Merge branch 'lazytime' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull lazytime mount option support from Al Viro:
 "Lazytime stuff from tytso"

* 'lazytime' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  ext4: add optimization for the lazytime mount option
  vfs: add find_inode_nowait() function
  vfs: add support for a lazytime mount option

15 files changed, 343 insertions, 37 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 28555f191b62..85404f15e53a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4174,6 +4174,65 @@ static int ext4_inode_blocks_set(handle_t *handle,
         return 0;
 }
 
+struct other_inode {
+        unsigned long           orig_ino;
+        struct ext4_inode       *raw_inode;
+};
+
+static int other_inode_match(struct inode * inode, unsigned long ino,
+                             void *data)
+{
+        struct other_inode *oi = (struct other_inode *) data;
+
+        if ((inode->i_ino != ino) ||
+            (inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW |
+                               I_DIRTY_SYNC | I_DIRTY_DATASYNC)) ||
+            ((inode->i_state & I_DIRTY_TIME) == 0))
+                return 0;
+        spin_lock(&inode->i_lock);
+        if (((inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW |
+                                I_DIRTY_SYNC | I_DIRTY_DATASYNC)) == 0) &&
+            (inode->i_state & I_DIRTY_TIME)) {
+                struct ext4_inode_info  *ei = EXT4_I(inode);
+
+                inode->i_state &= ~(I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED);
+                spin_unlock(&inode->i_lock);
+
+                spin_lock(&ei->i_raw_lock);
+                EXT4_INODE_SET_XTIME(i_ctime, inode, oi->raw_inode);
+                EXT4_INODE_SET_XTIME(i_mtime, inode, oi->raw_inode);
+                EXT4_INODE_SET_XTIME(i_atime, inode, oi->raw_inode);
+                ext4_inode_csum_set(inode, oi->raw_inode, ei);
+                spin_unlock(&ei->i_raw_lock);
+                trace_ext4_other_inode_update_time(inode, oi->orig_ino);
+                return -1;
+        }
+        spin_unlock(&inode->i_lock);
+        return -1;
+}
+
+/*
+ * Opportunistically update the other time fields for other inodes in
+ * the same inode table block.
+ */
+static void ext4_update_other_inodes_time(struct super_block *sb,
+                                          unsigned long orig_ino, char *buf)
+{
+        struct other_inode oi;
+        unsigned long ino;
+        int i, inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
+        int inode_size = EXT4_INODE_SIZE(sb);
+
+        oi.orig_ino = orig_ino;
+        ino = orig_ino & ~(inodes_per_block - 1);
+        for (i = 0; i < inodes_per_block; i++, ino++, buf += inode_size) {
+                if (ino == orig_ino)
+                        continue;
+                oi.raw_inode = (struct ext4_inode *) buf;
+                (void) find_inode_nowait(sb, ino, other_inode_match, &oi);
+        }
+}
+
 /*
  * Post the struct inode info into an on-disk inode location in the
  * buffer-cache.  This gobbles the caller's reference to the
@@ -4283,10 +4342,11 @@ static int ext4_do_update_inode(handle_t *handle,
                                 cpu_to_le16(ei->i_extra_isize);
                 }
         }
-
         ext4_inode_csum_set(inode, raw_inode, ei);
-
         spin_unlock(&ei->i_raw_lock);
+        if (inode->i_sb->s_flags & MS_LAZYTIME)
+                ext4_update_other_inodes_time(inode->i_sb, inode->i_ino,
+                                              bh->b_data);
 
         BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
         rc = ext4_handle_dirty_metadata(handle, NULL, bh);
@@ -4875,11 +4935,17 @@ int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
  * If the inode is marked synchronous, we don't honour that here - doing
  * so would cause a commit on atime updates, which we don't bother doing.
  * We handle synchronous inodes at the highest possible level.
+ *
+ * If only the I_DIRTY_TIME flag is set, we can skip everything.  If
+ * I_DIRTY_TIME and I_DIRTY_SYNC is set, the only inode fields we need
+ * to copy into the on-disk inode structure are the timestamp files.
  */
 void ext4_dirty_inode(struct inode *inode, int flags)
 {
         handle_t *handle;
 
+        if (flags == I_DIRTY_TIME)
+                return;
         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
         if (IS_ERR(handle))
                 goto out;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 10e8c6b7ca08..1adac6868e6f 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1126,6 +1126,7 @@ enum {
         Opt_noquota, Opt_barrier, Opt_nobarrier, Opt_err,
         Opt_usrquota, Opt_grpquota, Opt_i_version, Opt_dax,
         Opt_stripe, Opt_delalloc, Opt_nodelalloc, Opt_mblk_io_submit,
+        Opt_lazytime, Opt_nolazytime,
         Opt_nomblk_io_submit, Opt_block_validity, Opt_noblock_validity,
         Opt_inode_readahead_blks, Opt_journal_ioprio,
         Opt_dioread_nolock, Opt_dioread_lock,
@@ -1190,6 +1191,8 @@ static const match_table_t tokens = {
         {Opt_dax, "dax"},
         {Opt_stripe, "stripe=%u"},
         {Opt_delalloc, "delalloc"},
+        {Opt_lazytime, "lazytime"},
+        {Opt_nolazytime, "nolazytime"},
         {Opt_nodelalloc, "nodelalloc"},
         {Opt_removed, "mblk_io_submit"},
         {Opt_removed, "nomblk_io_submit"},
@@ -1448,6 +1451,12 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
         case Opt_i_version:
                 sb->s_flags |= MS_I_VERSION;
                 return 1;
+        case Opt_lazytime:
+                sb->s_flags |= MS_LAZYTIME;
+                return 1;
+        case Opt_nolazytime:
+                sb->s_flags &= ~MS_LAZYTIME;
+                return 1;
         }
 
         for (m = ext4_mount_opts; m->token != Opt_err; m++)
@@ -5044,6 +5053,7 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
         }
 #endif
 
+        *flags = (*flags & ~MS_LAZYTIME) | (sb->s_flags & MS_LAZYTIME);
         ext4_msg(sb, KERN_INFO, "re-mounted. Opts: %s", orig_data);
         kfree(orig_data);
         return 0;
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index c399152de397..073657f755d4 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -253,14 +253,19 @@ static bool inode_dirtied_after(struct inode *inode, unsigned long t)
         return ret;
 }
 
+#define EXPIRE_DIRTY_ATIME 0x0001
+
 /*
  * Move expired (dirtied before work->older_than_this) dirty inodes from
  * @delaying_queue to @dispatch_queue.
  */
 static int move_expired_inodes(struct list_head *delaying_queue,
                                struct list_head *dispatch_queue,
+                               int flags,
                                struct wb_writeback_work *work)
 {
+        unsigned long *older_than_this = NULL;
+        unsigned long expire_time;
         LIST_HEAD(tmp);
         struct list_head *pos, *node;
         struct super_block *sb = NULL;
@@ -268,13 +273,21 @@ static int move_expired_inodes(struct list_head *delaying_queue,
         int do_sb_sort = 0;
         int moved = 0;
 
+        if ((flags & EXPIRE_DIRTY_ATIME) == 0)
+                older_than_this = work->older_than_this;
+        else if ((work->reason == WB_REASON_SYNC) == 0) {
+                expire_time = jiffies - (HZ * 86400);
+                older_than_this = &expire_time;
+        }
         while (!list_empty(delaying_queue)) {
                 inode = wb_inode(delaying_queue->prev);
-                if (work->older_than_this &&
-                    inode_dirtied_after(inode, *work->older_than_this))
+                if (older_than_this &&
+                    inode_dirtied_after(inode, *older_than_this))
                         break;
                 list_move(&inode->i_wb_list, &tmp);
                 moved++;
+                if (flags & EXPIRE_DIRTY_ATIME)
+                        set_bit(__I_DIRTY_TIME_EXPIRED, &inode->i_state);
                 if (sb_is_blkdev_sb(inode->i_sb))
                         continue;
                 if (sb && sb != inode->i_sb)
@@ -315,9 +328,12 @@ out:
 static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work)
 {
         int moved;
+
         assert_spin_locked(&wb->list_lock);
         list_splice_init(&wb->b_more_io, &wb->b_io);
-        moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, work);
+        moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, 0, work);
+        moved += move_expired_inodes(&wb->b_dirty_time, &wb->b_io,
+                                     EXPIRE_DIRTY_ATIME, work);
         trace_writeback_queue_io(wb, work, moved);
 }
 
@@ -441,6 +457,8 @@ static void requeue_inode(struct inode *inode, struct bdi_writeback *wb,
                  * updates after data IO completion.
                  */
                 redirty_tail(inode, wb);
+        } else if (inode->i_state & I_DIRTY_TIME) {
+                list_move(&inode->i_wb_list, &wb->b_dirty_time);
         } else {
                 /* The inode is clean. Remove from writeback lists. */
                 list_del_init(&inode->i_wb_list);
@@ -487,7 +505,13 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
         spin_lock(&inode->i_lock);
 
         dirty = inode->i_state & I_DIRTY;
-        inode->i_state &= ~I_DIRTY;
+        if (((dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) &&
+             (inode->i_state & I_DIRTY_TIME)) ||
+            (inode->i_state & I_DIRTY_TIME_EXPIRED)) {
+                dirty |= I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED;
+                trace_writeback_lazytime(inode);
+        }
+        inode->i_state &= ~dirty;
 
         /*
          * Paired with smp_mb() in __mark_inode_dirty().  This allows
@@ -507,8 +531,10 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
 
         spin_unlock(&inode->i_lock);
 
+        if (dirty & I_DIRTY_TIME)
+                mark_inode_dirty_sync(inode);
         /* Don't write the inode if only I_DIRTY_PAGES was set */
-        if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) {
+        if (dirty & ~I_DIRTY_PAGES) {
                 int err = write_inode(inode, wbc);
                 if (ret == 0)
                         ret = err;
@@ -556,7 +582,7 @@ writeback_single_inode(struct inode *inode, struct bdi_writeback *wb,
          * make sure inode is on some writeback list and leave it there unless
          * we have completely cleaned the inode.
          */
-        if (!(inode->i_state & I_DIRTY) &&
+        if (!(inode->i_state & I_DIRTY_ALL) &&
             (wbc->sync_mode != WB_SYNC_ALL ||
              !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK)))
                 goto out;
@@ -571,7 +597,7 @@ writeback_single_inode(struct inode *inode, struct bdi_writeback *wb,
          * If inode is clean, remove it from writeback lists. Otherwise don't
          * touch it. See comment above for explanation.
          */
-        if (!(inode->i_state & I_DIRTY))
+        if (!(inode->i_state & I_DIRTY_ALL))
                 list_del_init(&inode->i_wb_list);
         spin_unlock(&wb->list_lock);
         inode_sync_complete(inode);
@@ -713,7 +739,7 @@ static long writeback_sb_inodes(struct super_block *sb,
                 wrote += write_chunk - wbc.nr_to_write;
                 spin_lock(&wb->list_lock);
                 spin_lock(&inode->i_lock);
-                if (!(inode->i_state & I_DIRTY))
+                if (!(inode->i_state & I_DIRTY_ALL))
                         wrote++;
                 requeue_inode(inode, wb, &wbc);
                 inode_sync_complete(inode);
@@ -1151,16 +1177,20 @@ static noinline void block_dump___mark_inode_dirty(struct inode *inode)
  * page->mapping->host, so the page-dirtying time is recorded in the internal
  * blockdev inode.
  */
+#define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC)
 void __mark_inode_dirty(struct inode *inode, int flags)
 {
         struct super_block *sb = inode->i_sb;
         struct backing_dev_info *bdi = NULL;
+        int dirtytime;
+
+        trace_writeback_mark_inode_dirty(inode, flags);
 
         /*
          * Don't do this for I_DIRTY_PAGES - that doesn't actually
          * dirty the inode itself
          */
-        if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) {
+        if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_TIME)) {
                 trace_writeback_dirty_inode_start(inode, flags);
 
                 if (sb->s_op->dirty_inode)
@@ -1168,6 +1198,9 @@ void __mark_inode_dirty(struct inode *inode, int flags)
 
                 trace_writeback_dirty_inode(inode, flags);
         }
+        if (flags & I_DIRTY_INODE)
+                flags &= ~I_DIRTY_TIME;
+        dirtytime = flags & I_DIRTY_TIME;
 
         /*
          * Paired with smp_mb() in __writeback_single_inode() for the
@@ -1175,16 +1208,21 @@ void __mark_inode_dirty(struct inode *inode, int flags)
          */
         smp_mb();
 
-        if ((inode->i_state & flags) == flags)
+        if (((inode->i_state & flags) == flags) ||
+            (dirtytime && (inode->i_state & I_DIRTY_INODE)))
                 return;
 
         if (unlikely(block_dump))
                 block_dump___mark_inode_dirty(inode);
 
         spin_lock(&inode->i_lock);
+        if (dirtytime && (inode->i_state & I_DIRTY_INODE))
+                goto out_unlock_inode;
         if ((inode->i_state & flags) != flags) {
                 const int was_dirty = inode->i_state & I_DIRTY;
 
+                if (flags & I_DIRTY_INODE)
+                        inode->i_state &= ~I_DIRTY_TIME;
                 inode->i_state |= flags;
 
                 /*
@@ -1231,8 +1269,10 @@ void __mark_inode_dirty(struct inode *inode, int flags)
                         }
 
                         inode->dirtied_when = jiffies;
-                        list_move(&inode->i_wb_list, &bdi->wb.b_dirty);
+                        list_move(&inode->i_wb_list, dirtytime ?
+                                  &bdi->wb.b_dirty_time : &bdi->wb.b_dirty);
                         spin_unlock(&bdi->wb.list_lock);
+                        trace_writeback_dirty_inode_enqueue(inode);
 
                         if (wakeup_bdi)
                                 bdi_wakeup_thread_delayed(bdi);
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index ec9c2d33477a..3e32bb8e2d7e 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -654,7 +654,7 @@ static int gfs2_fsync(struct file *file, loff_t start, loff_t end,
 {
         struct address_space *mapping = file->f_mapping;
         struct inode *inode = mapping->host;
-        int sync_state = inode->i_state & I_DIRTY;
+        int sync_state = inode->i_state & I_DIRTY_ALL;
         struct gfs2_inode *ip = GFS2_I(inode);
         int ret = 0, ret1 = 0;
 
@@ -667,7 +667,7 @@ static int gfs2_fsync(struct file *file, loff_t start, loff_t end,
         if (!gfs2_is_jdata(ip))
                 sync_state &= ~I_DIRTY_PAGES;
         if (datasync)
-                sync_state &= ~I_DIRTY_SYNC;
+                sync_state &= ~(I_DIRTY_SYNC | I_DIRTY_TIME);
 
         if (sync_state) {
                 ret = sync_inode_metadata(inode, 1);
diff --git a/fs/inode.c b/fs/inode.c
index 86bfaca724db..f00b16f45507 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -18,6 +18,7 @@
 #include <linux/buffer_head.h> /* for inode_has_buffers */
 #include <linux/ratelimit.h>
 #include <linux/list_lru.h>
+#include <trace/events/writeback.h>
 #include "internal.h"
 
 /*
@@ -30,7 +31,7 @@
  * inode_sb_list_lock protects:
  *   sb->s_inodes, inode->i_sb_list
  * bdi->wb.list_lock protects:
- *   bdi->wb.b_{dirty,io,more_io}, inode->i_wb_list
+ *   bdi->wb.b_{dirty,io,more_io,dirty_time}, inode->i_wb_list
  * inode_hash_lock protects:
  *   inode_hashtable, inode->i_hash
  *
@@ -403,7 +404,8 @@ static void inode_lru_list_add(struct inode *inode)
  */
 void inode_add_lru(struct inode *inode)
 {
-        if (!(inode->i_state & (I_DIRTY | I_SYNC | I_FREEING | I_WILL_FREE)) &&
+        if (!(inode->i_state & (I_DIRTY_ALL | I_SYNC |
+                                I_FREEING | I_WILL_FREE)) &&
             !atomic_read(&inode->i_count) && inode->i_sb->s_flags & MS_ACTIVE)
                 inode_lru_list_add(inode);
 }
@@ -634,7 +636,7 @@ int invalidate_inodes(struct super_block *sb, bool kill_dirty)
                         spin_unlock(&inode->i_lock);
                         continue;
                 }
-                if (inode->i_state & I_DIRTY && !kill_dirty) {
+                if (inode->i_state & I_DIRTY_ALL && !kill_dirty) {
                         spin_unlock(&inode->i_lock);
                         busy = 1;
                         continue;
@@ -1268,6 +1270,56 @@ struct inode *ilookup(struct super_block *sb, unsigned long ino)
 }
 EXPORT_SYMBOL(ilookup);
 
+/**
+ * find_inode_nowait - find an inode in the inode cache
+ * @sb:         super block of file system to search
+ * @hashval:    hash value (usually inode number) to search for
+ * @match:      callback used for comparisons between inodes
+ * @data:       opaque data pointer to pass to @match
+ *
+ * Search for the inode specified by @hashval and @data in the inode
+ * cache, where the helper function @match will return 0 if the inode
+ * does not match, 1 if the inode does match, and -1 if the search
+ * should be stopped.  The @match function must be responsible for
+ * taking the i_lock spin_lock and checking i_state for an inode being
+ * freed or being initialized, and incrementing the reference count
+ * before returning 1.  It also must not sleep, since it is called with
+ * the inode_hash_lock spinlock held.
+ *
+ * This is a even more generalized version of ilookup5() when the
+ * function must never block --- find_inode() can block in
+ * __wait_on_freeing_inode() --- or when the caller can not increment
+ * the reference count because the resulting iput() might cause an
+ * inode eviction.  The tradeoff is that the @match funtion must be
+ * very carefully implemented.
+ */
+struct inode *find_inode_nowait(struct super_block *sb,
+                                unsigned long hashval,
+                                int (*match)(struct inode *, unsigned long,
+                                             void *),
+                                void *data)
+{
+        struct hlist_head *head = inode_hashtable + hash(sb, hashval);
+        struct inode *inode, *ret_inode = NULL;
+        int mval;
+
+        spin_lock(&inode_hash_lock);
+        hlist_for_each_entry(inode, head, i_hash) {
+                if (inode->i_sb != sb)
+                        continue;
+                mval = match(inode, hashval, data);
+                if (mval == 0)
+                        continue;
+                if (mval == 1)
+                        ret_inode = inode;
+                goto out;
+        }
+out:
+        spin_unlock(&inode_hash_lock);
+        return ret_inode;
+}
+EXPORT_SYMBOL(find_inode_nowait);
+
 int insert_inode_locked(struct inode *inode)
 {
         struct super_block *sb = inode->i_sb;
@@ -1418,11 +1470,20 @@ static void iput_final(struct inode *inode)
  */
 void iput(struct inode *inode)
 {
-        if (inode) {
-                BUG_ON(inode->i_state & I_CLEAR);
-
-                if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock))
-                        iput_final(inode);
+        if (!inode)
+                return;
+        BUG_ON(inode->i_state & I_CLEAR);
+retry:
+        if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock)) {
+                if (inode->i_nlink && (inode->i_state & I_DIRTY_TIME)) {
+                        atomic_inc(&inode->i_count);
+                        inode->i_state &= ~I_DIRTY_TIME;
+                        spin_unlock(&inode->i_lock);
+                        trace_writeback_lazytime_iput(inode);
+                        mark_inode_dirty_sync(inode);
+                        goto retry;
+                }
+                iput_final(inode);
         }
 }
 EXPORT_SYMBOL(iput);
@@ -1481,14 +1542,9 @@ static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
         return 0;
 }
 
-/*
- * This does the actual work of updating an inodes time or version.  Must have
- * had called mnt_want_write() before calling this.
- */
-static int update_time(struct inode *inode, struct timespec *time, int flags)
+int generic_update_time(struct inode *inode, struct timespec *time, int flags)
 {
-        if (inode->i_op->update_time)
-                return inode->i_op->update_time(inode, time, flags);
+        int iflags = I_DIRTY_TIME;
 
         if (flags & S_ATIME)
                 inode->i_atime = *time;
@@ -1498,9 +1554,27 @@ static int update_time(struct inode *inode, struct timespec *time, int flags)
                 inode->i_ctime = *time;
         if (flags & S_MTIME)
                 inode->i_mtime = *time;
-        mark_inode_dirty_sync(inode);
+
+        if (!(inode->i_sb->s_flags & MS_LAZYTIME) || (flags & S_VERSION))
+                iflags |= I_DIRTY_SYNC;
+        __mark_inode_dirty(inode, iflags);
         return 0;
 }
+EXPORT_SYMBOL(generic_update_time);
+
+/*
+ * This does the actual work of updating an inodes time or version.  Must have
+ * had called mnt_want_write() before calling this.
+ */
+static int update_time(struct inode *inode, struct timespec *time, int flags)
+{
+        int (*update_time)(struct inode *, struct timespec *, int);
+
+        update_time = inode->i_op->update_time ? inode->i_op->update_time :
+                generic_update_time;
+
+        return update_time(inode, time, flags);
+}
 
 /**
  *      touch_atime     -       update the access time
diff --git a/fs/jfs/file.c b/fs/jfs/file.c
index 33aa0cc1f8b8..10815f8dfd8b 100644
--- a/fs/jfs/file.c
+++ b/fs/jfs/file.c
@@ -39,7 +39,7 @@ int jfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
                 return rc;
 
         mutex_lock(&inode->i_mutex);
-        if (!(inode->i_state & I_DIRTY) ||
+        if (!(inode->i_state & I_DIRTY_ALL) ||
             (datasync && !(inode->i_state & I_DIRTY_DATASYNC))) {
                 /* Make sure committed changes hit the disk */
                 jfs_flush_journal(JFS_SBI(inode->i_sb)->log, 1);
diff --git a/fs/libfs.c b/fs/libfs.c
index 005843ce5dbd..b2ffdb045be4 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -948,7 +948,7 @@ int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
 
         mutex_lock(&inode->i_mutex);
         ret = sync_mapping_buffers(inode->i_mapping);
-        if (!(inode->i_state & I_DIRTY))
+        if (!(inode->i_state & I_DIRTY_ALL))
                 goto out;
         if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
                 goto out;
diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
index 0f96f71ab32b..8db932da4009 100644
--- a/fs/proc_namespace.c
+++ b/fs/proc_namespace.c
@@ -44,6 +44,7 @@ static int show_sb_opts(struct seq_file *m, struct super_block *sb)
                 { MS_SYNCHRONOUS, ",sync" },
                 { MS_DIRSYNC, ",dirsync" },
                 { MS_MANDLOCK, ",mand" },
+                { MS_LAZYTIME, ",lazytime" },
                 { 0, NULL }
         };
         const struct proc_fs_info *fs_infop;
diff --git a/fs/sync.c b/fs/sync.c
index 01d9f18a70b5..fbc98ee62044 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -177,8 +177,16 @@ SYSCALL_DEFINE1(syncfs, int, fd)
  */
 int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync)
 {
+        struct inode *inode = file->f_mapping->host;
+
         if (!file->f_op->fsync)
                 return -EINVAL;
+        if (!datasync && (inode->i_state & I_DIRTY_TIME)) {
+                spin_lock(&inode->i_lock);
+                inode->i_state &= ~I_DIRTY_TIME;
+                spin_unlock(&inode->i_lock);
+                mark_inode_dirty_sync(inode);
+        }
         return file->f_op->fsync(file, start, end, datasync);
 }
 EXPORT_SYMBOL(vfs_fsync_range);
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index d94077fea1f8..aff923ae8c4b 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -55,6 +55,7 @@ struct bdi_writeback {
         struct list_head b_dirty;       /* dirty inodes */
         struct list_head b_io;          /* parked for writeback */
         struct list_head b_more_io;     /* parked for more writeback */
+        struct list_head b_dirty_time;  /* time stamps are dirty */
         spinlock_t list_lock;           /* protects the b_* lists */
 };
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0b5b146d0490..447932aed1e1 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1790,8 +1790,12 @@ struct super_operations {
 #define __I_DIO_WAKEUP          9
 #define I_DIO_WAKEUP            (1 << I_DIO_WAKEUP)
 #define I_LINKABLE              (1 << 10)
+#define I_DIRTY_TIME            (1 << 11)
+#define __I_DIRTY_TIME_EXPIRED  12
+#define I_DIRTY_TIME_EXPIRED    (1 << __I_DIRTY_TIME_EXPIRED)
 
 #define I_DIRTY (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_PAGES)
+#define I_DIRTY_ALL (I_DIRTY | I_DIRTY_TIME)
 
 extern void __mark_inode_dirty(struct inode *, int);
 static inline void mark_inode_dirty(struct inode *inode)
@@ -1954,6 +1958,7 @@ extern int current_umask(void);
 
 extern void ihold(struct inode * inode);
 extern void iput(struct inode *);
+extern int generic_update_time(struct inode *, struct timespec *, int);
 
 static inline struct inode *file_inode(const struct file *f)
 {
@@ -2492,6 +2497,11 @@ extern struct inode *ilookup(struct super_block *sb, unsigned long ino);
 
 extern struct inode * iget5_locked(struct super_block *, unsigned long, int (*test)(struct inode *, void *), int (*set)(struct inode *, void *), void *);
 extern struct inode * iget_locked(struct super_block *, unsigned long);
+extern struct inode *find_inode_nowait(struct super_block *,
+                                       unsigned long,
+                                       int (*match)(struct inode *,
+                                                    unsigned long, void *),
+                                       void *data);
 extern int insert_inode_locked4(struct inode *, unsigned long, int (*test)(struct inode *, void *), void *);
 extern int insert_inode_locked(struct inode *);
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index 6cfb841fea7c..6e5abd6d38a2 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -73,6 +73,36 @@ struct extent_status;
         { FALLOC_FL_ZERO_RANGE,         "ZERO_RANGE"})
 
 
+TRACE_EVENT(ext4_other_inode_update_time,
+        TP_PROTO(struct inode *inode, ino_t orig_ino),
+
+        TP_ARGS(inode, orig_ino),
+
+        TP_STRUCT__entry(
+                __field(        dev_t,  dev                     )
+                __field(        ino_t,  ino                     )
+                __field(        ino_t,  orig_ino                )
+                __field(        uid_t,  uid                     )
+                __field(        gid_t,  gid                     )
+                __field(        __u16, mode                     )
+        ),
+
+        TP_fast_assign(
+                __entry->orig_ino = orig_ino;
+                __entry->dev    = inode->i_sb->s_dev;
+                __entry->ino    = inode->i_ino;
+                __entry->uid    = i_uid_read(inode);
+                __entry->gid    = i_gid_read(inode);
+                __entry->mode   = inode->i_mode;
+        ),
+
+        TP_printk("dev %d,%d orig_ino %lu ino %lu mode 0%o uid %u gid %u",
+                  MAJOR(__entry->dev), MINOR(__entry->dev),
+                  (unsigned long) __entry->orig_ino,
+                  (unsigned long) __entry->ino, __entry->mode,
+                  __entry->uid, __entry->gid)
+);
+
 TRACE_EVENT(ext4_free_inode,
         TP_PROTO(struct inode *inode),
 
diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index 0e9310905413..5a14ead59696 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -18,6 +18,8 @@
                 {I_FREEING,             "I_FREEING"},           \
                 {I_CLEAR,               "I_CLEAR"},             \
                 {I_SYNC,                "I_SYNC"},              \
+                {I_DIRTY_TIME,          "I_DIRTY_TIME"},        \
+                {I_DIRTY_TIME_EXPIRED,  "I_DIRTY_TIME_EXPIRED"}, \
                 {I_REFERENCED,          "I_REFERENCED"}         \
         )
 
@@ -68,6 +70,7 @@ DECLARE_EVENT_CLASS(writeback_dirty_inode_template,
         TP_STRUCT__entry (
                 __array(char, name, 32)
                 __field(unsigned long, ino)
+                __field(unsigned long, state)
                 __field(unsigned long, flags)
         ),
 
@@ -78,16 +81,25 @@ DECLARE_EVENT_CLASS(writeback_dirty_inode_template,
                 strncpy(__entry->name,
                         bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
                 __entry->ino            = inode->i_ino;
+                __entry->state          = inode->i_state;
                 __entry->flags          = flags;
         ),
 
-        TP_printk("bdi %s: ino=%lu flags=%s",
+        TP_printk("bdi %s: ino=%lu state=%s flags=%s",
                 __entry->name,
                 __entry->ino,
+                show_inode_state(__entry->state),
                 show_inode_state(__entry->flags)
         )
 );
 
+DEFINE_EVENT(writeback_dirty_inode_template, writeback_mark_inode_dirty,
+
+        TP_PROTO(struct inode *inode, int flags),
+
+        TP_ARGS(inode, flags)
+);
+
 DEFINE_EVENT(writeback_dirty_inode_template, writeback_dirty_inode_start,
 
         TP_PROTO(struct inode *inode, int flags),
@@ -596,6 +608,52 @@ DEFINE_EVENT(writeback_single_inode_template, writeback_single_inode,
         TP_ARGS(inode, wbc, nr_to_write)
 );
 
+DECLARE_EVENT_CLASS(writeback_lazytime_template,
+        TP_PROTO(struct inode *inode),
+
+        TP_ARGS(inode),
+
+        TP_STRUCT__entry(
+                __field(        dev_t,  dev                     )
+                __field(unsigned long,  ino                     )
+                __field(unsigned long,  state                   )
+                __field(        __u16, mode                     )
+                __field(unsigned long, dirtied_when             )
+        ),
+
+        TP_fast_assign(
+                __entry->dev    = inode->i_sb->s_dev;
+                __entry->ino    = inode->i_ino;
+                __entry->state  = inode->i_state;
+                __entry->mode   = inode->i_mode;
+                __entry->dirtied_when = inode->dirtied_when;
+        ),
+
+        TP_printk("dev %d,%d ino %lu dirtied %lu state %s mode 0%o",
+                  MAJOR(__entry->dev), MINOR(__entry->dev),
+                  __entry->ino, __entry->dirtied_when,
+                  show_inode_state(__entry->state), __entry->mode)
+);
+
+DEFINE_EVENT(writeback_lazytime_template, writeback_lazytime,
+        TP_PROTO(struct inode *inode),
+
+        TP_ARGS(inode)
+);
+
+DEFINE_EVENT(writeback_lazytime_template, writeback_lazytime_iput,
+        TP_PROTO(struct inode *inode),
+
+        TP_ARGS(inode)
+);
+
+DEFINE_EVENT(writeback_lazytime_template, writeback_dirty_inode_enqueue,
+
+        TP_PROTO(struct inode *inode),
+
+        TP_ARGS(inode)
+);
+
 #endif /* _TRACE_WRITEBACK_H */
 
 /* This part must be outside protection */
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 3735fa0a6784..9b964a5920af 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -90,6 +90,7 @@ struct inodes_stat_t {
 #define MS_KERNMOUNT    (1<<22) /* this is a kern_mount call */
 #define MS_I_VERSION    (1<<23) /* Update inode I_version field */
 #define MS_STRICTATIME  (1<<24) /* Always perform atime updates */
+#define MS_LAZYTIME     (1<<25) /* Update the on-disk [acm]times lazily */
 
 /* These sb flags are internal to the kernel */
 #define MS_NOSEC        (1<<28)
@@ -100,7 +101,8 @@ struct inodes_stat_t {
 /*
  * Superblock flags that can be altered by MS_REMOUNT
  */
-#define MS_RMT_MASK     (MS_RDONLY|MS_SYNCHRONOUS|MS_MANDLOCK|MS_I_VERSION)
+#define MS_RMT_MASK     (MS_RDONLY|MS_SYNCHRONOUS|MS_MANDLOCK|MS_I_VERSION|\
+                         MS_LAZYTIME)
 
 /*
  * Old magic mount flag and mask
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 7690ec77c722..6dc4580df2af 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -49,10 +49,10 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
         unsigned long background_thresh;
         unsigned long dirty_thresh;
         unsigned long bdi_thresh;
-        unsigned long nr_dirty, nr_io, nr_more_io;
+        unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time;
         struct inode *inode;
 
-        nr_dirty = nr_io = nr_more_io = 0;
+        nr_dirty = nr_io = nr_more_io = nr_dirty_time = 0;
         spin_lock(&wb->list_lock);
         list_for_each_entry(inode, &wb->b_dirty, i_wb_list)
                 nr_dirty++;
@@ -60,6 +60,9 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
                 nr_io++;
         list_for_each_entry(inode, &wb->b_more_io, i_wb_list)
                 nr_more_io++;
+        list_for_each_entry(inode, &wb->b_dirty_time, i_wb_list)
+                if (inode->i_state & I_DIRTY_TIME)
+                        nr_dirty_time++;
         spin_unlock(&wb->list_lock);
 
         global_dirty_limits(&background_thresh, &dirty_thresh);
@@ -78,6 +81,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
                    "b_dirty:            %10lu\n"
                    "b_io:               %10lu\n"
                    "b_more_io:          %10lu\n"
+                   "b_dirty_time:       %10lu\n"
                    "bdi_list:           %10u\n"
                    "state:              %10lx\n",
                    (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
@@ -91,6 +95,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
                    nr_dirty,
                    nr_io,
                    nr_more_io,
+                   nr_dirty_time,
                    !list_empty(&bdi->bdi_list), bdi->state);
 #undef K
 
@@ -380,6 +385,7 @@ static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
         INIT_LIST_HEAD(&wb->b_dirty);
         INIT_LIST_HEAD(&wb->b_io);
         INIT_LIST_HEAD(&wb->b_more_io);
+        INIT_LIST_HEAD(&wb->b_dirty_time);
         spin_lock_init(&wb->list_lock);
         INIT_DELAYED_WORK(&wb->dwork, bdi_writeback_workfn);
 }