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authorDavid Woodhouse <dwmw2@infradead.org>2009-04-20 23:18:37 +0100
committerAl Viro <viro@zeniv.linux.org.uk>2009-04-20 23:01:16 -0400
commit2f9092e1020246168b1309b35e085ecd7ff9ff72 (patch)
treef8318c1e62e789718ae7637869f6c075b815bcb2 /fs/namei.c
parent1ba0c7dbbbc24230394100c5f0d0df38cb400cff (diff)
downloadlinux-2f9092e1020246168b1309b35e085ecd7ff9ff72.tar.bz2
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 <David.Woodhouse@intel.com> Umm-I-can-live-with-that-by: Al Viro <viro@zeniv.linux.org.uk> Reported-by: J. R. Okajima <hooanon05@yahoo.co.jp> Tested-by: J. Bruce Fields <bfields@citi.umich.edu> LKML-Reference: <8036.1237474444@jrobl> Cc: stable@kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/namei.c')
-rw-r--r--fs/namei.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/namei.c b/fs/namei.c
index b8433ebfae05..78f253cd2d4f 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1248,6 +1248,8 @@ struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
int err;
struct qstr this;
+ WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
+
err = __lookup_one_len(name, &this, base, len);
if (err)
return ERR_PTR(err);