linux-kernel - [PATCH 2/7] f2fs: avoid writing 0'th page in volatile writes

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Message-Id: <1461629220-16280-2-git-send-email-jaegeuk@kernel.org>
Date:	Mon, 25 Apr 2016 17:06:55 -0700
From:	Jaegeuk Kim <jaegeuk@...nel.org>
To:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net
Cc:	Jaegeuk Kim <jaegeuk@...nel.org>
Subject: [PATCH 2/7] f2fs: avoid writing 0'th page in volatile writes

The first page of volatile writes usually contains a sort of header information
which will be used for recovery.
(e.g., journal header of sqlite)

If this is written without other journal data, user needs to handle the stale
journal information.

Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---
 fs/f2fs/data.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index c29bcf4..e54489b 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1177,8 +1177,10 @@ write:
 		goto redirty_out;
 	if (f2fs_is_drop_cache(inode))
 		goto out;
-	if (f2fs_is_volatile_file(inode) && !wbc->for_reclaim &&
-			available_free_memory(sbi, BASE_CHECK))
+	/* we should not write 0'th page having journal header */
+	if (f2fs_is_volatile_file(inode) && (!page->index ||
+			(!wbc->for_reclaim &&
+			available_free_memory(sbi, BASE_CHECK))))
 		goto redirty_out;
 
 	/* Dentry blocks are controlled by checkpoint */
-- 
2.6.3