1. With various (debug and/or tracing?) kernel options enabled it's
possible for 'struct inode' and 'struct super_block' to exceed the
default frame size, leaving errors like this in config.log:
build/conftest.c:116:1: error: the frame size of 1048 bytes is larger
than 1024 bytes [-Werror=frame-larger-than=]
Fix this by removing the frame size warning for config checks
2. Without the correct headers included, it's possible for declarations
to be missed, leaving errors like this in the config.log:
build/conftest.c:131:14: error: ‘struct nameidata’ declared inside
parameter list [-Werror]
Fix this by adding appropriate headers.
Note: Both these issues can result in silent config failures because
the compile failure is taken to mean "this option is not supported by
this kernel" rather than "there's something wrong with the config
test". This can lead to something merely annoying (compile failures) to
something potentially serious (miscompiled or misused kernel primitives
or functions). E.g. the fixes included here resulted in these
additional defines in zfs_config.h with linux v4.14.19:
Also, drive-by whitespace fixes in config/* files which don't mention
"GNU" (those ones look to be imported from elsewhere so leave them
alone).
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chris Dunlop <chris@onthe.net.au>
Closes#7169
PaX/GrSecurity patched kernels implement a dialect of C that relies on a
GCC plugin for enforcement. A basic idea in this dialect is that
function pointers in structures should not change during runtime.
This causes code that modifies function pointers at runtime to fail to
compile in many instances. The autotools checks rely on whether or
not small test cases compile against a given kernel. Some
autotools checks assume some default case if other cases fail. When one
of these autotools checks tests a PaX/GrSecurity patched kernel by
modifying a function pointer at runtime, the default case will be used.
Early detection of such situations is possible by relying on compiler
warnings, which are compiler errors when --enable-debug is used.
Unfortunately, very few people build ZFS with --enable-debug. The more
common situation is that these issues manifest themselves as runtime
failures in the form of NULL pointer exceptions.
Previous patches that addressed such issues with PaX/GrSecurity
compatibility largely relied on rewriting autotools checks to avoid
runtime function pointer modification or the addition of PaX/GrSecurity
specific checks. This patch takes the previous work to its logical
conclusion by eliminating the use of runtime function pointer
modification. This permits the removal of PaX-specific autotools checks
in favor of ones that work across all supported kernels.
This should resolve issues that were reported to occur with
PaX/GrSecurity-patched Linux 3.7.5 kernels on Gentoo Linux.
https://bugs.gentoo.org/show_bug.cgi?id=457176
We should be able to prevent future regressions in PaX/GrSecurity
compatibility by ensuring that all changes to ZFSOnLinux avoid runtime
function pointer modification. At the same time, this does not solve the
issue of silent failures triggering default cases in the autotools
check, which is what permitted these regressions to become runtime
failures in the first place. This will need to be addressed in a future
patch.
Reported-by: Marcin Mirosław <bug@mejor.pl>
Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1300
As of Linux 2.6.37 the right way to register custom dentry
operations is to use the super block's ->s_d_op field.
For older kernels they should be registered as part of the
lookup operation.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1223
Lookups in the snapshot control directory for an existing snapshot
fail with ENOENT if an earlier lookup failed before the snapshot was
created. This is because the earlier lookup causes a negative dentry
to be cached which is never invalidated.
The bug can be reproduced as follows (the second ls should succeed):
$ ls /tank/.zfs/snapshot/s
ls: cannot access /tank/.zfs/snapshot/s: No such file or directory
$ zfs snap tank@s
$ ls /tank/.zfs/snapshot/s
ls: cannot access /tank/.zfs/snapshot/s: No such file or directory
To remedy this, always invalidate cached dentries in the snapshot
control directory. Since these entries never exist on disk there is
no significant performance penalty for the extra lookups.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1192
