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.
Unified · Split
| @@ -882,6 +882,7 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent) · 881 unmodified lines | ||
| 882 | 882 | sb->s_flags = (sb->s_flags & ~MS_POSIXACL) | |
| 883 | 883 | ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? |
| 884 | 884 | MS_POSIXACL : 0); |
| 885 | + sb->s_iflags |= SB_I_CGROUPWB; | |
| 885 | 886 | |
| 886 | 887 | if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV && |
| 887 | 888 | (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) || |
| @@ -1543,7 +1544,7 @@ static struct file_system_type ext2_fs_type = { · 655 unmodified lines | ||
| 1543 | 1544 | .name = "ext2", |
| 1544 | 1545 | .mount = ext2_mount, |
| 1545 | 1546 | .kill_sb = kill_block_super, |
| 1546 | − .fs_flags = FS_REQUIRES_DEV | FS_CGROUP_WRITEBACK, | |
| 1547 | + .fs_flags = FS_REQUIRES_DEV, | |
| 1547 | 1548 | }; |
| 1548 | 1549 | MODULE_ALIAS_FS("ext2"); |
| 1549 | 1550 | |
| @@ -260,7 +260,7 @@ static inline bool inode_cgwb_enabled(struct inode *inode) · 259 unmodified lines | ||
| 260 | 260 | |
| 261 | 261 | return bdi_cap_account_dirty(bdi) && |
| 262 | 262 | (bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) && |
| 263 | − (inode->i_sb->s_type->fs_flags & FS_CGROUP_WRITEBACK); | |
| 263 | + (inode->i_sb->s_iflags & SB_I_CGROUPWB); | |
| 264 | 264 | } |
| 265 | 265 | |
| 266 | 266 | /** |
| @@ -1241,6 +1241,8 @@ struct mm_struct; · 1240 unmodified lines | ||
| 1241 | 1241 | #define UMOUNT_NOFOLLOW 0x00000008 /* Don't follow symlink on umount */ |
| 1242 | 1242 | #define UMOUNT_UNUSED 0x80000000 /* Flag guaranteed to be unused */ |
| 1243 | 1243 | |
| 1244 | +/* sb->s_iflags */ | |
| 1245 | +#define SB_I_CGROUPWB 0x00000001 /* cgroup-aware writeback enabled */ | |
| 1244 | 1246 | |
| 1245 | 1247 | /* Possible states of 'frozen' field */ |
| 1246 | 1248 | enum { |
| @@ -1279,6 +1281,7 @@ struct super_block { · 32 unmodified lines | ||
| 1279 | 1281 | const struct quotactl_ops *s_qcop; |
| 1280 | 1282 | const struct export_operations *s_export_op; |
| 1281 | 1283 | unsigned long s_flags; |
| 1284 | + unsigned long s_iflags; /* internal SB_I_* flags */ | |
| 1282 | 1285 | unsigned long s_magic; |
| 1283 | 1286 | struct dentry *s_root; |
| 1284 | 1287 | struct rw_semaphore s_umount; |
| @@ -1912,7 +1915,6 @@ struct file_system_type { · 627 unmodified lines | ||
| 1912 | 1915 | #define FS_HAS_SUBTYPE 4 |
| 1913 | 1916 | #define FS_USERNS_MOUNT 8 /* Can be mounted by userns root */ |
| 1914 | 1917 | #define FS_USERNS_DEV_MOUNT 16 /* A userns mount does not imply MNT_NODEV */ |
| 1915 | −#define FS_CGROUP_WRITEBACK 32 /* Supports cgroup-aware writeback */ | |
| 1916 | 1918 | #define FS_RENAME_DOES_D_MOVE 32768 /* FS will handle d_move() during rename() internally. */ |
| 1917 | 1919 | struct dentry *(*mount) (struct file_system_type *, int, |
| 1918 | 1920 | const char *, void *); |