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authorTejun Heo <tj@kernel.org>2015-06-16 18:48:31 -0400
committerJens Axboe <axboe@fb.com>2015-06-17 12:47:39 -0600
commit46b15caa7cb19b0f6e3bc8ebaee5bc1bb2e35110 (patch)
tree88f100ba187aa71921ef99862129dd78de329241
parentdd73e4b7df9589fa603fc6d128b4f6cabb250e8e (diff)
downloadop-kernel-dev-46b15caa7cb19b0f6e3bc8ebaee5bc1bb2e35110.zip
op-kernel-dev-46b15caa7cb19b0f6e3bc8ebaee5bc1bb2e35110.tar.gz
vfs, writeback: replace FS_CGROUP_WRITEBACK with SB_I_CGROUPWB
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 <tj@kernel.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Jan Kara <jack@suse.cz> Cc: linux-ext4@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
-rw-r--r--fs/ext2/super.c3
-rw-r--r--include/linux/backing-dev.h2
-rw-r--r--include/linux/fs.h4
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 *);
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