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321579 |
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26-Jul-2017 |
mav |
MFC r319953: MFV r319951: 8311 ZFS_READONLY is a little too strict
illumos/illumos-gate@2889ec41c05e9ffe1890b529b3111354da325aeb
https://github.com/illumos/illumos-gate/commit/2889ec41c05e9ffe1890b529b3111354d
a325aeb
https://www.illumos.org/issues/8311
Description:
There was a misunderstanding about the enforcement details of the "Read-only"
flag introduced for SMB/CIFS compatibility, way back in 2007 in the Sun PSARC
2007/315 case.
The original authors thought enforcement of the READONLY flag should work
similarly as the IMMUTABLE flag. Unfortunately, that enforcement is
incompatible with the expectations of Windows applications using this feature
through the SMB service. Applications assume (and the MS File System Algorithm
s
MS-FSA confirms they should) that an SMB client can:
(a) Open an SMB handle on a file with read/write access,
(b) Set the DOS attributes to include the READONLY flag,
(c) continue to have write access via that handle.
This access model is essentially the same as a Unix/POSIX application that
creates a file (with read/write access), uses fchmod() to change the file mode
to something not granting write access (i.e. 0444), and then continues to writ
e
that file using the open handle it got before the mode change.
Currently, the SMB server works-around this problem in a way that will become
difficult to maintain as we implement support for SMB3 persistent handles, so
SMB depends on this fix.
I've written a test program that can be used to demonstrate this problem, and
added it to zfs-tests (tests/functional/acl/cifs/cifs_attr_004_pos).
It currently fails, but will pass when this problem fixed.
Steps to Reproduce:
Run the test program on a ZFS file system.
Expected Results:
Pass
Actual Results:
Fail.
Reviewed by: Sanjay Nadkarni <sanjay.nadkarni@nexenta.com>
Reviewed by: Yuri Pankov <yuri.pankov@nexenta.com>
Reviewed by: Andrew Stormont <andyjstormont@gmail.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Approved by: Prakash Surya <prakash.surya@delphix.com>
Author: Gordon Ross <gwr@nexenta.com>
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| #
303970 |
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11-Aug-2016 |
avg |
MFC r303763,303791,303869: zfs: honour and make use of vfs vnode locking protocol
ZFS POSIX Layer is originally written for Solaris VFS which is very
different from FreeBSD VFS. Most importantly many things that FreeBSD VFS
manages on behalf of all filesystems are implemented in ZPL in a different
way.
Thus, ZPL contains code that is redundant on FreeBSD or duplicates VFS
functionality or, in the worst cases, badly interacts / interferes
with VFS.
The most prominent problem is a deadlock caused by the lock order reversal
of vnode locks that may happen with concurrent zfs_rename() and lookup().
The deadlock is a result of zfs_rename() not observing the vnode locking
contract expected by VFS.
This commit removes all ZPL internal locking that protects parent-child
relationships of filesystem nodes. These relationships are protected
by vnode locks and the code is changed to take advantage of that fact
and to properly interact with VFS.
Removal of the internal locking allowed all ZPL dmu_tx_assign calls to
use TXG_WAIT mode.
Another victim, disputable perhaps, is ZFS support for filesystems with
mixed case sensitivity. That support is not provided by the OS anyway,
so in ZFS it was a buch of dead code.
To do:
- replace ZFS_ENTER mechanism with VFS managed / visible mechanism
- replace zfs_zget with zfs_vget[f] as much as possible
- get rid of not really useful now zfs_freebsd_* adapters
- more cleanups of unneeded / unused code
- fix / replace .zfs support
PR: 209158
Approved by: re (gjb)
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