| Message ID | 1434146254-26220-3-git-send-email-tj@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Jun 12, 2015 at 04:57:33PM -0500, Tejun Heo wrote: > FS_CGROUP_WRITEBACK indicates whether a file_system_type supports > cgroup writeback; however, different super_blocks of the same > file_system_type may or may not support cgroup writeback depending on > filesystem options. This patch replaces FS_CGROUP_WRITEBACK with a > kernel-internal super_block->s_flags MS_CGROUPWB. The concatenated > and abbreviated name is for consistency with other MS_* flags. Nak. As the uapi part makes it obvious the MS_ namespace is part of the userspace ABI. Please add a new in-kernel flags field instead. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hello, Christoph. On Sat, Jun 13, 2015 at 09:16:08AM -0700, Christoph Hellwig wrote: > On Fri, Jun 12, 2015 at 04:57:33PM -0500, Tejun Heo wrote: > > FS_CGROUP_WRITEBACK indicates whether a file_system_type supports > > cgroup writeback; however, different super_blocks of the same > > file_system_type may or may not support cgroup writeback depending on > > filesystem options. This patch replaces FS_CGROUP_WRITEBACK with a > > kernel-internal super_block->s_flags MS_CGROUPWB. The concatenated > > and abbreviated name is for consistency with other MS_* flags. > > Nak. As the uapi part makes it obvious the MS_ namespace is part > of the userspace ABI. Please add a new in-kernel flags field instead. Are MS_ACTIVE and MS_BORN part of userpace ABI? They seem pretty internal. I don't mind introducing a new internal flag field but it's weird to put this single flag there with other internal flags in ->s_flags. Assuming we add a new field, how do sb->s_iflags and SB_I_XXX sound? Any better suggestions? Thanks.
On Sun 14-06-15 00:42:36, Tejun Heo wrote: > Hello, Christoph. > > On Sat, Jun 13, 2015 at 09:16:08AM -0700, Christoph Hellwig wrote: > > On Fri, Jun 12, 2015 at 04:57:33PM -0500, Tejun Heo wrote: > > > FS_CGROUP_WRITEBACK indicates whether a file_system_type supports > > > cgroup writeback; however, different super_blocks of the same > > > file_system_type may or may not support cgroup writeback depending on > > > filesystem options. This patch replaces FS_CGROUP_WRITEBACK with a > > > kernel-internal super_block->s_flags MS_CGROUPWB. The concatenated > > > and abbreviated name is for consistency with other MS_* flags. > > > > Nak. As the uapi part makes it obvious the MS_ namespace is part > > of the userspace ABI. Please add a new in-kernel flags field instead. > > Are MS_ACTIVE and MS_BORN part of userpace ABI? They seem pretty > internal. I don't mind introducing a new internal flag field but it's > weird to put this single flag there with other internal flags in > ->s_flags. So you are right that there are other internal flags allocated from the top of the i_flags field, however we are pretty much running out of the flags available for the ABI so it's better to move internal flags elsewhere as that's simpler than creating a new ABI for mount... > Assuming we add a new field, how do sb->s_iflags and SB_I_XXX sound? > Any better suggestions? Looks good to me. Honza
diff --git a/fs/ext2/super.c b/fs/ext2/super.c index 549219d..472ed34 100644 --- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -879,7 +879,7 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent) if (!parse_options((char *) data, sb)) goto failed_mount; - sb->s_flags = (sb->s_flags & ~MS_POSIXACL) | + sb->s_flags = (sb->s_flags & ~MS_POSIXACL) | MS_CGROUPWB | ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0); @@ -1543,7 +1543,7 @@ static struct file_system_type ext2_fs_type = { .name = "ext2", .mount = ext2_mount, .kill_sb = kill_block_super, - .fs_flags = FS_REQUIRES_DEV | FS_CGROUP_WRITEBACK, + .fs_flags = FS_REQUIRES_DEV, }; MODULE_ALIAS_FS("ext2"); diff --git a/fs/namespace.c b/fs/namespace.c index 1f4f9da..507b90b 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2669,7 +2669,7 @@ long do_mount(const char *dev_name, const char __user *dir_name, flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | - MS_STRICTATIME); + MS_STRICTATIME | MS_CGROUPWB); if (flags & MS_REMOUNT) retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags, diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index dfce808..1489131 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -260,7 +260,7 @@ static inline bool inode_cgwb_enabled(struct inode *inode) return bdi_cap_account_dirty(bdi) && (bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) && - (inode->i_sb->s_type->fs_flags & FS_CGROUP_WRITEBACK); + (inode->i_sb->s_flags & MS_CGROUPWB); } /** diff --git a/include/linux/fs.h b/include/linux/fs.h index b5e1dcf..66e35dc 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1912,7 +1912,6 @@ struct file_system_type { #define FS_HAS_SUBTYPE 4 #define FS_USERNS_MOUNT 8 /* Can be mounted by userns root */ #define FS_USERNS_DEV_MOUNT 16 /* A userns mount does not imply MNT_NODEV */ -#define FS_CGROUP_WRITEBACK 32 /* Supports cgroup-aware writeback */ #define FS_RENAME_DOES_D_MOVE 32768 /* FS will handle d_move() during rename() internally. */ struct dentry *(*mount) (struct file_system_type *, int, const char *, void *); diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 9b964a5..60316e7 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -93,6 +93,7 @@ struct inodes_stat_t { #define MS_LAZYTIME (1<<25) /* Update the on-disk [acm]times lazily */ /* These sb flags are internal to the kernel */ +#define MS_CGROUPWB (1<<27) /* cgroup-aware writeback enabled */ #define MS_NOSEC (1<<28) #define MS_BORN (1<<29) #define MS_ACTIVE (1<<30)
FS_CGROUP_WRITEBACK indicates whether a file_system_type supports cgroup writeback; however, different super_blocks of the same file_system_type may or may not support cgroup writeback depending on filesystem options. This patch replaces FS_CGROUP_WRITEBACK with a kernel-internal super_block->s_flags MS_CGROUPWB. The concatenated and abbreviated name is for consistency with other MS_* flags. ext2_fill_super() is updated to assert MS_CGROUPWB. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Cc: Jan Kara <jack@suse.cz> Cc: linux-ext4@vger.kernel.org --- fs/ext2/super.c | 4 ++-- fs/namespace.c | 2 +- include/linux/backing-dev.h | 2 +- include/linux/fs.h | 1 - include/uapi/linux/fs.h | 1 + 5 files changed, 5 insertions(+), 5 deletions(-)