Hi, Thank you for your report including a test pointing out the issue.
Attached is a patch expected to fix it. Please test and report. Jean-Pierre Chris Roehrig wrote on 7/30/20 1:01 AM:
I'm trying to get my Linux-based NTFS backup drive to pass a CHKDSK and came upon this curious situation where CHKDSK finds errors. It seems to be some issue with how ntfs-3g modifies a directory index when renaming many files. The CHKDSK error always seems to be of the form: Stage 2: Examining file name linkage ... The first free byte, 0xc0, and bytes available, 0x150, for root index $I30 in file 0x40 are not equal. I've attached a python script (mkbaddir.py) that creates two (apparently) identical directories, one of which reliably causes this CHKDSK error; the other doesn't. How to demonstrate: - Format an NTFS partition or thumbdrive using Windows or mkfs.ntfs. - Mount the partition on a Linux system. I used Mint 20 with ntfs-3g 2017.3.23AR.3 integrated FUSE 28 and python 3.8.2. - Chdir to the new NTFS partition and run the script: /tmp/mkbaddir.py # creates 'baddir' in current dir. /tmp/mkbaddir.py -G # creates 'gooddir' in current dir. diff -r baddir gooddir # no difference du -sB1 baddir gooddir # same size (128K) - Boot into Windows (10 v1903) and run (from a terminal) chkdsk X: (where X: is the NTFS drive). - This will say: "Errors found. CHKDSK cannot continue in read-only mode." - Delete baddir (I used cygwin's rm -rf), and run chkdsk X: again. - This will now have no errors. My guess at what's happening: The script creates a directory of 410 empty files and then renames them with slightly larger names, which as I understand leaves a bunch of unused nodes in the b-tree. The -G option just renames the 410 known files; without the -G option, it uses os.walk() to traverse the directory which I'm guessing leaves the b-tree in a slightly different state with even more unused nodes. The 410 was chosen by trial-and-error so that some internal threshhold is just exceeded by the baddir but not by the gooddir. With more than 410 (using the -c option; say -c 500), both baddir and gooddir will cause CHKDSK errors. If I run the script on Windows/cygwin (Python 3.6.9) to create the folders, it does not give any CHKDSK errors even with many more files. So there seems to be some issue with how ntfs-3g modifies the b-tree when renaming many files that is causing CHKDSK to complain. I encountered this issue when trying to get my Linux-based NTFS backup drive to consistently pass a CHKDSK. I use a script to first rename POSIX names to valid windows names, replacing '?' with '@@3F', etc so I can reverse the renaming afterwards. I have some website mirror folders with many files of the form: details.asp?id=xxxxx&key=val which gave rise to this issue. (In the mkbaddir script I use only alphanumeric names to be clear this is not an illegal char issue).
--- libntfs-3g/index.c.ref 2017-03-23 10:42:44.000000000 +0100 +++ libntfs-3g/index.c 2020-08-01 12:16:39.760324300 +0200 @@ -1563,19 +1563,37 @@ INDEX_ENTRY *ie, INDEX_BLOCK *ib) { INDEX_ENTRY *ie_roam; + ATTR_RECORD *a; + int space; + int value_length; + BOOL at_end; int ret = STATUS_ERROR; - + ntfs_log_trace("Entering\n"); + at_end = ih->index_length == ih->allocated_size; ie_roam = ntfs_ie_dup_novcn(ie); if (!ie_roam) return STATUS_ERROR; ntfs_ie_delete(ih, ie); - if (ntfs_icx_parent_vcn(icx) == VCN_INDEX_ROOT_PARENT) + if (ntfs_icx_parent_vcn(icx) == VCN_INDEX_ROOT_PARENT) { + /* + * Recover the space which may have been freed + * while deleting an entry from root index + */ + space = le32_to_cpu(ih->allocated_size) + - le32_to_cpu(ih->index_length); + if (at_end && (space > 0) && !(space & 7)) { + a = icx->actx->attr; + ih->allocated_size = ih->index_length; + value_length = le32_to_cpu(a->value_length); + value_length -= space; + a->value_length = cpu_to_le32(value_length); + } ntfs_inode_mark_dirty(icx->actx->ntfs_ino); - else + } else if (ntfs_ib_write(icx, ib)) goto out;
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