ufs: fix deadlocks introduced by sb mutex merge

Commit 0244756edc4b ("ufs: sb mutex merge + mutex_destroy") introduces
deadlocks in ufs_new_inode() and ufs_free_inode().
Most callers of that functions acqure the mutex by themselves and
ufs_{new,free}_inode() do that via lock_ufs(),
i.e we have an unavoidable double lock.

The patch proposes to resolve the issue by making sure that
ufs_{new,free}_inode() are not called with the mutex held.

Found by Linux Driver Verification project (linuxtesting.org).

Cc: stable@vger.kernel.org # 3.16
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/ufs/inode.c b/fs/ufs/inode.c
index 7c580c97990ee05dee7e5ad42a9c5754bfe4384d..be7d42c7d9382bf8072a7e6e9eff7e03b24bab25 100644 (file)
--- a/fs/ufs/inode.c
+++ b/fs/ufs/inode.c
@@ -902,9 +902,6 @@ void ufs_evict_inode(struct inode * inode)
        invalidate_inode_buffers(inode);
        clear_inode(inode);
 
-       if (want_delete) {
-               lock_ufs(inode->i_sb);
-               ufs_free_inode (inode);
-               unlock_ufs(inode->i_sb);
-       }
+       if (want_delete)
+               ufs_free_inode(inode);
 }

diff --git a/fs/ufs/namei.c b/fs/ufs/namei.c
index 90d74b8f8eba8dacd536c74ac161cceddc241196..2df62a73f20ce2071c17d81c343ada85ae287d2a 100644 (file)
--- a/fs/ufs/namei.c
+++ b/fs/ufs/namei.c
@@ -126,12 +126,12 @@ static int ufs_symlink (struct inode * dir, struct dentry * dentry,
        if (l > sb->s_blocksize)
                goto out_notlocked;
 
-       lock_ufs(dir->i_sb);
        inode = ufs_new_inode(dir, S_IFLNK | S_IRWXUGO);
        err = PTR_ERR(inode);
        if (IS_ERR(inode))
-               goto out;
+               goto out_notlocked;
 
+       lock_ufs(dir->i_sb);
        if (l > UFS_SB(sb)->s_uspi->s_maxsymlinklen) {
                /* slow symlink */
                inode->i_op = &ufs_symlink_inode_operations;
@@ -181,13 +181,9 @@ static int ufs_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
        struct inode * inode;
        int err;
 
-       lock_ufs(dir->i_sb);
-       inode_inc_link_count(dir);
-
        inode = ufs_new_inode(dir, S_IFDIR|mode);
-       err = PTR_ERR(inode);
        if (IS_ERR(inode))
-               goto out_dir;
+               return PTR_ERR(inode);
 
        inode->i_op = &ufs_dir_inode_operations;
        inode->i_fop = &ufs_dir_operations;
@@ -195,6 +191,9 @@ static int ufs_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
 
        inode_inc_link_count(inode);
 
+       lock_ufs(dir->i_sb);
+       inode_inc_link_count(dir);
+
        err = ufs_make_empty(inode, dir);
        if (err)
                goto out_fail;
@@ -212,7 +211,6 @@ out_fail:
        inode_dec_link_count(inode);
        inode_dec_link_count(inode);
        iput (inode);
-out_dir:
        inode_dec_link_count(dir);
        unlock_ufs(dir->i_sb);
        goto out;