1 files changed, 41 insertions, 121 deletions

diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index c5dc7ea85260..077c86b6cb22 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -1708,111 +1708,6 @@ std_return:
 }
 
 #ifdef DEBUG
-/*
- * Some counters to see if (and how often) we are hitting some deadlock
- * prevention code paths.
- */
-
-int xfs_rm_locks;
-int xfs_rm_lock_delays;
-int xfs_rm_attempts;
-#endif
-
-/*
- * The following routine will lock the inodes associated with the
- * directory and the named entry in the directory. The locks are
- * acquired in increasing inode number.
- *
- * If the entry is "..", then only the directory is locked. The
- * vnode ref count will still include that from the .. entry in
- * this case.
- *
- * There is a deadlock we need to worry about. If the locked directory is
- * in the AIL, it might be blocking up the log. The next inode we lock
- * could be already locked by another thread waiting for log space (e.g
- * a permanent log reservation with a long running transaction (see
- * xfs_itruncate_finish)). To solve this, we must check if the directory
- * is in the ail and use lock_nowait. If we can't lock, we need to
- * drop the inode lock on the directory and try again. xfs_iunlock will
- * potentially push the tail if we were holding up the log.
- */
-STATIC int
-xfs_lock_dir_and_entry(
-        xfs_inode_t     *dp,
-        xfs_inode_t     *ip)    /* inode of entry 'name' */
-{
-        int             attempts;
-        xfs_ino_t       e_inum;
-        xfs_inode_t     *ips[2];
-        xfs_log_item_t  *lp;
-
-#ifdef DEBUG
-        xfs_rm_locks++;
-#endif
-        attempts = 0;
-
-again:
-        xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
-
-        e_inum = ip->i_ino;
-
-        xfs_itrace_ref(ip);
-
-        /*
-         * We want to lock in increasing inum. Since we've already
-         * acquired the lock on the directory, we may need to release
-         * if if the inum of the entry turns out to be less.
-         */
-        if (e_inum > dp->i_ino) {
-                /*
-                 * We are already in the right order, so just
-                 * lock on the inode of the entry.
-                 * We need to use nowait if dp is in the AIL.
-                 */
-
-                lp = (xfs_log_item_t *)dp->i_itemp;
-                if (lp && (lp->li_flags & XFS_LI_IN_AIL)) {
-                        if (!xfs_ilock_nowait(ip, XFS_ILOCK_EXCL)) {
-                                attempts++;
-#ifdef DEBUG
-                                xfs_rm_attempts++;
-#endif
-
-                                /*
-                                 * Unlock dp and try again.
-                                 * xfs_iunlock will try to push the tail
-                                 * if the inode is in the AIL.
-                                 */
-
-                                xfs_iunlock(dp, XFS_ILOCK_EXCL);
-
-                                if ((attempts % 5) == 0) {
-                                        delay(1); /* Don't just spin the CPU */
-#ifdef DEBUG
-                                        xfs_rm_lock_delays++;
-#endif
-                                }
-                                goto again;
-                        }
-                } else {
-                        xfs_ilock(ip, XFS_ILOCK_EXCL);
-                }
-        } else if (e_inum < dp->i_ino) {
-                xfs_iunlock(dp, XFS_ILOCK_EXCL);
-
-                ips[0] = ip;
-                ips[1] = dp;
-                xfs_lock_inodes(ips, 2, XFS_ILOCK_EXCL);
-        }
-        /* else  e_inum == dp->i_ino */
-        /*     This can happen if we're asked to lock /x/..
-         *     the entry is "..", which is also the parent directory.
-         */
-
-        return 0;
-}
-
-#ifdef DEBUG
 int xfs_locked_n;
 int xfs_small_retries;
 int xfs_middle_retries;
@@ -1946,6 +1841,45 @@ again:
 #endif
 }
 
+void
+xfs_lock_two_inodes(
+        xfs_inode_t             *ip0,
+        xfs_inode_t             *ip1,
+        uint                    lock_mode)
+{
+        xfs_inode_t             *temp;
+        int                     attempts = 0;
+        xfs_log_item_t          *lp;
+
+        ASSERT(ip0->i_ino != ip1->i_ino);
+
+        if (ip0->i_ino > ip1->i_ino) {
+                temp = ip0;
+                ip0 = ip1;
+                ip1 = temp;
+        }
+
+ again:
+        xfs_ilock(ip0, xfs_lock_inumorder(lock_mode, 0));
+
+        /*
+         * If the first lock we have locked is in the AIL, we must TRY to get
+         * the second lock. If we can't get it, we must release the first one
+         * and try again.
+         */
+        lp = (xfs_log_item_t *)ip0->i_itemp;
+        if (lp && (lp->li_flags & XFS_LI_IN_AIL)) {
+                if (!xfs_ilock_nowait(ip1, xfs_lock_inumorder(lock_mode, 1))) {
+                        xfs_iunlock(ip0, lock_mode);
+                        if ((++attempts % 5) == 0)
+                                delay(1); /* Don't just spin the CPU */
+                        goto again;
+                }
+        } else {
+                xfs_ilock(ip1, xfs_lock_inumorder(lock_mode, 1));
+        }
+}
+
 int
 xfs_remove(
         xfs_inode_t             *dp,
@@ -2018,9 +1952,7 @@ xfs_remove(
                 goto out_trans_cancel;
         }
 
-        error = xfs_lock_dir_and_entry(dp, ip);
-        if (error)
-                goto out_trans_cancel;
+        xfs_lock_two_inodes(dp, ip, XFS_ILOCK_EXCL);
 
         /*
          * At this point, we've gotten both the directory and the entry
@@ -2047,9 +1979,6 @@ xfs_remove(
                 }
         }
 
-        /*
-         * Entry must exist since we did a lookup in xfs_lock_dir_and_entry.
-         */
         XFS_BMAP_INIT(&free_list, &first_block);
         error = xfs_dir_removename(tp, dp, name, ip->i_ino,
                                         &first_block, &free_list, resblks);
@@ -2155,7 +2084,6 @@ xfs_link(
 {
         xfs_mount_t             *mp = tdp->i_mount;
         xfs_trans_t             *tp;
-        xfs_inode_t             *ips[2];
         int                     error;
         xfs_bmap_free_t         free_list;
         xfs_fsblock_t           first_block;
@@ -2203,15 +2131,7 @@ xfs_link(
                 goto error_return;
         }
 
-        if (sip->i_ino < tdp->i_ino) {
-                ips[0] = sip;
-                ips[1] = tdp;
-        } else {
-                ips[0] = tdp;
-                ips[1] = sip;
-        }
-
-        xfs_lock_inodes(ips, 2, XFS_ILOCK_EXCL);
+        xfs_lock_two_inodes(sip, tdp, XFS_ILOCK_EXCL);
 
         /*
          * Increment vnode ref counts since xfs_trans_commit &