1 files changed, 76 insertions, 48 deletions

diff --git a/fs/inode.c b/fs/inode.c
index b2ba83d2c4e1..4d8e3be55976 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -14,6 +14,7 @@
 #include <linux/module.h>
 #include <linux/backing-dev.h>
 #include <linux/wait.h>
+#include <linux/rwsem.h>
 #include <linux/hash.h>
 #include <linux/swap.h>
 #include <linux/security.h>
@@ -87,14 +88,18 @@ static struct hlist_head *inode_hashtable __read_mostly;
 DEFINE_SPINLOCK(inode_lock);
 
 /*
- * iprune_mutex provides exclusion between the kswapd or try_to_free_pages
+ * iprune_sem provides exclusion between the kswapd or try_to_free_pages
  * icache shrinking path, and the umount path.  Without this exclusion,
  * by the time prune_icache calls iput for the inode whose pages it has
  * been invalidating, or by the time it calls clear_inode & destroy_inode
  * from its final dispose_list, the struct super_block they refer to
  * (for inode->i_sb->s_op) may already have been freed and reused.
+ *
+ * We make this an rwsem because the fastpath is icache shrinking. In
+ * some cases a filesystem may be doing a significant amount of work in
+ * its inode reclaim code, so this should improve parallelism.
  */
-static DEFINE_MUTEX(iprune_mutex);
+static DECLARE_RWSEM(iprune_sem);
 
 /*
  * Statistics gathering..
@@ -123,7 +128,7 @@ static void wake_up_inode(struct inode *inode)
 int inode_init_always(struct super_block *sb, struct inode *inode)
 {
         static const struct address_space_operations empty_aops;
-        static struct inode_operations empty_iops;
+        static const struct inode_operations empty_iops;
         static const struct file_operations empty_fops;
         struct address_space *const mapping = &inode->i_data;
 
@@ -381,7 +386,7 @@ static int invalidate_list(struct list_head *head, struct list_head *dispose)
                 /*
                  * We can reschedule here without worrying about the list's
                  * consistency because the per-sb list of inodes must not
-                 * change during umount anymore, and because iprune_mutex keeps
+                 * change during umount anymore, and because iprune_sem keeps
                  * shrink_icache_memory() away.
                  */
                 cond_resched_lock(&inode_lock);
@@ -420,7 +425,7 @@ int invalidate_inodes(struct super_block *sb)
         int busy;
         LIST_HEAD(throw_away);
 
-        mutex_lock(&iprune_mutex);
+        down_write(&iprune_sem);
         spin_lock(&inode_lock);
         inotify_unmount_inodes(&sb->s_inodes);
         fsnotify_unmount_inodes(&sb->s_inodes);
@@ -428,7 +433,7 @@ int invalidate_inodes(struct super_block *sb)
         spin_unlock(&inode_lock);
 
         dispose_list(&throw_away);
-        mutex_unlock(&iprune_mutex);
+        up_write(&iprune_sem);
 
         return busy;
 }
@@ -467,7 +472,7 @@ static void prune_icache(int nr_to_scan)
         int nr_scanned;
         unsigned long reap = 0;
 
-        mutex_lock(&iprune_mutex);
+        down_read(&iprune_sem);
         spin_lock(&inode_lock);
         for (nr_scanned = 0; nr_scanned < nr_to_scan; nr_scanned++) {
                 struct inode *inode;
@@ -509,7 +514,7 @@ static void prune_icache(int nr_to_scan)
         spin_unlock(&inode_lock);
 
         dispose_list(&freeable);
-        mutex_unlock(&iprune_mutex);
+        up_read(&iprune_sem);
 }
 
 /*
@@ -695,13 +700,15 @@ void unlock_new_inode(struct inode *inode)
         }
 #endif
         /*
-         * This is special!  We do not need the spinlock
-         * when clearing I_LOCK, because we're guaranteed
-         * that nobody else tries to do anything about the
-         * state of the inode when it is locked, as we
-         * just created it (so there can be no old holders
-         * that haven't tested I_LOCK).
+         * This is special!  We do not need the spinlock when clearing I_LOCK,
+         * because we're guaranteed that nobody else tries to do anything about
+         * the state of the inode when it is locked, as we just created it (so
+         * there can be no old holders that haven't tested I_LOCK).
+         * However we must emit the memory barrier so that other CPUs reliably
+         * see the clearing of I_LOCK after the other inode initialisation has
+         * completed.
          */
+        smp_mb();
         WARN_ON((inode->i_state & (I_LOCK|I_NEW)) != (I_LOCK|I_NEW));
         inode->i_state &= ~(I_LOCK|I_NEW);
         wake_up_inode(inode);
@@ -1234,7 +1241,16 @@ void generic_delete_inode(struct inode *inode)
 }
 EXPORT_SYMBOL(generic_delete_inode);
 
-static void generic_forget_inode(struct inode *inode)
+/**
+ *      generic_detach_inode - remove inode from inode lists
+ *      @inode: inode to remove
+ *
+ *      Remove inode from inode lists, write it if it's dirty. This is just an
+ *      internal VFS helper exported for hugetlbfs. Do not use!
+ *
+ *      Returns 1 if inode should be completely destroyed.
+ */
+int generic_detach_inode(struct inode *inode)
 {
         struct super_block *sb = inode->i_sb;
 
@@ -1244,7 +1260,7 @@ static void generic_forget_inode(struct inode *inode)
                 inodes_stat.nr_unused++;
                 if (sb->s_flags & MS_ACTIVE) {
                         spin_unlock(&inode_lock);
-                        return;
+                        return 0;
                 }
                 WARN_ON(inode->i_state & I_NEW);
                 inode->i_state |= I_WILL_FREE;
@@ -1262,6 +1278,14 @@ static void generic_forget_inode(struct inode *inode)
         inode->i_state |= I_FREEING;
         inodes_stat.nr_inodes--;
         spin_unlock(&inode_lock);
+        return 1;
+}
+EXPORT_SYMBOL_GPL(generic_detach_inode);
+
+static void generic_forget_inode(struct inode *inode)
+{
+        if (!generic_detach_inode(inode))
+                return;
         if (inode->i_data.nrpages)
                 truncate_inode_pages(&inode->i_data, 0);
         clear_inode(inode);
@@ -1392,31 +1416,31 @@ void touch_atime(struct vfsmount *mnt, struct dentry *dentry)
         struct inode *inode = dentry->d_inode;
         struct timespec now;
 
-        if (mnt_want_write(mnt))
-                return;
         if (inode->i_flags & S_NOATIME)
-                goto out;
+                return;
         if (IS_NOATIME(inode))
-                goto out;
+                return;
         if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
-                goto out;
+                return;
 
         if (mnt->mnt_flags & MNT_NOATIME)
-                goto out;
+                return;
         if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
-                goto out;
+                return;
 
         now = current_fs_time(inode->i_sb);
 
         if (!relatime_need_update(mnt, inode, now))
-                goto out;
+                return;
 
         if (timespec_equal(&inode->i_atime, &now))
-                goto out;
+                return;
+
+        if (mnt_want_write(mnt))
+                return;
 
         inode->i_atime = now;
         mark_inode_dirty_sync(inode);
-out:
         mnt_drop_write(mnt);
 }
 EXPORT_SYMBOL(touch_atime);
@@ -1437,34 +1461,37 @@ void file_update_time(struct file *file)
 {
         struct inode *inode = file->f_path.dentry->d_inode;
         struct timespec now;
-        int sync_it = 0;
-        int err;
+        enum { S_MTIME = 1, S_CTIME = 2, S_VERSION = 4 } sync_it = 0;
 
+        /* First try to exhaust all avenues to not sync */
         if (IS_NOCMTIME(inode))
                 return;
 
-        err = mnt_want_write_file(file);
-        if (err)
-                return;
-
         now = current_fs_time(inode->i_sb);
-        if (!timespec_equal(&inode->i_mtime, &now)) {
-                inode->i_mtime = now;
-                sync_it = 1;
-        }
+        if (!timespec_equal(&inode->i_mtime, &now))
+                sync_it = S_MTIME;
 
-        if (!timespec_equal(&inode->i_ctime, &now)) {
-                inode->i_ctime = now;
-                sync_it = 1;
-        }
+        if (!timespec_equal(&inode->i_ctime, &now))
+                sync_it |= S_CTIME;
 
-        if (IS_I_VERSION(inode)) {
-                inode_inc_iversion(inode);
-                sync_it = 1;
-        }
+        if (IS_I_VERSION(inode))
+                sync_it |= S_VERSION;
+
+        if (!sync_it)
+                return;
 
-        if (sync_it)
-                mark_inode_dirty_sync(inode);
+        /* Finally allowed to write? Takes lock. */
+        if (mnt_want_write_file(file))
+                return;
+
+        /* Only change inode inside the lock region */
+        if (sync_it & S_VERSION)
+                inode_inc_iversion(inode);
+        if (sync_it & S_CTIME)
+                inode->i_ctime = now;
+        if (sync_it & S_MTIME)
+                inode->i_mtime = now;
+        mark_inode_dirty_sync(inode);
         mnt_drop_write(file->f_path.mnt);
 }
 EXPORT_SYMBOL(file_update_time);
@@ -1592,7 +1619,8 @@ void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
         else if (S_ISSOCK(mode))
                 inode->i_fop = &bad_sock_fops;
         else
-                printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o)\n",
-                       mode);
+                printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
+                                  " inode %s:%lu\n", mode, inode->i_sb->s_id,
+                                  inode->i_ino);
 }
 EXPORT_SYMBOL(init_special_inode);