The previous patch allows us to relax the buffer.c requirement that the page
lock be held in order to avoid writepage zeroing out new data beyond isize.
[actually as I said I think it still has a bug due to writepage requiring
i_size_read]
---
fs/buffer.c | 28 ++++++++--------------------
mm/shmem.c | 6 +++---
2 files changed, 11 insertions(+), 23 deletions(-)
Index: linux-2.6/fs/buffer.c
===================================================================
--- linux-2.6.orig/fs/buffer.c
+++ linux-2.6/fs/buffer.c
@@ -2049,33 +2049,20 @@ int generic_write_end(struct file *file,
struct page *page, void *fsdata)
{
struct inode *inode = mapping->host;
- int i_size_changed = 0;
copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
+ unlock_page(page);
+ page_cache_release(page);
+
/*
* No need to use i_size_read() here, the i_size
* cannot change under us because we hold i_mutex.
- *
- * But it's important to update i_size while still holding page lock:
- * page writeout could otherwise come in and zero beyond i_size.
*/
if (pos+copied > inode->i_size) {
i_size_write(inode, pos+copied);
- i_size_changed = 1;
- }
-
- unlock_page(page);
- page_cache_release(page);
-
- /*
- * Don't mark the inode dirty under page lock. First, it unnecessarily
- * makes the holding time of page lock longer. Second, it forces lock
- * ordering of page lock and transaction start for journaling
- * filesystems.
- */
- if (i_size_changed)
mark_inode_dirty(inode);
+ }
return copied;
}
@@ -2624,14 +2611,15 @@ int nobh_write_end(struct file *file, st
SetPageUptodate(page);
set_page_dirty(page);
+
+ unlock_page(page);
+ page_cache_release(page);
+
if (pos+copied > inode->i_size) {
i_size_write(inode, pos+copied);
mark_inode_dirty(inode);
}
- unlock_page(page);
- page_cache_release(page);
-
while (head) {
bh = head;
head = head->b_this_page;
Index: linux-2.6/mm/shmem.c
===================================================================
--- linux-2.6.orig/mm/shmem.c
+++ linux-2.6/mm/shmem.c
@@ -1631,13 +1631,13 @@ shmem_write_end(struct file *file, struc
{
struct inode *inode = mapping->host;
- if (pos + copied > inode->i_size)
- i_size_write(inode, pos + copied);
-
unlock_page(page);
set_page_dirty(page);
page_cache_release(page);
+ if (pos + copied > inode->i_size)
+ i_size_write(inode, pos + copied);
+
return copied;
}
--
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