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authorJ. Bruce Fields <bfields@redhat.com>2011-09-20 09:14:34 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2013-11-09 00:16:42 -0500
commitb21996e36c8e3b92a84e972378bde80b43acd890 (patch)
tree0ed5eb8a3d11434ad6aa9c7efe24823bdb52b1e7 /ipc
parent9accbb977ab78234b8f298df5f306ed08d06bedb (diff)
downloadlinux-b21996e36c8e3b92a84e972378bde80b43acd890.tar.gz
locks: break delegations on unlink
We need to break delegations on any operation that changes the set of links pointing to an inode. Start with unlink. Such operations also hold the i_mutex on a parent directory. Breaking a delegation may require waiting for a timeout (by default 90 seconds) in the case of a unresponsive NFS client. To avoid blocking all directory operations, we therefore drop locks before waiting for the delegation. The logic then looks like: acquire locks ... test for delegation; if found: take reference on inode release locks wait for delegation break drop reference on inode retry It is possible this could never terminate. (Even if we take precautions to prevent another delegation being acquired on the same inode, we could get a different inode on each retry.) But this seems very unlikely. The initial test for a delegation happens after the lock on the target inode is acquired, but the directory inode may have been acquired further up the call stack. We therefore add a "struct inode **" argument to any intervening functions, which we use to pass the inode back up to the caller in the case it needs a delegation synchronously broken. Cc: David Howells <dhowells@redhat.com> Cc: Tyler Hicks <tyhicks@canonical.com> Cc: Dustin Kirkland <dustin.kirkland@gazzang.com> Acked-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'ipc')
-rw-r--r--ipc/mqueue.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index ae1996d3c53..95827ce2f3c 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -886,7 +886,7 @@ SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
err = -ENOENT;
} else {
ihold(inode);
- err = vfs_unlink(dentry->d_parent->d_inode, dentry);
+ err = vfs_unlink(dentry->d_parent->d_inode, dentry, NULL);
}
dput(dentry);