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ufs: Fix possible deadlock when looking up directories

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commit 514d748f69 upstream.

Commit e4502c63f5 (ufs: deal with nfsd/iget races) made ufs
create inodes with I_NEW flag set. However ufs_mkdir() never cleared
this flag. Thus if someone ever tried to lookup the directory by inode
number, he would deadlock waiting for I_NEW to be cleared. Luckily this
mostly happens only if the filesystem is exported over NFS since
otherwise we have the inode attached to dentry and don't look it up by
inode number. In rare cases dentry can get freed without inode being
freed and then we'd hit the deadlock even without NFS export.

Fix the problem by clearing I_NEW before instantiating new directory
inode.

Fixes: e4502c63f5
Reported-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jan Kara
2015-06-02 11:26:34 +02:00
committed by Greg Kroah-Hartman
parent 918ef5dc2e
commit b94332a90b
1 changed files with 1 additions and 0 deletions
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1
fs/ufs/namei.c
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@@ -212,6 +212,7 @@ static int ufs_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
goto out_fail;
unlock_ufs(dir->i_sb);
unlock_new_inode(inode);
d_instantiate(dentry, inode);
out:
return err;