From 2f9092e1020246168b1309b35e085ecd7ff9ff72 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Mon, 20 Apr 2009 23:18:37 +0100 Subject: Fix i_mutex vs. readdir handling in nfsd Commit 14f7dd63 ("Copy XFS readdir hack into nfsd code") introduced a bug to generic code which had been extant for a long time in the XFS version -- it started to call through into lookup_one_len() and hence into the file systems' ->lookup() methods without i_mutex held on the directory. This patch fixes it by locking the directory's i_mutex again before calling the filldir functions. The original deadlocks which commit 14f7dd63 was designed to avoid are still avoided, because they were due to fs-internal locking, not i_mutex. While we're at it, fix the return type of nfsd_buffered_readdir() which should be a __be32 not an int -- it's an NFS errno, not a Linux errno. And return nfserrno(-ENOMEM) when allocation fails, not just -ENOMEM. Sparse would have caught that, if it wasn't so busy bitching about __cold__. Commit 05f4f678 ("nfsd4: don't do lookup within readdir in recovery code") introduced a similar problem with calling lookup_one_len() without i_mutex, which this patch also addresses. To fix that, it was necessary to fix the called functions so that they expect i_mutex to be held; that part was done by J. Bruce Fields. Signed-off-by: David Woodhouse Umm-I-can-live-with-that-by: Al Viro Reported-by: J. R. Okajima Tested-by: J. Bruce Fields LKML-Reference: <8036.1237474444@jrobl> Cc: stable@kernel.org Signed-off-by: Al Viro --- fs/nfsd/nfs4recover.c | 46 +++++++++------------------------------------- 1 file changed, 9 insertions(+), 37 deletions(-) (limited to 'fs/nfsd/nfs4recover.c') diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c index 3444c0052a8..5275097a756 100644 --- a/fs/nfsd/nfs4recover.c +++ b/fs/nfsd/nfs4recover.c @@ -229,21 +229,23 @@ nfsd4_list_rec_dir(struct dentry *dir, recdir_func *f) goto out; status = vfs_readdir(filp, nfsd4_build_namelist, &names); fput(filp); + mutex_lock(&dir->d_inode->i_mutex); while (!list_empty(&names)) { entry = list_entry(names.next, struct name_list, list); dentry = lookup_one_len(entry->name, dir, HEXDIR_LEN-1); if (IS_ERR(dentry)) { status = PTR_ERR(dentry); - goto out; + break; } status = f(dir, dentry); dput(dentry); if (status) - goto out; + break; list_del(&entry->list); kfree(entry); } + mutex_unlock(&dir->d_inode->i_mutex); out: while (!list_empty(&names)) { entry = list_entry(names.next, struct name_list, list); @@ -254,36 +256,6 @@ out: return status; } -static int -nfsd4_remove_clid_file(struct dentry *dir, struct dentry *dentry) -{ - int status; - - if (!S_ISREG(dir->d_inode->i_mode)) { - printk("nfsd4: non-file found in client recovery directory\n"); - return -EINVAL; - } - mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT); - status = vfs_unlink(dir->d_inode, dentry); - mutex_unlock(&dir->d_inode->i_mutex); - return status; -} - -static int -nfsd4_clear_clid_dir(struct dentry *dir, struct dentry *dentry) -{ - int status; - - /* For now this directory should already be empty, but we empty it of - * any regular files anyway, just in case the directory was created by - * a kernel from the future.... */ - nfsd4_list_rec_dir(dentry, nfsd4_remove_clid_file); - mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT); - status = vfs_rmdir(dir->d_inode, dentry); - mutex_unlock(&dir->d_inode->i_mutex); - return status; -} - static int nfsd4_unlink_clid_dir(char *name, int namlen) { @@ -294,18 +266,18 @@ nfsd4_unlink_clid_dir(char *name, int namlen) mutex_lock(&rec_dir.dentry->d_inode->i_mutex); dentry = lookup_one_len(name, rec_dir.dentry, namlen); - mutex_unlock(&rec_dir.dentry->d_inode->i_mutex); if (IS_ERR(dentry)) { status = PTR_ERR(dentry); - return status; + goto out_unlock; } status = -ENOENT; if (!dentry->d_inode) goto out; - - status = nfsd4_clear_clid_dir(rec_dir.dentry, dentry); + status = vfs_rmdir(rec_dir.dentry->d_inode, dentry); out: dput(dentry); +out_unlock: + mutex_unlock(&rec_dir.dentry->d_inode->i_mutex); return status; } @@ -348,7 +320,7 @@ purge_old(struct dentry *parent, struct dentry *child) if (nfs4_has_reclaimed_state(child->d_name.name, false)) return 0; - status = nfsd4_clear_clid_dir(parent, child); + status = vfs_rmdir(parent->d_inode, child); if (status) printk("failed to remove client recovery directory %s\n", child->d_name.name); -- cgit v1.2.3