maindavfs2 - Support: sr #109594, 0-byte files, Input/output error


sr #109594: 0-byte files, Input/output error

Submitter:  Massimo <massimo_b>
Submitted:  Fri 30 Nov 2018 10:33:39 AM UTC
Category:  None Priority:  5 - Normal
Severity:  3 - Normal Status:  Need Info
Privacy:  Public Assigned to:  _71007
Open/Closed:  Open Operating System:  GNU/Linux
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Add a New Comment (Rich Markup)

Tue 04 Dec 2018 06:07:09 PM UTC, comment #1: 

There is something special about 0-byte-files in webDAV because they may be created as side effect of locking.

But we need some more investigation. So please do this:

  • add option "debug most" to your davfs2.conf file.
  • mount the file system
  • issue just one command: cat /mnt/sd2dav/0-byte-Windows
  • umount the file system
  • search your log-files for entries from mount.davfs and attach them to this item


- <_71007>
Fri 30 Nov 2018 10:33:39 AM UTC, original submission:  

Creating 0-byte size files on the Webdav-Server, any reading results in I/O error. First I thought the issue is a bug on the Webdav Server. But with a different client, using Windows Explorer, I can't reproduce.

Steps to reproduce:
1. Create a 0-byte file "0-byte-Windows" from Windows Explorer or any other Webdav client.

2. Mount from Linux:

$ mount.davfs -V
davfs2 1.5.4

$ mount |grep dav on /mnt/sd2dav type fuse (rw,nosuid,nodev,noexec,relatime,user_id=4728,group_id=4728,allow_other,max_read=16384,uid=4728,gid=4728,user=mb,helper=davfs)

$ cd /mnt/sd2dav

$ stat 0-byte-Windows
  File: 0-byte-Windows
  Size: 0         Blocks: 0          IO Block: 4096   regular empty file
Device: 3eh/62d Inode: 93931767225792  Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 4728/      mb)   Gid: ( 4728/      mb)
Access: 2018-11-30 11:17:37.000000000 +0100
Modify: 2018-11-30 11:17:22.000000000 +0100
Change: 2018-11-30 11:17:22.000000000 +0100
 Birth: -
$ md5sum 0-byte-Windows
md5sum: 0-byte-Windows: Input/output error

However creating a 0-byte file from the local mount works:

$ touch 0-byte-Linux
$ md5sum 0-byte-Linux
d41d8cd98f00b204e9800998ecf8427e  0-byte-Linux

But every 0-byte file created from any other clients fails to be synced or read. I guess this is some bug on the caching or something.

Weird enough, on Android the app "FolderSync" has the same issue, which cannot be reproduced with Windows Explorer either. Maybe some library on Android is similar to davfs2.

I don't have any other reference client or testing webdav server.

Massimo <massimo_b>


(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

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    Follow 3 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2019-12-26 _71007 StatusIn Progress Need Info
    2018-12-04 _71007 StatusNone In Progress
        Assigned toNone _71007

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