[PATCH 4/4] hfsplus: get rid of write_super

Artem Bityutskiy
2012-06-13T11:36:41Z

This patch makes hfsplus stop using the VFS '->write_super()' method along with
the 's_dirt' superblock flag, because they are on their way out.

The whole "superblock write-out" VFS infrastructure is served by the
'sync_supers()' kernel thread, which wakes up every 5 (by default) seconds and
writes out all dirty superblocks using the '->write_super()' call-back. But the
problem with this thread is that it wastes power by waking up the system every
5 seconds, even if there are no diry superblocks, or there are no client
file-systems which would need this (e.g., btrfs does not use
'->write_super()'). So we want to kill it completely and thus, we need to make
file-systems to stop using the '->write_super()' VFS service, and then remove
it together with the kernel thread.

Tested using fsstress from the LTP project.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
---
fs/hfsplus/bitmap.c | 4 ++--
fs/hfsplus/dir.c | 2 +-
fs/hfsplus/hfsplus_fs.h | 6 +++++-
fs/hfsplus/inode.c | 6 +++---
fs/hfsplus/super.c | 41 +++++++++++++++++++++++++++++++++--------
5 files changed, 44 insertions(+), 15 deletions(-)

diff --git a/fs/hfsplus/bitmap.c b/fs/hfsplus/bitmap.c
index 1cad80c..4cfbe2e 100644
--- a/fs/hfsplus/bitmap.c
+++ b/fs/hfsplus/bitmap.c
@@ -153,7 +153,7 @@ done:
kunmap(page);
*max = offset + (curr - pptr) * 32 + i - start;
sbi->free_blocks -= *max;
- sb->s_dirt = 1;
+ hfsplus_mark_mdb_dirty(sb);
dprint(DBG_BITMAP, "-> %u,%u\n", start, *max);
out:
mutex_unlock(&sbi->alloc_mutex);
@@ -228,7 +228,7 @@ out:
set_page_dirty(page);
kunmap(page);
sbi->free_blocks += len;
- sb->s_dirt = 1;
+ hfsplus_mark_mdb_dirty(sb);
mutex_unlock(&sbi->alloc_mutex);

return 0;
diff --git a/fs/hfsplus/dir.c b/fs/hfsplus/dir.c
index 26b53fb..8375504 100644
--- a/fs/hfsplus/dir.c
+++ b/fs/hfsplus/dir.c
@@ -316,7 +316,7 @@ static int hfsplus_link(struct dentry *src_dentry, struct inode *dst_dir,
inode->i_ctime = CURRENT_TIME_SEC;
mark_inode_dirty(inode);
sbi->file_count++;
- dst_dir->i_sb->s_dirt = 1;
+ hfsplus_mark_mdb_dirty(dst_dir->i_sb);
out:
mutex_unlock(&sbi->vh_mutex);
return res;
diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h
index 66a9365..558dbb4 100644
--- a/fs/hfsplus/hfsplus_fs.h
+++ b/fs/hfsplus/hfsplus_fs.h
@@ -153,8 +153,11 @@ struct hfsplus_sb_info {
gid_t gid;

int part, session;
-
unsigned long flags;
+
+ int work_queued; /* non-zero delayed work is queued */
+ struct delayed_work sync_work; /* FS sync delayed work */
+ spinlock_t work_lock; /* protects sync_work and work_queued */
};

#define HFSPLUS_SB_WRITEBACKUP 0
@@ -428,6 +431,7 @@ int hfsplus_show_options(struct seq_file *, struct dentry *);

/* super.c */
struct inode *hfsplus_iget(struct super_block *, unsigned long);
+void hfsplus_mark_mdb_dirty(struct super_block *sb);

/* tables.c */
extern u16 hfsplus_case_fold_table[];
diff --git a/fs/hfsplus/inode.c b/fs/hfsplus/inode.c
index 82b69ee..ad1f16f 100644
--- a/fs/hfsplus/inode.c
+++ b/fs/hfsplus/inode.c
@@ -431,7 +431,7 @@ struct inode *hfsplus_new_inode(struct super_block *sb, umode_t mode)
sbi->file_count++;
insert_inode_hash(inode);
mark_inode_dirty(inode);
- sb->s_dirt = 1;
+ hfsplus_mark_mdb_dirty(sb);

return inode;
}
@@ -442,7 +442,7 @@ void hfsplus_delete_inode(struct inode *inode)

if (S_ISDIR(inode->i_mode)) {
HFSPLUS_SB(sb)->folder_count--;
- sb->s_dirt = 1;
+ hfsplus_mark_mdb_dirty(sb);
return;
}
HFSPLUS_SB(sb)->file_count--;
@@ -455,7 +455,7 @@ void hfsplus_delete_inode(struct inode *inode)
inode->i_size = 0;
hfsplus_file_truncate(inode);
}
- sb->s_dirt = 1;
+ hfsplus_mark_mdb_dirty(sb);
}

void hfsplus_inode_read_fork(struct inode *inode, struct hfsplus_fork_raw *fork)
diff --git a/fs/hfsplus/super.c b/fs/hfsplus/super.c
index f4f3d54..cb6b9c1 100644
--- a/fs/hfsplus/super.c
+++ b/fs/hfsplus/super.c
@@ -124,7 +124,7 @@ static int hfsplus_system_write_inode(struct inode *inode)

if (fork->total_size != cpu_to_be64(inode->i_size)) {
set_bit(HFSPLUS_SB_WRITEBACKUP, &sbi->flags);
- inode->i_sb->s_dirt = 1;
+ hfsplus_mark_mdb_dirty(inode->i_sb);
}
hfsplus_inode_write_fork(inode, fork);
if (tree)
@@ -173,7 +173,7 @@ static int hfsplus_sync_fs(struct super_block *sb, int wait)

dprint(DBG_SUPER, "hfsplus_sync_fs\n");

- sb->s_dirt = 0;
+ cancel_delayed_work(&sbi->sync_work);

/*
* Explicitly write out the special metadata inodes.
@@ -226,12 +226,34 @@ out:
return error;
}

-static void hfsplus_write_super(struct super_block *sb)
+static void delayed_sync_fs(struct work_struct *work)
{
- if (!(sb->s_flags & MS_RDONLY))
- hfsplus_sync_fs(sb, 1);
- else
- sb->s_dirt = 0;
+ struct hfsplus_sb_info *sbi;
+
+ sbi = container_of(work, struct hfsplus_sb_info, sync_work.work);
+
+ spin_lock(&sbi->work_lock);
+ sbi->work_queued = 0;
+ spin_unlock(&sbi->work_lock);
+
+ hfsplus_sync_fs(sbi->alloc_file->i_sb, 1);
+}
+
+void hfsplus_mark_mdb_dirty(struct super_block *sb)
+{
+ struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
+ unsigned long delay;
+
+ if (sb->s_flags & MS_RDONLY)
+ return;
+
+ spin_lock(&sbi->work_lock);
+ if (!sbi->work_queued) {
+ delay = msecs_to_jiffies(dirty_writeback_interval * 10);
+ queue_delayed_work(system_long_wq, &sbi->sync_work, delay);
+ sbi->work_queued = 1;
+ }
+ spin_unlock(&sbi->work_lock);
}

static void hfsplus_put_super(struct super_block *sb)
@@ -240,6 +262,8 @@ static void hfsplus_put_super(struct super_block *sb)

dprint(DBG_SUPER, "hfsplus_put_super\n");

+ cancel_delayed_work_sync(&sbi->sync_work);
+
if (!(sb->s_flags & MS_RDONLY) && sbi->s_vhdr) {
struct hfsplus_vh *vhdr = sbi->s_vhdr;

@@ -325,7 +349,6 @@ static const struct super_operations hfsplus_sops = {
.write_inode = hfsplus_write_inode,
.evict_inode = hfsplus_evict_inode,
.put_super = hfsplus_put_super,
- .write_super = hfsplus_write_super,
.sync_fs = hfsplus_sync_fs,
.statfs = hfsplus_statfs,
.remount_fs = hfsplus_remount,
@@ -352,6 +375,8 @@ static int hfsplus_fill_super(struct super_block *sb, void *data, int silent)
sb->s_fs_info = sbi;
mutex_init(&sbi->alloc_mutex);
mutex_init(&sbi->vh_mutex);
+ spin_lock_init(&sbi->work_lock);
+ INIT_DELAYED_WORK(&sbi->sync_work, delayed_sync_fs);
hfsplus_fill_defaults(sbi);

err = -EINVAL;
--
1.7.7.6