Re: [PATCH 4/4] fs: kill I_WILL_FREE

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 little typos

On the 24.10.2010 19:40, Christoph Hellwig wrote:
The I_WILL_FREE is currently set for inodes that we write out during
umount after dropping their last reference.  It is handled equally
to I_FREEING in most places.  The two execptions are:

  - writeback_single_inode skips all list manipulations for I_FREEING,
    but not for I_WILL_FREE.  We don't care about which list an
    I_WILL_FREE inode is on, because we will remove it from the list
    a little bit later.
  - __mark_inode_dirty skips I_FREEING inodes but not I_WILL_FREE
    inodes.  This only matters for filesystem that re-dirty the inode
    during writeback and then use the I_DIRTY flags inside ->evict_inode.
    The formers is done by XFS, but it uses it's internal state to flush
    the inode.  I could not find any filesystem that looks at I_DIRTY
    inside ->evict_inode either.

Besides cleaning up the code removing I_WILL_FREE will allow us to
avoid one i_lock roundtrip once inode_lock is split and keep iput_final
more logic.  This includes removing the __remove_inode_hash call in
iput_final, given that we never drop the protection from lookups now
that I_FREEING is set earlier.

Signed-off-by: Christoph Hellwig<hch@xxxxxx>

Index: linux-2.6/fs/btrfs/inode.c
===================================================================
--- linux-2.6.orig/fs/btrfs/inode.c	2010-10-24 16:30:05.000000000 +0200
+++ linux-2.6/fs/btrfs/inode.c	2010-10-24 16:32:43.647253791 +0200
@@ -3862,8 +3862,7 @@ again:
  		else if (inode->i_ino>  entry->vfs_inode.i_ino)
  			p =&parent->rb_right;
  		else {
-			WARN_ON(!(entry->vfs_inode.i_state&
-				  (I_WILL_FREE | I_FREEING)));
+			WARN_ON(!(entry->vfs_inode.i_state&  I_FREEING));
  			rb_erase(parent,&root->inode_tree);
  			RB_CLEAR_NODE(parent);
  			spin_unlock(&root->inode_lock);
Index: linux-2.6/fs/drop_caches.c
===================================================================
--- linux-2.6.orig/fs/drop_caches.c	2010-10-24 16:30:05.000000000 +0200
+++ linux-2.6/fs/drop_caches.c	2010-10-24 16:32:43.647253791 +0200
@@ -18,7 +18,7 @@ static void drop_pagecache_sb(struct sup

  	spin_lock(&inode_lock);
  	list_for_each_entry(inode,&sb->s_inodes, i_sb_list) {
-		if (inode->i_state&  (I_FREEING|I_WILL_FREE|I_NEW))
+		if (inode->i_state&  (I_FREEING | I_NEW))
  			continue;
  		if (inode->i_mapping->nrpages == 0)
  			continue;
Index: linux-2.6/fs/gfs2/inode.c
===================================================================
--- linux-2.6.orig/fs/gfs2/inode.c	2010-10-24 16:30:05.000000000 +0200
+++ linux-2.6/fs/gfs2/inode.c	2010-10-24 16:32:43.650253651 +0200
@@ -84,7 +84,7 @@ static int iget_skip_test(struct inode *
  	struct gfs2_skip_data *data = opaque;

  	if (ip->i_no_addr == data->no_addr) {
-		if (inode->i_state&  (I_FREEING|I_WILL_FREE)){
+		if (inode->i_state&  I_FREEING){
  			data->skipped = 1;
  			return 0;
  		}
Index: linux-2.6/fs/fs-writeback.c
===================================================================
--- linux-2.6.orig/fs/fs-writeback.c	2010-10-24 16:32:39.000000000 +0200
+++ linux-2.6/fs/fs-writeback.c	2010-10-24 16:32:43.654254629 +0200
@@ -301,8 +301,7 @@ static void inode_wait_for_writeback(str

  /*
   * Write out an inode's dirty pages.  Called under inode_lock.  Either the
- * caller has ref on the inode (either via __iget or via syscall against an fd)
- * or the inode has I_WILL_FREE set (via generic_forget_inode)
+ * caller has ref on the inode or the inode is beeing freed.
   *
   * If `wait' is set, wait on the writeout.
   *
@@ -320,9 +319,7 @@ writeback_single_inode(struct inode *ino
  	int ret;

  	if (!atomic_read(&inode->i_count))
-		WARN_ON(!(inode->i_state&  (I_WILL_FREE|I_FREEING)));
-	else
-		WARN_ON(inode->i_state&  I_WILL_FREE);
+		WARN_ON(!(inode->i_state&  I_FREEING));

  	if (inode->i_state&  I_SYNC) {
  		/*
@@ -492,7 +489,7 @@ static int writeback_sb_inodes(struct su
  		 * kind does not need peridic writeout yet, and for the latter
  		 * kind writeout is handled by the freer.
don't know again:
freer inode
or
releaser
  		*/
-		if (inode->i_state&  (I_NEW | I_FREEING | I_WILL_FREE)) {
+		if (inode->i_state&  (I_NEW | I_FREEING)) {
  			requeue_io(inode);
  			continue;
  		}
@@ -1043,7 +1040,7 @@ static void wait_sb_inodes(struct super_
  	list_for_each_entry(inode,&sb->s_inodes, i_sb_list) {
  		struct address_space *mapping;

-		if (inode->i_state&  (I_FREEING|I_WILL_FREE|I_NEW))
+		if (inode->i_state&  (I_FREEING | I_NEW))
  			continue;
  		mapping = inode->i_mapping;
  		if (mapping->nrpages == 0)
@@ -1154,7 +1151,7 @@ EXPORT_SYMBOL(sync_inodes_sb);
   * This function commits an inode to disk immediately if it is dirty. This is
   * primarily needed by knfsd.
   *
- * The caller must either have a ref on the inode or must have set I_WILL_FREE.
+ * The caller must either have a ref on the inode or must have set I_FREEING.
   */
  int write_inode_now(struct inode *inode, int sync)
  {
Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c	2010-10-24 16:32:20.000000000 +0200
+++ linux-2.6/fs/inode.c	2010-10-24 16:33:46.912003547 +0200
@@ -667,7 +667,7 @@ repeat:
  			continue;
  		if (!test(inode, data))
  			continue;
-		if (inode->i_state&  (I_FREEING|I_WILL_FREE)) {
+		if (inode->i_state&  I_FREEING) {
  			__wait_on_freeing_inode(inode);
  			goto repeat;
  		}
@@ -693,7 +693,7 @@ repeat:
  			continue;
  		if (inode->i_sb != sb)
  			continue;
-		if (inode->i_state&  (I_FREEING|I_WILL_FREE)) {
+		if (inode->i_state&  I_FREEING) {
  			__wait_on_freeing_inode(inode);
  			goto repeat;
  		}
@@ -964,7 +964,7 @@ EXPORT_SYMBOL(iunique);
  struct inode *igrab(struct inode *inode)
  {
  	spin_lock(&inode_lock);
-	if (!(inode->i_state&  (I_FREEING|I_WILL_FREE)))
+	if (!(inode->i_state&  I_FREEING))
  		__iget(inode);
  	else
  		/*
@@ -1211,7 +1211,7 @@ int insert_inode_locked(struct inode *in
  				continue;
  			if (old->i_sb != sb)
  				continue;
-			if (old->i_state&  (I_FREEING|I_WILL_FREE))
+			if (old->i_state&  I_FREEING)
  				continue;
  			break;
  		}
@@ -1250,7 +1250,7 @@ int insert_inode_locked4(struct inode *i
  				continue;
  			if (!test(old, data))
  				continue;
-			if (old->i_state&  (I_FREEING|I_WILL_FREE))
+			if (old->i_state&  I_FREEING)
  				continue;
  			break;
  		}
@@ -1305,6 +1305,8 @@ static void iput_final(struct inode *ino
  	const struct super_operations *op = inode->i_sb->s_op;
  	int drop;

+	WARN_ON(inode->i_state&  I_NEW);
+
  	if (op&&  op->drop_inode)
  		drop = op->drop_inode(inode);
  	else
@@ -1313,25 +1315,19 @@ static void iput_final(struct inode *ino
  	if (!drop) {
  		if (sb->s_flags&  MS_ACTIVE) {
  			inode->i_state |= I_REFERENCED;
-			if (!(inode->i_state&  (I_DIRTY|I_SYNC))) {
+			if (!(inode->i_state&  (I_DIRTY|I_SYNC)))
  				inode_lru_list_add(inode);
-			}
  			spin_unlock(&inode_lock);
  			return;
  		}
-		WARN_ON(inode->i_state&  I_NEW);
-		inode->i_state |= I_WILL_FREE;
+		inode->i_state |= I_FREEING;
  		spin_unlock(&inode_lock);
  		write_inode_now(inode, 1);
  		spin_lock(&inode_lock);
-		WARN_ON(inode->i_state&  I_NEW);
-		inode->i_state&= ~I_WILL_FREE;
-		__remove_inode_hash(inode);
+	} else {
+		inode->i_state |= I_FREEING;
  	}

-	WARN_ON(inode->i_state&  I_NEW);
-	inode->i_state |= I_FREEING;
-
  	/*
  	 * Move the inode off the IO lists and LRU once I_FREEING is
  	 * set so that it won't get moved back on there if it is dirty.
Index: linux-2.6/fs/notify/inode_mark.c
===================================================================
--- linux-2.6.orig/fs/notify/inode_mark.c	2010-10-24 16:30:05.000000000 +0200
+++ linux-2.6/fs/notify/inode_mark.c	2010-10-24 16:32:43.661255957 +0200
@@ -244,11 +244,11 @@ void fsnotify_unmount_inodes(struct list
  		struct inode *need_iput_tmp;

  		/*
-		 * We cannot __iget() an inode in state I_FREEING,
-		 * I_WILL_FREE, or I_NEW which is fine because by that point
-		 * the inode cannot have any associated watches.
+		 * We cannot __iget() an inode in state I_FREEING or I_NEW,
+		 * which is fine because by that point the inode cannot
+		 * have any associated watches.
  		 */
-		if (inode->i_state&  (I_FREEING|I_WILL_FREE|I_NEW))
+		if (inode->i_state&  (I_FREEING | I_NEW))
  			continue;

  		/*
@@ -272,7 +272,7 @@ void fsnotify_unmount_inodes(struct list
  		/* In case the dropping of a reference would nuke next_i. */
  		if ((&next_i->i_sb_list != list)&&
  		atomic_read(&next_i->i_count)&&
-		    !(next_i->i_state&  (I_FREEING | I_WILL_FREE))) {
+		    !(next_i->i_state&  I_FREEING)) {
  			__iget(next_i);
  			need_iput = next_i;
  		}
Index: linux-2.6/fs/quota/dquot.c
===================================================================
--- linux-2.6.orig/fs/quota/dquot.c	2010-10-24 16:30:05.000000000 +0200
+++ linux-2.6/fs/quota/dquot.c	2010-10-24 16:32:43.665253722 +0200
@@ -898,7 +898,7 @@ static void add_dquot_ref(struct super_b

  	spin_lock(&inode_lock);
  	list_for_each_entry(inode,&sb->s_inodes, i_sb_list) {
-		if (inode->i_state&  (I_FREEING|I_WILL_FREE|I_NEW))
+		if (inode->i_state&  (I_FREEING | I_NEW))
  			continue;
  #ifdef CONFIG_QUOTA_DEBUG
  		if (unlikely(inode_get_rsv_space(inode)>  0))
Index: linux-2.6/fs/xfs/linux-2.6/xfs_iops.c
===================================================================
--- linux-2.6.orig/fs/xfs/linux-2.6/xfs_iops.c	2010-10-24 16:30:05.000000000 +0200
+++ linux-2.6/fs/xfs/linux-2.6/xfs_iops.c	2010-10-24 16:32:43.665253722 +0200
@@ -80,7 +80,7 @@ xfs_mark_inode_dirty_sync(
  {
  	struct inode	*inode = VFS_I(ip);

-	if (!(inode->i_state&  (I_WILL_FREE|I_FREEING)))
+	if (!(inode->i_state&  I_FREEING))
  		mark_inode_dirty_sync(inode);
  }

@@ -90,7 +90,7 @@ xfs_mark_inode_dirty(
  {
  	struct inode	*inode = VFS_I(ip);

-	if (!(inode->i_state&  (I_WILL_FREE|I_FREEING)))
+	if (!(inode->i_state&  I_FREEING))
  		mark_inode_dirty(inode);
  }

Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h	2010-10-24 16:30:05.000000000 +0200
+++ linux-2.6/include/linux/fs.h	2010-10-24 16:32:43.673253652 +0200
@@ -1601,8 +1601,8 @@ struct super_operations {
   * I_DIRTY_DATASYNC and I_DIRTY_PAGES.
   *
   * Four bits define the lifetime of an inode.  Initially, inodes are I_NEW,
comma too much?!
- * until that flag is cleared.  I_WILL_FREE, I_FREEING and I_CLEAR are set at
- * various stages of removing an inode.
+ * until that flag is cleared.  I_FREEING and I_CLEAR are set at various
+ * stages of removing an inode.
   *
   * Two bits are used for locking and completion notification, I_NEW and I_SYNC.
   *
@@ -1613,46 +1613,39 @@ struct super_operations {
   *			don't have to write inode on fdatasync() when only
   *			mtime has changed in it.
   * I_DIRTY_PAGES	Inode has dirty pages.  Inode itself may be clean.
+ * I_FREEING		Set when inode is about to be freed but still has dirty
+ *			pages or buffers attached or the inode itself is still
maybe a comma:
, or the inode itself is
+ *			dirty.
+ * I_CLEAR		Added by end_writeback().  In this state the inode is
+ *			clean and can be destroyed.  Inode keeps I_FREEING.
+ * I_REFERENCED		Inode was recently referenced on the LRU and got another
+ *			pass before eviction.
   * I_NEW		Serves as both a mutex and completion notification.
maybe:
Serves as both: a mutex and a completion notification.
   *			New inodes set I_NEW.  If two processes both create
   *			the same inode, one of them will release its inode and
, then one of them
   *			wait for I_NEW to be released before returning.
- *			Inodes in I_WILL_FREE, I_FREEING or I_CLEAR state can
- *			also cause waiting on I_NEW, without I_NEW actually
- *			being set.  find_inode() uses this to prevent returning
- *			nearly-dead inodes.
- * I_WILL_FREE		Must be set when calling write_inode_now() if i_count
- *			is zero.  I_FREEING must be set when I_WILL_FREE is
- *			cleared.
- * I_FREEING		Set when inode is about to be freed but still has dirty
- *			pages or buffers attached or the inode itself is still
- *			dirty.
- * I_CLEAR		Added by end_writeback().  In this state the inode is clean
- *			and can be destroyed.  Inode keeps I_FREEING.
- *
- *			Inodes that are I_WILL_FREE, I_FREEING or I_CLEAR are
- *			prohibited for many purposes.  iget() must wait for
- *			the inode to be completely released, then create it
- *			anew.  Other functions will just ignore such inodes,
- *			if appropriate.  I_NEW is used for waiting.
- *
+ *			Inodes in I_FREEING state can also cause waiting on
+ *			I_NEW, without I_NEW actually being set.  find_inode()
+ *			uses this to prevent returning nearly-dead inodes.
   * I_SYNC		Synchonized write of dirty inode data.  The bits is
The bit is
   *			set during data writeback, and cleared with a wakeup
   *			on the bit address once it is done.
   *
- * Q: What is the difference between I_WILL_FREE and I_FREEING?
+ * Inodes that have I_FREEING set are prohibited for many purposes.
+ * iget*_locked() must wait for the inode to be completely released, then
+ * create it anew.  Other functions will just ignore such inodes, if
+ * appropriate.  I_NEW is used for waiting.
appropriated
   */
  #define I_DIRTY_SYNC		(1<<  0)
  #define I_DIRTY_DATASYNC	(1<<  1)
  #define I_DIRTY_PAGES		(1<<  2)
-#define __I_NEW			3
+#define I_FREEING		(1<<  3)
+#define I_CLEAR			(1<<  4)
+#define I_REFERENCED		(1<<  5)
+#define __I_NEW			6
  #define I_NEW			(1<<  __I_NEW)
-#define I_WILL_FREE		(1<<  4)
-#define I_FREEING		(1<<  5)
-#define I_CLEAR			(1<<  6)
  #define __I_SYNC		7
  #define I_SYNC			(1<<  __I_SYNC)
-#define I_REFERENCED		(1<<  8)

  #define I_DIRTY (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_PAGES)


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