On Fri, Jul 18, 2014 at 12:09 PM, Jeremy Allison <jra@xxxxxxxxx> wrote: > On Fri, Jul 18, 2014 at 01:15:07AM -0500, Steve French wrote: >> I created a patch to cifs.ko to add fallocate FALLOC_FL_KEEP_SIZE >> support and did some tests against a Samba server (Samba 4.1.6 on ext4 >> on Ubuntu) and also a Windows 8.1 server (NTFS file system) and ran >> into an obvious problem. How to tell if the allocation size is >> changed? Neither stat on the Samba server local file system nor the >> Windows 8.1 properties show the size on disk changing. >> >> I am sending SMB3 SetInfo level 0x13 (set allocation size) and getting >> success back from the Windows server and from Samba server. >> >> If I set the length past the end of file I get no error, but the >> properties of the file in Windows Explorer still show the same (e.g. >> zero) as the file size. If I try setting it to a size smaller than >> the size of the file, the file shrinks (by the way this is an awkward >> behavior to work around since on Linux fallocate can't shrink the file >> - so if you have any ideas short of revalidating the file size before >> deciding whether to send the fallocate request to Windows ...). >> >> Any ideas why Samba shows success but doesn't actually call ext4 to >> update the allocation size? > > smbd does use VFS_FALLOCATE_KEEP_SIZE, which maps > into fallocate FALLOC_FL_KEEP_SIZE if the underlying > storage supports it. > > You need to set "strict allocate = true" on the > share in order to get this behavior though. > > If you're setting allocation size smaller > than file size we just use ftruncate, I > don't see another possibility here. What > behavior do you expect in the shrink case ? Windows shrinks the file (unlike Linux) when you do the allocate before end of file, but when I tried the same call to Samba it seemed to ignore it, return success and leave file size alone. -- Thanks, Steve -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
