[RFC:PATCH 009/012] Wrap i_size_write

[Dave Kleikamp <shaggy@linux.vnet.ibm.com>]

Wrap i_size_write

If CONFIG_FILE_TAILS is set, i_size_write is defined in file_tail.c

This adds considerable overhead to i_size_write, but i_size_read is unaffected.

Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
---

 include/linux/fs.h |    5 +++++
 mm/file_tail.c     |   12 ++++++++++++
 2 files changed, 17 insertions(+)

diff -Nurp linux008/include/linux/fs.h linux009/include/linux/fs.h
--- linux008/include/linux/fs.h	2007-05-23 22:53:11.000000000 -0500
+++ linux009/include/linux/fs.h	2007-05-23 22:53:12.000000000 -0500
@@ -661,7 +661,12 @@ static inline loff_t i_size_read(const s
  * (normally i_mutex), otherwise on 32bit/SMP an update of i_size_seqcount
  * can be lost, resulting in subsequent i_size_read() calls spinning forever.
  */
+#ifdef CONFIG_VM_FILE_TAILS
+extern void i_size_write(struct inode *, loff_t); /* defined in file_tail.c */
+static inline void _i_size_write(struct inode *inode, loff_t i_size)
+#else
 static inline void i_size_write(struct inode *inode, loff_t i_size)
+#endif
 {
 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
 	write_seqcount_begin(&inode->i_size_seqcount);
diff -Nurp linux008/mm/file_tail.c linux009/mm/file_tail.c
--- linux008/mm/file_tail.c	2007-05-23 22:53:11.000000000 -0500
+++ linux009/mm/file_tail.c	2007-05-23 22:53:12.000000000 -0500
@@ -188,6 +188,18 @@ int __unpack_file_tail(struct address_sp
 	return rc;
 }
 
+void i_size_write(struct inode *inode, loff_t i_size)
+{
+	struct address_space *mapping = inode->i_mapping;
+
+	write_lock_irq(&mapping->tree_lock);
+	if (mapping->tail && (i_size > i_size_read(inode)))
+		__unpack_file_tail(mapping);
+	_i_size_write(inode, i_size);
+	write_unlock_irq(&mapping->tree_lock);
+}
+EXPORT_SYMBOL(i_size_write);
+
 static void init_once(void *ptr, struct kmem_cache *cachep, unsigned long flags)
 {
 	struct page *page = (struct page *)ptr;

-- 
David Kleikamp
IBM Linux Technology Center

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