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, 23 insertions, 15 deletions

diff --git a/fs/ntfs/mft.c b/fs/ntfs/mft.c
index 4e0bf39426c..0975d738834 100644
--- a/fs/ntfs/mft.c
+++ b/fs/ntfs/mft.c
@@ -1,7 +1,7 @@
 /**
  * mft.c - NTFS kernel mft record operations. Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001-2004 Anton Altaparmakov
+ * Copyright (c) 2001-2005 Anton Altaparmakov
  * Copyright (c) 2002 Richard Russon
  *
  * This program/include file is free software; you can redistribute it and/or
@@ -287,7 +287,7 @@ MFT_RECORD *map_extent_mft_record(ntfs_inode *base_ni, MFT_REF mref,
                         }
                         unmap_mft_record(ni);
                         ntfs_error(base_ni->vol->sb, "Found stale extent mft "
-                                        "reference! Corrupt file system. "
+                                        "reference! Corrupt filesystem. "
                                         "Run chkdsk.");
                         return ERR_PTR(-EIO);
                 }
@@ -318,7 +318,7 @@ map_err_out:
         /* Verify the sequence number if it is present. */
         if (seq_no && (le16_to_cpu(m->sequence_number) != seq_no)) {
                 ntfs_error(base_ni->vol->sb, "Found stale extent mft "
-                                "reference! Corrupt file system. Run chkdsk.");
+                                "reference! Corrupt filesystem. Run chkdsk.");
                 destroy_ni = TRUE;
                 m = ERR_PTR(-EIO);
                 goto unm_err_out;
@@ -1292,19 +1292,20 @@ static int ntfs_mft_bitmap_extend_allocation_nolock(ntfs_volume *vol)
         /*
          * Determine the last lcn of the mft bitmap.  The allocated size of the
          * mft bitmap cannot be zero so we are ok to do this.
-         * ntfs_find_vcn() returns the runlist locked on success.
          */
+        down_write(&mftbmp_ni->runlist.lock);
         read_lock_irqsave(&mftbmp_ni->size_lock, flags);
         ll = mftbmp_ni->allocated_size;
         read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
-        rl = ntfs_find_vcn(mftbmp_ni, (ll - 1) >> vol->cluster_size_bits, TRUE);
+        rl = ntfs_find_vcn_nolock(mftbmp_ni,
+                        (ll - 1) >> vol->cluster_size_bits, TRUE);
         if (unlikely(IS_ERR(rl) || !rl->length || rl->lcn < 0)) {
+                up_write(&mftbmp_ni->runlist.lock);
                 ntfs_error(vol->sb, "Failed to determine last allocated "
                                 "cluster of mft bitmap attribute.");
-                if (!IS_ERR(rl)) {
-                        up_write(&mftbmp_ni->runlist.lock);
+                if (!IS_ERR(rl))
                         ret = -EIO;
-                } else
+                else
                         ret = PTR_ERR(rl);
                 return ret;
         }
@@ -1428,6 +1429,8 @@ static int ntfs_mft_bitmap_extend_allocation_nolock(ntfs_volume *vol)
                 // TODO: Deal with this by moving this extent to a new mft
                 // record or by starting a new extent in a new mft record or by
                 // moving other attributes out of this mft record.
+                // Note: It will need to be a special mft record and if none of
+                // those are available it gets rather complicated...
                 ntfs_error(vol->sb, "Not enough space in this mft record to "
                                 "accomodate extended mft bitmap attribute "
                                 "extent.  Cannot handle this yet.");
@@ -1719,19 +1722,20 @@ static int ntfs_mft_data_extend_allocation_nolock(ntfs_volume *vol)
          * Determine the preferred allocation location, i.e. the last lcn of
          * the mft data attribute.  The allocated size of the mft data
          * attribute cannot be zero so we are ok to do this.
-         * ntfs_find_vcn() returns the runlist locked on success.
          */
+        down_write(&mft_ni->runlist.lock);
         read_lock_irqsave(&mft_ni->size_lock, flags);
         ll = mft_ni->allocated_size;
         read_unlock_irqrestore(&mft_ni->size_lock, flags);
-        rl = ntfs_find_vcn(mft_ni, (ll - 1) >> vol->cluster_size_bits, TRUE);
+        rl = ntfs_find_vcn_nolock(mft_ni, (ll - 1) >> vol->cluster_size_bits,
+                        TRUE);
         if (unlikely(IS_ERR(rl) || !rl->length || rl->lcn < 0)) {
+                up_write(&mft_ni->runlist.lock);
                 ntfs_error(vol->sb, "Failed to determine last allocated "
                                 "cluster of mft data attribute.");
-                if (!IS_ERR(rl)) {
-                        up_write(&mft_ni->runlist.lock);
+                if (!IS_ERR(rl))
                         ret = -EIO;
-                } else
+                else
                         ret = PTR_ERR(rl);
                 return ret;
         }
@@ -1858,7 +1862,11 @@ static int ntfs_mft_data_extend_allocation_nolock(ntfs_volume *vol)
                 // moving other attributes out of this mft record.
                 // Note: Use the special reserved mft records and ensure that
                 // this extent is not required to find the mft record in
-                // question.
+                // question.  If no free special records left we would need to
+                // move an existing record away, insert ours in its place, and
+                // then place the moved record into the newly allocated space
+                // and we would then need to update all references to this mft
+                // record appropriately.  This is rather complicated...
                 ntfs_error(vol->sb, "Not enough space in this mft record to "
                                 "accomodate extended mft data attribute "
                                 "extent.  Cannot handle this yet.");
@@ -2021,7 +2029,7 @@ static int ntfs_mft_record_layout(const ntfs_volume *vol, const s64 mft_no,
                                 "reports this as corruption, please email "
                                 "linux-ntfs-dev@lists.sourceforge.net stating "
                                 "that you saw this message and that the "
-                                "modified file system created was corrupt.  "
+                                "modified filesystem created was corrupt.  "
                                 "Thank you.");
         }
         /* Set the update sequence number to 1. */