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zfs/config/kernel-fst-mount.m4

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Allow mounting datasets more than once Currently mounting an already mounted zfs dataset results in an error, whereas it is typically allowed with other filesystems. This causes some bad interactions with mount namespaces. Take this sequence for example: - Create a dataset - Create a snapshot of the dataset - Create a clone of the snapshot - Create a new mount namespace - Rename the original dataset The rename results in unmounting and remounting the clone in the original mount namespace, however the remount fails because the dataset is still mounted in the new mount namespace. (Note that this means the mount in the new mount namespace is never being unmounted, so perhaps the unmount/remount of the clone isn't actually necessary.) The problem here is a result of the way mounting is implemented in the kernel module. Since it is not mounting block devices it uses mount_nodev() instead of the usual mount_bdev(). However, mount_nodev() is written for filesystems for which each mount is a new instance (i.e. a new super block), and zfs should be able to detect when a mount request can be satisfied using an existing super block. Change zpl_mount() to call sget() directly with it's own test callback. Passing the objset_t object as the fs data allows checking if a superblock already exists for the dataset, and in that case we just need to return a new reference for the sb's root dentry. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Tom Caputi <tcaputi@datto.com> Signed-off-by: Alek Pinchuk <apinchuk@datto.com> Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Closes #5796 Closes #7207
2018-04-12 19:24:38 +00:00
dnl #
dnl # 2.6.38 API change
dnl # The .get_sb callback has been replaced by a .mount callback
dnl # in the file_system_type structure.
dnl #
Perform KABI checks in parallel Reduce the time required for ./configure to perform the needed KABI checks by allowing kbuild to compile multiple test cases in parallel. This was accomplished by splitting each test's source code from the logic handling whether that code could be compiled or not. By introducing this split it's possible to minimize the number of times kbuild needs to be invoked. As importantly, it means all of the tests can be built in parallel. This does require a little extra care since we expect some tests to fail, so the --keep-going (-k) option must be provided otherwise some tests may not get compiled. Furthermore, since a failure during the kbuild modpost phase will result in an early exit; the final linking phase is limited to tests which passed the initial compilation and produced an object file. Once everything has been built the configure script proceeds as previously. The only significant difference is that it now merely needs to test for the existence of a .ko file to determine the result of a given test. This vastly speeds up the entire process. New test cases should use ZFS_LINUX_TEST_SRC to declare their test source code and ZFS_LINUX_TEST_RESULT to check the result. All of the existing kernel-*.m4 files have been updated accordingly, see config/kernel-current-time.m4 for a basic example. The legacy ZFS_LINUX_TRY_COMPILE macro has been kept to handle special cases but it's use is not encouraged. master (secs) patched (secs) ------------- ---------------- autogen.sh 61 68 configure 137 24 (~17% of current run time) make -j $(nproc) 44 44 make rpms 287 150 Reviewed-by: Tony Hutter <hutter2@llnl.gov> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #8547 Closes #9132 Closes #9341
2019-10-01 19:50:34 +00:00
AC_DEFUN([ZFS_AC_KERNEL_SRC_FST_MOUNT], [
ZFS_LINUX_TEST_SRC([file_system_type_mount], [
Allow mounting datasets more than once Currently mounting an already mounted zfs dataset results in an error, whereas it is typically allowed with other filesystems. This causes some bad interactions with mount namespaces. Take this sequence for example: - Create a dataset - Create a snapshot of the dataset - Create a clone of the snapshot - Create a new mount namespace - Rename the original dataset The rename results in unmounting and remounting the clone in the original mount namespace, however the remount fails because the dataset is still mounted in the new mount namespace. (Note that this means the mount in the new mount namespace is never being unmounted, so perhaps the unmount/remount of the clone isn't actually necessary.) The problem here is a result of the way mounting is implemented in the kernel module. Since it is not mounting block devices it uses mount_nodev() instead of the usual mount_bdev(). However, mount_nodev() is written for filesystems for which each mount is a new instance (i.e. a new super block), and zfs should be able to detect when a mount request can be satisfied using an existing super block. Change zpl_mount() to call sget() directly with it's own test callback. Passing the objset_t object as the fs data allows checking if a superblock already exists for the dataset, and in that case we just need to return a new reference for the sb's root dentry. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Tom Caputi <tcaputi@datto.com> Signed-off-by: Alek Pinchuk <apinchuk@datto.com> Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Closes #5796 Closes #7207
2018-04-12 19:24:38 +00:00
#include <linux/fs.h>
static struct dentry *
mount(struct file_system_type *fs_type, int flags,
const char *osname, void *data) {
struct dentry *d = NULL;
return (d);
}
static struct file_system_type fst __attribute__ ((unused)) = {
.mount = mount,
};
Perform KABI checks in parallel Reduce the time required for ./configure to perform the needed KABI checks by allowing kbuild to compile multiple test cases in parallel. This was accomplished by splitting each test's source code from the logic handling whether that code could be compiled or not. By introducing this split it's possible to minimize the number of times kbuild needs to be invoked. As importantly, it means all of the tests can be built in parallel. This does require a little extra care since we expect some tests to fail, so the --keep-going (-k) option must be provided otherwise some tests may not get compiled. Furthermore, since a failure during the kbuild modpost phase will result in an early exit; the final linking phase is limited to tests which passed the initial compilation and produced an object file. Once everything has been built the configure script proceeds as previously. The only significant difference is that it now merely needs to test for the existence of a .ko file to determine the result of a given test. This vastly speeds up the entire process. New test cases should use ZFS_LINUX_TEST_SRC to declare their test source code and ZFS_LINUX_TEST_RESULT to check the result. All of the existing kernel-*.m4 files have been updated accordingly, see config/kernel-current-time.m4 for a basic example. The legacy ZFS_LINUX_TRY_COMPILE macro has been kept to handle special cases but it's use is not encouraged. master (secs) patched (secs) ------------- ---------------- autogen.sh 61 68 configure 137 24 (~17% of current run time) make -j $(nproc) 44 44 make rpms 287 150 Reviewed-by: Tony Hutter <hutter2@llnl.gov> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #8547 Closes #9132 Closes #9341
2019-10-01 19:50:34 +00:00
],[])
])
AC_DEFUN([ZFS_AC_KERNEL_FST_MOUNT], [
AC_MSG_CHECKING([whether fst->mount() exists])
ZFS_LINUX_TEST_RESULT([file_system_type_mount], [
Allow mounting datasets more than once Currently mounting an already mounted zfs dataset results in an error, whereas it is typically allowed with other filesystems. This causes some bad interactions with mount namespaces. Take this sequence for example: - Create a dataset - Create a snapshot of the dataset - Create a clone of the snapshot - Create a new mount namespace - Rename the original dataset The rename results in unmounting and remounting the clone in the original mount namespace, however the remount fails because the dataset is still mounted in the new mount namespace. (Note that this means the mount in the new mount namespace is never being unmounted, so perhaps the unmount/remount of the clone isn't actually necessary.) The problem here is a result of the way mounting is implemented in the kernel module. Since it is not mounting block devices it uses mount_nodev() instead of the usual mount_bdev(). However, mount_nodev() is written for filesystems for which each mount is a new instance (i.e. a new super block), and zfs should be able to detect when a mount request can be satisfied using an existing super block. Change zpl_mount() to call sget() directly with it's own test callback. Passing the objset_t object as the fs data allows checking if a superblock already exists for the dataset, and in that case we just need to return a new reference for the sb's root dentry. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Tom Caputi <tcaputi@datto.com> Signed-off-by: Alek Pinchuk <apinchuk@datto.com> Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Closes #5796 Closes #7207
2018-04-12 19:24:38 +00:00
AC_MSG_RESULT(yes)
],[
Linux compat: Minimum kernel version 3.10 Increase the minimum supported kernel version from 2.6.32 to 3.10. This removes support for the following Linux enterprise distributions. Distribution | Kernel | End of Life ---------------- | ------ | ------------- Ubuntu 12.04 LTS | 3.2 | Apr 28, 2017 SLES 11 | 3.0 | Mar 32, 2019 RHEL / CentOS 6 | 2.6.32 | Nov 30, 2020 The following changes were made as part of removing support. * Updated `configure` to enforce a minimum kernel version as specified in the META file (Linux-Minimum: 3.10). configure: error: *** Cannot build against kernel version 2.6.32. *** The minimum supported kernel version is 3.10. * Removed all `configure` kABI checks and matching C code for interfaces which solely predate the Linux 3.10 kernel. * Updated all `configure` kABI checks to fail when an interface is missing which was in the 3.10 kernel up to the latest 5.1 kernel. Removed the HAVE_* preprocessor defines for these checks and updated the code to unconditionally use the verified interface. * Inverted the detection logic in several kABI checks to match the new interface as it appears in 3.10 and newer and not the legacy interface. * Consolidated the following checks in to individual files. Due the large number of changes in the checks it made sense to handle this now. It would be desirable to group other related checks in the same fashion, but this as left as future work. - config/kernel-blkdev.m4 - Block device kABI checks - config/kernel-blk-queue.m4 - Block queue kABI checks - config/kernel-bio.m4 - Bio interface kABI checks * Removed the kABI checks for sops->nr_cached_objects() and sops->free_cached_objects(). These interfaces are currently unused. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #9566
2019-11-12 16:59:06 +00:00
ZFS_LINUX_TEST_ERROR([fst->mount()])
Allow mounting datasets more than once Currently mounting an already mounted zfs dataset results in an error, whereas it is typically allowed with other filesystems. This causes some bad interactions with mount namespaces. Take this sequence for example: - Create a dataset - Create a snapshot of the dataset - Create a clone of the snapshot - Create a new mount namespace - Rename the original dataset The rename results in unmounting and remounting the clone in the original mount namespace, however the remount fails because the dataset is still mounted in the new mount namespace. (Note that this means the mount in the new mount namespace is never being unmounted, so perhaps the unmount/remount of the clone isn't actually necessary.) The problem here is a result of the way mounting is implemented in the kernel module. Since it is not mounting block devices it uses mount_nodev() instead of the usual mount_bdev(). However, mount_nodev() is written for filesystems for which each mount is a new instance (i.e. a new super block), and zfs should be able to detect when a mount request can be satisfied using an existing super block. Change zpl_mount() to call sget() directly with it's own test callback. Passing the objset_t object as the fs data allows checking if a superblock already exists for the dataset, and in that case we just need to return a new reference for the sb's root dentry. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Tom Caputi <tcaputi@datto.com> Signed-off-by: Alek Pinchuk <apinchuk@datto.com> Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Closes #5796 Closes #7207
2018-04-12 19:24:38 +00:00
])
])