlock internals. That way we can kill
mrlock_t entirely once rw_semaphores grow an islocked facility. Also
remove unused flags to the ilock family of functions.

SGI-PV: 976035
SGI-Modid: xfs-linux-melb:xfs-kern:30902a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

1 files changed, 76 insertions, 64 deletions

diff --git a/fs/xfs/xfs_iget.c b/fs/xfs/xfs_iget.c
index e657c5128460..b07604b94d9f 100644
--- a/fs/xfs/xfs_iget.c
+++ b/fs/xfs/xfs_iget.c
@@ -593,8 +593,9 @@ xfs_iunlock_map_shared(
  *              XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL
  */
 void
-xfs_ilock(xfs_inode_t   *ip,
-          uint          lock_flags)
+xfs_ilock(
+        xfs_inode_t             *ip,
+        uint                    lock_flags)
 {
         /*
          * You can't set both SHARED and EXCL for the same lock,
@@ -607,16 +608,16 @@ xfs_ilock(xfs_inode_t	*ip,
                (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
         ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
 
-        if (lock_flags & XFS_IOLOCK_EXCL) {
+        if (lock_flags & XFS_IOLOCK_EXCL)
                 mrupdate_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));
-        } else if (lock_flags & XFS_IOLOCK_SHARED) {
+        else if (lock_flags & XFS_IOLOCK_SHARED)
                 mraccess_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));
-        }
-        if (lock_flags & XFS_ILOCK_EXCL) {
+
+        if (lock_flags & XFS_ILOCK_EXCL)
                 mrupdate_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
-        } else if (lock_flags & XFS_ILOCK_SHARED) {
+        else if (lock_flags & XFS_ILOCK_SHARED)
                 mraccess_nested(&ip->i_lock, XFS_ILOCK_DEP(lock_flags));
-        }
+
         xfs_ilock_trace(ip, 1, lock_flags, (inst_t *)__return_address);
 }
 
@@ -631,15 +632,12 @@ xfs_ilock(xfs_inode_t	*ip,
  * lock_flags -- this parameter indicates the inode's locks to be
  *       to be locked.  See the comment for xfs_ilock() for a list
  *       of valid values.
- *
  */
 int
-xfs_ilock_nowait(xfs_inode_t    *ip,
-                 uint           lock_flags)
+xfs_ilock_nowait(
+        xfs_inode_t             *ip,
+        uint                    lock_flags)
 {
-        int     iolocked;
-        int     ilocked;
-
         /*
          * You can't set both SHARED and EXCL for the same lock,
          * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
@@ -651,37 +649,30 @@ xfs_ilock_nowait(xfs_inode_t	*ip,
                (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
         ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_DEP_MASK)) == 0);
 
-        iolocked = 0;
         if (lock_flags & XFS_IOLOCK_EXCL) {
-                iolocked = mrtryupdate(&ip->i_iolock);
-                if (!iolocked) {
-                        return 0;
-                }
+                if (!mrtryupdate(&ip->i_iolock))
+                        goto out;
         } else if (lock_flags & XFS_IOLOCK_SHARED) {
-                iolocked = mrtryaccess(&ip->i_iolock);
-                if (!iolocked) {
-                        return 0;
-                }
+                if (!mrtryaccess(&ip->i_iolock))
+                        goto out;
         }
         if (lock_flags & XFS_ILOCK_EXCL) {
-                ilocked = mrtryupdate(&ip->i_lock);
-                if (!ilocked) {
-                        if (iolocked) {
-                                mrunlock(&ip->i_iolock);
-                        }
-                        return 0;
-                }
+                if (!mrtryupdate(&ip->i_lock))
+                        goto out_undo_iolock;
         } else if (lock_flags & XFS_ILOCK_SHARED) {
-                ilocked = mrtryaccess(&ip->i_lock);
-                if (!ilocked) {
-                        if (iolocked) {
-                                mrunlock(&ip->i_iolock);
-                        }
-                        return 0;
-                }
+                if (!mrtryaccess(&ip->i_lock))
+                        goto out_undo_iolock;
         }
         xfs_ilock_trace(ip, 2, lock_flags, (inst_t *)__return_address);
         return 1;
+
+ out_undo_iolock:
+        if (lock_flags & XFS_IOLOCK_EXCL)
+                mrunlock_excl(&ip->i_iolock);
+        else if (lock_flags & XFS_IOLOCK_SHARED)
+                mrunlock_shared(&ip->i_iolock);
+ out:
+        return 0;
 }
 
 /*
@@ -697,8 +688,9 @@ xfs_ilock_nowait(xfs_inode_t	*ip,
  *
  */
 void
-xfs_iunlock(xfs_inode_t *ip,
-            uint        lock_flags)
+xfs_iunlock(
+        xfs_inode_t             *ip,
+        uint                    lock_flags)
 {
         /*
          * You can't set both SHARED and EXCL for the same lock,
@@ -713,31 +705,25 @@ xfs_iunlock(xfs_inode_t	*ip,
                         XFS_LOCK_DEP_MASK)) == 0);
         ASSERT(lock_flags != 0);
 
-        if (lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) {
-                ASSERT(!(lock_flags & XFS_IOLOCK_SHARED) ||
-                       (ismrlocked(&ip->i_iolock, MR_ACCESS)));
-                ASSERT(!(lock_flags & XFS_IOLOCK_EXCL) ||
-                       (ismrlocked(&ip->i_iolock, MR_UPDATE)));
-                mrunlock(&ip->i_iolock);
-        }
+        if (lock_flags & XFS_IOLOCK_EXCL)
+                mrunlock_excl(&ip->i_iolock);
+        else if (lock_flags & XFS_IOLOCK_SHARED)
+                mrunlock_shared(&ip->i_iolock);
 
-        if (lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) {
-                ASSERT(!(lock_flags & XFS_ILOCK_SHARED) ||
-                       (ismrlocked(&ip->i_lock, MR_ACCESS)));
-                ASSERT(!(lock_flags & XFS_ILOCK_EXCL) ||
-                       (ismrlocked(&ip->i_lock, MR_UPDATE)));
-                mrunlock(&ip->i_lock);
+        if (lock_flags & XFS_ILOCK_EXCL)
+                mrunlock_excl(&ip->i_lock);
+        else if (lock_flags & XFS_ILOCK_SHARED)
+                mrunlock_shared(&ip->i_lock);
 
+        if ((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) &&
+            !(lock_flags & XFS_IUNLOCK_NONOTIFY) && ip->i_itemp) {
                 /*
                  * Let the AIL know that this item has been unlocked in case
                  * it is in the AIL and anyone is waiting on it.  Don't do
                  * this if the caller has asked us not to.
                  */
-                if (!(lock_flags & XFS_IUNLOCK_NONOTIFY) &&
-                     ip->i_itemp != NULL) {
-                        xfs_trans_unlocked_item(ip->i_mount,
-                                                (xfs_log_item_t*)(ip->i_itemp));
-                }
+                xfs_trans_unlocked_item(ip->i_mount,
+                                        (xfs_log_item_t*)(ip->i_itemp));
         }
         xfs_ilock_trace(ip, 3, lock_flags, (inst_t *)__return_address);
 }
@@ -747,21 +733,47 @@ xfs_iunlock(xfs_inode_t	*ip,
  * if it is being demoted.
  */
 void
-xfs_ilock_demote(xfs_inode_t    *ip,
-                 uint           lock_flags)
+xfs_ilock_demote(
+        xfs_inode_t             *ip,
+        uint                    lock_flags)
 {
         ASSERT(lock_flags & (XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL));
         ASSERT((lock_flags & ~(XFS_IOLOCK_EXCL|XFS_ILOCK_EXCL)) == 0);
 
-        if (lock_flags & XFS_ILOCK_EXCL) {
-                ASSERT(ismrlocked(&ip->i_lock, MR_UPDATE));
+        if (lock_flags & XFS_ILOCK_EXCL)
                 mrdemote(&ip->i_lock);
-        }
-        if (lock_flags & XFS_IOLOCK_EXCL) {
-                ASSERT(ismrlocked(&ip->i_iolock, MR_UPDATE));
+        if (lock_flags & XFS_IOLOCK_EXCL)
                 mrdemote(&ip->i_iolock);
+}
+
+#ifdef DEBUG
+/*
+ * Debug-only routine, without additional rw_semaphore APIs, we can
+ * now only answer requests regarding whether we hold the lock for write
+ * (reader state is outside our visibility, we only track writer state).
+ *
+ * Note: this means !xfs_isilocked would give false positives, so don't do that.
+ */
+int
+xfs_isilocked(
+        xfs_inode_t             *ip,
+        uint                    lock_flags)
+{
+        if ((lock_flags & (XFS_ILOCK_EXCL|XFS_ILOCK_SHARED)) ==
+                        XFS_ILOCK_EXCL) {
+                if (!ip->i_lock.mr_writer)
+                        return 0;
         }
+
+        if ((lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) ==
+                        XFS_IOLOCK_EXCL) {
+                if (!ip->i_iolock.mr_writer)
+                        return 0;
+        }
+
+        return 1;
 }
+#endif
 
 /*
  * The following three routines simply manage the i_flock