From 9d9cc48d44908a2e476167fb1345d250225a8e69 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Thu, 5 Mar 2009 02:35:15 -0500 Subject: [PATCH] ext4: Fix deadlock in ext4_write_begin() and ext4_da_write_begin() (cherry picked from commit ebd3610b110bbb18ea6f9f2aeed1e1068c537227) Functions ext4_write_begin() and ext4_da_write_begin() call grab_cache_page_write_begin() without AOP_FLAG_NOFS. Thus it can happen that page reclaim is triggered in that function and it recurses back into the filesystem (or some other filesystem). But this can lead to various problems as a transaction is already started at that point. Add the necessary flag. http://bugzilla.kernel.org/show_bug.cgi?id=11688 Signed-off-by: Jan Kara Signed-off-by: "Theodore Ts'o" Signed-off-by: Greg Kroah-Hartman --- fs/ext4/inode.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index c794e61127cf5..b7f20b0bb0ee5 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1347,6 +1347,10 @@ retry: goto out; } + /* We cannot recurse into the filesystem as the transaction is already + * started */ + flags |= AOP_FLAG_NOFS; + page = grab_cache_page_write_begin(mapping, index, flags); if (!page) { ext4_journal_stop(handle); @@ -1356,7 +1360,7 @@ retry: *pagep = page; ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata, - ext4_get_block); + ext4_get_block); if (!ret && ext4_should_journal_data(inode)) { ret = walk_page_buffers(handle, page_buffers(page), @@ -2603,6 +2607,9 @@ retry: ret = PTR_ERR(handle); goto out; } + /* We cannot recurse into the filesystem as the transaction is already + * started */ + flags |= AOP_FLAG_NOFS; page = grab_cache_page_write_begin(mapping, index, flags); if (!page) { -- 2.47.2