[PATCH 3.2 010/125] reiserfs: call truncate_setsize under tailpack mutex

From: Ben Hutchings
Date: Tue Jul 08 2014 - 15:47:49 EST

3.2.61-rc1 review patch. If anyone has any objections, please let me know.


From: Jeff Mahoney <jeffm@xxxxxxxx>

commit 22e7478ddbcb670e33fab72d0bbe7c394c3a2c84 upstream.

Prior to commit 0e4f6a791b1e (Fix reiserfs_file_release()), reiserfs
truncates serialized on i_mutex. They mostly still do, with the exception
of reiserfs_file_release. That blocks out other writers via the tailpack
mutex and the inode openers counter adjusted in reiserfs_file_open.

However, NFS will call reiserfs_setattr without having called ->open, so
we end up with a race when nfs is calling ->setattr while another
process is releasing the file. Ultimately, it triggers the
BUG_ON(inode->i_size != new_file_size) check in maybe_indirect_to_direct.

The solution is to pull the lock into reiserfs_setattr to encompass the
truncate_setsize call as well.

Signed-off-by: Jeff Mahoney <jeffm@xxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
fs/reiserfs/inode.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

--- a/fs/reiserfs/inode.c
+++ b/fs/reiserfs/inode.c
@@ -3211,8 +3211,14 @@ int reiserfs_setattr(struct dentry *dent
attr->ia_size != i_size_read(inode)) {
error = inode_newsize_ok(inode, attr->ia_size);
if (!error) {
+ /*
+ * Could race against reiserfs_file_release
+ * if called from NFS, so take tailpack mutex.
+ */
+ mutex_lock(&REISERFS_I(inode)->tailpack);
truncate_setsize(inode, attr->ia_size);
- reiserfs_vfs_truncate_file(inode);
+ reiserfs_truncate_file(inode, 1);
+ mutex_unlock(&REISERFS_I(inode)->tailpack);

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