[Ocfs2-devel] [PATCH] ocfs2: lock the page in __ocfs2_page_mkwrite()

[Wengang Wang]

Lock the page in __ocfs2_page_mkwrite(). Or we may get -EINVAL error
from ocfs2_grab_pages_for_write() if the page(page cache) gets truncated.

regards,
wengang.

Signed-off-by: Wengang Wang <wen.gang.wang at oracle.com>
---
 fs/ocfs2/aops.c |    9 +++++++--
 fs/ocfs2/mmap.c |   10 +++++++---
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index f1e962c..ade2f48 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -1097,6 +1097,7 @@ static int ocfs2_grab_pages_for_write(struct address_space *mapping,
 	unsigned long start, target_index, end_index, index;
 	struct inode *inode = mapping->host;
 	loff_t last_byte;
+	int lockpg= !PageLocked(mmap_page);
 
 	target_index = user_pos >> PAGE_CACHE_SHIFT;
 
@@ -1133,11 +1134,15 @@ static int ocfs2_grab_pages_for_write(struct address_space *mapping,
 			 * ocfs2_pagemkwrite() is a little different
 			 * and wants us to directly use the page
 			 * passed in.
+			 * in ocfs2_page_mkwirte() path, the page is already
+			 * locked, don't lock it again.
 			 */
-			lock_page(mmap_page);
+			if (lockpg)
+				lock_page(mmap_page);
 
 			if (mmap_page->mapping != mapping) {
-				unlock_page(mmap_page);
+				if (lockpg)
+					unlock_page(mmap_page);
 				/*
 				 * Sanity check - the locking in
 				 * ocfs2_pagemkwrite() should ensure
diff --git a/fs/ocfs2/mmap.c b/fs/ocfs2/mmap.c
index 7e32db9..bb29335 100644
--- a/fs/ocfs2/mmap.c
+++ b/fs/ocfs2/mmap.c
@@ -79,9 +79,10 @@ static int __ocfs2_page_mkwrite(struct file *file, struct buffer_head *di_bh,
 	 * from do_generic_file_read.
 	 */
 	last_index = (size - 1) >> PAGE_CACHE_SHIFT;
+	lock_page(page);
 	if (unlikely(!size || page->index > last_index)) {
 		ret = -EINVAL;
-		goto out;
+		goto out_unlock;
 	}
 
 	/*
@@ -96,7 +97,7 @@ static int __ocfs2_page_mkwrite(struct file *file, struct buffer_head *di_bh,
 		 * So return 0 here and let VFS retry.
 		 */
 		ret = 0;
-		goto out;
+		goto out_unlock;
 	}
 
 	/*
@@ -117,7 +118,7 @@ static int __ocfs2_page_mkwrite(struct file *file, struct buffer_head *di_bh,
 	if (ret) {
 		if (ret != -ENOSPC)
 			mlog_errno(ret);
-		goto out;
+		goto out_unlock;
 	}
 
 	ret = ocfs2_write_end_nolock(mapping, pos, len, len, locked_page,
@@ -128,6 +129,9 @@ static int __ocfs2_page_mkwrite(struct file *file, struct buffer_head *di_bh,
 	}
 	BUG_ON(ret != len);
 	ret = 0;
+	goto out;
+out_unlock:
+	unlock_page(page);
 out:
 	return ret;
 }
-- 
1.7.2.3