fedc1d96a8
On Linux, ftruncate(2) always changes the file timestamps, even if the file size is not changed. However, in case of a successfull truncate(2), the timestamps are updated only if the file size changes. This translates to the VFS calling the ZFS Posix Layer "setattr" function (zpl_setattr) with ATTR_MTIME and ATTR_CTIME unconditionally set on the iattr mask only when doing a ftruncate(2), while the truncate(2) is left to the filesystem implementation to be dealt with. This behaviour is consistent with POSIX:2004/SUSv3 specifications where there's no explicit requirement for file size changes to update the timestamps only for ftruncate(2): http://pubs.opengroup.org/onlinepubs/009695399/functions/truncate.html http://pubs.opengroup.org/onlinepubs/009695399/functions/ftruncate.html This has been later updated in POSIX:2008/SUSv4 where, for both truncate(2)/ftruncate(2), there's no mention of this size change requirement: http://austingroupbugs.net/view.php?id=489 http://pubs.opengroup.org/onlinepubs/9699919799/functions/truncate.html http://pubs.opengroup.org/onlinepubs/9699919799/functions/ftruncate.html Unfortunately the Linux VFS is still calling into the ZPL without ATTR_MTIME/ATTR_CTIME set in the truncate(2) case: we fix this by explicitly updating the timestamps when detecting the ATTR_SIZE bit, which is always set in do_truncate(), on the iattr mask. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: loli10K <ezomori.nozomu@gmail.com> Closes #6811 Closes #6819 |
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README.markdown
ZFS is an advanced file system and volume manager which was originally
developed for Solaris and is now maintained by the Illumos community.
ZFS on Linux, which is also known as ZoL, is currently feature complete. It includes fully functional and stable SPA, DMU, ZVOL, and ZPL layers. And it's native!
Official Resources
Installation
Full documentation for installing ZoL on your favorite Linux distribution can be found at our site.
Contribute & Develop
We have a separate document with contribution guidelines.