[patch] new aop block_write_begin fix

From: Dmitriy Monakhov
Date: Wed Jun 13 2007 - 06:49:39 EST


After we enter to block_write_begin with *pagep == NULL and
some page was grabed we remember this page in *pagep
And if __block_prepare_write() we have to clear *pagep , as
it was before. Because this may confuse caller.
for example caller may have folowing code:
ret = block_write_begin(..., pagep,...)
if (ret && *pagep != NULL) {
unlock_page(*pagep);
page_cache_release(*pagep);
}
Signed-off-by: Dmitriy Monakhov <dmonakhov@xxxxxxxxxx>

diff --git a/fs/buffer.c b/fs/buffer.c
index 07cd457..df933ba 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1982,6 +1982,7 @@ int block_write_begin(struct file *file, struct address_space *mapping,
if (ownpage) {
unlock_page(page);
page_cache_release(page);
+ *pagep = NULL;

/*
* prepare_write() may have instantiated a few blocks

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