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ceph: fix pending vmtruncate race

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The locking order for pending vmtruncate is wrong, it can lead to
following race:

        write                  wmtruncate work
------------------------    ----------------------
lock i_mutex
check i_truncate_pending   check i_truncate_pending
truncate_inode_pages()     lock i_mutex (blocked)
copy data to page cache
unlock i_mutex
                           truncate_inode_pages()

The fix is take i_mutex before calling __ceph_do_pending_vmtruncate()

Fixes: http://tracker.ceph.com/issues/5453
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Sage Weil <sage@inktank.com>
This commit is contained in:
Yan, Zheng
2013-07-02 12:40:19 +08:00
committed by Sage Weil
parent 5446429630
commit b415bf4f9f
4 changed files with 13 additions and 11 deletions
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14
fs/ceph/inode.c
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@@ -1465,7 +1465,9 @@ static void ceph_vmtruncate_work(struct work_struct *work)
struct inode *inode = &ci->vfs_inode;
dout("vmtruncate_work %p\n", inode);
__ceph_do_pending_vmtruncate(inode, true);
mutex_lock(&inode->i_mutex);
__ceph_do_pending_vmtruncate(inode);
mutex_unlock(&inode->i_mutex);
iput(inode);
}
@@ -1492,7 +1494,7 @@ void ceph_queue_vmtruncate(struct inode *inode)
* Make sure any pending truncation is applied before doing anything
* that may depend on it.
*/
void __ceph_do_pending_vmtruncate(struct inode *inode, bool needlock)
void __ceph_do_pending_vmtruncate(struct inode *inode)
{
struct ceph_inode_info *ci = ceph_inode(inode);
u64 to;
@@ -1525,11 +1527,7 @@ retry:
ci->i_truncate_pending, to);
spin_unlock(&ci->i_ceph_lock);
if (needlock)
mutex_lock(&inode->i_mutex);
truncate_inode_pages(inode->i_mapping, to);
if (needlock)
mutex_unlock(&inode->i_mutex);
spin_lock(&ci->i_ceph_lock);
if (to == ci->i_truncate_size) {
@@ -1588,7 +1586,7 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
if (ceph_snap(inode) != CEPH_NOSNAP)
return -EROFS;
__ceph_do_pending_vmtruncate(inode, false);
__ceph_do_pending_vmtruncate(inode);
err = inode_change_ok(inode, attr);
if (err != 0)
@@ -1770,7 +1768,7 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
ceph_cap_string(dirtied), mask);
ceph_mdsc_put_request(req);
__ceph_do_pending_vmtruncate(inode, false);
__ceph_do_pending_vmtruncate(inode);
return err;
out:
spin_unlock(&ci->i_ceph_lock);