ntfs3: fix mount failure on volumes with fragmented MFT bitmap

When the $MFT's $BITMAP attribute is fragmented across multiple MFT
records (base record + extent records), ntfs_fill_super() fails with
-ENOENT during wnd_init() because the MFT bitmap's run list only
contains runs from the base MFT record.

The issue is that wnd_init() (which calls wnd_rescan()) is invoked
before ni_load_all_mi(), so the extent MFT records containing
additional $BITMAP runs have not been loaded yet. When wnd_rescan()
tries to look up a VCN beyond the base record's runs, run_lookup_entry()
fails and returns -ENOENT.

This affects NTFS volumes with a large or heavily fragmented MFT, which
is common on long-used Windows systems where the MFT bitmap's run list
doesn't fit in the base MFT record and spills into extent records.

Fix this by:
1. Moving ni_load_all_mi() before wnd_init() so all extent records
   are available.
2. After ni_load_all_mi(), iterating through the attribute list to
   find any $BITMAP extent attributes and unpacking their runs into
   sbi->mft.bitmap.run before wnd_init() is called.

Tested on a 664GB NTFS volume with 86 MFT bitmap runs spanning
records 0 (VCN 0-105) and 17 (VCN 106-165). Before the fix, mount
fails with -ENOENT. After the fix, mount succeeds and all read/write
operations work correctly. Stress-tested with 8 test categories
(large file integrity, 10K small files, copy, move, delete/recreate
cycles, concurrent writes, deep directories, overwrite persistence).

Signed-off-by: Ruslan Elishev <relishev@gmail.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
index 174a7cb202a08c550b3b8497cdf6105192be2e43..46160b06b6357cdb3f9bd75e8ec21dfe7cedbe97 100644 (file)
--- a/fs/ntfs3/super.c
+++ b/fs/ntfs3/super.c
@@ -1426,16 +1426,47 @@ static int ntfs_fill_super(struct super_block *sb, struct fs_context *fc)
        tt = inode->i_size >> sbi->record_bits;
        sbi->mft.next_free = MFT_REC_USER;
 
-       err = wnd_init(&sbi->mft.bitmap, sb, tt);
-       if (err)
-               goto put_inode_out;
-
        err = ni_load_all_mi(ni);
        if (err) {
                ntfs_err(sb, "Failed to load $MFT's subrecords (%d).", err);
                goto put_inode_out;
        }
 
+       /* Merge MFT bitmap runs from extent records loaded by ni_load_all_mi. */
+       {
+               struct ATTRIB *a = NULL;
+               struct ATTR_LIST_ENTRY *le = NULL;
+
+               while ((a = ni_enum_attr_ex(ni, a, &le, NULL))) {
+                       CLST svcn, evcn;
+                       u16 roff;
+
+                       if (a->type != ATTR_BITMAP || !a->non_res)
+                               continue;
+
+                       svcn = le64_to_cpu(a->nres.svcn);
+                       if (!svcn)
+                               continue; /* Base record runs already loaded. */
+
+                       evcn = le64_to_cpu(a->nres.evcn);
+                       roff = le16_to_cpu(a->nres.run_off);
+
+                       err = run_unpack_ex(&sbi->mft.bitmap.run, sbi,
+                                           MFT_REC_MFT, svcn, evcn, svcn,
+                                           Add2Ptr(a, roff),
+                                           le32_to_cpu(a->size) - roff);
+                       if (err < 0) {
+                               ntfs_err(sb, "Failed to unpack $MFT bitmap extent (%d).", err);
+                               goto put_inode_out;
+                       }
+                       err = 0;
+               }
+       }
+
+       err = wnd_init(&sbi->mft.bitmap, sb, tt);
+       if (err)
+               goto put_inode_out;
+
        sbi->mft.ni = ni;
 
        /* Load $Bitmap. */