NTFS: - Split ntfs_map_runlist() into ntfs_map_runlist() and a non-locking

	helper ntfs_map_runlist_nolock() which is used by ntfs_map_runlist().
	This allows us to map runlist fragments with the runlist lock already
	held without having to drop and reacquire it around the call.  Adapt
	all callers.
      - Change ntfs_find_vcn() to ntfs_find_vcn_nolock() which takes a locked
	runlist.  This allows us to find runlist elements with the runlist
	lock already held without having to drop and reacquire it around the
	call.  Adapt all callers.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

1 files changed, 12 insertions, 27 deletions

diff --git a/fs/ntfs/lcnalloc.c b/fs/ntfs/lcnalloc.c
index 5346596fa871..8db4492b139c 100644
--- a/fs/ntfs/lcnalloc.c
+++ b/fs/ntfs/lcnalloc.c
@@ -849,7 +849,8 @@ s64 __ntfs_cluster_free(struct inode *vi, const VCN start_vcn, s64 count,
         total_freed = real_freed = 0;
 
         /* This returns with ni->runlist locked for reading on success. */
-        rl = ntfs_find_vcn(ni, start_vcn, FALSE);
+        down_read(&ni->runlist.lock);
+        rl = ntfs_find_vcn_nolock(ni, start_vcn, FALSE);
         if (IS_ERR(rl)) {
                 if (!is_rollback)
                         ntfs_error(vol->sb, "Failed to find first runlist "
@@ -863,7 +864,7 @@ s64 __ntfs_cluster_free(struct inode *vi, const VCN start_vcn, s64 count,
                         ntfs_error(vol->sb, "First runlist element has "
                                         "invalid lcn, aborting.");
                 err = -EIO;
-                goto unl_err_out;
+                goto err_out;
         }
         /* Find the starting cluster inside the run that needs freeing. */
         delta = start_vcn - rl->vcn;
@@ -881,7 +882,7 @@ s64 __ntfs_cluster_free(struct inode *vi, const VCN start_vcn, s64 count,
                         if (!is_rollback)
                                 ntfs_error(vol->sb, "Failed to clear first run "
                                                 "(error %i), aborting.", err);
-                        goto unl_err_out;
+                        goto err_out;
                 }
                 /* We have freed @to_free real clusters. */
                 real_freed = to_free;
@@ -901,30 +902,15 @@ s64 __ntfs_cluster_free(struct inode *vi, const VCN start_vcn, s64 count,
                 if (unlikely(rl->lcn < LCN_HOLE)) {
                         VCN vcn;
 
-                        /*
-                         * Attempt to map runlist, dropping runlist lock for
-                         * the duration.
-                         */
+                        /* Attempt to map runlist. */
                         vcn = rl->vcn;
-                        up_read(&ni->runlist.lock);
-                        err = ntfs_map_runlist(ni, vcn);
-                        if (err) {
-                                if (!is_rollback)
-                                        ntfs_error(vol->sb, "Failed to map "
-                                                        "runlist fragment.");
-                                if (err == -EINVAL || err == -ENOENT)
-                                        err = -EIO;
-                                goto err_out;
-                        }
-                        /*
-                         * This returns with ni->runlist locked for reading on
-                         * success.
-                         */
-                        rl = ntfs_find_vcn(ni, vcn, FALSE);
+                        rl = ntfs_find_vcn_nolock(ni, vcn, FALSE);
                         if (IS_ERR(rl)) {
                                 err = PTR_ERR(rl);
                                 if (!is_rollback)
-                                        ntfs_error(vol->sb, "Failed to find "
+                                        ntfs_error(vol->sb, "Failed to map "
+                                                        "runlist fragment or "
+                                                        "failed to find "
                                                         "subsequent runlist "
                                                         "element.");
                                 goto err_out;
@@ -937,7 +923,7 @@ s64 __ntfs_cluster_free(struct inode *vi, const VCN start_vcn, s64 count,
                                                         (unsigned long long)
                                                         rl->lcn);
                                 err = -EIO;
-                                goto unl_err_out;
+                                goto err_out;
                         }
                 }
                 /* The number of clusters in this run that need freeing. */
@@ -953,7 +939,7 @@ s64 __ntfs_cluster_free(struct inode *vi, const VCN start_vcn, s64 count,
                                 if (!is_rollback)
                                         ntfs_error(vol->sb, "Failed to clear "
                                                         "subsequent run.");
-                                goto unl_err_out;
+                                goto err_out;
                         }
                         /* We have freed @to_free real clusters. */
                         real_freed += to_free;
@@ -974,9 +960,8 @@ s64 __ntfs_cluster_free(struct inode *vi, const VCN start_vcn, s64 count,
         /* We are done.  Return the number of actually freed clusters. */
         ntfs_debug("Done.");
         return real_freed;
-unl_err_out:
-        up_read(&ni->runlist.lock);
 err_out:
+        up_read(&ni->runlist.lock);
         if (is_rollback)
                 return err;
         /* If no real clusters were freed, no need to rollback. */