From: Tejun Heo Subject: [PATCH 2/3] vfs, writeback: replace FS_CGROUP_WRITEBACK with SB_I_CGROUPWB Date: Tue, 16 Jun 2015 18:48:31 -0400 Message-ID: <1434494912-31043-3-git-send-email-tj@kernel.org> References: <1434494912-31043-1-git-send-email-tj@kernel.org> Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, kernel-team-b10kYP2dOMg@public.gmane.org, Tejun Heo , Alexander Viro , Christoph Hellwig , Jan Kara , linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org Return-path: In-Reply-To: <1434494912-31043-1-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-ext4.vger.kernel.org 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 per-super_block flag. super_block->s_flags carries some internal flags in the high bits but it's exposd to userland through uapi header and running out of space anyway. This patch adds a new field super_block->s_iflags to carry kernel-internal flags. It is currently only used by the new SB_I_CGROUPWB flag whose concatenated and abbreviated name is for consistency with other super_block flags. ext2_fill_super() is updated to set SB_I_CGROUPWB. v2: Added super_block->s_iflags instead of stealing another high bit from sb->s_flags as suggested by Christoph and Jan. Signed-off-by: Tejun Heo Cc: Alexander Viro Cc: linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: Christoph Hellwig Cc: Jan Kara Cc: linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org --- fs/ext2/super.c | 3 ++- include/linux/backing-dev.h | 2 +- include/linux/fs.h | 4 +++- 3 files changed, 6 insertions(+), 3 deletions(-) diff --git a/fs/ext2/super.c b/fs/ext2/super.c index 549219d..900e19c 100644 --- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -882,6 +882,7 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent) sb->s_flags = (sb->s_flags & ~MS_POSIXACL) | ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0); + sb->s_iflags |= SB_I_CGROUPWB; if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV && (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) || @@ -1543,7 +1544,7 @@ 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/include/linux/backing-dev.h b/include/linux/backing-dev.h index dfce808..a13181a 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_iflags & SB_I_CGROUPWB); } /** diff --git a/include/linux/fs.h b/include/linux/fs.h index b5e1dcf..2c5e33a 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1241,6 +1241,8 @@ struct mm_struct; #define UMOUNT_NOFOLLOW 0x00000008 /* Don't follow symlink on umount */ #define UMOUNT_UNUSED 0x80000000 /* Flag guaranteed to be unused */ +/* sb->s_iflags */ +#define SB_I_CGROUPWB 0x00000001 /* cgroup-aware writeback enabled */ /* Possible states of 'frozen' field */ enum { @@ -1279,6 +1281,7 @@ struct super_block { const struct quotactl_ops *s_qcop; const struct export_operations *s_export_op; unsigned long s_flags; + unsigned long s_iflags; /* internal SB_I_* flags */ unsigned long s_magic; struct dentry *s_root; struct rw_semaphore s_umount; @@ -1912,7 +1915,6 @@ 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 *); -- 2.4.3