fs/ufs: get rid of write_super

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

The way we implement this is that we schedule a delay job instead relying on
's_dirt' and '->write_super()'.

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>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/ufs/balloc.c b/fs/ufs/balloc.c
index 42694e1..1b3e410 100644 (file)
--- a/fs/ufs/balloc.c
+++ b/fs/ufs/balloc.c
@@ -116,7 +116,7 @@ void ufs_free_fragments(struct inode *inode, u64 fragment, unsigned count)
        ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
        if (sb->s_flags & MS_SYNCHRONOUS)
                ubh_sync_block(UCPI_UBH(ucpi));
-       sb->s_dirt = 1;
+       ufs_mark_sb_dirty(sb);
        
        unlock_super (sb);
        UFSD("EXIT\n");
@@ -214,7 +214,7 @@ do_more:
                goto do_more;
        }
 
-       sb->s_dirt = 1;
+       ufs_mark_sb_dirty(sb);
        unlock_super (sb);
        UFSD("EXIT\n");
        return;
@@ -557,7 +557,7 @@ static u64 ufs_add_fragments(struct inode *inode, u64 fragment,
        ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
        if (sb->s_flags & MS_SYNCHRONOUS)
                ubh_sync_block(UCPI_UBH(ucpi));
-       sb->s_dirt = 1;
+       ufs_mark_sb_dirty(sb);
 
        UFSD("EXIT, fragment %llu\n", (unsigned long long)fragment);
        
@@ -677,7 +677,7 @@ succed:
        ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
        if (sb->s_flags & MS_SYNCHRONOUS)
                ubh_sync_block(UCPI_UBH(ucpi));
-       sb->s_dirt = 1;
+       ufs_mark_sb_dirty(sb);
 
        result += cgno * uspi->s_fpg;
        UFSD("EXIT3, result %llu\n", (unsigned long long)result);

diff --git a/fs/ufs/ialloc.c b/fs/ufs/ialloc.c
index 4ec5c10..e84cbe2 100644 (file)
--- a/fs/ufs/ialloc.c
+++ b/fs/ufs/ialloc.c
@@ -116,7 +116,7 @@ void ufs_free_inode (struct inode * inode)
        if (sb->s_flags & MS_SYNCHRONOUS)
                ubh_sync_block(UCPI_UBH(ucpi));
        
-       sb->s_dirt = 1;
+       ufs_mark_sb_dirty(sb);
        unlock_super (sb);
        UFSD("EXIT\n");
 }
@@ -288,7 +288,7 @@ cg_found:
        ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
        if (sb->s_flags & MS_SYNCHRONOUS)
                ubh_sync_block(UCPI_UBH(ucpi));
-       sb->s_dirt = 1;
+       ufs_mark_sb_dirty(sb);
 
        inode->i_ino = cg * uspi->s_ipg + bit;
        inode_init_owner(inode, dir, mode);

diff --git a/fs/ufs/super.c b/fs/ufs/super.c
index ad56c6d..444927e 100644 (file)
--- a/fs/ufs/super.c
+++ b/fs/ufs/super.c
@@ -302,7 +302,7 @@ void ufs_error (struct super_block * sb, const char * function,
        if (!(sb->s_flags & MS_RDONLY)) {
                usb1->fs_clean = UFS_FSBAD;
                ubh_mark_buffer_dirty(USPI_UBH(uspi));
-               sb->s_dirt = 1;
+               ufs_mark_sb_dirty(sb);
                sb->s_flags |= MS_RDONLY;
        }
        va_start (args, fmt);
@@ -334,7 +334,7 @@ void ufs_panic (struct super_block * sb, const char * function,
        if (!(sb->s_flags & MS_RDONLY)) {
                usb1->fs_clean = UFS_FSBAD;
                ubh_mark_buffer_dirty(USPI_UBH(uspi));
-               sb->s_dirt = 1;
+               ufs_mark_sb_dirty(sb);
        }
        va_start (args, fmt);
        vsnprintf (error_buf, sizeof(error_buf), fmt, args);
@@ -715,7 +715,6 @@ static int ufs_sync_fs(struct super_block *sb, int wait)
                ufs_set_fs_state(sb, usb1, usb3,
                                UFS_FSOK - fs32_to_cpu(sb, usb1->fs_time));
        ufs_put_cstotal(sb);
-       sb->s_dirt = 0;
 
        UFSD("EXIT\n");
        unlock_super(sb);
@@ -724,12 +723,31 @@ static int ufs_sync_fs(struct super_block *sb, int wait)
        return 0;
 }
 
-static void ufs_write_super(struct super_block *sb)
+static void delayed_sync_fs(struct work_struct *work)
 {
-       if (!(sb->s_flags & MS_RDONLY))
-               ufs_sync_fs(sb, 1);
-       else
-               sb->s_dirt = 0;
+       struct ufs_sb_info *sbi;
+
+       sbi = container_of(work, struct ufs_sb_info, sync_work.work);
+
+       spin_lock(&sbi->work_lock);
+       sbi->work_queued = 0;
+       spin_unlock(&sbi->work_lock);
+
+       ufs_sync_fs(sbi->sb, 1);
+}
+
+void ufs_mark_sb_dirty(struct super_block *sb)
+{
+       struct ufs_sb_info *sbi = UFS_SB(sb);
+       unsigned long delay;
+
+       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 ufs_put_super(struct super_block *sb)
@@ -740,6 +758,7 @@ static void ufs_put_super(struct super_block *sb)
 
        if (!(sb->s_flags & MS_RDONLY))
                ufs_put_super_internal(sb);
+       cancel_delayed_work_sync(&sbi->sync_work);
 
        ubh_brelse_uspi (sbi->s_uspi);
        kfree (sbi->s_uspi);
@@ -774,6 +793,7 @@ static int ufs_fill_super(struct super_block *sb, void *data, int silent)
        if (!sbi)
                goto failed_nomem;
        sb->s_fs_info = sbi;
+       sbi->sb = sb;
 
        UFSD("flag %u\n", (int)(sb->s_flags & MS_RDONLY));
        
@@ -785,6 +805,8 @@ static int ufs_fill_super(struct super_block *sb, void *data, int silent)
        }
 #endif
        mutex_init(&sbi->mutex);
+       spin_lock_init(&sbi->work_lock);
+       INIT_DELAYED_WORK(&sbi->sync_work, delayed_sync_fs);
        /*
         * Set default mount options
         * Parse mount options
@@ -1304,7 +1326,6 @@ static int ufs_remount (struct super_block *sb, int *mount_flags, char *data)
                        ufs_set_fs_state(sb, usb1, usb3,
                                UFS_FSOK - fs32_to_cpu(sb, usb1->fs_time));
                ubh_mark_buffer_dirty (USPI_UBH(uspi));
-               sb->s_dirt = 0;
                sb->s_flags |= MS_RDONLY;
        } else {
        /*
@@ -1454,7 +1475,6 @@ static const struct super_operations ufs_super_ops = {
        .write_inode    = ufs_write_inode,
        .evict_inode    = ufs_evict_inode,
        .put_super      = ufs_put_super,
-       .write_super    = ufs_write_super,
        .sync_fs        = ufs_sync_fs,
        .statfs         = ufs_statfs,
        .remount_fs     = ufs_remount,

diff --git a/fs/ufs/ufs.h b/fs/ufs/ufs.h
index 528750b..343e6fc 100644 (file)
--- a/fs/ufs/ufs.h
+++ b/fs/ufs/ufs.h
@@ -20,6 +20,10 @@ struct ufs_sb_info {
        unsigned s_mount_opt;
        struct mutex mutex;
        struct task_struct *mutex_owner;
+       struct super_block *sb;
+       int work_queued; /* non-zero if the delayed work is queued */
+       struct delayed_work sync_work; /* FS sync delayed work */
+       spinlock_t work_lock; /* protects sync_work and work_queued */
 };
 
 struct ufs_inode_info {
@@ -123,6 +127,7 @@ extern __printf(3, 4)
 void ufs_error(struct super_block *, const char *, const char *, ...);
 extern __printf(3, 4)
 void ufs_panic(struct super_block *, const char *, const char *, ...);
+void ufs_mark_sb_dirty(struct super_block *sb);
 
 /* symlink.c */
 extern const struct inode_operations ufs_fast_symlink_inode_operations;

diff --git a/fs/ufs/ufs_fs.h b/fs/ufs/ufs_fs.h
index 8aba544..0cbd5d3 100644 (file)
--- a/fs/ufs/ufs_fs.h
+++ b/fs/ufs/ufs_fs.h
@@ -34,6 +34,7 @@
 #include <linux/kernel.h>
 #include <linux/stat.h>
 #include <linux/fs.h>
+#include <linux/workqueue.h>
 
 #include <asm/div64.h>
 typedef __u64 __bitwise __fs64;