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Linux 2.6.36 compat, fs_struct->lock type change

Browse Source 
In the linux-2.6.36 kernel the fs_struct lock was changed from a
rwlock_t to a spinlock_t.  If the kernel would export the set_fs_pwd()
symbol by default this would not have caused us any issues, but they
don't.  So we're forced to add a new autoconf check which sets the
HAVE_FS_STRUCT_SPINLOCK define when a spinlock_t is used.  We can
then correctly use either spin_lock or write_lock in our custom
set_fs_pwd() implementation.
This commit is contained in:
Brian Behlendorf 2010-11-09 11:15:32 -08:00
parent a50cede388
commit 9b2048c26b
4 changed files with 176 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
config/spl-build.m4
View File

@ -66,6 +66,7 @@ AC_DEFUN([SPL_AC_CONFIG_KERNEL], [
SPL_AC_2ARGS_SET_FS_PWD
SPL_AC_2ARGS_VFS_UNLINK
SPL_AC_4ARGS_VFS_RENAME
SPL_AC_FS_STRUCT_SPINLOCK
SPL_AC_CRED_STRUCT
SPL_AC_GROUPS_SEARCH
SPL_AC_PUT_TASK_STRUCT
@ -1547,6 +1548,28 @@ AC_DEFUN([SPL_AC_4ARGS_VFS_RENAME],
])
])
dnl #
dnl # 2.6.36 API change,
dnl # The 'struct fs_struct->lock' was changed from a rwlock_t to
dnl # a spinlock_t to improve the fastpath performance.
dnl #
AC_DEFUN([SPL_AC_FS_STRUCT_SPINLOCK], [
AC_MSG_CHECKING([whether struct fs_struct uses spinlock_t])
SPL_LINUX_TRY_COMPILE([
#include <linux/sched.h>
#include <linux/fs_struct.h>
],[
struct fs_struct fs;
spin_lock_init(&fs.lock);
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_FS_STRUCT_SPINLOCK, 1,
[struct fs_struct uses spinlock_t])
],[
AC_MSG_RESULT(no)
])
])
dnl #
dnl # 2.6.29 API change,
dnl # check whether 'struct cred' exists

134
configure vendored
View File

@ -14903,6 +14903,73 @@ fi
{ $as_echo "$as_me:$LINENO: checking whether struct fs_struct uses spinlock_t" >&5
$as_echo_n "checking whether struct fs_struct uses spinlock_t... " >&6; }
cat confdefs.h - <<_ACEOF >conftest.c
/* confdefs.h. */
_ACEOF
cat confdefs.h >>conftest.$ac_ext
cat >>conftest.$ac_ext <<_ACEOF
/* end confdefs.h. */
#include <linux/sched.h>
#include <linux/fs_struct.h>
int
main (void)
{
struct fs_struct fs;
spin_lock_init(&fs.lock);
;
return 0;
}
_ACEOF
rm -Rf build && mkdir -p build
echo "obj-m := conftest.o" >build/Makefile
if { ac_try='cp conftest.c build && make modules -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; }; then
{ $as_echo "$as_me:$LINENO: result: yes" >&5
$as_echo "yes" >&6; }
cat >>confdefs.h <<\_ACEOF
#define HAVE_FS_STRUCT_SPINLOCK 1
_ACEOF
else
$as_echo "$as_me: failed program was:" >&5
sed 's/^/| /' conftest.$ac_ext >&5
{ $as_echo "$as_me:$LINENO: result: no" >&5
$as_echo "no" >&6; }
fi
rm -Rf build
{ $as_echo "$as_me:$LINENO: checking whether struct cred exists" >&5
$as_echo_n "checking whether struct cred exists... " >&6; }
@ -18525,6 +18592,73 @@ fi
{ $as_echo "$as_me:$LINENO: checking whether struct fs_struct uses spinlock_t" >&5
$as_echo_n "checking whether struct fs_struct uses spinlock_t... " >&6; }
cat confdefs.h - <<_ACEOF >conftest.c
/* confdefs.h. */
_ACEOF
cat confdefs.h >>conftest.$ac_ext
cat >>conftest.$ac_ext <<_ACEOF
/* end confdefs.h. */
#include <linux/sched.h>
#include <linux/fs_struct.h>
int
main (void)
{
struct fs_struct fs;
spin_lock_init(&fs.lock);
;
return 0;
}
_ACEOF
rm -Rf build && mkdir -p build
echo "obj-m := conftest.o" >build/Makefile
if { ac_try='cp conftest.c build && make modules -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; }; then
{ $as_echo "$as_me:$LINENO: result: yes" >&5
$as_echo "yes" >&6; }
cat >>confdefs.h <<\_ACEOF
#define HAVE_FS_STRUCT_SPINLOCK 1
_ACEOF
else
$as_echo "$as_me: failed program was:" >&5
sed 's/^/| /' conftest.$ac_ext >&5
{ $as_echo "$as_me:$LINENO: result: no" >&5
$as_echo "no" >&6; }
fi
rm -Rf build
{ $as_echo "$as_me:$LINENO: checking whether struct cred exists" >&5
$as_echo_n "checking whether struct cred exists... " >&6; }

24
module/spl/spl-vnode.c
View File

@ -617,16 +617,24 @@ EXPORT_SYMBOL(releasef);
void
set_fs_pwd(struct fs_struct *fs, struct path *path)
{
struct path old_pwd;
struct path old_pwd;
write_lock(&fs->lock);
old_pwd = fs->pwd;
fs->pwd = *path;
path_get(path);
write_unlock(&fs->lock);
# ifdef HAVE_FS_STRUCT_SPINLOCK
spin_lock(&fs->lock);
old_pwd = fs->pwd;
fs->pwd = *path;
path_get(path);
spin_unlock(&fs->lock);
# else
write_lock(&fs->lock);
old_pwd = fs->pwd;
fs->pwd = *path;
path_get(path);
write_unlock(&fs->lock);
# endif /* HAVE_FS_STRUCT_SPINLOCK */
if (old_pwd.dentry)
path_put(&old_pwd);
if (old_pwd.dentry)
path_put(&old_pwd);
}
# else
/* Used from 2.6.11 - 2.6.24 */

3
spl_config.h.in
View File

@ -78,6 +78,9 @@
/* fls64() is available */
#undef HAVE_FLS64
/* struct fs_struct uses spinlock_t */
#undef HAVE_FS_STRUCT_SPINLOCK
/* get_vmalloc_info() is available */
#undef HAVE_GET_VMALLOC_INFO