linux-kernel - [PATCH v2 4/6] vfs: Allow truncate, chomd and chown to be interrupted by fatal signals

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Date:	Fri,  3 Jul 2015 10:40:41 -0400
From:	Matthew Wilcox <matthew.r.wilcox@...el.com>
To:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	Alexander Viro <viro@...iv.linux.org.uk>
Cc:	Matthew Wilcox <matthew.r.wilcox@...el.com>, willy@...ux.intel.com
Subject: [PATCH v2 4/6] vfs: Allow truncate, chomd and chown to be interrupted by fatal signals

If another task dies while holding the i_mutex, tasks trying to truncate,
chmod or chown the file will hang.  Allowing a fatal interrupt to kill
the task is beneficial for the system administrator trying to get the
machine to shut down more cleanly.

Signed-off-by: Matthew Wilcox <willy@...ux.intel.com>
---
 fs/open.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/open.c b/fs/open.c
index e0250bd..4b0061e 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -56,7 +56,8 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
 	if (ret)
 		newattrs.ia_valid |= ret | ATTR_FORCE;
 
-	mutex_lock(&dentry->d_inode->i_mutex);
+	if (mutex_lock_killable(&dentry->d_inode->i_mutex))
+		return -EINTR;
 	/* Note any delegations or leases have already been broken: */
 	ret = notify_change(dentry, &newattrs, NULL);
 	mutex_unlock(&dentry->d_inode->i_mutex);
@@ -508,7 +509,8 @@ static int chmod_common(struct path *path, umode_t mode)
 	if (error)
 		return error;
 retry_deleg:
-	mutex_lock(&inode->i_mutex);
+	if (mutex_lock_killable(&inode->i_mutex))
+		return -EINTR;
 	error = security_path_chmod(path, mode);
 	if (error)
 		goto out_unlock;
@@ -591,7 +593,8 @@ retry_deleg:
 	if (!S_ISDIR(inode->i_mode))
 		newattrs.ia_valid |=
 			ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
-	mutex_lock(&inode->i_mutex);
+	if (mutex_lock_killable(&inode->i_mutex))
+		return -EINTR;
 	error = security_path_chown(path, uid, gid);
 	if (!error)
 		error = notify_change(path->dentry, &newattrs, &delegated_inode);
-- 
2.1.4

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